Unenhanced calf MR angiography at 3.0 T using electrocardiography-gated partial-fourier fast spin echo imaging with variable flip angle.

Abstract

This study was to evaluate diagnostic performance of unenhanced electrocardiography-gated fast spin echo based MRA with variable flip angle on 3.0 T for assessment of calf arteries in patients with peripheral arterial occlusive disease (PAOD). 64 patients underwent unenhanced MRA (UE), time-resolved contrast-enhanced MRA of the calf and bolus-chase contrast-enhanced lower peripheral MRA (BCE). Diagnostic performance of UE was evaluated and compared with contrast-enhanced MRA in 61 patients and x-ray angiography in 10 patients. With UE, 852 of 960 segments (88.75%) were diagnostic even in patients with arrhythmia, demonstrating similar image quality with those on BCE (P > 0.05). For those diagnostic segments, statistics revealed good agreement between unenhanced and contrast-enhanced techniques with a Kappa value of 0.77 and 0.75 for stenosis detection and visualized vessel length, respectively. When using X-ray angiography as reference standard, no significant difference was found between UE and contrast-enhanced MRA concerning sensitivity and specificity in depiction of severe stenosis and occlusion (P > 0.05). Although further technical refinements are required, this optimized UE technique may be used as a supplement to contrast-enhanced MRA particularly in patients with PAOD in whom venous contamination occurs frequently.