EP1317208A1 - Method for pictorially depicting and diagnosing thrombi by means of nuclear spin tomography involving the use of particulate contrast agents - Google Patents

Method for pictorially depicting and diagnosing thrombi by means of nuclear spin tomography involving the use of particulate contrast agents

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Publication number
EP1317208A1
EP1317208A1 EP01980343A EP01980343A EP1317208A1 EP 1317208 A1 EP1317208 A1 EP 1317208A1 EP 01980343 A EP01980343 A EP 01980343A EP 01980343 A EP01980343 A EP 01980343A EP 1317208 A1 EP1317208 A1 EP 1317208A1
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EP
European Patent Office
Prior art keywords
thrombus
thrombi
contrast
iron oxide
contrast medium
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Application number
EP01980343A
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German (de)
French (fr)
Inventor
Stephan Schmitz
Mayk Kresse
Susanne Wagner
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Bayer Pharma AG
Original Assignee
Institut fuer Diagnostikforschung GmbH
Bayer Schering Pharma AG
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Publication of EP1317208A1 publication Critical patent/EP1317208A1/en
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/44—Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
    • G01R33/48—NMR imaging systems
    • G01R33/54—Signal processing systems, e.g. using pulse sequences ; Generation or control of pulse sequences; Operator console
    • G01R33/56—Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution
    • G01R33/5601—Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution involving use of a contrast agent for contrast manipulation, e.g. a paramagnetic, super-paramagnetic, ferromagnetic or hyperpolarised contrast agent
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
    • A61B5/026—Measuring blood flow
    • A61B5/0263—Measuring blood flow using NMR
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
    • A61B5/026—Measuring blood flow
    • A61B5/0275—Measuring blood flow using tracers, e.g. dye dilution
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K49/00—Preparations for testing in vivo
    • A61K49/06—Nuclear magnetic resonance [NMR] contrast preparations; Magnetic resonance imaging [MRI] contrast preparations
    • A61K49/18—Nuclear magnetic resonance [NMR] contrast preparations; Magnetic resonance imaging [MRI] contrast preparations characterised by a special physical form, e.g. emulsions, microcapsules, liposomes
    • A61K49/1818—Nuclear magnetic resonance [NMR] contrast preparations; Magnetic resonance imaging [MRI] contrast preparations characterised by a special physical form, e.g. emulsions, microcapsules, liposomes particles, e.g. uncoated or non-functionalised microparticles or nanoparticles
    • A61K49/1821—Nuclear magnetic resonance [NMR] contrast preparations; Magnetic resonance imaging [MRI] contrast preparations characterised by a special physical form, e.g. emulsions, microcapsules, liposomes particles, e.g. uncoated or non-functionalised microparticles or nanoparticles coated or functionalised microparticles or nanoparticles
    • A61K49/1824—Nuclear magnetic resonance [NMR] contrast preparations; Magnetic resonance imaging [MRI] contrast preparations characterised by a special physical form, e.g. emulsions, microcapsules, liposomes particles, e.g. uncoated or non-functionalised microparticles or nanoparticles coated or functionalised microparticles or nanoparticles coated or functionalised nanoparticles
    • A61K49/1827—Nuclear magnetic resonance [NMR] contrast preparations; Magnetic resonance imaging [MRI] contrast preparations characterised by a special physical form, e.g. emulsions, microcapsules, liposomes particles, e.g. uncoated or non-functionalised microparticles or nanoparticles coated or functionalised microparticles or nanoparticles coated or functionalised nanoparticles having a (super)(para)magnetic core, being a solid MRI-active material, e.g. magnetite, or composed of a plurality of MRI-active, organic agents, e.g. Gd-chelates, or nuclei, e.g. Eu3+, encapsulated or entrapped in the core of the coated or functionalised nanoparticle
    • A61K49/1851—Nuclear magnetic resonance [NMR] contrast preparations; Magnetic resonance imaging [MRI] contrast preparations characterised by a special physical form, e.g. emulsions, microcapsules, liposomes particles, e.g. uncoated or non-functionalised microparticles or nanoparticles coated or functionalised microparticles or nanoparticles coated or functionalised nanoparticles having a (super)(para)magnetic core, being a solid MRI-active material, e.g. magnetite, or composed of a plurality of MRI-active, organic agents, e.g. Gd-chelates, or nuclei, e.g. Eu3+, encapsulated or entrapped in the core of the coated or functionalised nanoparticle having a (super)(para)magnetic core coated or functionalised with an organic macromolecular compound, i.e. oligomeric, polymeric, dendrimeric organic molecule
    • A61K49/1863—Nuclear magnetic resonance [NMR] contrast preparations; Magnetic resonance imaging [MRI] contrast preparations characterised by a special physical form, e.g. emulsions, microcapsules, liposomes particles, e.g. uncoated or non-functionalised microparticles or nanoparticles coated or functionalised microparticles or nanoparticles coated or functionalised nanoparticles having a (super)(para)magnetic core, being a solid MRI-active material, e.g. magnetite, or composed of a plurality of MRI-active, organic agents, e.g. Gd-chelates, or nuclei, e.g. Eu3+, encapsulated or entrapped in the core of the coated or functionalised nanoparticle having a (super)(para)magnetic core coated or functionalised with an organic macromolecular compound, i.e. oligomeric, polymeric, dendrimeric organic molecule the organic macromolecular compound being a polysaccharide or derivative thereof, e.g. chitosan, chitin, cellulose, pectin, starch
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/05—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves 
    • A61B5/055—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves  involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging

Definitions

  • the invention relates to a new method for imaging and diagnosis of thrombi and the use of particle suspensions for the production of contrast media for the imaging of thrombi by means of magnetic resonance imaging.
  • a thrombus is a circumscribed blood solidification that arises in arteries or veins through intravascular blood clotting.
  • Thrombosis i.e. a partial or complete occlusion of the artery or vein by a thrombus can lead to anemia and tissue death of an organ (infarction).
  • a typical example of arterial thrombosis is that of the coronary arteries (cor narthrombose). If a thrombus detaches from the wall of the vessel, it is flushed away with the blood stream. In the sense of thromboembolism, this thrombus can occlude a downstream smaller vessel.
  • the brain arteries are a typical example of thromboembolism in arteries.
  • the very common thromboses of the pelvic and leg veins typically lead to thromboembolism of the pulmonary arteries. Pulmonary artery embolism is particularly feared because it is difficult to detect and often fatal.
  • Angiography is increasingly using magnetic resonance imaging
  • Magnetic resonance angiography Magnetic resonance angiography
  • Siewert et al. Schwier. Röntgenstr. 156 (1992), pp. 549-554.
  • This procedure presents thrombi as areas with no flow in the vessel. Possible errors occur in small veins with slow or no flow. Such vessels are not shown.
  • Magnetic resonance imaging using contrast media is an improvement over flow-dependent methods.
  • An example of such a method is given by Schmitz et al. in progress Röntgenstr. 170 (1999), pp. 316-321.
  • Contrast agents injected intravenously mix with the blood and selectively represent those vessels in which the contrast agent-mixed blood is distributed. Thrombi are indirectly visible as recesses (filling defects) in the vessels.
  • the agents described there are peptides to which a complexing agent is coupled in each case.
  • the complexing agent can complex a metal ion which either emits radioactive radiation and can be detected with a gamma camera, or is a gadolinium or other paramagnetic metal ion which is suitable for use as a contrast agent in magnetic resonance imaging.
  • the object of the present invention is therefore to develop a new method for diagnosing arterial and venous thrombi and to find suitable contrast media for such a method.
  • MR blood pool contrast media such as superparamagnetic iron oxide (SPIO), especially in a formulation with small particles (ultrasmall superparamagnetic iron oxide, USPIO), accumulate in experimental thrombi in an animal model and after a time interval of several blood half-lives are visible in magnetic resonance tomograms and can be used diagnostically. It was found that the contrast medium accumulates preferentially in the thrombi, but often also in the adjacent vessel wall and surroundings.
  • SPIO superparamagnetic iron oxide
  • USPIO ultrasmall superparamagnetic iron oxide
  • a particulate MR contrast medium is therefore first administered to the patient, and after the contrast medium has been concentrated in the thrombus and / or the adjacent vessel wall and environment (i.e. after a time interval of several blood half-lives)
  • Magnetic resonance imaging recorded A particularly good representation can be achieved with Tl-weighted magnetic resonance tomograms. After intracellular uptake of the contrast medium in the macrophages (phagocytes) of thrombi, an effect can also be generated in T2-weighted images.
  • the ultra-small superparamagnetic iron oxide particles (USPIO) used in the experiment described in detail below consist of one Iron oxide core and a carboxydextran shell.
  • the average diameter of the particles is preferably less than 50 ⁇ m, particularly preferably approximately 25 nm.
  • the production of such particles is described, for example, in the patents EP 656 368 and WO 98/05430.
  • Such a particle-containing contrast medium is currently being developed by Schering AG.
  • the iron-containing contrast media are used, for example, in a dosage of 200 ⁇ mol Fe / kg body weight.
  • the contrast medium If the contrast medium accumulates extracellularly, it can make the thrombus visible on Tl-weighted images with its Tl effect. If the contrast medium is absorbed by macrophages (stress cells) that regularly migrate into the vessel wall or into the rim of the thrombus as part of the thrombus breakdown (thrombus organization), the T2 effect of the contrast medium can predominate, as a result of which the marked tissue is signal-poor in T2 or T2 * -weighted images appear.
  • macrophages stress cells
  • Tlw-MP-RAGE and T2 * w-FLASH nuclear magnetic resonance tomograms were carried out at 1.5 Tesla before and 24 hours after intravenous application of ultra-small superparamagnetic iron oxide (USPIO, Particle size approx. 25 nm) measured in a dose of 200 ⁇ mol Fe / kg body weight.
  • USPIO ultra-small superparamagnetic iron oxide
  • X-ray phlebography and histology served as the gold standard.
  • the length of the thrombus visible in SD reconstructions of the Tlw-MP-RAGE sequence was expressed in relation to the true thrombus length.
  • the structure, the signal intensity and the contrast range of the thrombus in the T2 * w technique became subjective Subjected to analysis with a defined scaling. 25 rabbits with age-appropriate thrombi served as controls.
  • a formulation of ultra small superparamagnetic iron oxide particles (USPIO) was used.
  • the particles consist of an iron oxide core and a carboxydextran shell with a total diameter of 25 nm.
  • the effective plasma half-life is 56 ⁇ 17 minutes and the LD50 is 35 mmol Fe / kg body weight.
  • the estimated plasma half-life is approximately 6 hours.
  • the contrast medium was slowly injected in a dose of 200 ⁇ mol Fe / kg body weight in a volume of 2-3 ml into an ear vein on the healthy side and followed by 2 ml of physiological saline.
  • Embolisat a mixture of an oily iodine-containing lymphography X-ray contrast agent (Lipiodol, Byk Gulden, Constance) and a butyl cyanoacrylate tissue adhesive (Histoacryl, B. Braun, Melsungen) in a ratio of 1: 1 was injected so slowly that the embolisate adhered the vessel wall and, on the other hand, a mixture of embolisate and blood could take place. After this
  • the vessel was closed using a second microcatheter to apply 100 units of bovine thrombin (Sigma-Aldrich, Chemie GmbH, Steinheim).
  • bovine thrombin Sigma-Aldrich, Chemie GmbH, Steinheim.
  • the embolisate should lead to a temporary closure of the vessel for a few days. Because of the iodine content, the embolisate should be visible on the X-ray phlebographs, as well as hyperintensively on Tl-weighted MRI images, because of the glue-fixed blood breakdown products.
  • thrombus-carrying animals were randomly assigned to the contrast agent group (D) or the control group (K). A further subdivision was made according to the thrombus age at the time of the first MRI measurement (1, 3, 5, 7 or 9 days). Accordingly, there was an assignment in 5 contrast medium groups (DI, D3, D5, D7 and D9) and 5 control groups (K1, K3, K5, K7 and K9). Each subgroup comprised five test animals. In all experimental animals, the thrombus was documented by X-ray phlebography before the initial MRI. Animals from the contrast medium group (K) received this after this initial MRI
  • T1-weighted images were generated in a coronary slice orientation using a 3D magnetization-prepared rapid gradient echo imaging sequence (3D-MP-RAGE) [Mugler JPd, Brookeman JR. Three-dimensional magnetization-prepared rapid gradient-echo imaging (3D MP RAGE). Magn Reson Med 1990; . 15: 152-7].
  • the sequence used suppresses the signal of fat by a sequential selective water excitation pulse and that of blood by the choice of the delay time [Moody AR, Pollock JG, O'Connor AR, Bagnall M. Lower-limb deep venous thrombosis: direct MR imaging of the thrombus , Radiology 1998; 209:. 349-55].
  • T2 * -weighted axial images were generated with a 3D gradient echo sequence (Fast Low Angle Shot, FLASH) [Frahm J, Haase A, Matthaei D. Rapid three-dimensional MR imaging using the FLASH technique. J Comput Assist Tomogr 1986; . 10: 363-8].
  • FLASH 3D gradient echo sequence
  • the sequence represents the vein lumen hyperintense to fat and muscle.
  • the moderate T2 * weighting is intended to depict intracellularly enriched blood breakdown products or SPIOs signal arms.
  • the following recording parameters were used: repetition time 54 ms; Echo time 18 ms; Flip angle 15 °; Block sealing thickness 80 mm, partitions 40; Layer thickness 2 mm; Image 80 x 80 mm; Matrix 256 x 256; Acquisition time 22:08 minutes; Pixel size 0.31 x 0.31 x 0.2 mm.
  • the animals were killed by an overdose of xylazine.
  • the caudal and cranial segments of the external jugular vein and the facial vein were prepared, fixed in 10% formalin for 24 hours and in five each
  • the histological sections, hard copies of the phlebographies and the MRI were evaluated by a radiologist.
  • the length of the thrombus in the external jugular vein was measured using phlebography. Histology served as a second method of detecting the thrombus, especially in the case of fresh, occluding thrombi that are not surrounded by contrast media.
  • shrinkage artifacts due to the well-known shrinkage artifacts during histological processing, it is only suitable for length determination to a limited extent.
  • the length of the thrombus was then determined on the Tl-weighted SD reconstructions of the MP-RAGE sequence.
  • the thrombus was defined as visible if it was hyperintense and clearly distinguishable from the surroundings. In the case of a sketchy representation, only the visible thrombus portions were measured.
  • the thrombus length determined by the gold standard was normalized to 1.0 and the thrombus length measured in the 3D reconstruction of the MP-RAGE sequence was given in proportions of 1.0, e.g. 0.4.
  • the T2 * weighted gradient echo sequence images were only subjected to a qualitative analysis. A representative layer was selected for the evaluation, which was clearly determined by the reference methods and was characteristic of the individual thrombus. If the thrombus could not be distinguished from the surrounding blood, the reference methods were used to locate the thrombus.
  • the structure of the thrombus was classified as "homogeneous”, “heterogeneously disordered” or “heterogeneous-concentric” (central hyperintense, peripheral hypointense).
  • the contrast range of the thrombus was determined based on the definitions of the signal intensity as the difference between the minimum and maximum signal intensity. The result is a 4-point scale.
  • the data were separated with the mean value and the standard deviation according to groups (controls, contrast medium) and the thrombus age (days) or summarized or graphically represented (StatView 4.5, SAS Institute Inc., Cary, NC, USA).
  • a comparison of the first measurement with the course measurement was carried out with the t-test for pair comparisons separately for groups D and K.
  • the individual groups, e.g. Dl versus Kl were compared to the analysis of variance (ANOVA), for which a significance test was carried out using the Fischer's Protected Least Significant Difference (PLSD). The level of significance was ⁇ ⁇ 0.05 in all cases.
  • the length of the thrombus in the external jugular vein of the group Kl of the controls was 43 ⁇ 8 mm and in the group Dl of the contrast medium animals 36 ⁇ 10 mm.
  • the length decreased significantly during the study period and was ⁇ 10 and 11 ⁇ 8 mm, respectively, in groups K9 and D923 ( Figure 3). There was never a significantly different length between control and contrast medium groups of the same thrombus age.
  • groups Kl and Dl found a fresh thrombus consisting of tightly packed erythrocytes (hemostasis) interspersed with trabecular trabeculae; in groups K3 and D3 a tightly packed hemostasis with central resolution of the erythrocytes in individual animals; in groups K5 and D5, the erythocytes in the thrombus center were dissolved in all cases (homogenization) and the marginal immigration of mononuclear cells; in groups K7 and D7 the increasing penetration of the thrombus by mononuclear cells and the beginning of endothelialization with occasionally sprouting capillaries; and in groups K9 and D9 the almost complete penetration of the thrombus by mononuclear cells and capillaries with the start of connective tissue formation.
  • the moderate T2 * -weighted FLASh sequence showed a considerable thrombus age-dependent variability of the structure, the signal intensity and the contrast range.
  • a single example can be found in Figure 5.
  • the "heterogeneous disordered” and “heterogeneous concentric” thrombus structure predominated up to the 7th day ( Figure 6). From the 7th day, a "homogeneous" thrombus structure dominates in the controls.
  • the leading signal intensity of the thrombus in the control animals Kl was the "middle", ie isointense to the muscles, but with a clear spread ( Figure 1).
  • X-ray phlebography shows incomplete occlusion of the left external jugular vein three days after thrombus induction.
  • the external jugular vein receives another inflow from the medial, the facial vein.
  • the outflow of the contrast medium takes place partly. over the opposite side.
  • the embolisate (arrow) is radiopaque in phlebography (a).
  • the position of the embolisate before (b) and 24 hours after the administration of superparamagnetic iron oxide (c) is marked by an arrow.
  • the cranial end of the visible thrombus portion was marked with an arrow head (b and c).
  • An X-ray phlebography (a) five days after embolization shows an embolizate (arrow). Individual thrombus portions are washed around in the cranial internal jugular vein (a, arrowhead). There are ipsilateral collaterals (a, thin arrow). In the 3D reconstruction of the native MP-RAGE sequence, the thrombus cannot be recognized and the embolisate is poorly recognizable (b, arrow). 24 hours after the administration of contrast medium (c) the entire thrombus from the embolisate (arrow) to the cranial external jugular vein (arrowhead) and a lateral ear vein are visible.
  • K controls
  • D contrast agent administration
  • the heterogeneous thrombus structure predominated heterogeneously disordered and heterogeneous.
  • the homogeneous thrombus structure dominates from the 7th day.
  • FIG. 7 Thrombus signal intensity in the T2 * -weighted FLASH sequence on a 5-point scale from signal-free (1), signal-poor (2), muscle-isointense (3), signal-rich (4) and very signal-rich (5). Groups of controls (K) and contrast medium animals are shown separately according to the thrombus age. Both baseline and follow-up MRI are shown - there was no follow-up MRI on the K7 and K9 controls.
  • Figure 8 Thrombus signal intensity in the T2 * -weighted FLASH sequence on a 5-point scale from signal-free (1), signal-poor (2), muscle-isointense (3), signal-rich (4) and very signal-rich (5). Groups of controls (K) and contrast medium animals are shown separately according to the thrombus age. Both baseline and follow-up MRI are shown - there was no follow-up MRI on the K7 and K9 controls.
  • Figure 8
  • Contrast range of experimental thrombi in the T2 * -weighted gradient sequence It can be seen that the range of contrast for controls (K) as well as for contrast medium animals (D) decreases over a period of nine days, i.e. the thrombus becomes more homogeneous. There was no significant change in the contrast range between the initial and follow-up examination in any group.

Abstract

The invention relates to a novel method for pictorially depicting and diagnosing thrombi and to the use of particle suspensions for producing contrast agents for depicting thrombin by means of nuclear spin tomography.

Description

Verfahren zur bildlichen Darstellung und Diagnose von Thromben mittels Kernspintomographie unter Verwendung partikulärer KontrastmittelProcess for imaging and diagnosis of thrombi using magnetic resonance imaging using particulate contrast media
Die Erfindung betrifft ein neues Verfahren zur bildlichen Darstellung und Diagnose von Thromben sowie die Nerwendung von Partikelsuspensionen zur Herstellung von Kontrastmitteln für die Darstellung von Thromben mittels Kernspintomographie.The invention relates to a new method for imaging and diagnosis of thrombi and the use of particle suspensions for the production of contrast media for the imaging of thrombi by means of magnetic resonance imaging.
Ein Thrombus ist eine umschriebene Blutverfestigung, welche in Arterien oder Venen durch intravasale Blutgerinnung entsteht. Eine Thrombose, d.h. ein teilweiser oder vollständiger Verschluß der Arterie oder Vene durch einen Thrombus, kann zu einer Blutarmut und Gewebstod eines Organs (Infarkt) führen. Ein. typisches Beispiel für eine arterielle Thrombose ist die der Herzkranzarterien (Kor narthrombose). Löst sich ein Thrombus von der Gefäßwand, so wird er mit dem Blutstrom fortgespült. Dieser Thrombus kann im Sinne einer Thromboembolie ein nachgeordnetes kleineres Gefäß verschließen. Die hirnversorgenden Arterien sind ein typisches Beispiel für Thromboembolien in Arterien. Die sehr häufigen Thrombosen der Becken- und Beinvenen führen typischerweise zu einer Thromboembolie der Lungenarterien. Die Lungenarterienembolie ist besonders gefürchtet, da sie schwer zu erkennen ist und oft einen tödlichen Ausgang nimmt.A thrombus is a circumscribed blood solidification that arises in arteries or veins through intravascular blood clotting. Thrombosis, i.e. a partial or complete occlusion of the artery or vein by a thrombus can lead to anemia and tissue death of an organ (infarction). On. A typical example of arterial thrombosis is that of the coronary arteries (cor narthrombose). If a thrombus detaches from the wall of the vessel, it is flushed away with the blood stream. In the sense of thromboembolism, this thrombus can occlude a downstream smaller vessel. The brain arteries are a typical example of thromboembolism in arteries. The very common thromboses of the pelvic and leg veins typically lead to thromboembolism of the pulmonary arteries. Pulmonary artery embolism is particularly feared because it is difficult to detect and often fatal.
Bisher werden Thromben mit Hilfe verschiedener Verfahren diagnostiziert. Die am häufigsten angewandten Verfahren sind die Katheter-Röntgen-Angiographie, die Röntgen-Phlebographie und verschiedene Ultraschallverfahren.So far, thrombi have been diagnosed using various methods. The most commonly used procedures are catheter x-ray angiography, x-ray phlebography and various ultrasound procedures.
Die Angiographie wird zunehmend mit Hilfe der KernspintomographieAngiography is increasingly using magnetic resonance imaging
(Kernspinangiographie) durchgeführt, wobei der Blutfluß in den Gefäßen dargestellt wird. Ein Beispiel für dieses Verfahren wird von Siewert et al., Fortschr. Röntgenstr. 156 (1992), S. 549 - 554, beschrieben. Dieses Verfahren stellt Thromben als Areale mit fehlendem Fluß in dem Gefäß dar. Fehlermöglichkeiten entstehen in kleinen Venen mit langsamem oder fehlendem Fluß. Solche Gefäße werden nicht abgebildet. Die Kernspinangiographie unter Verwendung von Kontrastmitteln ist eine Verbesserung gegenüber flußabhängigen Verfahren. Ein Beispiel für ein solches Verfahren wird von Schmitz et al. in Fortschr. Röntgenstr. 170 (1999), S. 316 - 321, beschrieben. Intravenös injizierte Kontrastmittel mischen sich mit dem Blut und stellen selektiv solche Gefäße dar, in denen sich das kontrastmittelvermischte Blut verteilt. Thromben werden als Aussparungen (Füllungsdefekte) in den Gefäßen indirekt sichtbar.(Magnetic resonance angiography) performed, showing the blood flow in the vessels. An example of this method is given by Siewert et al., Schwier. Röntgenstr. 156 (1992), pp. 549-554. This procedure presents thrombi as areas with no flow in the vessel. Possible errors occur in small veins with slow or no flow. Such vessels are not shown. Magnetic resonance imaging using contrast media is an improvement over flow-dependent methods. An example of such a method is given by Schmitz et al. in progress Röntgenstr. 170 (1999), pp. 316-321. Contrast agents injected intravenously mix with the blood and selectively represent those vessels in which the contrast agent-mixed blood is distributed. Thrombi are indirectly visible as recesses (filling defects) in the vessels.
Bei der Röntgen-Phlebographie werden nicht alle Gefäße erreicht. Von den Ultraschallverfahren ist ein häufig angewandtes Verfahren das der Duplex-Sonographie FKDS, welches allerdings nur oberflächliche Venen darstellen kann und im Bereich des Beckens versagt. Alle diese Diagnoseverfahren liefern keine zweifelsfreien Resultate und können zu Fehldiagnosen führen.Not all vessels are reached in X-ray phlebography. Of the ultrasound methods, a method that is frequently used is that of duplex sonography FKDS, which, however, can only represent superficial veins and fails in the area of the pelvis. All of these diagnostic methods do not provide unequivocal results and can lead to incorrect diagnoses.
In der internationalen Patentanmeldung WO 98/16256 wird ein Verfahren zur Darstellung von Thromben mittels Kernspintomographie vorgeschlagen, bei dem dem Patienten Kontrastmittel appliziert werden, welche aus Chelatoren und daran gekoppelten Integrin-bindenden Molekülen bestehen. Die Chelatoren komplexieren paramagnetische Metallionen, wie z.B. Gadoliniumionen.International patent application WO 98/16256 proposes a method for imaging thrombi by means of magnetic resonance imaging, in which contrast agents are applied to the patient, which consist of chelators and integrin-binding molecules coupled to them. The chelators complex paramagnetic metal ions, e.g. Gadolinium ions.
Ahnliche Kontrastmittel werden auch in der internationalen Anmeldung WO 95/20603 vorgeschlagen. Die dort beschriebenen Mittel sind Peptide, an die jeweils ein Komplexbildner gekoppelt ist. Der Komplexbildner kann ein Metallion komplexieren, das entweder radioaktive Strahlung abgeben und mit einer Gammakamera detektiert werden kann, oder ein Gadolinium- bzw. anderes paramagnetisches Metallion ist, welches für den Einsatz als Kontrastmittel in der Kernspintomographie geeignet ist.Similar contrast media are also proposed in international application WO 95/20603. The agents described there are peptides to which a complexing agent is coupled in each case. The complexing agent can complex a metal ion which either emits radioactive radiation and can be detected with a gamma camera, or is a gadolinium or other paramagnetic metal ion which is suitable for use as a contrast agent in magnetic resonance imaging.
Diese Patentanmeldungen beschreiben allerdings nur die Synthese der Kontrastmittel und erste in-vitro Versuche. Es werden keine in-vivo Experimente oder Kernspintomogramme gezeigt, mit denen die Wirksamkeit der Mittel zweifelsfrei demonstriert werden könnte. Derartige Kontrastmittel sind bisher auch nicht von Pharmafirmen entwickelt worden oder als gebrauchsfähige Kontrastmittel käuflich zu erwerben. Es besteht daher weiter ein Bedarf an einem neuen, zweifelsfreien und sicheren Diagnoseverfahren für arterielle und venöse Thromben sowie an den für ein solches Verfahren geeigneten Kontrastmitteln.However, these patent applications only describe the synthesis of the contrast agents and first in-vitro experiments. No in vivo experiments or magnetic resonance imaging are shown, with which the effectiveness of the agents could be demonstrated beyond doubt. Contrast agents of this type have not yet been developed by pharmaceutical companies or are commercially available as useful contrast agents. There is therefore still a need for a new, unambiguous and safe diagnostic method for arterial and venous thrombi and for the contrast media suitable for such a method.
Aufgabe der vorliegenden Erfindung ist es daher, ein neues Verfahren zur Diagnose arterieller und venöser Thromben zu entwickeln sowie geeignete Kontrastmittel für ein derartiges Verfahren zu finden.The object of the present invention is therefore to develop a new method for diagnosing arterial and venous thrombi and to find suitable contrast media for such a method.
Diese Aufgabe wird mit dem neuen Verfahren gemäß Patentanspruch 1 sowie der Verwendung von Partikelsuspensionen zur Herstellung von Kontrastmitteln gemäß Patentanspruch 6 gelöst.This object is achieved with the new method according to claim 1 and the use of particle suspensions for the production of contrast media according to claim 6.
Überraschend wurde gefunden, daß sich MR blood pool-Kontrastmittel, wie superparamagnetisches Eisenoxid (superparamagnetic iron oxide, SPIO), speziell in einer Formulierung mit kleinen Partikeln (ultrasmall superparamagnetic iron oxide, USPIO), in einem Tiermodell in experimentellen Thromben anreichern und nach einem Zeitintervall von mehreren Bluthalbwertszeiten in Kernspintomogrammen sichtbar und diagnostisch verwertbar sind. Es wurde gefunden, daß sich das Kontrastmittel bevorzugt in den Thromben, aber häufig auch in der angrenzenden Gefäßwand und -Umgebung anreichert.Surprisingly, it was found that MR blood pool contrast media, such as superparamagnetic iron oxide (SPIO), especially in a formulation with small particles (ultrasmall superparamagnetic iron oxide, USPIO), accumulate in experimental thrombi in an animal model and after a time interval of several blood half-lives are visible in magnetic resonance tomograms and can be used diagnostically. It was found that the contrast medium accumulates preferentially in the thrombi, but often also in the adjacent vessel wall and surroundings.
Beim erfindungsgemäßen Verfahren wird demnach zunächst dem Patienten ein partikuläres MR-Kontrastmittel verabreicht, und nach der Anreicherung des Kontrastmittels im Thrombus und/oder der angrenzenden Gefäßwand und -Umgebung (d.h. nach einem Zeitintervall von mehreren Bluthalbwertszeiten) wird einIn the method according to the invention, a particulate MR contrast medium is therefore first administered to the patient, and after the contrast medium has been concentrated in the thrombus and / or the adjacent vessel wall and environment (i.e. after a time interval of several blood half-lives)
Kernspintomogramm aufgenommen. Eine besonders gute Darstellung erreicht man mit Tl-gewichteten Kernspintomogrammen. Nach einer intrazellulären Aufnahme des Kontrastmittels in den Makrophagen (Freßzellen) von Thromben kann auch ein Effekt in T2-gewichteten Bildern erzeugt werden.Magnetic resonance imaging recorded. A particularly good representation can be achieved with Tl-weighted magnetic resonance tomograms. After intracellular uptake of the contrast medium in the macrophages (phagocytes) of thrombi, an effect can also be generated in T2-weighted images.
Die in dem nachfolgend ausführlich beschriebenen Experiment verwendeten ultrakleinen superparamagnetischen Eisenoxidpartikel (USPIO) bestehen aus einem Eisenoxidkern und einer Carboxydextran-Hülle. Der mittlere Durchmesser der Teilchen liegt vorzugsweise unter 50 um, besonders bevorzugt bei ca. 25 nm. Die Herstellung derartiger Partikel wird z.B. in den Patentschriften EP 656 368 und WO 98/05430 beschrieben. Ein solche Partikel enthaltendes Kontrastmittel wird zur Zeit von der Firma Schering AG entwickelt.The ultra-small superparamagnetic iron oxide particles (USPIO) used in the experiment described in detail below consist of one Iron oxide core and a carboxydextran shell. The average diameter of the particles is preferably less than 50 μm, particularly preferably approximately 25 nm. The production of such particles is described, for example, in the patents EP 656 368 and WO 98/05430. Such a particle-containing contrast medium is currently being developed by Schering AG.
Die eisenhaltigen Kontrastmittel werden beispielsweise in einer Dosierung von 200 μmol Fe/kg KG eingesetzt.The iron-containing contrast media are used, for example, in a dosage of 200 μmol Fe / kg body weight.
Nach einer Wartezeit von mehreren Bluthalbwertszeiten, in der sich das Kontrastmittel in den Thromben anreichert, werden Bilder mit einem Kernspintomographen aufgenommen. Die Thromben sind in den so erhaltenen Bildern deutlich sichtbar.After a waiting period of several blood half-lives, during which the contrast agent accumulates in the thrombi, images are taken with an MRI scanner. The thrombi are clearly visible in the images thus obtained.
Reichert sich das Kontrastmittel extrazellulär an, dann kann es durch seinen Tl-Effekt den Thrombus signalreich auf Tl-gewichteten Bildern sichtbar machen. Wird das Kontrastmittel von Makrophagen (Freßzellen), die im Rahmen des Thrombusabbaus (Thrombusorganisation) regelmäßig in die Gefäßwand oder in den Rand des Thrombus einwandern, aufgenommen, kann der T2-Effekt des Kontrastmittels überwiegen, wodurch das markierte Gewebe Signalarm in T2- oder T2*-gewichteten Bildern erscheint.If the contrast medium accumulates extracellularly, it can make the thrombus visible on Tl-weighted images with its Tl effect. If the contrast medium is absorbed by macrophages (stress cells) that regularly migrate into the vessel wall or into the rim of the thrombus as part of the thrombus breakdown (thrombus organization), the T2 effect of the contrast medium can predominate, as a result of which the marked tissue is signal-poor in T2 or T2 * -weighted images appear.
Nachfolgend wird detailliert ein Tierexperiment beschrieben, bei dem in 25 Kaninchen Thromben durch Kathetere bolisation und Thrombininjektion in der Vena jugularis externa erzeugt wurden. Nach 1, 3, 5, 7 und 9 Tagen (je n=5) wurden mittels Tlw-MP- RAGE und T2*w-FLASH Kemspintomogramme bei 1,5 Tesla vor und 24 Stunden nach intravenöser Applikation von ultrakleinem superparamagnetischen Eisenoxid (USPIO, Partikelgröße ca. 25 nm) in einer Dosis von 200 μmol Fe/kg KG gemessen. Die Röntgenphlebographie und Histologie dienten als Goldstandard. Die Länge des in SD- Rekonstruktionen der Tlw-MP-RAGE-Sequenz sichtbaren Thrombus wurde im Verhältnis zur wahren Thrombuslänge ausgedrückt. Die Struktur, die Signalintensität und der Kontrastumfang des Thrombus in der T2*w-Technik wurden einer subjektiven Analyse mit einer definierten Skalierung unterzogen. 25 Kaninchen mit altersentsprechenden Thromben dienten als Kontrollen.An animal experiment is described in detail below, in which thrombi were generated in 25 rabbits by catheterization and thrombin injection in the external jugular vein. After 1, 3, 5, 7 and 9 days (n = 5 each), Tlw-MP-RAGE and T2 * w-FLASH nuclear magnetic resonance tomograms were carried out at 1.5 Tesla before and 24 hours after intravenous application of ultra-small superparamagnetic iron oxide (USPIO, Particle size approx. 25 nm) measured in a dose of 200 μmol Fe / kg body weight. X-ray phlebography and histology served as the gold standard. The length of the thrombus visible in SD reconstructions of the Tlw-MP-RAGE sequence was expressed in relation to the true thrombus length. The structure, the signal intensity and the contrast range of the thrombus in the T2 * w technique became subjective Subjected to analysis with a defined scaling. 25 rabbits with age-appropriate thrombi served as controls.
Dieses Experiment soll die Erfindung verdeutlichen, ohne sie auf dieses beschränken zu wollen. This experiment is intended to illustrate the invention, without wishing to restrict it thereto.
Beispiel für den Nachweis experimenteller Thromben mittels Kernspintomographie nach Injektion partikulärer KontrastmittelExample for the detection of experimental thrombi using magnetic resonance imaging after injection of particulate contrast media
Material und MethodeMaterial and method
Kontrastmittelcontrast agents
Es wurde eine Formulierung von ultrakleinen superparamagnetischen Eisenoxidpartikeln (USPIO) verwendet. Die Partikel bestehen aus einem Eisenoxidkern und einer Carboxydextran-Hülle mit einem Gesamtdurchmesser von 25 nm. In der Ratte beträgt die effektive Plasmahalbwertszeit 56±17 Minuten und die LD50 35 mmol Fe/kg KG. Im Kaninchen beträgt die geschätzte Plasmahalbwertszeit ca. 6 Stunden. Das Kontrastmittel wurde in einer Dosierung von 200 μmol Fe/kg KG in einem Volumen von 2-3 ml in eine Ohrvene der gesunden Seite langsam und gefolgt von 2 ml physiologischer Kochsalzlösung injiziert.A formulation of ultra small superparamagnetic iron oxide particles (USPIO) was used. The particles consist of an iron oxide core and a carboxydextran shell with a total diameter of 25 nm. In the rat, the effective plasma half-life is 56 ± 17 minutes and the LD50 is 35 mmol Fe / kg body weight. In rabbits, the estimated plasma half-life is approximately 6 hours. The contrast medium was slowly injected in a dose of 200 μmol Fe / kg body weight in a volume of 2-3 ml into an ear vein on the healthy side and followed by 2 ml of physiological saline.
Tiermodell Die Experimente wurden in Übereinstimmung mit dem deutschen Tierschutzgesetz durchgeführt. Eine Zustimmung der zuständigen Landesbehörde lag vor. Es wurden Chinchilla-Bastard-Kaninchen beiderlei Geschlechts (2,6 - 3,8 kg) verwendet. Alle Untersuchungen wurden in tiefer Narkose durch subkutane Injektion von 40 mg/kg Ketamin-HCl (Ketanest-50, Parke-Davis GmbH, Berlin) und 17 mg/kg Xylazin-HCl (Rompun 2%; Bayer, Leverkusen) durchgeführt. Vor der Thrombusinduktion wurden die Halsvenen zunächst mittels Röntgenphlebographie mit Injektion eines Standardkontrastmittels in eine Ohrvene in zwei Ebenen dokumentiert. In Anlehnung an die von Wessler verwendete Methode wurde ein Stagnationsthrombus durch Blutstase und Hyperkoagulabilität erzeugt [Wessler S. Thrombosis in the presence of vascular stasis. Am J Med 1962; 33:648-666.]. Die Stase wurde jedoch nicht durch operative Ligatur der Vene, sondern durch eine Katheterembolisation herbeigeführt. Von einer Ohrvene aus wurde mit Hilfe einer Schleuse und eines Führungsdrahtes ein ca. 20 cm langer Führungskatheter (3 French) in die Vena jugularis externa vorgeschoben. Über den Führungskatheter wurde ein Mikrokatheter mit einem Außendurchmesser von 0,61 Millimetern mit der Katheterspitze auf Höhe des 4. oder 5. Halswirbels positioniert. Das / -7-Animal model The experiments were carried out in accordance with the German Animal Welfare Act. Approval from the responsible state authority was obtained. Chinchilla bastard rabbits of both sexes (2.6-3.8 kg) were used. All examinations were carried out under deep anesthesia by subcutaneous injection of 40 mg / kg ketamine HCl (Ketanest-50, Parke-Davis GmbH, Berlin) and 17 mg / kg xylazine HCl (Rompun 2%; Bayer, Leverkusen). Before the thrombus induction, the cervical veins were first documented on two levels by means of X-ray phlebography with injection of a standard contrast medium into an ear vein. Following the method used by Wessler, a stagnation thrombus was created by blood stasis and hypercoagulability [Wessler S. Thrombosis in the presence of vascular stasis. On J Med 1962; . 33: 648-666]. However, the stasis was not caused by surgical ligature of the vein, but by catheter embolization. An approx. 20 cm long guide catheter (3 French) was advanced from an ear vein into the external jugular vein using a sheath and a guide wire. A microcatheter with an outer diameter of 0.61 millimeters was positioned over the guide catheter with the catheter tip at the level of the 4th or 5th cervical vertebra. The / -7-
Embolisat, eine Mischung eines öligen jodhaltigen Lymphographie- Röntgenkontrastmittels (Lipiodol, Byk Gulden, Konstanz) und eines Butylcyanoacrylat- Gewebsklebstoffes (Histoacryl, B. Braun, Melsungen) im Verhältnis 1:1, wurde so langsam injiziert, daß einerseits eine Haftung des Embolisates an der Gefäßwand und andererseits eine Mischung von Embolisat und Blut erfolgen konnte. Nach demEmbolisat, a mixture of an oily iodine-containing lymphography X-ray contrast agent (Lipiodol, Byk Gulden, Constance) and a butyl cyanoacrylate tissue adhesive (Histoacryl, B. Braun, Melsungen) in a ratio of 1: 1 was injected so slowly that the embolisate adhered the vessel wall and, on the other hand, a mixture of embolisate and blood could take place. After this
Verschluß des Gefäßes wurden über einen zweiten Mirkokatheter 100 Einheiten bovines Thrombin (Sigma-Aldrich, Chemie GmbH, Steinheim) appliziert. Das Embolisat sollte für wenige Tage zu einem passageren Verschluß des Gefäßes fuhren. Das Embolisat sollte wegen des Jodanteils sowohl röntgendicht auf den Röntgenphlebographien als auch wegen der im klebstoffixierten Blutabbauprodukte hyperintens auf Tl-gewichteten MRT-Bildern sichtbar sein.The vessel was closed using a second microcatheter to apply 100 units of bovine thrombin (Sigma-Aldrich, Chemie GmbH, Steinheim). The embolisate should lead to a temporary closure of the vessel for a few days. Because of the iodine content, the embolisate should be visible on the X-ray phlebographs, as well as hyperintensively on Tl-weighted MRI images, because of the glue-fixed blood breakdown products.
Experimentelles DesignExperimental design
Fünfzig thrombustragende Versuchstiere wurden zufällig der Kontrastmittelgruppe (D) oder der Kontrollgruppe (K) zugeteilt. Eine weiterfuhrende Unterteilung erfolgte entsprechend dem Thrombusalter zum Zeitpunkt der ersten MRT-Messung (1, 3, 5, 7 oder 9 Tage). Dementsprechend ergab sich eine Zuordnung in jeweils 5 Kontrastmittelgruppen (Dl, D3, D5, D7 und D9) und 5 Kontrollgrappen (Kl, K3, K5, K7 und K9). Jede Untergruppe umfaßte fünf Versuchstiere. Bei allen Versuchtieren wurden vor der Ausgangs-MRT der Thrombus per Röntgenphlebographie dokumentiert. Tiere der Kontrastmittelgruppe (K) erhielten nach dieser Ausgangs-MRT dasFifty thrombus-carrying animals were randomly assigned to the contrast agent group (D) or the control group (K). A further subdivision was made according to the thrombus age at the time of the first MRI measurement (1, 3, 5, 7 or 9 days). Accordingly, there was an assignment in 5 contrast medium groups (DI, D3, D5, D7 and D9) and 5 control groups (K1, K3, K5, K7 and K9). Each subgroup comprised five test animals. In all experimental animals, the thrombus was documented by X-ray phlebography before the initial MRI. Animals from the contrast medium group (K) received this after this initial MRI
Kontrastmittel und nach einem 24-Stunden-Intervall die Verlaufs-MRT. In Gruppe D3 erfolgte z.B. nach Embolisation am Tag 0, eine Ausgangs-MRT am Tag 3 und eine Verlaufs-MRT am Tag 4. Von den Kontrollen erhielten nur Tiere der Gruppen Kl, K3 und K5 eine Verlaufs-MRT, nicht jedoch Tiere der Gruppen K7 und K9, die am Anfang der Experimente gemessen worden waren, als die Länge des Verlaufsintervalls noch nicht feststand.Contrast medium and after a 24-hour interval the progressive MRI. In group D3 e.g. after embolization on day 0, a baseline MRI on day 3 and a follow-up MRI on day 4. Of the controls, only animals from groups K1, K3 and K5 received a follow-up MRI, but not animals from groups K7 and K9 who had been measured at the beginning of the experiments when the length of the course interval had not yet been determined.
MRTMRI
Die Untersuchungen wurden in einem 1,5-Tesla-Magneten (Vision, Siemens, Erlangen) mit einer Standard-Kniespule durchgeführt. Die narkotisierten Tiere wurden in Rückenlage in einer U-förmigen Schaumstoffunterlage positioniert. Ein wasserhaltiger Plastikbeutel wurde auf die ventrale Halsseite gelegt, um die Fettsättigung zu verbessern.The investigations were carried out in a 1.5 Tesla magnet (Vision, Siemens, Erlangen) with a standard knee coil. The anesthetized animals were placed supine in a U-shaped foam pad. A watery one Plastic bags were placed on the ventral side of the neck to improve fat saturation.
Tl-gewichtete Bilder wurden in koronarer Schichtorientierung mit einer 3D- Magnetization-Prepared Rapid Gradient-Echo Imaging-Sequenz (3D-MP-RAGE) erzeugt [ Mugler JPd, Brookeman JR. Three-dimensional magnetization-prepared rapid gradient-echo imaging (3D MP RAGE). Magn Reson Med 1990; 15:152-7.]. Die verwendete Sequenz unterdrückt das Signal von Fett durch einen sequenzeigenen selektiven Wasserexzitationspuls und das von Blut durch die Wahl der Verzögerangszeit [ Moody AR, Pollock JG, O'Connor AR, Bagnall M. Lower-limb deep venous thrombosis: direct MR imaging of the thrombus. Radiology 1998; 209:349-55.]. Folgende Parameter wurden verwendet: Repetitionszeit 10,3 ms; Echozeit 4,0 ms; Flipwinkel 15°; Inversionszeit 20 ms; Verzögerungszeit 1.000 ms; Zahl der Schichten 100; Akquisitionen 1; Schichtdicke 0,8 mm; Bildfeld 100 x 200 mm; Matrix 128 x 256; Akquisitionszeit 5:30 Minuten; Pixelgröße 0,78 x 0,78 x0,8 mm. Von den 2D-Quellbildern wurden ca. 1,5 cm dicke 3D-Maximum-Intensitäts- Projektionsrekonstruktionen (MIP) angefertigt.T1-weighted images were generated in a coronary slice orientation using a 3D magnetization-prepared rapid gradient echo imaging sequence (3D-MP-RAGE) [Mugler JPd, Brookeman JR. Three-dimensional magnetization-prepared rapid gradient-echo imaging (3D MP RAGE). Magn Reson Med 1990; . 15: 152-7]. The sequence used suppresses the signal of fat by a sequential selective water excitation pulse and that of blood by the choice of the delay time [Moody AR, Pollock JG, O'Connor AR, Bagnall M. Lower-limb deep venous thrombosis: direct MR imaging of the thrombus , Radiology 1998; 209:. 349-55]. The following parameters were used: repetition time 10.3 ms; Echo time 4.0 ms; Flip angle 15 °; Inversion time 20 ms; Delay time 1,000 ms; Number of layers 100; Acquisitions 1; Layer thickness 0.8 mm; Image field 100 x 200 mm; Matrix 128 x 256; Acquisition time 5:30 minutes; Pixel size 0.78 x 0.78 x0.8 mm. Approx. 1.5 cm thick 3D maximum intensity projection reconstructions (MIP) were made from the 2D source images.
T2*-gewichtete axiale Bilder wurden mit einer 3D-Gradientenechosequenz (Fast Low Angle Shot, FLASH) erzeugt [ Frahm J, Haase A, Matthaei D. Rapid three- dimensional MR imaging using the FLASH technique. J Comput Assist Tomogr 1986; 10:363-8.]. Die Sequenz stellt mittels des sequenzinhärenten Bright-Blood-Effekts das Venenlumen hyperintens zu Fett und Muskelatur dar. Durch die moderate T2*- Wichtung sollen intrazellulär angereicherte Blutabbauprodukte oder SPIOs Signalarm abgebildet werden. Folgende Aufnahmeparameter wurden verwendet: Repetitionszeit 54 ms; Echozeit 18 ms; Flipwinkel 15°; Blockdichtdicke 80 mm, Partitionen 40; Schichtdicke 2 mm; Bildausschmtt 80 x 80 mm; Matrix 256 x 256; Akquisitionszeit 22:08 Minuten; Pixel-Größe 0,31 x 0,31 x 0,2 mm.T2 * -weighted axial images were generated with a 3D gradient echo sequence (Fast Low Angle Shot, FLASH) [Frahm J, Haase A, Matthaei D. Rapid three-dimensional MR imaging using the FLASH technique. J Comput Assist Tomogr 1986; . 10: 363-8]. Using the sequence-inherent bright blood effect, the sequence represents the vein lumen hyperintense to fat and muscle. The moderate T2 * weighting is intended to depict intracellularly enriched blood breakdown products or SPIOs signal arms. The following recording parameters were used: repetition time 54 ms; Echo time 18 ms; Flip angle 15 °; Block sealing thickness 80 mm, partitions 40; Layer thickness 2 mm; Image 80 x 80 mm; Matrix 256 x 256; Acquisition time 22:08 minutes; Pixel size 0.31 x 0.31 x 0.2 mm.
Pathologiepathology
Nach der Verlaufs-MRT wurden die Tiere durch eine Überdosis Xylazin getötet. Das kaudale und kraniale Segment der Vena jugularis externa und die Vena facialis wurden präpariert, für 24 Stunden in 10-prozentigem Formalin fixiert und in je fünfAfter the progressive MRI, the animals were killed by an overdose of xylazine. The caudal and cranial segments of the external jugular vein and the facial vein were prepared, fixed in 10% formalin for 24 hours and in five each
Gefäßzylinder von 3 mm Länge zerteilt. Nach Einbettung in Paraffin wurde das kaudale Ende eines jeden Zylinders auf 3 μm Dicke geschnitten und mit Berliner-Blau auf Eisen gefärbt.Vessel cylinder of 3 mm length divided. After embedding in paraffin, the caudal Cut the end of each cylinder to a thickness of 3 μm and stained it with iron blue in Berlin.
Bildanalyseimage analysis
Die histologischen Schnitte, Hardcopies der Phlebographien und der MRTs wurden durch einen Radiologen ausgewertet. Die Länge des Thrombus in der Vena jugularis externa wurden mit Hilfe der Phlebographie gemessen. Die Histologie diente als zweites Nachweisverfahren des Thrombus, speziell bei frischen, okkludierenden Thromben, die nicht von Kontrastmittel umspült werden. Sie ist jedoch wegen der wohlbekannten Schrumpfungsartefakte während der histologischen Aufarbeitung nur begrenzt zur Längenbestimmungen geeignet.The histological sections, hard copies of the phlebographies and the MRI were evaluated by a radiologist. The length of the thrombus in the external jugular vein was measured using phlebography. Histology served as a second method of detecting the thrombus, especially in the case of fresh, occluding thrombi that are not surrounded by contrast media. However, due to the well-known shrinkage artifacts during histological processing, it is only suitable for length determination to a limited extent.
Anschließend wurde die Länge des Thrombus auf den Tl-gewichteten SD- Rekonstruktionen der MP-RAGE-Sequenz bestimmt. Der Thrombus wurde als sichtbar definiert, wenn er hyperintens und klar von der Umgebung abgrenzbar war. Bei einer lückenhaften Darstellung wurden nur die sichtbaren Thrombusanteile gemessen. Um einen Einfluß der individuellen und vom Thrombusalter abhängigen Varianz der Thrombuslänge auszuschalten, wurde die durch den Goldstandard bestimmte Thrombuslänge auf 1,0 normiert und die in der 3D-Rekonstruktion der MP-RAGE- Sequenz gemessene Thrombuslänge in Anteilen von 1,0 angegeben, z.B. 0,4.The length of the thrombus was then determined on the Tl-weighted SD reconstructions of the MP-RAGE sequence. The thrombus was defined as visible if it was hyperintense and clearly distinguishable from the surroundings. In the case of a sketchy representation, only the visible thrombus portions were measured. In order to eliminate an influence of the individual and thrombus age-dependent variance of the thrombus length, the thrombus length determined by the gold standard was normalized to 1.0 and the thrombus length measured in the 3D reconstruction of the MP-RAGE sequence was given in proportions of 1.0, e.g. 0.4.
Die T2*-gewichteten Gradientenechosequenz-Bilder wurden nur einer qualitativen Analyse unterzogen. Für die Auswertung wurde eine repräsentative Schicht ausgesucht, die eindeutig durch die Referenzmethoden erfaßt wurde und charakteristisch für den individuellen Thrombus war. Bei einer fehlenden Abgrenzbarkeit des Thrombus vom umgebenden Blut wurde auf die Referenzmethoden zurückgegriffen, um den Thrombus zu lokalisieren. Die Struktur des Thrombus wurde als "homogen", "heterogen- ungeordnet" oder "heterogen-konzentrisch" (zentral hyperintens, peripher hypointens) eingeteilt. Die Signalintensität des "homogenen" Thrombus, die führende Signalintensität, d.h. die des größten sichtbaren Thrombusanteils des "heterogen- ungordneten" Thormbus oder die Signalintensiät des Zentrums im Fall eines "heterogenkonzentrischen" Thrombus wurde auf einer 5 -Punkteskala von signalfrei bis signalreich eingestuft:The T2 * weighted gradient echo sequence images were only subjected to a qualitative analysis. A representative layer was selected for the evaluation, which was clearly determined by the reference methods and was characteristic of the individual thrombus. If the thrombus could not be distinguished from the surrounding blood, the reference methods were used to locate the thrombus. The structure of the thrombus was classified as "homogeneous", "heterogeneously disordered" or "heterogeneous-concentric" (central hyperintense, peripheral hypointense). The signal intensity of the "homogeneous" thrombus, the leading signal intensity, i.e. that of the largest visible thrombus portion of the "heterogeneously disordered" thorax or the signal intensity of the center in the case of a "heterogeneous" thrombus was rated on a 5-point scale from signal-free to signal-rich:
1 - signalfrei, Signalintensität wie kompakter Knochen oder Hintergrund 2 - Signalarm, zwischen 1 und 31 - signal-free, signal intensity such as compact bone or background 2 - Signal arm, between 1 and 3
3 - mittlere Signalintensität, muskelisointens3 - medium signal intensity, muscle isointense
4 - signalreich, zwischen 3 und 54 - rich in signals, between 3 and 5
5 - sehr signalreich, entsprechend einem "Glühbirneneffekt" Der Kontrastumfang des Thrombus wurde basierend auf den Definitionen der Signalintensität bestimmt als Differenz zwischen der minimalen und maximalen Signalintensität. Es ergibt sich eine 4-Punkteskala.5 - very rich in signals, corresponding to a "light bulb effect" The contrast range of the thrombus was determined based on the definitions of the signal intensity as the difference between the minimum and maximum signal intensity. The result is a 4-point scale.
Um bei thrombustragenden Venen eine Kontrastmittelanreicherung der Wand und Gefaßumgebung zu untersuchen, wurden diese auf einer repräsentativen Schicht der T2*-gewichteten Sequenz in muskelisointens (normal) oder Signalarm eingestuft.In order to investigate a contrast medium enrichment of the wall and vascular environment in thrombus-bearing veins, these were classified on a representative layer of the T2 * -weighted sequence into muscle isointense (normal) or signal arm.
Statistikstatistics
Die Daten wurden mit dem Mittelwert und der Standardabweichung separiert nach Gruppen (Kontrollen, Kontrastmittel) und dem Thrombusalter (Tage) zusammengefaßt oder graphisch dargestellt (StatView 4.5, SAS Institute Inc., Cary, NC, USA). Ein Vergleich der ersten Messung mit der Verlaufsmessung erfolgte mit dem t-Test für Paarvergleiche jeweils getrennt für die Gruppen D und K. Die einzelnen Gruppen, z.B. Dl versus Kl, wurden mit der Varianzanalyse (ANOVA) verglichen, für die eine Signifikanzprüfung mit dem Fischer Test (Fischer's Protected Least Significant Difference, PLSD) durchgeführt wurde. Das Signifikanzniveau betrug in allen Fällen ρ<0.05.The data were separated with the mean value and the standard deviation according to groups (controls, contrast medium) and the thrombus age (days) or summarized or graphically represented (StatView 4.5, SAS Institute Inc., Cary, NC, USA). A comparison of the first measurement with the course measurement was carried out with the t-test for pair comparisons separately for groups D and K. The individual groups, e.g. Dl versus Kl were compared to the analysis of variance (ANOVA), for which a significance test was carried out using the Fischer's Protected Least Significant Difference (PLSD). The level of significance was ρ <0.05 in all cases.
ErgebnisseResults
Tiermodellanimal model
Sieben Tiere verstarben während oder nach der Katheter-Embolisation durch eine Schockreaktion vermutlich durch mechanische Reizung von Blutdruckregulatoren, durch Fortspülen des Embolisates in die Lunge oder aus ungeklärter Ursache. Diese Tiere wurden aus dem Experiment ausgeschlossen. In den übrigen Tieren ließen sich in allen Fällen Thromben erzeugen. Das Embolisat konnte aufgrund des Lipiodolanteils in allen Fällen in der Röntgen-Phlebographie erkannt werden (Abbildung 1 und 2). In 44 der 50 Fälle war es auch auf der 3D-MIP-Rekonstruktion der MP-RAGE-Sequenz signalreich sichtbar. In den übrigen sechs Fällen konnte es zumindest auf den 2D- Quellbildern der MP-RAGE-Sequenz ausgemacht werden.Seven animals died during or after catheter embolization due to a shock reaction, presumably due to mechanical irritation of blood pressure regulators, by flushing the embolizate into the lungs or from an unknown cause. These animals were excluded from the experiment. Thrombi could be produced in the remaining animals in all cases. Due to the lipiodol content, the embolisate could be recognized in X-ray phlebography in all cases (Figures 1 and 2). In 44 of the 50 cases, it was also on the 3D MIP reconstruction of the MP-RAGE sequence Visibly rich in signals. In the remaining six cases, it could be seen at least on the 2D source images of the MP-RAGE sequence.
Röntgen-phlebographisch betrug die Länge des Thrombus in der Vena jugularis externa der Gruppe Kl der Kontrollen 43±8 und in der Gruppe Dl der Kontrastmitteltiere 36±10 mm. Die Länge nahm im Untersuchungszeitraum deutlich ab und betrug bei den Gruppen K9 und D923±10 bzw. 11±8 mm (Abbildung 3). Eine signifikant unterschiedliche Länge zwischen Kontroll- und Kontrastmittel-Gruppen gleichen Thrombenalters bestand zu keinem Zeitpunkt.X-ray phlebographically, the length of the thrombus in the external jugular vein of the group Kl of the controls was 43 ± 8 mm and in the group Dl of the contrast medium animals 36 ± 10 mm. The length decreased significantly during the study period and was ± 10 and 11 ± 8 mm, respectively, in groups K9 and D923 (Figure 3). There was never a significantly different length between control and contrast medium groups of the same thrombus age.
Histologisch fand sich in den Gruppen Kl und Dl ein frischer Thrombus bestehend aus dicht gepackten Erythrozyten (Hämostase) durchsetzt mit Fibrinbälkchen; in den Gruppen K3 und D3 eine dicht gepackte Hämostase mit zentraler Auflösung der Erythrozyten bei einzelnen Tieren; in den Gruppen K5 und D5 eine Auflösung der Erythozyten im Thrombuszentrum in allen Fällen (Homogenisierung) sowie die marginale Einwanderung von mononukleären Zellen; in den Gruppen K7 und D7 die zunehmende Durchsetzung des Thrombus durch mononukleäre Zellen und die beginnende Endothelialisierung mit vereinzelnd einsprossenden Kapillaren; und in den Gruppen K9 und D9 die fast vollständige Durchsetzung des Thrombus durch mononukleäre Zellen und Kapillaren mit einer beginnenden Bindgewebsbildung.Histologically, groups Kl and Dl found a fresh thrombus consisting of tightly packed erythrocytes (hemostasis) interspersed with trabecular trabeculae; in groups K3 and D3 a tightly packed hemostasis with central resolution of the erythrocytes in individual animals; in groups K5 and D5, the erythocytes in the thrombus center were dissolved in all cases (homogenization) and the marginal immigration of mononuclear cells; in groups K7 and D7 the increasing penetration of the thrombus by mononuclear cells and the beginning of endothelialization with occasionally sprouting capillaries; and in groups K9 and D9 the almost complete penetration of the thrombus by mononuclear cells and capillaries with the start of connective tissue formation.
MRT Thromben waren auf den 3D-Rekonstruktionen der T 1 -gewichteten MP-RAGE-Sequenz als wurmformige hyperintense Strukturen sichtbar (Abbildung 1 und 2). Vereinzelt fand sich in der Verlaufsmessung bei Kontrastmitteltieren auch ein leicht erhöhtes Signal in größeren Halsgefäßen im Sinne eines residuellen Angiographieeffektes. Ohne Berücksichtigung des Thrombusalters fand sich bei der Gruppe K eine Übereinstimmung der relativen Thrombuslänge der 3D-MP-RAGE-Sequenz derMRI thrombi were visible on the 3D reconstructions of the T 1 -weighted MP-RAGE sequence as worm-like hyperintense structures (Figures 1 and 2). Occasionally, the course measurement of contrast medium animals also showed a slightly increased signal in larger neck vessels in the sense of a residual angiography effect. Without taking the thrombus age into account, group K found the relative thrombus length of the 3D-MP-RAGE sequence of the
Ausgangs-MRT und Phlebographie von 0,2±0,3 und bei D von 0,1±0,3. Bei den Tieren der Gruppe D (n=25) fand sich im 24-Stunden- Verlauf eine signifikante Zunahme der übereinstimmenden relativen Thrombuslänge von 0,1 ±0,3 vor Kontrastmittelgabe auf 0,5±0,5 24 Stunden danach, p=0,001 (Abbildung 1, 2 und 4); nicht jedoch bei Kontrollen (nur Gruppe Kl, K3 und K5), p=0,34. Die Analyse der einzelnenOutput MRI and phlebography of 0.2 ± 0.3 and at D of 0.1 ± 0.3. In the animals of group D (n = 25) there was a significant increase in the corresponding relative thrombus length from 0.1 ± 0.3 before contrast medium administration to 0.5 ± 0.5 24 hours afterwards over the 24-hour course, p = 0.001 (Figures 1, 2 and 4); but not for controls (only groups Kl, K3 and K5), p = 0.34. The analysis of each
Tagesgruppen zeigt eine Abhängigkeit des in der MP-RAGE-Sequenz sichtbaren Thrombusanteils vom Thrombusalter (Abbildung 4). Dieser war bei geringem Thrombusalter in den Gruppen Kl, K3 und K5 0,2±0,3 bis 0,4±0,5, bzw. bei höherem Alter in den Gruppen K7 und K9 0,1±0,1 und 0. Nach Kontrastmittelgabe zeigte sich eine signifikante Zunahme des sichtbaren Thrombusanteils bei folgenden Gruppen: D3, von 0,6±4 auf 0,8±0,4, D5, von 0, 1±0, 1 auf 1±0, 1 , und D7 von 0 auf 0,6±0,4. Kein signifikanter Unterschied fand sich bei bei Kontrastmitteltieren der Gruppen Dl und D9.Day groups shows a dependency of what is visible in the MP-RAGE sequence Thrombus portion from thrombus age (Figure 4). At low thrombus age this was 0.2 ± 0.3 to 0.4 ± 0.5 in groups Kl, K3 and K5, or 0.1 ± 0.1 and 0 in groups K7 and K9 at higher age. After administration of contrast medium, there was a significant increase in the visible thrombus proportion in the following groups: D3, from 0.6 ± 4 to 0.8 ± 0.4, D5, from 0, 1 ± 0, 1 to 1 ± 0, 1, and D7 from 0 to 0.6 ± 0.4. No significant difference was found in contrast medium animals in groups Dl and D9.
Die moderat T2*-gewichtete FLASh-Sequenz zeigte eine erhebliche thrombusalter- abhängige Variabilität der Struktur, der Signalintensiät und des Kontrastumfanges. Ein einzelnes Beispiel findet sich in Abbildung 5. Bei Kontrollen überwogen bis zum 7. Tag die "heterogen-ungeordnete" und "heterogen-konzentrische" Thrombusstruktur (Abbildung 6). Ab dem 7. Tag dominiert bei den Kontrollen eine "homogene" Thrombusstruktur. Die führende Signalintensität des Thrombus war bei den Kontrolltieren Kl die "mittlere", d.h.isointens zur Muskulatur, jedoch mit einer deutlichen Streuung (Abbildung 1). Bis zum dritten 3. Tag nahm die Signalintensität des Thrombus bei den Kontrolltieren tendentiell auf "signalreich" zu, um bis zum 9. Tag auf eine als "signalarm" definierte Intensität abzufallen. Der Kontrastumfang von frischen Thromben betrug in der Gruppe Kl im Mittel 1,6 und bei K9 0,4 (Abbildung 8). Insgesamt fand sich nur bei vier Tieren der Guppe K nach Kontrastmittelgabe eine Signalreduktion des Thrombus in der moderat T2*-gewichteten FLASH-Sequenz die als möglicher Kontrastmitteleffekt gewertet wurde (Abbildung 5). Ein Vergleich der Ausgangs- und der Verlaufsmessung zeigte in der Gesamtheit oder getrennt nach Thrombusalter keine signifikante Änderung der Thrombusstruktur (Abbildung 6), des Thrombussignals (Abbildung 7) oder des Kontrastumfangs des Thrombus (Abbildung 8). Auf repräsentativen Schichten der T2*-gewichteten Sequenz fand sich bei 6 von 50 Tieren bereits nativ eine partielle (n=4) oder zirkuläre (n=2) Signalarmut der Wand und der unmittelbaren Gefäßumgebung. Nach der Kontrastmittelgabe bestand bei allen 6 Tieren die Signalarmut fort. Bei 11 weiteren Tieren fand sich eine Signalarmut der Wand und unmittelbaren Gefäßumgebung nur in der Verlaufskontrolle; bei 2 Tieren in der zirkulären und bei 9 in der partiellen Ausprägung. Von diesen 11 Tieren war eines eine Kontrolle. Die übrigen 10 hatten Kontrastmittel erhalten. Von diesen 10 kontrastverstärkten Untersuchungen waren 4 von Gruppe Dl und 4 von D3, d.h. die Kontrastmittelanreicherung der Venenwand und unmittelbaren Gefaßumgebung fand sich vorzugsweise bei jungen Thrombusstadien in je 4 von 5 Fällen. The moderate T2 * -weighted FLASh sequence showed a considerable thrombus age-dependent variability of the structure, the signal intensity and the contrast range. A single example can be found in Figure 5. In controls, the "heterogeneous disordered" and "heterogeneous concentric" thrombus structure predominated up to the 7th day (Figure 6). From the 7th day, a "homogeneous" thrombus structure dominates in the controls. The leading signal intensity of the thrombus in the control animals Kl was the "middle", ie isointense to the muscles, but with a clear spread (Figure 1). By the third third day, the signal intensity of the thrombus in the control animals tended to increase to "signal-rich" in order to drop to an intensity defined as "low-signal" by the 9th day. The contrast range of fresh thrombi was 1.6 in the Kl group and 0.4 in the K9 group (Figure 8). A total of only four animals in group K showed a signal reduction of the thrombus in the moderately T2 * -weighted FLASH sequence after contrast agent administration, which was evaluated as a possible contrast agent effect (Figure 5). A comparison of the initial and the course measurement showed no significant change in the thrombus structure (Figure 6), the thrombus signal (Figure 7) or the contrast range of the thrombus (Figure 8) in total or separately according to thrombus age. On representative layers of the T2 * -weighted sequence, partial (n = 4) or circular (n = 2) signal deficiency of the wall and the immediate vascular environment was found natively in 6 of 50 animals. After the administration of contrast medium, all 6 animals remained low in signal. In 11 other animals, there was only a low level of signal in the wall and immediate vascular surroundings during follow-up control; in 2 animals in the circular and in 9 in the partial expression. Of these 11 animals, one was a control. The remaining 10 had received contrast media. Of these 10 contrast-enhanced examinations, 4 were from group Dl and 4 from D3, ie the Contrast enhancement of the vein wall and immediate vascular environment was found preferably in young thrombus stages in 4 out of 5 cases.
Detaillierte Beschreibung der AbbildungenDetailed description of the pictures
Abbildung 1illustration 1
In der Röntgen-Phlebographie (a) zeigt sich ein inkompletter Verschluß der linken Vena jugularis externa drei Tage nach Thrombusinduktion. Die Vena jugularis externa erhält einen weiteren Zufluß von medial, die Vena facialis. Der Abstrom des Kontrastmittels erfolgt z.T. über die Gegenseite. Das Embolisat (Pfeil) ist in Phlebographie röntgendicht (a). In 3D-Rekonstruktionen der MP-RAGE-Sequenz ist Position des Embolisates vor (b) und 24 Stunden nach Gabe von superparamagnetischem Eisenoxid (c) durch einen Pfeil markiert. Das kraniale Ende des sichtbaren Thrombusanteils wurde jeweils durch einen Pfeilkopf markiert (b und c). Nach Kontrastmittelgabe (c) sind in der MP-RAGE- Sequenz zusätzliche kraniale Thrombusanteile im Vergleich zur Ausgangs-MRT (b) sichtbar. Nach Kontrastmittelgabe lag eine vollständige Übereinstimmung der Thrombuslänge in der MP-RAGE-Sequenz und dem Goldstandard vor. Es findet sich auch ein residueller Angiographieeffekt des Kontrastmittels in den übrigen Halsgefäßen.X-ray phlebography (a) shows incomplete occlusion of the left external jugular vein three days after thrombus induction. The external jugular vein receives another inflow from the medial, the facial vein. The outflow of the contrast medium takes place partly. over the opposite side. The embolisate (arrow) is radiopaque in phlebography (a). In 3D reconstructions of the MP-RAGE sequence, the position of the embolisate before (b) and 24 hours after the administration of superparamagnetic iron oxide (c) is marked by an arrow. The cranial end of the visible thrombus portion was marked with an arrow head (b and c). After contrast medium administration (c), additional cranial thrombus portions are visible in the MP-RAGE sequence compared to the original MRI (b). After contrast medium administration, there was complete agreement of the thrombus length in the MP-RAGE sequence and the gold standard. There is also a residual angiography effect of the contrast agent in the other neck vessels.
Abbildung 2Figure 2
In der Röntgen-Phlebographie (a) fünf Tage nach Embolisation ist ein Embolisat (Pfeil) zu erkennen. Einzelne Thrombusanteile werden in der kranialen Vena jugularis interna umspült (a, Pfeilspitze). Es finden sich ipsilaterale Kollateralen (a, dünner Pfeil). In der 3D-Rekonstruktion der nativen MP-RAGE-Sequenz ist der Thrombus nicht und das Embolisat schwach zu erkennen (b, Pfeil). 24 Stunden nach Kontrastmittelgabe (c) ist der- gesamte Thrombus vom Embolisat (Pfeil) bis in die kraniale Vena jugularis externa (Pfeilspitze) und eine lateral liegende Ohrvene sichtbar.An X-ray phlebography (a) five days after embolization shows an embolizate (arrow). Individual thrombus portions are washed around in the cranial internal jugular vein (a, arrowhead). There are ipsilateral collaterals (a, thin arrow). In the 3D reconstruction of the native MP-RAGE sequence, the thrombus cannot be recognized and the embolisate is poorly recognizable (b, arrow). 24 hours after the administration of contrast medium (c) the entire thrombus from the embolisate (arrow) to the cranial external jugular vein (arrowhead) and a lateral ear vein are visible.
Abbildung 3Figure 3
Länge des Thrombus in der Vena jugularis externa. Es zeigt sich eine Abnahme derLength of the thrombus in the external jugular vein. There is a decrease in the
Thrombuslänge von Tag 1 bis 9. Äbbildung 4Thrombus length from day 1 to 9. Figure 4
Überemstimmung der relativen Thrombuslänge in 3D-Rekonstruktion der Tl- gewichteten MP-RAGE-Sequenz und Röntgenphlebographie getrennt nach Kontrastmitteltieren (D) und Kontrollen (K) sowie Thrombusalter (1.-9. Tage). Es wird das Ergebnis der Ausgangs- und der 24-Stunden- Verlaufs-MRT gezeigt. Fehlende Übereinstimmung wird durch den Wert 0, vollständige durch 1 ausgedrückt. Nach Gabe von DDM34 fand sich eine signifikant höhere Übereinstimmung der in der MPR- RAGE-Sequenz sichtbaren Thrombuslänge bei den Gruppen D3, D5 und D7, nicht aber bei frischen (Dl) und organisierten Thromben (D9).Matching of the relative thrombus length in 3D reconstruction of the Tl-weighted MP-RAGE sequence and X-ray phlebography separated by contrast medium animals (D) and controls (K) as well as thrombus age (1-9 days). The result of the baseline and 24-hour history MRI is shown. Mismatch is expressed by the value 0, complete by 1. After administration of DDM34, the thrombus length visible in the MPR-RAGE sequence was found to be significantly higher in groups D3, D5 and D7, but not in fresh (DI) and organized thrombi (D9).
Abbildung 5Figure 5
In der moderat T2*-gewichteten FLASH-Sequenz findet sich vor Kontrastmittelgabe (a) in der Vena jugularis externa (Pfeil) ein sieben Tage alter Thrombus mit einer als "homogen" definierten Thrombusstraktur und einer "mittleren" Signalintensität. Nach Kontrastmittelgabe ist der Thrombus "signalarm" (b, Pfeil). Deutlicher Signalverlust der Wirbelsäule nach SPIO-Gabe (b, Pfeilspitze).In the moderately T2 * -weighted FLASH sequence, prior to the administration of contrast medium (a), a seven-day-old thrombus with a thrombus fracture defined as "homogeneous" and a "medium" signal intensity was found in the external jugular vein (arrow). After administration of contrast medium, the thrombus is "low-signal" (b, arrow). Significant signal loss of the spine after administration of SPIO (b, arrow head).
Abbildung 6Figure 6
Thrombusstruktur in der T2*-gewichteten FLASH-Sequenz bei Kontrollen (K) und Tieren vor der Kontrastmittelgabe (D) getrennt nach Tagen (1.-9. Tag). Bis zum 7. Tag überwiegen die heterogenen Thrombusstruktur heterogen-ungeordnet und heterogenkonzentrisch. Ab dem ca. 7. Tag dominiert die homogene Thrombusstruktur.Thrombus structure in the T2 * -weighted FLASH sequence in controls (K) and animals before contrast agent administration (D) separated by days (1st-9th day). By the 7th day, the heterogeneous thrombus structure predominated heterogeneously disordered and heterogeneous. The homogeneous thrombus structure dominates from the 7th day.
Abbildung 7 Signalintensität des Thrombus in der T2*-gewichteten FLASH-Sequenz auf einer 5- Punkte Skala von signalfrei (1), signalarm (2), muskelisointens (3), signalreich (4) und sehr signalreich (5). Es werden Gruppen der Kontrollen (K) und Kontrastmitteltiere getrennt nach dem Thrombusalter dargestellt. Sowohl die Ausgangs- als auch die Verlaufs-MRT werden gezeigt - bei den Kontrollen der K7 und K9 gab es keine Verlaufs-MRT. Abbildung 8Figure 7 Thrombus signal intensity in the T2 * -weighted FLASH sequence on a 5-point scale from signal-free (1), signal-poor (2), muscle-isointense (3), signal-rich (4) and very signal-rich (5). Groups of controls (K) and contrast medium animals are shown separately according to the thrombus age. Both baseline and follow-up MRI are shown - there was no follow-up MRI on the K7 and K9 controls. Figure 8
Kontrastumfang von experimentellen Thromben in der T2*-gewichteten Gradientensequenz. Es zeigt sich, daß der Kontrastumfang sowohl bei Kontrollen (K) als auch bei Kontrastmitteltieren (D) im Zeitraum von neun Tagen abnimmt, d.h. der Thrombus homogener wird. Eine signifikante Änderung des Kontrastumfangs zwischen der Ausgangs- und Verlaufsuntersuchung fand sich in keiner Gruppe. Contrast range of experimental thrombi in the T2 * -weighted gradient sequence. It can be seen that the range of contrast for controls (K) as well as for contrast medium animals (D) decreases over a period of nine days, i.e. the thrombus becomes more homogeneous. There was no significant change in the contrast range between the initial and follow-up examination in any group.

Claims

Patentansprüche claims
1. Verfahren zur bildlichen Darstellung und Diagnose von Thromben, dadurch gekennzeichnet, daß dem Patienten zunächst ein partikuläres MR-Kontrastmittel verabreicht wird, und nach Anreicherung des Kontrastmittels im Thrombus und/oder der angrenzenden Gefäßwand und -Umgebung ein Kemspintomogramm aufgenommen wird.1. A method for the visual representation and diagnosis of thrombi, characterized in that the patient is initially administered a particulate MR contrast medium, and after the contrast medium has been accumulated in the thrombus and / or the adjacent vessel wall and environment, a nuclear magnetic resonance tomogram is recorded.
2. Verfahren gemäß Anspruch 1, dadurch gekennzeichnet, daß das partikuläre Kontrastmittel superparamagnetische Eisenoxidteilchen (SPIO) enthält.2. The method according to claim 1, characterized in that the particulate contrast medium contains superparamagnetic iron oxide particles (SPIO).
3. Verfahren gemäß Anspruch 2, dadurch gekennzeichnet, daß die superparamagnetischen Eisenoxidteilchen ultrakleine superparamagnetische Eisenoxidteilchen (USPIO) mit einem mittleren Teilchendurchmesser von weniger als 50 nm sind. 3. The method according to claim 2, characterized in that the superparamagnetic iron oxide particles are ultra-small superparamagnetic iron oxide particles (USPIO) with an average particle diameter of less than 50 nm.
4. Verfahren gemäß Anspruch 1, dadurch gekennzeichnet, daß das Kernspintomogramm als Tl-gewichtetes Bild aufgenommen wird.4. The method according to claim 1, characterized in that the magnetic resonance tomogram is recorded as a Tl-weighted image.
5. Verfahren gemäß Anspruch 1, dadurch gekennzeichnet, daß das Kernspintomogramm als T2- oder T2*-gewichtetes Bild aufgenommen wird.5. The method according to claim 1, characterized in that the magnetic resonance tomogram is recorded as a T2- or T2 * -weighted image.
6. Verwendung von Partikelsuspensionen zur Herstellung von Kontrastmitteln für die Darstellung von Thromben mittels Kernspintomographie.6. Use of particle suspensions for the production of contrast media for the imaging of thrombi by means of magnetic resonance imaging.
7. Verwendung gemäß Anspruch 6, dadurch gekennzeichnet, daß die Partikelsuspension eine Suspension von superparamagnetischen Eisenoxidteilchen ist.7. Use according to claim 6, characterized in that the particle suspension is a suspension of superparamagnetic iron oxide particles.
8. Verwendung gemäß Anspruch 7, dadurch gekennzeichnet, daß die superparamagnetischen Eisenoxidteilchen ultrakleine superparamagnetische8. Use according to claim 7, characterized in that the superparamagnetic iron oxide particles are ultra-small superparamagnetic
Eisenoxidteilchen mit einem mittleren Durchmesser von weniger als 50 nm sind. Are iron oxide particles with an average diameter of less than 50 nm.
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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1991015243A1 (en) * 1990-04-02 1991-10-17 Cockbain, Julian, Roderick, Michaelson Diagnostic agents
EP0656368A1 (en) * 1992-08-05 1995-06-07 Meito Sangyo Kabushiki Kaisha Small-diameter composite composed of water-soluble carboxypolysaccharide and magnetic iron oxide
WO1998016256A1 (en) * 1996-10-16 1998-04-23 The Burnham Institute Magnetic resonance imaging of thrombi

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB9401483D0 (en) 1994-01-26 1994-03-23 Sandoz Ltd Organic compounds
DE19509694A1 (en) * 1995-03-08 1996-09-19 Schering Ag Use of magnetites to determine the perfusion of human tissue using MR diagnostics
HUP0001608A3 (en) 1996-08-05 2001-01-29 Schering Ag Process for producing contrasting agents for magnetic resonance tomography
DE19811349C1 (en) * 1998-03-16 1999-10-07 Siemens Ag Process for contrast substance tracing using medical imaging appts.
WO2000061191A2 (en) * 1999-04-09 2000-10-19 Advanced Magnetics, Inc. Heat stable coated colloidal iron oxides
EP1181571B1 (en) * 1999-05-21 2008-12-17 GE Healthcare AS Method of magnetic resonance imaging

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1991015243A1 (en) * 1990-04-02 1991-10-17 Cockbain, Julian, Roderick, Michaelson Diagnostic agents
EP0656368A1 (en) * 1992-08-05 1995-06-07 Meito Sangyo Kabushiki Kaisha Small-diameter composite composed of water-soluble carboxypolysaccharide and magnetic iron oxide
WO1998016256A1 (en) * 1996-10-16 1998-04-23 The Burnham Institute Magnetic resonance imaging of thrombi

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of WO0222011A1 *

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