REDUCTION OF MEASUREMENT TIME BY H-1-MR T URBO SPECTROSCOPIC IMAGING OF THE BRAIN

Purpose: Development of a new technique for reduction of measurement t ime in H-1-MR spectroscopic imaging of the brain. Optimisation of the sequence parameters in volunteer and in patient examinations and compa rison to the results obtained with conventional 2 D-SI. Methods: Exami nation of 20 healthy Volunteers and 5 patients in a 1.5T whole-body MR system. In ''turbo-spectroscopic imaging'' (TSI) sequences, a train o f spin-echo signals with different phase encoding is acquired after ea ch 90 degrees excitation. 32 x 32 matrix elements covered a field of v iew of 20 cm, and additional volume selection was performed by double spin echo excitation. Measurement duration 9 min with acquisition of f our phase encoding steps per T-R interval, whereas the corresponding 2 D-SI sequence (TRITE 2000/272 ms) took 30 min. Results: The TSI data sets yielded maps of the regional distribution of metabolite concentra tions with a quality comparable to the 2 D-SI results. Signal homogene ity and delineation of brain lesions, however, were superior in conven tional spectroscopic imaging. The T-2 relaxation of the metabolites re quired a reduced sampling interval for each phase-encoded echo, and he nce the frequency resolution of the corresponding TSI spectra was not always sufficient for separating choline and creatine signals. Conclus ion: With measurement durations <10 min the TSI technique allows in cl inical studies a combination with single-voxel MRS for accurate quanti fication and with a diagnostic MRI within a total examination time of less than one hour.