Updates in Magnetic Resonance Venous Imaging

Superior arterial signal suppression in lower extremity magnetic resonance venography: A comparative study of tracking and fixed saturation pulses

PURPOSE

This study aimed to compare the suppression of arterial signal intensity between tracking and fixed saturation pulses in lower extremity magnetic resonance venography (MRV).

METHODS

Forty patients with varicose veins who underwent 2D true fast imaging with steady-state free precession using tracking and fixed saturation pulses on MRV were included. A fixed saturation pulse was applied from April 2020 to May 2021, and a tracking saturation pulse was applied from June 2021 to July 2022. The arterial, venous, and muscle signal intensities obtained at the femoral and popliteal levels were used to calculate the contrast ratios between veins and arteries (CRVA) and veins and muscles (CRVM). Two experienced radiologists graded the images based on vein-artery contrast, suppression of arterial signal intensity, and visualization of lower leg perforators using a 9-point scale.

RESULTS

Tracking saturation pulse images yielded significantly superior CRVA and CRVM compared with fixed saturation pulse images at both the femoral and popliteal levels. For the same saturation pulse type, the CRVA was higher at the femoral level than at the popliteal level, while the CRVM was comparable between the two levels. MRV with a tracking saturation pulse showed significantly superior vein-artery contrast, arterial signal suppression, and lower leg perforator visualization. Most scores for vein-artery contrast and arterial signal suppression with the tracking saturation pulse were positive (3.5-5), whereas few scores with the fixed saturation pulse were positive.

CONCLUSION

Tracking saturation pulse was more effective in suppressing arterial signal intensity in lower extremity MRV.

Non-contrast MR angiography: physical principles and clinical applications in chest, abdomen and pelvis imaging

This review article focuses on the advancements in non-contrast magnetic resonance angiography (NC-MRA) and its increasing importance in body imaging, especially for patients with renal complications, pregnant women, and children. It highlights the relevance of NC-MRA in chest, abdominal, and pelvis imaging and details various bright-blood NC-MRA techniques like cardiac-gated 3D Fast Spin Echo (FSE), balanced Steady-State Free Precession (bSSFP), Arterial Spin Labeling (ASL), and 4D flow methods. The article explains the operational principles of these techniques, their clinical applications, and their advantages over traditional contrast-enhanced methods. Special attention is given to the utility of these techniques in diverse imaging scenarios, including liver, renal, and pelvic imaging. The article underscores the growing importance of NC-MRA in medical diagnostics, offering insights into current practices and potential future developments. This comprehensive review is a valuable resource for radiologists and clinicians, emphasizing NC-MRA's role in enhancing patient care and diagnostic accuracy across various medical conditions.

Noninvasive diagnostic imaging of pelvic venous disorders

It is estimated that chronic pelvic pain (CPP) may affect up to 24% of women. Unfortunately, very often, despite extensive diagnostics, the cause of CPP remains unknown. The pathophysiology of CPP could be explained to a large extent by the occurrence of pelvic venous disorders (PVD). Although pelvic venography is still considered the gold standard for the diagnosis of PVD, noninvasive diagnostic imaging techniques seem to be instrumental in the initial identification of patients with PVD. This literature review aimed to analyze and evaluate the usefulness of noninvasive diagnostic imaging techniques like transvaginal ultrasonography, transabdominal ultrasonography, magnetic resonance, and computed tomography in the diagnosis and identification of patients with PVD. Forty-one articles published between 1984 and 2023 were included in this literature review. Based on this literature review, we conclude that the clinical application of noninvasive diagnostic techniques in the diagnosis of PVD seems to be very promising. Future studies investigating the role of noninvasive diagnostic imaging techniques in the diagnosis of PVD are required.

Efficacy of modified time of flight magnetic resonance venography in diagnosis of iliac vein compression syndrome

OBJECTIVE

We investigated the diagnostic efficacy of modified time of flight magnetic resonance venography (mTOF-MRV) for iliac vein compression syndrome diagnosis by optimizing the scanning parameters and improving image quality.

METHODS

A retrospective study was conducted on 69 patients who underwent routine time of flight magnetic resonance venography (TOF-MRV) and 85 patients who received mTOF-MRV. Assessment of image quality of the two methods was performed by two radiologists using a four-point method. The sensitivity, specificity, positive and negative predictive values of TOF-MRV and mTOF-MRV in the diagnosis of significant iliac vein compression (stenosis >50%) were analyzed by calculating the iliac vein stenosis rates of the two methods and using digital subtraction angiography (DSA) as the gold standard.

RESULTS

Inter-observer assessment of objective data measurement revealed excellent agreement {ICC [95% confidence interval (CI)]: 0.972 (0.953 to 0.983) for TOF-MRV and 0.979 (0.965 to 0.988) for m-TOF MRV, 0.976 (0.960 to 0.986) for DSA}. The mean error of stenosis rate of mTOF-MRV was markedly smaller than that of TOF-MRV (p < 0.05). Sensitivity, specificity, positive and negative predictive values of TOF-MRV in the diagnosis of significant stenosis were 100%, 95%, 67% and 100%, respectively. The sensitivity, specificity, positive and negative predictive values of mTOF-MRV were 100%. The mean image score for the mTOF-MRV was 3.63 ± 0.59, which was significantly higher compared with that of TOF-MRV (2.19 ± 0.42).

CONCLUSION

mTOF-MRV has better image quality and can accurately diagnose venous stenosis. Therefore, it can be used for the detection of iliac vein compression syndrome and further assessment after endovascular interventions.

Non-Contrast Magnetic Resonance Angiography: Techniques, Principles, and Applications

Several non-contrast magnetic resonance angiography (MRA) techniques have been developed, providing an attractive alternative to contrast-enhanced MRA and a radiation-free alternative to computed tomography (CT) CT angiography. This review describes the physical principles, limitations, and clinical applications of bright-blood (BB) non-contrast MRA techniques. The principles of BB MRA techniques can be broadly divided into (a) flow-independent MRA, (b) blood-inflow-based MRA, (c) cardiac phase dependent, flow-based MRA, (d) velocity sensitive MRA, and (e) arterial spin-labeling MRA. The review also includes emerging multi-contrast MRA techniques that provide simultaneous BB and black-blood images for combined luminal and vessel wall evaluation.

Superficial Venous Reflux Intervention Guided by Triggered Angiography Non-Contrast-Enhanced Sequence Magnetic Resonance Imaging: Different QFlow Pattern from Health Controls

(1) Background: To assess the effectiveness of triggered angiography non-contrast-enhanced (TRANCE)-magnetic resonance imaging (MRI) in superficial venous reflux and its difference from health controls. (2) Methods: Thirty patients underwent TRANCE MRI before surgical intervention of their superficial venous reflux of the legs. Ten healthy volunteers were included as a control. (3) Results: TRANCE MRI involves the major tributaries, thus enhances the additional ablations in 20% of patients. QFlow pattern of superficial venous reflux (QFlow GSV/PV MF ratio > 1) was compared with the duplex scan (SFJ reflux) using Cohen’s kappa coefficient at 0.967. The 30 morbid legs undergoing TRANCE MRI-guide interventions and the healthy volunteers’ legs on the same side were compared. The stroke volumes (SV) are higher in EIV (p = 0.021) in the left-leg-intervention group. The mean flux (MF) is higher in the EIV (p = 0.012) and trend of increasing in GSV segment (p = 0.087) in the left-leg-intervention group. The QFlow of 10 patients with right leg intervention are higher in GSV in the right-leg-intervention group (SV p = 0.002; FFV p = 0.001; MF p = 0.001). QFlow data is shown for all legs for superficial venous intervention with GSV/PV (MF) ratio > 1. (4) Conclusions: Typical figures in QFlow (GSV/PV MF ratio > 1) could be observed in the morbid limbs but not in the controls.