RU2454174C2 - Method of diagnosing cervical tumours - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention relates to medicine, radiodiagnostics and can be used for detection and evaluation of extension of cervical tumours by means of magnetic-resonance tomography with application of intravaginal contrasting viscous substance (IVCVS). First, carried out is native examination of area of interest with analysis of T1 fast spin-echo SI in sagittal, axial planes and in plane with perpendicular location of examination axis to tumour, as well as coronary T2 SI in mode with fat-suppression. After that, performed is dynamic examination with contrast amplification in the same planes. Double contrasting is performed, which includes intravenous introduction of contrasting preparation gadolinium and intravaginal introduction of IVCVS, as such used is colloidal starch solution with viscosity 55000-65000 cP in volume 80-120 ml. Dynamic scanning is started when contrasting preparation in visualised in terminal part of abdominal aorta.

EFFECT: method ensures high accuracy of evaluation of tumour extension, increase of visualising image characteristics due to contrasting light background with respect to dark vagina wall, reduction of IVCVS allergenicity.

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Description

The invention relates to medicine, namely to radiation diagnostics and can be used if necessary to identify and assess the prevalence of cervical tumors.

Currently, one of the main tasks in magnetic resonance diagnostics is to accurately determine the stage and prevalence of the tumor process. The solution to this problem will allow a more differential approach to the patient’s treatment tactics both at the preoperative stage (determination of indications for neoadjuvant chemoradiotherapy or chemotherapy), the intraoperative stage (determination of the scope of surgical intervention), and in the postoperative period to decide whether it is advisable to undergo adjuvant chemoradiation or chemotherapy.

There is a method of optimizing the assessment of the local prevalence of cervical tumors by applying itravaginal contrast during magnetic resonance imaging, including intravaginal administration of a contrasting viscous substance and conducting studies in axial, coronary and sagittal projections [Leiven Van Hoe, Dirk Vanbeckevoort, Raymond Oyen, Ulrike Itzlinger Ignace Vergote Cervical carcinoma: Optimized Local staging with intravaginal contrast-enhanced MR-imaging - Preliminary results.// Radiology 1999 - 213: 608-611]. In the known method as an intravaginal contrasting viscous substance, a mixture of 20 ml of calcium maltodextrin calcium lactate (Nutrition, Zoetermeer the Netherlands), 100 ml of water, 100 ml of dissolved barium sulfate is used.

Research is carried out on a tomograph with a field power of 0.3T. At the beginning, a native study of T1 spin echo and T2 VI of fast spin-echo sequences in axial, sagittal projections, in projections with a perpendicular location of the research axis to the tumor and coronary T2 VI using fat suppression is performed. Then fill the vagina with a contrasting mixture (volume from 220 ml) and carry out similar research protocols in similar projections.

However, when using the known method in clinical practice, the following technical (diagnostic) results cannot be achieved for the following reasons:

- potentially high allergenicity of intravaginal contrast agent,

- the difficulty of differentiating the unchanged vaginal wall from the affected tumor in the case of a small spread of the tumor in the vaginal wall,

- the high cost of the components of the contrasting mixture and the complexity of its preparation.

At the same time, a known method for examining the colon by magnetic resonance imaging [Wallengren NO, Holtås S, Andren-Sandberg A, Jonsson E, Kristoffersson DT, McGill S. Rectal carcinoma: double-contrast MR imaging for preoperative staging. Radiology 2000 Apr; 215 (1): 108-14], including the intrarectal administration of a contrasting viscous substance and the conduct of native research in axial, coronary and sagittal projections, and then the administration of preparations containing gadolinium salts, intravenously (iv) and dynamic scanning in the same planes - comparative image analysis. In the known method, viscous microcrystalline cellulose with xantham rubber-like granules with the addition of iron-containing contrast material Abdoskan (Nycomed) consisting of a sulfonated styrene-divinylbenzene copolymer associated with iron oxides of two and trivalent is used as an intrectal contrasting viscous substance. For dynamic contrast enhancement, Omniscan (Nycomed) is used, administered intravenously at a dose of 1 mmol / kg body weight. Research is carried out on a tomograph with a field power of 0.3T. At the beginning, a native study of T1 spin echo and T2 VI of fast spin-echo sequences in axial, sagittal projections, in projections with a perpendicular location of the axis of the study to the tumor and coronary T2 VI using fat suppression is performed. Then the intestine is filled with a contrasting mixture (volume from 200 to 400 ml, maximum 450 ml) and a study is carried out in similar projections with a bolus contrast enhancement followed by analysis of the obtained T1 fast spin-echoes of the VI with fat suppression, in the sagittal plane and the plane perpendicular to the axis passing through the part of the intestine containing the tumor.

The disadvantages of this method are the potentially high allergenicity of the intrarectal contrast medium, the difficulty of differentiating the intestinal wall and the lumen filled with contrast medium, which complicates the analysis of the obtained images due to the low contrast between the dark background of the intestinal lumen and the dark intestinal wall (the image shows a negative background of the intestinal lumen), high the cost of the components of the contrasting mixture and the complexity of its preparation.

The invention is aimed at solving the problem of identifying and assessing the prevalence of cervical tumors.

Using in clinical practice the proposed method allows to achieve several technical (diagnostic) results:

- the ability to accurately assess the prevalence of the tumor, thanks to the use of intravenous contrast enhancement with gadolinium salts,

- improving the visualization characteristics of the image due to the contrasting light background in relation to the dark wall of the vagina,

- reduction of allergenicity of intravaginal contrast agent,

- reduction of economic costs with sufficient indicators of diagnostic efficiency due to the low cost of the used intravaginal contrast agent with a relatively short duration of the preparatory phase prior to the study.

These technical and diagnostic results in the implementation of the invention are achieved due to the fact that, as in the known method, the detection and assessment of the prevalence of cervical tumors is carried out by native research T1 spin echo and T2 VI fast spin echo sequences in axial, sagittal projections, in projections with the perpendicular arrangement of the axis of the study to the tumor and coronary T2 VI using the regimes of fat suppression, intravaginal administration of a contrasting viscous substance and prov Denia similar study protocol in similar projections.

A feature of the proposed method lies in the fact that magnetic resonance imaging is carried out by double contrasting, including an intravenous contrast drug containing gadolinium salts and intravaginal administration of a contrast agent. Moreover, a colloidal starch solution with a viscosity of 55,000-65,000 cP in a volume of 80-120 ml is used as a contrasting substance. Dynamic scanning begins when a contrast agent is detected in the terminal abdominal aorta.

The invention consists in the following.

Identification of the primary cervical tumor in locally advanced processes does not cause particular difficulties, however, to date, the assessment of the prevalence of the tumor is difficult, especially if the tumor is localized in the vaginal portion of the cervix, has a massive exophytic component intimately adjacent to the arches and walls of the vagina. In these cases, certain difficulties may arise for interpreting the state of closely spaced structures.

In other words, the difficulty of differentiating the intimate diligence of a tumor with true involvement. In cases where vaginal structures are involved in the tumor process, difficulties may arise in determining the extent of the identified involvement against the background of diligence of the tumor.

The inventive method allows to solve these problems by using an intravenous contrast enhancement with gadolinium salts, which allows a significantly greater accuracy to evaluate the spread of the tumor along the vaginal wall, together with intravaginal administration of a starch solution as a contrasting viscous substance. Improving the visualization characteristics of the image is achieved due to the contrasting light background in relation to the dark wall of the vagina, which generally increases the accuracy of diagnosis.

As a rule, tumor tissues have a more developed vasculature, consisting of atypical vessels. Normally, a typical accumulation of a contrast agent in the vasculature is observed for all tissues and organs of the small pelvis. The dynamic contrast enhancement technique allows you to visualize areas of atypical accumulation against their background. On scans obtained in the process of dynamic contrast enhancement, areas of tumor tissue are visualized by areas of increased MR signal (amplification is more intense compared to adjacent tissues). Altered lymph nodes, which make up the regional lymph drainage collectors, also have the same characteristics. Thus, dynamic intravenous contrast enhancement allows the visualization of tumor changes in the cervix, vaginal wall and secondarily changed regional lymph nodes.

The advantages of using a colloidal starch solution with a viscosity of 55,000-65,000 cP as a contrast agent are due to the following physicochemical properties. Evenly filling the vaginal cavity, starch pushes its walls and fills the free spaces between them and the tumor, straightens the walls of the vagina, thereby significantly improving the visualization of the revealed changes. It was experimentally established that the specified range of viscosity is necessary and sufficient for uniform volumetric exposure to the walls of the vagina and their expansion.

Starch refers to non-toxic drugs, does not affect the microflora of the vagina and the wall of the vagina, is not absorbed, does not have systemic effects, is chemically inert. Colloidal starch solution is easy to prepare and available in any region of the Russian Federation.

The method is as follows.

Before the start of the study, an intravaginal contrast agent is prepared, using food starch (C ₆ H ₁₀ O ₅ ) _n . The contrast agent is used in the form of a colloidal solution of uniform consistency with a viscosity of 55,000-65,000 cP. The viscosity value is evaluated at a cylinder speed of a rotational viscometer of 20 s-1 and room temperature.

For intravenous bolus contrast enhancement, any of the contrast preparations containing gadolinium salts is used in the required dosages according to the instructions for its use.

Initially, a region of interest is scanned without contrast enhancement, then a dynamic MR study is performed, the start of which is combined with the start of the administration of a contrast drug containing gadolinium salts. After the end of its introduction, saline solution is completely introduced; after 7 seconds from the beginning of the administration of the contrast agent, scanning begins, parallel to the completion of the administration of saline. This sequence has a saturation time of 2 seconds and is repeated after 2 seconds. Scanning is performed in order to obtain T1 VI using 3-dimensional gradient echo sequences (3D GRE - TE: 2.49 ms, TR: 6ms, flip angle: 10, thickness: 2.5 mm, FOV: 40-43 cm, matrix: 128 × 192) pre-saturated fat (fatsat SE). Further, the sequences used in all patients are used: T1 VI images of spin-echo sequences (SE) and spin-echo sequences with pre-saturated fat (fatsat SE). The region of interest is sequentially scanned six times, thus, the dynamics of filling the vascular and microvasculature with a contrast agent are reflected in the obtained images.

A dynamic MRI study is performed with a vagina contrasted with an intravaginal contrast medium (colloidal starch solution). A contrast agent (colloidal starch solution) is introduced into the vagina through a silicone catheter. A catheter is inserted to the length of the vagina to the level of the cervix. The output section of the vagina is swabbed with a gauze swab to prevent leakage of the colloidal starch solution and create conditions for straightening the walls of the vagina.

The patient is evenly and conveniently placed on the table, as for a routine examination of the pelvic organs, a gradient coil is placed on top and fixed, an intravenous catheter connected to a syringe injector charged with a contrast agent is placed on top of the patient. Diagnostic research is carried out by sequential analysis of native T1 fast spin-echo VI in the sagittal plane, T2 fast spin-echo VI in three planes (sagittal, axial and the plane perpendicular to the axis passing through the part of the vagina and cervix containing the tumor), coronary T2 VI in fat reduction mode. Then, before the start of the dynamic sequence, the study is stopped, the patient is pulled out of the tomograph tunnel, and the gradient coil is removed; intravaginally, in the patient’s position on the back with the legs apart, legs bent at the knees, the resulting colloidal starch solution is injected into the vagina in an amount of 80-120 ml under the control of the patient’s sensations.

When performing the introduction, the patient’s displacement is avoided as much as possible, for the most accurate comparison of the obtained images of dynamic contrast enhancement with native images. After that, the patient assumes the initial comfortable and even position on the table, the gradient coil is laid back and secured, the table with the patient is pushed into the tunnel, re-marking scans, shimming and a study with dynamic contrast enhancement (Dynamic 3D Fatsat, FFE sequence) are performed. Then, dynamic contrast images T1 VI are analyzed for fast spin-echo with fat suppression, made in the plane perpendicular to the segment of the vagina containing the tumor. Compare these images with native images obtained in three planes.

Execution examples

The authors use a contrasting drug for intravenous contrast enhancement "Omniscan" at a dosage of 20.0., Saline solution of sodium chloride 0.9% at a dosage of 200.0. These substances are collected in two standard syringes for an automatic injector synchronized with an MRI scanner; syringes are connected with a standard system for intravenous infusion.

Example 1

Patient A., born in 1957 She was admitted with a diagnosis of cervical cancer T2a stage. In accordance with the claimed method, the vagina was contrasted with 110 ml of starch with a viscosity of 55,000 cP and 20.0 ml of the Omniscan intravenous contrast drug (gadolinium salt), 80.0 ml of saline. The study was performed on a Toshiba EXCELART Vantage Titan 1.5T tomograph using a flexible four-segment gradient coil QD body coil A. In this case, dynamic scanning was started when a contrast agent was detected in the terminal abdominal aorta. Images were obtained in axial, coronary and sagittal projections, then a comparative analysis of the images was carried out to clarify the spatial distribution of the tumor. On the series obtained by MRI, a circular tumor formation up to 2.5 cm long is determined in the cervix that extends to the entire thickness of the stromal ring and with the involvement of the vagina to the level of its middle third (the left wall of the vagina is infiltratively thickened to 1.9 cm with loss of layer differentiation, the extent of the changes is up to 2.8 cm).

Example 2

Patient F., born in 1949 A vaginal-parametrial variant was admitted with a diagnosis of cervical cancer T2b stage. In accordance with the claimed method, the vagina was contrasted with 90 ml of starch with a viscosity of 55,000 cP and 20.0 ml of the intravenous contrast drug (gadolinium salt) Omniscan 20.0 ml of 80.0 ml of saline. On the series obtained by MRI, a circular tumor formation up to 3.6 cm long is determined in the cervix that extends to the entire thickness of the stromal ring with signs of the process going out to the left parametrium to a depth of 1.0 cm in a 1.5 cm section and involving the vagina to the level of its lower third (vaginal wall infiltratively thickened to 1.6 cm with loss of differentiation of the layers, the extent of the changes is up to 3.9 cm).

Figure 1 presents the image of the contrasted vagina with the presence of a tumor located in the left semicircle (example 1);

Figure 2 presents the image of the contrasted vagina, in the upper third of which the spread of the cervical tumor to the upper third of the vagina is determined (example 2).

Thus, the claimed method has the following advantages: simple to perform, does not require the preparation of complex solutions, does not require a lot of preparation time, allows you to obtain diagnostic images with higher visualization characteristics. Intravenous contrast enhancement increases diagnostic efficacy in detecting the prevalence of a cervical tumor, has a low cost.

Claims (1)

A method for detecting and evaluating the prevalence of cervical tumors by magnetic resonance imaging using an intravaginal contrasting viscous substance, characterized in that at first they conduct a native study of the area of interest with the T1 analysis of fast VI echoes in the sagittal, axial plane and the plane with the perpendicular axis of the study axis to the tumor, as well as coronary T2 VI in the regime with fat suppression, then conduct a dynamic study with contrast enhancement in the same planes, etc. this uses double contrasting, including intravenous administration of a contrast agent gadolinium and intravaginal administration of a contrasting viscous substance, which is used as a colloidal starch solution with a viscosity of 55,000-65,000 cP in a volume of 80-120 ml, and dynamic scanning is started when a contrast agent is detected in the terminal abdominal aorta.

Images