QUANTIFICATION OF LIVER FLOOD VOLUME - COMPARISON OF ULTRA-SHORT TI INVERSION-RECOVERY ECHO-PLANAR IMAGING (ULSTIR-EPI), WITH DYNAMIC 3D-GRADIENT RECALLED ECHO IMAGING

An ultra-short TI inversion recovery echo-planar imaging (ULSTIR-EPI) sequence was designed to reduce the influence of water exchange on fra ctional tissue blood volume (BV) estimation by measurement of T-1-chan ges induced by a gadolinium-based macromolecular contrast medium (MMCM ), Fractional liver BV in rats, estimated by ULSTIR-EPI was compared f or accuracy to a fast T-1-weighted three-dimensional gradient-echo (3D -SPGR, do-spoiled gradient recalled acquisition in a steady state) seq uence using an in vitro inductively coupled plasma atomic emission spe ctroscopy (ICP-AES) assay for BV as a standard, Liver images for fract ional BV estimation were acquired in eight rats using both ULSTIR-EPI and 3D-SPGR before and after (within 3 to 12 min) intravenous bolus ad ministration of albumin-Gd-DTPA(30) (0.05 mmol Gd/kg), Whereas both MR techniques may be useful for fractional tissue BV estimation, ULSTIR- EPI offers certain advantages including greater accuracy, direct T-1 m aps, and minimization of transendothelial proton exchange effects, 3D- SPGR imaging offers better spatial resolution, current availability on standard clinical MR systems, and acceptable accuracy.