TWI815656B - Method of obtaining pelvic vein images and blood flow velocity using non-contrast magnetic resonance angiography - Google Patents

Abstract

A method that uses non-contrast magnetic resonance angiography to obtain pelvic vein images and blood flow velocity. The patient is placed in a supine position for magnetic resonance scanning, and is equipped with an electrocardiogram monitor and a respiratory monitor; the renal vein, inferior vena cava, and total vena cava are scanned. The coronal and transverse planes of the iliac veins and external iliac veins are used to obtain a two-dimensional image. The two-dimensional image uses a balanced turbine field echo pulse sequence; the coronal plane of the main veins of the abdominal cavity is scanned to obtain a three-dimensional image. , the three-dimensional image uses fast spin echo short inversion time inversion recovery wave sequence, and samples the signal when the above-mentioned electrocardiogram monitor monitors the cardiac systole; quantitative phase contrast analysis technology is used to measure the veins in a two-dimensional plane scan cross-sectional blood flow.

Description

Method of obtaining pelvic vein images and blood flow velocity using non-contrast magnetic resonance angiography

The present invention is a method for obtaining pelvic vein images and blood flow velocity, particularly a method for obtaining pelvic vein images and blood flow velocity using non-contrast magnetic resonance angiography. In this way, pelvic venous lesions and abnormal blood vessel locations can be assessed in a radiation-free manner without the need for imaging agents or other drugs, thereby improving patient safety and diagnostic accuracy.

Pelvic Congestion Syndrome is a common cause of chronic pelvic pain in women of childbearing age. It is usually divided into two structural pathological manifestations, pelvic varicose veins and left ovarian vein congestion and reflux. The cause may be a primary lesion caused by venous insufficiency, or a secondary lesion caused by external compression of the veins. In addition to causing pain, severe injuries may even cause disability. Therefore, it is important to evaluate pelvic depression syndrome to make a correct diagnosis. Common evaluation methods currently include ultrasonic scanning (Ultrasonography), contrast-enhanced Magnetic Resonance Angiography (CE-MRA), computed tomography angiography (CTA) or non-contrast MR imaging. Angiography (Non-contrast Magnetic Resonance Angiography, NC-MRA), etc.

Ultrasound scanning is often the standard test of choice in the evaluation of patients with chronic pelvic pain and can provide hemodynamic information about pelvic venous blood flow. However, ultrasound scans cannot easily reveal specific anatomic pathology, such as the development of collateral vessels. In addition, its interpretation is easily affected by patient obesity, edema, or hip replacement, which in turn affects its accuracy. Although transvaginal ultrasound scans (Transvaginal Ultrasound) can more sensitively detect pelvic diseases, the examination process may cause discomfort to the patient, and the examination execution and image interpretation require professional training.

Another common test tool is contrast-enhanced magnetic resonance angiography and computed tomography angiography. Although these two tests can image the pelvic veins more clearly, they require the use of large amounts of contrast medication, which may cause adverse reactions or complications for the patient. The cumulative radiation dose from CT scans also increases a patient's risk of cancer. Therefore, the above examination is contraindicated in children, pregnant women, or patients with renal insufficiency.

Next, another examination method is non-contrast magnetic resonance angiography, which is a magnetic resonance technology that can obtain blood flow information of blood vessels without the use of contrast agents, eliminating the concern of radiation dose. However, this technology is currently limited to analysis of intracranial arteries and intracranial veins, and some examinations of the heart and aorta. Obtaining pelvic venous images for the assessment of pelvic depression syndrome is still quite limited.

In view of this, the present invention provides a method for obtaining pelvic vein images and blood flow velocity using non-contrast magnetic resonance angiography, which includes: Step 1: The patient lies in a supine position for magnetic resonance scanning, and is equipped with an electrocardiogram monitor and a respiratory Monitor; Step 2: Scan the coronal and transverse planes of the renal vein, inferior vena cava, common iliac vein, and external iliac vein to obtain a two-dimensional image. The above two-dimensional image is obtained using a balanced turbine field echo pulse sequence. ; Step 3: Scan the coronal plane of the main veins in the abdominal cavity to obtain a three-dimensional image. The above three-dimensional image is obtained by using the fast spin echo short inversion time inversion recovery wave sequence and monitoring the systolic phase of the heart with the above-mentioned electrocardiogram monitor. Sampling signals; Step 4: Use quantitative phase contrast analysis technology to measure the cross-sectional blood flow of the vein in a two-dimensional plane scan.

The advantage of this invention is that it provides pelvic vein images and hemodynamic information in a non-invasive manner without relying on contrast agents and radiation-assisted imaging. The above-mentioned two-dimensional images can confirm the relative relationship of blood vessel anatomy; through the above-mentioned three-dimensional images, the position of abnormal blood vessels can be evaluated and the anatomical pathology can be confirmed; through the above-mentioned measurement of the cross-sectional blood flow of the veins, hypothetical symptoms can be confirmed through data analysis. This improves the safety of the test and the accuracy of diagnosis, making the detection of pelvic depression syndrome and other pelvic venous lesions more accurate, convenient and safe.

This invention acquires two-dimensional images through balanced turbine field echo pulse wave sequences, acquires three-dimensional images through fast spin echo short inversion time inversion recovery wave sequences, and measures the cross-sectional blood flow of veins through quantitative phase contrast analysis technology. . The three-dimensional image obtains different signals through the difference in blood flow velocity between the systolic and diastolic phases of the heart. With silhouette technology, the diastolic image and the systolic image are subtracted to remove arterial, bone and soft tissue signals to obtain clear of this three-dimensional image.

Referring to Figure 1, the present invention discloses a method for obtaining pelvic vein images and blood flow velocity using non-contrast magnetic resonance angiography. The steps are as follows:

Step 1 S1: The patient is placed in a supine position for magnetic resonance scanning, and is equipped with an electrocardiogram monitor and a respiratory monitor.

Step 2 S2: Scan the coronal and transverse planes of the renal vein, inferior vena cava, common iliac vein, and external iliac vein to obtain a two-dimensional image. The above two-dimensional image uses a balanced turbine field echo pulse sequence. Among them, the time for scanning the coronal and transverse planes of the renal vein, inferior vena cava, common iliac vein, and external iliac vein is 3 minutes and 45 seconds.

Step 3 S3: Scan the coronal plane of the main veins in the abdominal cavity to obtain a three-dimensional image. The above three-dimensional image is obtained by using the fast spin echo short inversion time inversion recovery wave sequence and monitoring the systolic phase of the heart with the above-mentioned electrocardiogram monitor. Sample the signal. Among them, the time for scanning the coronal plane of the main veins in the abdominal cavity is 2 minutes and 39 seconds.

Step 4 S4: Use quantitative phase contrast analysis technology to measure the cross-sectional blood flow of the vein in a two-dimensional plane scan. Among them, two planes are scanned in the above two-dimensional plane scanning, and each scanning time is 1 minute and 6 seconds.

The total scanning time mentioned above is 8 minutes and 36 seconds, and the complete magnetic resonance imaging examination process takes 30 minutes.

Among them, the parameters of the two-dimensional image using the balanced turbine field echo pulse sequence are: multi-lens two-dimensional mode, echo time = shortest, repetition time = shortest, pixel size = 1.4 × 1 mm, slice thickness = 7 mm, gap = 3.5 mm, signal mean = 1 and fat suppression. The balanced turbine field echo pulse sequence is a gradient echo pulse sequence with a balanced gradient waveform, with data acquisition following an initial preparation pulse to enhance contrast. By combining fat suppression, fat tissue is distinguished from water to produce an image with low signal in background tissue and high signal in blood vessels and body fluids. The clinical advantage of this wave sequence is that it can provide MR images with a high signal-to-noise ratio in a short image acquisition time. It can present clear images of arterial and venous structures at the same time, which is helpful to confirm the relative relationship of vascular anatomy and to diagnose venous compression syndrome with complex manifestations.

Among them, the parameters of this three-dimensional image using fast spin echo short inversion time inversion recovery wave sequence are: multi-lens three-dimensional mode, echo time = 85 milliseconds, repetition time = 1 heart beat, turbine spin echo factor = 37 , inversion recovery delay time = 160 ms and voxel size = 1.7 × 1.9 × 4 mm. Use an electrocardiogram monitor to trigger signals sampled during systole. The scanning plane is the coronal plane, and the scanning area includes the main veins of the entire abdominal cavity.

Among them, the parameters for measuring the cross-sectional blood flow of veins in two-dimensional plane scanning using quantitative phase contrast analysis technology are: two-dimensional quantification, echo time = shortest, repetition time = shortest, flip angle = 20 degrees, pixel size = 1.6 ×2.1 mm, slice thickness = 6 mm and encoding speed = 120 cm/sec. The direction of fluid velocity toward the head is coded as a positive value, while the direction of fluid velocity toward the feet is coded as a negative value. This quantitative analysis of phase contrast scans includes four steps: (a) segmentation of pelvic venous structures; (b) extraction of venous blood flow velocity-time curves; (c) aliasing correction; (d) calculation of quantitative parameters of venous blood flow . The following venous segments were scanned by circling the region of interest: (1) inferior vena cava, (2) left ovarian vein, (3) right external iliac vein, and (4) left external iliac vein. The following quantitative parameters can be obtained for each analyzed venous segment: (1) stroke volume, (2) forward flow, (3) reverse flow, (4) reflux fraction, (5) absolute stroke volume, (6) average Flux, (7) travel distance, (8) average speed.

Referring to Figure 2, the two-dimensional image of actual non-contrast magnetic resonance angiography obtained by the method of the present invention is shown. Because the use of this balanced turbine field echo pulse sequence can present clear images of arterial and venous structures at the same time, helping to confirm the relative relationship of vascular anatomy. As shown in Figure 2 (a), the transverse image shows the congested left renal vein 10. As shown in Figure 2 (b), the coronal image shows the congested left ovarian vein 11.

Refer to Figure 3, which is a schematic diagram of the method of obtaining the three-dimensional image using the short inversion time inversion recovery wave sequence of fast spin echo. As shown in Figure 3(a), the signal intensity time curve of the abdominal aorta is shown. During diastole, the signal in the arteries and veins is higher. During systole, the arterial signal disappears due to the flow void effect caused by rapid blood flow, while the venous signal remains high. In addition, the arterial signal shows low signal during systole and high signal during diastole. Therefore, by triggering the sampling signal at the appropriate time using Gated Imaging Acquisition Technology, the target blood vessel data set can be obtained and used with silhouette imaging technology to reconstruct the three-dimensional blood vessel structure, that is, the three-dimensional image. As shown in Figure 3(b), using gated imaging acquisition technology with the ECG monitor to acquire images during cardiac systole, and using short inversion time inversion recovery technology to suppress the background (fat and bone) signals, only the signal with This three-dimensional image of the venous structure (magnetic venography).

Refer to Figure 4, which is an actual three-dimensional image obtained by the method of the present invention. Because the fast spin echo inverts the recovery wave sequence with a short inversion time and does not rely on flow velocity imaging, it can present a high-resolution independent venous system, which is particularly suitable for showing venous pressure marks, varicose veins, and congested venous structures. As shown in Figure 4 (a), it is a front view of the pelvis, showing left ovarian vein congestion 12 and pelvic varicose veins 13 . As shown in Figure 4(b), it is an oblique view of the pelvis, showing the left common iliac vein pressure mark 14 clearly. The above characteristics are typical manifestations of pelvic depression syndrome.

Refer to FIG. 5 , which is a schematic diagram of the method of measuring a vein segment (region of interest) using quantitative phase contrast analysis technology according to the present invention. The core technology is the use of phase contrast magnetic resonance imaging, which uses the repeated action of bipolar gradients to cause the fluid to exhibit varying degrees of image shifting (Phase Shifting); the greater the fluid velocity, the greater the image shift. Therefore, by measuring the image motion of the target fluid, the velocity behavior of the fluid can be estimated. Quantitative phase contrast analysis technology can analyze hemodynamic models of healthy and pathological blood flow based on objective data results. Image data of two transverse planes are obtained through phase contrast magnetic resonance scanning. By further measuring the image motion signals of pixels within the four venous segments, a hemodynamic model of the pelvic venous system can be effectively established to predict pelvic depression syndrome.

Referring to Table 1 below, the quantitative phase contrast analysis of the present invention is used to analyze the difference in results between 36 patients with pelvic depression syndrome and 10 healthy controls. The results showed that there were differences in the venous measurement parameters of the two groups of subjects, and a number of measurement targets had reached statistically significant differences. In particular, left ovarian venous reflux is more pronounced in patients with pelvic depression syndrome. Patients with pelvic depression syndrome have more significant reflux in the left ovarian vein.

Table 1. Pairwise comparison between 36 patients with pelvic depression syndrome and 10 healthy controls using quantitative phase contrast analysis. If the p value is <0.05, the symbol (*) indicates a significant difference. venous segment disease group healthy control group p value average value standard deviation average value standard deviation stroke amount left ovarian vein 0.79 1.10 0.96 0.42 0.637 inferior vena cava 14.60 4.24 18.55 6.66 0.027* right external iliac vein 5.51 2.18 4.29 1.20 0.029* left external iliac vein 4.58 1.98 3.85 1.28 0.275 forward traffic left ovarian vein 0.31 0.30 0.89 0.51 0.006* inferior vena cava 14.96 4.36 19.20 6.59 0.02* right external iliac vein 5.62 2.20 4.45 1.35 0.303 left external iliac vein 4.69 2.16 3.94 1.30 0.119 reverse traffic left ovarian vein 2.13 9.48 0.07 0.22 0.5 inferior vena cava 0.35 0.96 0.64 1.13 0.422 right external iliac vein 0.10 0.30 0.16 0.33 0.63 left external iliac vein 0.10 0.47 0.09 0.20 0.904 Reflux score left ovarian vein 12.87 22.37 0.00 0.00 0.001* inferior vena cava 2.21 5.24 3.35 5.83 0.555 right external iliac vein 1.95 5.41 2.81 5.30 0.66 left external iliac vein 1.45 4.71 1.97 4.83 0.758 Absolute stroke volume left ovarian vein 0.87 1.06 0.96 0.42 0.793 inferior vena cava 15.31 4.68 19.84 6.72 0.018* right external iliac vein 5.72 2.20 4.61 1.56 0.146 left external iliac vein 4.79 2.42 4.02 1.36 0.343 average flux left ovarian vein 0.95 1.36 1.02 0.48 0.874 inferior vena cava 17.50 5.87 19.95 8.49 0.296 right external iliac vein 6.30 2.78 4.31 1.25 0.003* left external iliac vein 5.17 2.18 3.86 1.29 0.078 Travel distance left ovarian vein -0.37 3.01 3.36 2.81 0.001* inferior vena cava 8.92 2.88 12.76 7.40 0.14 right external iliac vein 5.81 2.06 4.44 1.42 0.054 left external iliac vein 5.18 1.75 3.65 1.12 0.013* average speed left ovarian vein -0.46 3.62 3.53 3.14 0.003* inferior vena cava 13.34 7.01 13.34 7.01 0.266 right external iliac vein 6.59 2.37 4.43 1.28 0.008* left external iliac vein 5.89 2.09 3.65 1.04 0.002*

Refer to Table 2 below, which discloses the statistics of the results of 46 subjects using the present invention and ultrasound to diagnose pelvic depression syndrome. The results in Table 2 are then calculated by the formulas in Table 3 to obtain the values in Table 3. The final results showed that the sensitivity, specificity and accuracy of non-contrast magnetic resonance imaging were 80.6%, 90% and 82.6% respectively. The inter-rater reliability (Inter-Rater Agreement) result shows that the Cohen’s Kappa value is 0.58, which is moderate agreement (Moderate Agreement).

Table 2 shows the statistics of the results of using the present invention and ultrasound to diagnose pelvic depression syndrome respectively. Ultrasound result was positive Ultrasound results were negative The result of this invention is positive 29(TP) 1(FP) The result of this invention is negative 7(FN) 9(TN)

In the above Table 2, when the ultrasound result is positive and the result of the present invention is also positive, it is expressed as True Positive (TP); when the ultrasound result is negative and the result of the present invention is positive, it is expressed as False Positive (TP). Positive, FP); when the ultrasound result is positive and the invention is negative, it is expressed as False Negative (FN); when the ultrasound result is negative and the invention is negative, it is expressed as True Negative , TN) represents it. Enter the above true positives, false positives, true negatives and false negatives into the formulas in Table 3 below.

Table 3. Calculation of the results of diagnosing pelvic depression syndrome using the present invention and ultrasound respectively. Value (percentage) Formula calculation Sensitivity(TPR) 80.6% TPR=TP/(TP+FN) Specificity (SPC) 90% SPC=TN/(FP+TN) Precision (PPV) 96.7% PPV=TP/(TP+FP) Negative predictive value (NPV) 56.3% NPV=TN/(TN+FN) False positive rate (FPR) 3% FPR=FP/(FP+TN) False discovery rate (FDR) 4% FDR=FP/(FP+TP) False Negative Rate (FNR) 19.4% FNR=FN/(FN+TP) Accuracy(ACC) 82.6% ACC=(TP+TN)/(TP+TN+FP+FN)

Based on the above and the statistical inference from Table 1, Table 2 and Table 3, the method of using non-contrast magnetic resonance angiography to obtain pelvic vein images and blood flow velocity according to the present invention can effectively evaluate the pelvic venous system and help diagnose pelvic congestion. Syndrome.

10: Congested left renal vein

11:Congested left ovarian vein

12: Left ovarian vein congestion

13:Pelvic varicose veins

14: Left common iliac vein pressure mark

S1: Step 1

S2: Step 2

S3: Step three

S4: Step four

[Figure 1] is a block diagram of the operation flow of the present invention. [Figure 2] is an actual two-dimensional image obtained by the method of the present invention. [Figure 3] is a schematic diagram of the method of obtaining three-dimensional images using fast spin echo short inversion time inversion recovery wave sequence. [Figure 4] is the actual three-dimensional image obtained by the method of the present invention. [Figure 5] is a schematic diagram of the method of measuring venous segments using quantitative phase contrast analysis technology according to the present invention.

S1: Step 1

S2: Step 2

S3: Step three

S4: Step four

Claims (5)

A method of using non-contrast magnetic resonance angiography to obtain pelvic vein images and blood flow velocity, including: Step 1: The patient lies in a supine position for magnetic resonance scanning, and is equipped with an electrocardiogram monitor and a respiratory monitor; Step 2: Scan The coronal and transverse planes of the renal vein, inferior vena cava, common iliac vein, and external iliac vein are used to obtain two-dimensional images. The above two-dimensional images are obtained using a balanced turbine field echo pulse sequence; Step 3: Scan the abdominal cavity The coronal plane of the main veins is used to obtain a three-dimensional image. The above three-dimensional image is made by using the fast spin echo short inversion time inversion recovery wave sequence, and the signal is sampled when the above-mentioned electrocardiogram monitor monitors the systole of the heart; Step 4: Quantitative phase contrast analysis technology is used to measure the cross-sectional blood flow of veins in a two-dimensional plane scan, wherein the above-mentioned quantitative phase contrast analysis technology includes the following steps when performing quantitative analysis of phase contrast scans: (a) Segmentation of pelvic vein structures ; (b) Extract venous blood flow velocity time curve; (c) aliasing correction; (d) Calculate quantitative parameters of venous blood flow. The method of using non-contrast magnetic resonance angiography to obtain pelvic vein images and blood flow velocity as described in claim 1, wherein the parameters used in the above-mentioned balanced turbine field echo pulse sequence are multi-lens two-dimensional mode, echo Wave time, repetition time, pixel size, slice thickness, gaps, signal averaging and fat suppression. The method of using non-contrast magnetic resonance angiography to obtain pelvic vein images and blood flow velocity as described in claim 1, wherein the parameters used in the fast spin echo short inversion time inversion recovery wave sequence are multi-lens 3D mode, echo time, repetition time, turbine spin echo factor, inversion recovery delay time and voxel size. Use of non-contrast magnetic resonance angiography to obtain pelvic venograms as described in claim 1 The method of imaging and blood flow velocity, wherein the parameters used in the above quantitative phase contrast analysis are two-dimensional quantization, echo time, repetition time, flip angle, pixel size, slice thickness and encoding speed. The method of using non-contrast magnetic resonance angiography to obtain pelvic vein images and blood flow velocity as described in claim 1, wherein the above-mentioned sampling signal is acquired through gated imaging acquisition technology.