Improved short tau inversion recovery (iSTIR) for increased tumor conspicuity in the abdomen

Abstract

To develop an improved short tau inversion recovery (iSTIR) technique with simultaneous suppression of fat, blood vessels and fluid to increase tumor conspicuity in the abdomen for cancer screening. An adiabatic spectrally selective inversion pulse was used for fat suppression to overcome the reduced signal to noise ratio associated with chemically non-selective inversion pulse of STIR. A motion-sensitizing driven equilibrium was used for blood vessel suppression and a dual-echo single-shot fast spin echo acquisition was used for fluid suppression. The technique was optimized on four normal subjects and later tested on five patients referred for metastatic tumor evaluation. A velocity encoding of 2 cm/s achieved effective blood suppression even in small vessels. Subtraction of two images (one with 60 ms and the other with 280 ms echo time) acquired in the same echo train achieved excellent fluid suppression (>70% reduction). Simultaneous suppression of fat, blood vessels and fluid improved the tumor conspicuity compared to corresponding fat-suppressed (STIR) image. This technique generated two complementary images from a single scan: one that is equivalent to a STIR image and the other that qualitatively resembles a diffusion-weighted image and may have potential for magnetic resonance imaging cancer screening.