RU2546092C1 - Method for contrast magnetic resonance angiography of cerebral vessels - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention can be used in conducting 3DFFE pulse-train magnetic resonance brain imaging (MRI). That is characterised by low rotation angles FA=13, and the first phase of 3DFFE angiography prior to contrast enhancement has a section thickness up to 2.4 mm, which covers the brain completely and lasts for 60 s. The second phase accompanies intermittent intravenous administration of a contrast preparation in the concentration of 0.25 mmol/ml, in a dose of 0.2 mmol/kg at 1 ml/s. The contrast preparation is gadolinium preparation - Gd-DTPA, Gd-DO3A, Gd-DOTA or a manganese complex of Mn(II)-trans-1,2-cyclohexanediamine-N,N,N',N'-tetraacetic acid.

EFFECT: higher accessibility of contrast MRA, and the information value of the contrast 3DFFE MRA as compared to contrast-free 3DTOF angiography in diagnosing arterial aneurisms.

3 dwg, 1 tbl

Description

The invention relates to medicine, namely to the field of radiation diagnostics, and can be used in magnetic resonance imaging when conducting magnetic resonance angiographic studies of the brain.

A known method of magnetic resonance contrast imaging of cerebral vessels for the diagnosis of arterial aneurysms, presented in detail [1, 2, 3] and consisting in the intravenous administration of a subject gadolinium-containing compounds (Gd-DTPA, Gd-DO3A, Gd-DOTA, etc.) dose volume up to 20 ml at a concentration of 0.5 mmol / ml at a rate of 1-2 ml / sec, followed by washing the system with physiological saline in a volume of up to 30 ml. Scanning is performed using a 3D fast gradient echo pulse sequence (3DFFE, 3DFLASH), usually using a high-field superconducting MP tomograph with a field strength of 3.0 Tesla and subsequent three-dimensional reconstruction of the distribution of the gadolinium-containing drug.

The disadvantages of the presented method should be highlighted - the low availability of a high-field superconducting MP scanner with a field strength of 3.0 Tesla, the lack of advantages of contrast 3DFFE angiography relative to non-contrast 3DTOF angiography, and the lack of dynamics. informativeness in their joint assessment, as a result, the unreasonably high cost of magnetic resonance angiographic research.

This method is the closest to the claimed technical essence and the achieved result and is selected as a prototype.

The objective of the invention is to increase the availability of the method of contrast magnetic resonance angiography (MRA) using a high-field superconducting MRI tomograph with a field strength of 1.5 Tesla, to increase the information content of the contrast 3DFFE MRA relative to the non-contrast 3DTOF MRA in the diagnosis of arterial aneurysms.

The problem is solved by conducting a comprehensive magnetic resonance angiographic study of the brain by sequentially performing 2D studies weighted by T2 and T1 before and after administration of a contrast paramagnet preparation, as well as non-contrast 3DTOF and contrast three-phase 3DFFE angiography. To increase the contrast of the arterial vessels of the brain, small rotation angles of FA = 13 are used and a gadolinium- or manganese-containing contrast agent is administered during the entire first phase of 3DFFE studies at a rate of 1 ml / sec at a concentration of 0.25 mmol / ml, in a dosage depending on the duration single phase 3DFFE studies: 0.1 mmol / kg - up to 20 seconds, 0.15 mmol / kg - up to 40 seconds and 0.2 mmol / kg - up to 60 seconds. As a paramagnetic contrast agent, gadolinium-containing contrast agents (based on Gd-DTPA, Gd-DO3A or Gd-DOTA) or a complex of manganese (II) with trans-1,2-cyclohexanediamine-N, N, N ′, N′-tetraacetic are used acid (CDTA).

New in the proposed method is the use of a low angle of rotation FA = 13, a reduced concentration of paramagnet to increase the volume of the injected contrast drug without loss of quality of angiographic images due to the dose-dependent effect of paramagnets and prolonged circulation of cyclic contrast compounds (Gd-DO3A, Gd-DOTA and Mn-CDTA) ; the use of a complex of Mn (II) with trans-1,2-cyclohexanediamine-N, N, N, N-tetraacetic acid (CDTA) as a paramagnetic contrast agent, and the use of doses of a contrast compound depending on the duration of one phase of the 3DFFE study.

The invention will be clear from the following. In experimental studies on phantoms (Fig. 1), changes in the image intensity of a T1-weighted 3DFFE image with Mn-CDTA and Gd-DTPA are visualized: with a decrease in the degree of deviation (FA), a gradual increase in the intensity of phantoms containing a contrast compound is observed in each case. At an angle of deviation of FA = 12 degrees, according to Student's criterion, a significant difference in the intensity of the image of water (p << 0.05) from the phantom is determined at FA = 30 degrees, and at an angle of deviation of FA = 13 degrees, the differences in intensities of the phantom with water differ insignificantly (p> 0.05) . Thus, FA = 13 degrees should be considered the most optimal deflection angle.

At a rotation angle of FA = 30 degrees, the contrast-noise coefficients (CNR) for the phantoms 0.25, 0.5, 1.0, and 2.0 mmol / L were 2.5 ± 2.4, 11.2 ± 3, 28.2 ± 4.6, 58.1 ± 6.3, respectively. With a decrease in the rotation angle to FA = 13 degrees, the contrast noise coefficients (CNR) were 17.1 ± 1.5, 32.6 ± 1.5, 52.7 ± 2.3, 74.0 ± 2.7, respectively. In a statistical paired analysis by the T-criterion, the differences are significant (p <0.05). Thus, reducing the rotation angle to 13 degrees causes a significant increase in 3DFFE image.

When using a standard dose of 0.1 mmol / kg and with a scan time of 53 seconds, a marked decrease in the contrast effect is noted (Fig. 2). In this example, the contrast-noise ratio for the supracavernous segment of the ICA (right) in the arterial phase was CNR = 11.9, and in the venous phase CNR = 22.1.

In a clinical study (Table 1), the goal was to find the optimal dose of contrast medium (Gd-DO3A) when performing contrast MPA according to the 3DFFE protocol with a duration of one phase of scanning up to 60 seconds.

Table 1 presents the contrast noise ratio (CNR) for the middle cerebral artery on both sides with contrasting MPA with the Gadovist drug (Gd-DO3A) at a dose of 0.2 and 0.15 mmol / kg weight for up to 60 seconds.

Table 1 Dose 0.2 mmol / kg (n-20) 0.15 mmol / kg (n = 20) Mean Lower quartile Upper quartile SD Mean Lower quartile Upper quartile SD FROM FROM N N R R Arterial phase SMA on the right 72.1 64.9 88.4 14.7 53.6 38.8 73.9 22.2 SMA on the left 64.5 53.9 81.2 16.3 40 30.6 69.5 22.3 Venous phase SMA on the right 63 56.7 69.3 8.5 61.8 51,2 74.7 16.3 SMA on the left 59.6 52,5 67.2 9.5 64.1 50.6 69.5 15.7 Note: n is the total number of measurement points in 16 angiographic studies at a dose of 0.15 and 0.2 mmol / kg, Mean CNR is the average value of the contrast-noise ratio, SD is the standard deviation, SMA is the average cerebral artery.

Statistical assessment of differences in contrast-noise (CNR) coefficients on the left and right SMA in the first group with a dose of 0.15 mmol / kg for dependent samples in the arterial and venous phases by Wilcoxon test revealed significant differences (p <0.05) in contrast-noise coefficients ( CNR) only on the left artery in the arterial and venous phases. In the arterial phase, the contrast of the left MCA is at a low level, and in the venous phase it increases, which indicates that the dose of the contrast agent is insufficient to obtain optimal contrast of the arteries. In the second group, at a dose of 0.2 mmol / kg, significant differences were revealed (p <0.05) in both the left and right SMA in the arterial and venous phases, and at a dose of 0.2 mmol / kg, the contrast of the left and right SMA in the arterial phase is higher than into the venous. Thus, the contrast effect depends on the dose, and not on the concentration of the solution of the contrast drug.

In a clinical example (Fig. 3), it is shown that with an increase in the dose of the contrast agent to 0.2 mmol / kg of weight, as well as with the dilution of the contrast agent (reptile in a ratio of 1: 3) and the rate of administration of the contrast agent to 1 ml / sec the predominance of the intensity of the arteries of the brain over the intensity from the vessels of the venous channel during the first phase of the scan. In the second phase of the scan, an equalization of the contrast of the arteries and veins of the brain was observed.

When studying the pathology of cerebral vessels using 3DTOF and 3DFFE angiography in patients (n = 88) with arterial aneurysms and malformations of the cerebral vessels, it was revealed that when using 3DFFE angiography, there were no significant differences (according to Kappa analysis) with 3DTOF in the information content of the diagnosis of arterial aneurysms although 3DTOF showed 3 false negative results that were clearly visible with 3D FFE angiography. When diagnosing vascular malformations (arterial, venous and mixed) using 3DFFE angiography, there is a significant increase in sensitivity by 53% compared to 3DTOF relative to the results of a combined diagnosis, including a 2D study, weighted by T2 and T1 before and after contrast enhancement, as well as non-contrast 3D TOF and contrast 3D FFE angiography.

The principal advantage of the proposed algorithm for complex magnetic resonance angiographic examination of the brain is that this technique can be performed on any magnetic resonance tomographs with a magnetic field strength of 1.5 Tesla and with a diagnostic accuracy of 100%.

Distinctive features showed in the claimed combination fundamentally new properties that are not derived from the prior art and are not obvious to a specialist.

We did not find an identical population in known solutions. The proposed method can be used in practical health care for brain research. Based on the foregoing, the claimed invention should be considered relevant to the conditions of patentability "Novelty", "Inventive step", "Practical applicability".

The invention will be apparent from the following description and the accompanying drawings.

Fig. 1 shows a phantom experiment in 3DFFE mode with a deflection angle of 30 (left) and 13 (right) degrees: in columns from top to bottom, the concentration changes 0.25, 0.5, 1.0 and 2.0 mmol / l, in the line from left to right there are contrast compounds of different prescription: Mn-CDTA (1 week), Mn-CDTA (3 years), Mn-CDTA (4 years) and Gd-DTPA (omniscan 4-5 years).

Figure 2 shows a clinical example of patient K., 41 years old. Projections of the maximum intensity of subtraction contrast MPA of high spatial resolution in the arterial, venous and late venous phases.

Figure 3 shows a clinical example of patient A., 53 g. Subtraction images of the projections of maximum intensities during MP angiography of 3DFFE cerebral vessels with gadovist (Gd-DO3A): arterial and venous phase of contrast enhancement. The ratio of contrast noise in the arterial phase of both SMA was 60.2 ± 14.0

The method is as follows.

The patient is placed on the diagnostic table of the MP scanner in accordance with the design requirements of a particular MP scanner. Then, magnetic resonance imaging is performed in T2- and T1-weighted modes, in standard modes for this type of equipment, in axial, sagittal or frontal planes or in planes oriented along planes parallel to the base of the brain with full coverage of the brain.

Then perform non-contrast 3DTOF angiography with a slice thickness of at least 1.3 mm with interpolation and full coverage of the brain area. Then, the first phase of 3DFFE angiography is performed to contrast enhancement with a slice thickness of up to 2.4 mm, a total of up to 80, with a full coverage of the brain area, the duration of one phase of scanning is up to 60 seconds. The second phase of the 3DFFE study is performed against the background of a bolus intravenous administration of a contrast agent based on gadolinium (Gd-DTPA, Gd-DO3A or Gd-DOTA) or a solution of manganese (II) -CDTA at a concentration of 0.25 mmol / ml, at a dose of 0.2 mmol / kg, at a rate of 1 ml / sec. The start time of the second phase scan can be fixed at 13 seconds or can be selected prospectively using the function of monitoring the receipt of a bolus in the area of interest. The third and fourth phases of contrast 3DFFE angiography are performed sequentially (Fig. 3). Then perform magnetic resonance imaging with obtaining T1-weighted images in compliance with the same research parameters as before the introduction of this paramagnetic contrast medium.

Then, the intensity of magnetic resonance imaging images is compared in a T1-weighted mode before and after administration of the contrast compound. The enhancement of the MRI image of the brain as a result of the administration of a contrast agent occurs in proportion to the accumulation, which in turn reflects the degree of damage to the blood-brain barrier of brain tissue. Angiographic images of non-contrast and contrast angiography are first evaluated separately, and then the results are compared with each other and with a 2D study before and after contrast enhancement.

The proposed method was investigated with gadolinium-containing contrast agents in a group of patients with vascular pathology (n = 88). Data were obtained on the information content of the diagnosis of cerebrovascular diseases by the method of complex magnetic resonance angiography using complex gadolinium compounds (Gd-DO3A and Gd-DTPA). The equivalence of visualization capabilities of large vessels of the body and the head region in the experiment between Gd-DO3A and Mn-CDTA is proved. Based on the greater availability and low cost (a fact that does not require proof) of magnetic resonance imaging scanners with a magnetic field strength of 1.5 Tesla than 3.0 Tesla, as well as the high efficiency of visualization of cerebral vessels in animal experiments and in clinical studies, we can conclude that using the method will significantly improve the diagnosis of cerebrovascular disease, and if introduced into clinical practice, the Mn-CDTA compound as a contrast agent will reduce the cost of research compared with traditionally used visualization methods.

Literature

1. Pierot L, Portefaix C, Rodriguez-Régent C, Gallas S, Meder JF, Oppenheim C Role of MRA in the detection of intracranial aneurysm in the acute phase of subarachnoid hemorrhage. J Neuroradiol. 2013 Jul; 40 (3): 204-10. doi: 10.1016 / j. neurad. 2013.03.004. Epub 2013 May 9.

2. Pierot L, Portefaix C, Boulin A, Gauvrit JY. Follow-up of coiled intracranial aneurysms: comparison of 3D time-of-flight and contrast-enhanced magnetic resonance angiography at 3T in a large, prospective series Eur Radiol 2012 Oct; 22 (10): 2255-63. doi: 10.1007 / s00330-012-2466-6. Epub 2012 May 9.

3. Mujagić S, Bećirović-Ibrišević J. The developmental venous anomaly associated with the cavernous malformation Acta Med Acad. 2012; 41 (2): 219-20. doi: 10.5644 / ama2006-l24.55.

Claims (1)

A method of contrast magnetic resonance angiography of the brain based on the 3DFFE pulse sequence, characterized in that they use small rotation angles FA = 13, and the first phase 3DFFE angiography, before contrast amplification, is performed with a slice thickness of up to 2.4 mm with a full coverage of the brain area with a duration phases up to 60 s, and the second phase is performed against the background of a bolus intravenous administration of a contrast drug at a concentration of 0.25 mmol / ml, at a dose of 0.2 mmol / kg, at a rate of 1 ml / s, using the drug as a contrast drug t based on gadolinium - Gd-DTPA, Gd-DO3A, Gd-DOTA or a manganese-containing complex of Mn (II) -trans-1,2-cyclohexanediamine-N, N, N ', N'-tetraacetic acid.

Images