Comparison of Proton T1 and T2 Relaxation Times of Cerebral Metabolites between 1.5T and 3.0T MRI using a Phantom

Purpose : To present the T1 and T2 relaxation times of the major cerebral metabolites at 1.5T and 3.0T and compare those between 1.5T and 3.0T. Materials and Methods : Using the phantom containing N-acetyl aspartate (NAA), Choline (Cho), and Creatine (Cr) at both 1.5T and 3.0T MRI, the T1 relaxation times were calculated from the spectral data obtained with 5000 ms repetition time (TR), 20 ms echo time (TE), and 11 different mixing time (TM)s using STEAM (STimulated Echo-Acquisition Mode) method. The T2 relaxation times were obtained from the spectral data obtained with 3000 ms TR and 5 different TEs using PRESS (Point-RESolved Spectroscopy) method. The T1 and T2 relaxation times obtained at 1.5T were compared with those of 3.0T. Results : The T1 relaxation times of NAA were at 1.5T and at 3.0T (11.6% increase at 3.0T). The T1 relaxation times of Cho were at 1.5T and at 3.0T (4.1% increase at 3.0T). The T1 relaxation times of Cr were at 1.5T and at 3.0T (4.8% increase). The T2 relaxation times of NAA were at 1.5T and at 3.0T (11.0% decrease at 3.0T). The T2 relaxation times of Cho were at 1.5T and at 3.0T (17.3% decrease at 3.0T). The T2 relaxation times of Cr were at 1.5T and at 3.0T (4.8% decrease at 3.0T). Conclusion : The T1 relaxation times of the major cerebral metabolites (NAA, Cr, Cho), which were measured at the phantom, were 4.1%-11.6% longer at 3.0T than at 1.5T. The T2 relaxation times of them were 4.8%-17.3% shorter at 3.0T than at 1.5T. To optimize MR spectroscopy at 3.0T, TR should be lengthened and TE should be shortened.