MR SPECTROSCOPY IN THE EVALUATION OF ENHANCING LESIONS IN THE BRAIN IN MULTIPLE-SCLEROSIS

PURPOSE: To compare proton MR spectroscopic alterations with the degre e of contrast enhancement in multiple sclerosis (MS) lesions. METHODS: Thirty-five patients with clinically diagnosed MS were studied with M R spectroscopy. A total of 47 lesions were examined. Solvent-suppresse d proton spectra were acquired with an echo time of 16 milliseconds us ing the point-resolved spectroscopic localization method from 1.5 cm(3 ) voxels. Marker peaks/creatine (Cr) ratios obtained from these spectr a were plotted against the relative enhancement of the lesion seen aft er administration of contrast material. The relative enhancement was d efined as S-contrast-S-0/S-0, where S-0 is the signal intensity of a T 1-weighted image and S-contrast is the signal intensity after administ ration of gadopentetate dimeglumine. RESULTS: We found a positive line ar relationship between the marker peaks/Cr ratio and the degree of en hancement of the lesion. That is, the marker peaks/Cr ratio was higher in the lesions that showed the greatest enhancement. CONCLUSION: The MR/Cr ratio obtained with the use of short-echo-time proton MR spectro scopy correlates with the degree of contrast enhancement. This ratio m ay therefore serve as a means for evaluating and quantifying the level of inflammatory activity within the plaques of patients with MS.