Short-echo spectroscopic imaging combined with lactate editing in a single scan

Abstract

A short-echo spectroscopic imaging sequence extended with a frequency-selective multiple-quantum- coherence technique (Sel-MQC) is presented. The method enables acquisition of a complete water-suppressed proton spectrum with a short echo time and filtering of the J-coupling metabolite, lactate, from co-resonant lipids in one scan. The purpose of the study was to validate this combined pulse sequence in vitro and in vivo. Measurements on phantoms confirmed the feasibility of the method, and, for a practical in vivo application, experiments were carried out on eight tumors from two different tumor models [UT-SCC-8 (n = 4) and SAS (n = 4)]. T(1)- and T(2)-weighted metabolite and lipid ratios were calculated, and the tumors showed different values in the central and outer regions. The ratio of the lipid methylene peak area (1.30 ppm) to choline peak area (3.20 ppm) was significantly (p < 0.01) different in the central tumor area between the two models, and lactate was detected in only three out of four tumors in the SAS tumor line. The present approach of combining short-echo spectroscopic imaging and lactate editing allows the characterization of tumor-specific metabolites such as choline, lipid methylene and methyl resonances as well as lactate in a single scan.