Comparison of Phase-Sensitive and Alternating Repetition Time SSFP for Flow-Independent Peripheral Angiography

Introduction: Magnetic resonance angiography of the extremities can help in the diagnosis of conditions such as peripheral arterial disease and peripheral vascular occlusion. In recent work, non-contrast-enhanced high-resolution flow-independent angiograms of the hand have been acquired with SNR-efficient balanced steady-state free precession (SSFP) imaging [1]. The simple and efficient phase-sensitive (PS) SSFP method [2] was used to remove fat; however, the method suffers from partial volume effects. In the case of small vessels in the vicinity of bone marrow and subcutaneous fat tissue, partial volume averaging leads to a loss of blood signal. Instead, alternating repetition time (ATR) SSFP can be used to suppress fat signal [3]. Partial volume effects are significantly reduced, enhancing the visualization of vascular structure. When B0 inhomogeneity or susceptibility variations are significant, fat suppression will be imperfect in certain regions due to the wedge-shaped stop-band of fatsuppressing ATR. Another ATR image with a shift in the echo-time can be used for fatwater separation through post-processing.