[The proton relaxation times in normal and neoplastic thyroid tissue. An in vitro study].

Aim of the work is the in vitro evaluation of normal and tumoral thyroid tissue relaxation times, in order to obtain useful information for MR Imaging in vivo. Water proton high-resolution MR spectra, together with T1 and T2 relaxation times, have been measured in normal and tumoral thyroid tissues. The longitudinal relaxation time T1 was particularly sensitive to pathologic tissue: significant differences (mean: 243 ms) were observed between normal and tumoral tissues, which is a useful finding for the successful application of MR techniques to the detection of tumors in the thyroid gland. The average T1 relaxation time, for each class of examined tumors, correlates qualitatively with the degree of malignancy. On the contrary, the transverse relaxation time T2 was insensitive to pathologic changes in the tissues. The analysis of water proton spectra showed the overall Free Induction Decay constant T2 to allow an easier discrimination than T2 between normal and pathologic thyroid tissue. Thus, T1-weighted sequences probably provide better discrimination than T2-weighted scans in the evaluation of normal and tumoral thyroid tissues.