Free-Breathing Fast Low-Angle Shot Quiescent-Interval Slice-Selective Magnetic Resonance Angiography for Improved Detection of Vascular Stenoses in the Pelvis and Abdomen: Technical Development.

OBJECTIVES: Balanced steady-state free precession-based quiescent-interval slice-selective (bSSFP QISS) magnetic resonance angiography (MRA) is accurate for the noncontrast evaluation of peripheral arterial disease (PAD); however, drawbacks include the need for breath-holding when imaging the abdomen and pelvis, and sensitivity to off-resonance artifacts. The purpose of this study was to evaluate the image quality and diagnostic accuracy in the pelvis and abdomen of free-breathing fast low-angle shot-based QISS (FLASH QISS) techniques in comparison to bSSFP QISS in patients with PAD, using computed tomographic angiography as the reference.
MATERIALS AND METHODS: Twenty-seven patients (69 ± 10 years, 17 men) with PAD were enrolled in this institutional review board-approved, Health Insurance Portability and Accountability Act-compliant prospective study between April and December 2018. Patients underwent noncontrast MRA using standard bSSFP QISS and prototype free-breathing radial-FLASH and Cartesian-FLASH QISS at 3 T. A subset of patients (n = 22) also underwent computed tomographic angiography as the reference standard. Nine arterial segments per patient were evaluated spanning the abdomen, pelvis, and upper thigh regions. Objective (signal intensity ratio and relative standard deviation) and subjective image quality (4-point scale) and stenosis (>50%) were evaluated by 2 readers and compared using one-way analysis of variance, Wilcoxon, and McNemar tests, respectively.
RESULTS: A total of 179 vascular segments were available for analysis by all QISS techniques. No significant difference was observed among bSSFP, radial-FLASH, and Cartesian-FLASH QISS techniques in signal intensity ratio (P = 0.428) and relative standard deviation (P = 0.220). Radial-FLASH QISS demonstrated the best image quality (P < 0.0001) and the highest interreader agreement (κ = 0.721). The sensitivity values of bSSFP, radial-FLASH, and Cartesian-FLASH QISS for the detection of greater than 50% stenosis were 76.0%, 84.0%, and 80.0%, respectively, whereas specificity values were 97.6%, 94.0%, and 92.8%, respectively. Moreover, FLASH QISS consistently reduced off-resonance artifacts compared with bSSFP QISS.
CONCLUSIONS: Free-breathing FLASH QISS MRA techniques provide improved image quality and sensitivity, high specificity, and reduced off-resonance artifacts for vascular stenosis detection in the abdomen and pelvis.