High Resolution Cartilage and Whole Organ Knee Joint Assessment: 3D Radial Fat-Suppressed Alternating TR SSFP

INTRODUCTION Effective cartilage imaging and whole organ joint assessment requires both high isotropic resolution and fat suppression or separation. SSFP lends itself to this task as it rapidly creates high signal-to-noise ratio (SNR) and T2-like contrast with bright fluid signal. However, SSFP also produces bright fat signal which may interfere with visualization of the critical cartilage/bone interface. Here we propose a single pass, 3D radial fat-suppressed Alternating TR (FS-ATR) SSFP acquisition which provides ultra-high isotropic resolution of 0.33 mm (voxel volume of 1/27 mm) throughout the entire knee joint. The radial trajectory provides significantly higher resolution than a Cartesian trajectory could provide within the TR constraint. We contrast the method against a two pass, 3D radial Linear Combination SSFP (LC-SSFP) method [1]. The benefit from not redundantly sampling data and reducing off-resonance blurring are demonstrated in the depiction of minute, focal cartilage defects at ultra-high isotropic resolution.