Accuracy of stepping-table lower extremity MR angiography with dual-level bolus timing and separate calf acquisition: hybrid peripheral MR angiography.

PURPOSE: To retrospectively evaluate the accuracy of hybrid peripheral magnetic resonance (MR) angiography by using conventional digital subtraction angiography (DSA) as the reference standard.
MATERIALS AND METHODS: This retrospective study protocol received approval from the Office of Sponsored Research at Northwestern University, which included review by the Office for the Protection of Research Subjects. Informed consent was waived for this HIPAA-compliant study. One hundred twenty-one consecutive patients (67 men: mean age, 66 years +/- 12 [standard deviation]; 54 women: mean age, 69 years +/- 14), who were referred for evaluation of peripheral vascular disease, underwent peripheral contrast material-enhanced MR angiography. By using a hybrid technique, two independent timing measurements were performed in the pelvis and calves followed by MR angiography of the calves and, subsequently, a pelvis-thigh stepping-table acquisition. Images were evaluated for extent of disease, on the basis of degree of stenosis; for venous contamination, on the basis of venous signal intensity; and for diagnostic quality, on the basis of diagnostic confidence of the observer. DSA correlation of the extent of vascular disease was available in 45 of these patients, which was used to evaluate the diagnostic power of the hybrid technique.
RESULTS: For detection of stenosis greater than 50%, the hybrid technique had 95% sensitivity (P < .05), 95% specificity (P < .05), and 95% accuracy (P < .05). There was no significant venous contamination in any of the examinations performed with this technique.
CONCLUSION: The hybrid peripheral MR angiography technique provides diagnostic-quality examinations and virtually eliminates venous contamination. RSNA, 2006