3D Noncontrast MR Angiography of the Distal Lower Extremities Using Flow-Sensitive Dephasing (FSD)-Prepared Balanced SSFP

摘要

While three-dimensional contrast-enhanced MR angiography (MRA) is becoming the method of choice for clinical peripheral arterial disease (PAD) examinations, safety concerns with contrast administration in patients with renal insufficiency have triggered a renaissance of noncontrast MRA. In this work, a noncontrast-MRA technique using electrocardiography-triggered three-dimensional segmented balanced steady-state free precession with flow-sensitive dephasing (FSD) magnetization preparation was developed and tested in the distal lower extremities. FSD preparation was used to induce arterial flow voids at systolic cardiac phase while having little effect on venous blood and static tissues. High-spatial-resolution MRA was obtained by means of magnitude subtraction between a dark-artery scan with FSD preparation at systole and a bright-artery scan without FSD preparation at mid-diastole. In nine healthy volunteers, FSD parameters, including the gradient waveform and the first-order gradient moment, were optimized for excellent MRA image quality. Furthermore, arterial stenosis and occlusion in two peripheral arterial disease patients were identified using the noncontrast-MRA technique, as confirmed by contrast-enhanced MRA. In conclusion, FSD-prepared balanced steady-state free precession in conjunction with electrocardiography gating and image subtraction provides a promising noncontrast-MRA strategy for the distal lower extremities.