Usefulness of Three-dimensional Contrast-Enhanced MR Angiography in the Evaluation of Pelvic and Lower Extremity Arteries

Kim, Young Kon; Han, Young Min; Lee, Jeong Min

Abstract

PURPOSE
To evaluate the feasibility and clinical usefulness of three-dimensional contrast-enhanced MR angiography (3D-CE-MRA) as a screening test in the evaluation of pelvic and lower extremity arterial diseases.
MATERIALS AND METHODS
Forty-four patients who underwent 3D-CE-MRA were included in this study. Coronal 3-dimensional gradient-echo, pre-and post contrast image were acquired with a dedicated peripheral vascular coil and moving-bed technique on a 1.5T MR system. Timing of start of data acquisition was determined by MR fluoroscopy technique, and 0.2mmol/kg Gd-DTPA was injected into an antecubital vein, at a rate of 1cc/sec with an autoinjector. For quantitative analysis, signal to noise ratio (SNR) and artery to soft tissue contrast to noise ratio (CNR) of lower extremities arterial system including lower abdominal aorta were calculated. For qualitative analysis, arterial systems were divided into six segments, and were evaluated in terms of conspicuity of arterial systems and the degree of venous enhancement by three- and four-point scale respectively. In eight patients who underwent both MR angiography and conventional angiography, the degree of the stenosis of MR angiography was compared with conventional angiography as standard reference. Imaging analysis was done by means of consensus between two experienced radiologists.
RESULTS
The mean time for the examination was about 15min (+/-5 min). The mean SNR of arterial system was 26.5+/-11.6, and mean artery to soft tissue contrast to noise ratio (CNR) was 24.6+/-11.2. Among the total 525 arterial segments, 498 arterial segments (94.9%) could be demonstrated with good delineation of entire arterial tree. Good arterial imaging without or with minimal venous enhancement were demonstrated in 98.5% (260/264) in above knee and 89% (211/261) in below knee (p<0.01). Ten of 525 segments (1.9%) demonstrated severe venous overlapping and it mostly occurred in the calf region. In comparison with DSA, the sensitivity and the specificity for MR angiography for the detection of occlusions were 96% and 98,8%, respectively, and for the detection of more than 50% stenosis, 82.2% and 92.9%, respectively.
CONCLUSION
3D-CE-MRA provided adequate image for the evaluation of the lower extremity artery, and could be used as a screening test for arterial occlusive diseases.