Quantification of liver blood volume: comparison of ultra short ti inversion recovery echo planar imaging (ulstir‐epi), with dynamic 3d‐gradient recalled echo imaging

Abstract

An ultra‐short TI inversion recovery echo‐planar imaging (ULSTIR‐EPI) sequence was designed to reduce the influence of water exchange on fractional tissue blood volume (BV) estimation by measurement of T₁‐changes induced by a gadolinium‐based macromolecular contrast medium (MMCM). Fractional liver BV in rats, estimated by ULSTIR‐EPI was compared for accuracy to a fast T₁‐weighted three‐dimensional gradient‐echo (3D‐SPGR, 3D‐spoiled gradient recalled acquisition in a steady state) sequence using an in vitro inductively coupled plasma atomic emission spectroscopy (ICP‐AES) assay for BV as a standard. Liver images for fractional BV estimation were acquired in eight rats using both ULSTIR‐EPI and 3D‐SPGR before and after (within 3 to 12 min) intravenous bolus administration of albumin‐Gd‐DTPA₃₀ (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 T₁ maps, and minimization of transendothelial proton exchange effects. 3D‐SPGR imaging offers better spatial resolution, current availability on standard clinical MR systems, and acceptable accuracy.