FRONTOTEMPORAL DEMENTIA AND EARLY ALZHEIMER-DISEASE - DIFFERENTIATIONWITH FRONTAL-LOBE H-1 NTR SPECTROSCOPY

PURPOSE: To evaluate cerebral biochemical abnormalities in patients wi th frontotemporal dementia and Alzheimer disease and to determine whet her proton (hydrogen-1) magnetic resonance (MR) spectroscopy can help differentiate among these two patient groups and healthy (control) sub jects. MATERIALS AND METHODS: MR imaging and H-1 MR spectroscopy were performed in 14 patients with frontotemporal dementia, 12 with probabl e Alzheimer disease (Alzheimer), and II healthy (control) elderly subj ects. Spectra were acquired from midfrontal and temporoparietal gray m atter with a double spin-echo sequence (repetition time, 3,000 msec; e cho time, 30 msec). Results were expressed in metabolite concentration s corrected for the presence of cerebrospinal fluid. RESULTS: In front otemporal dementia patients, the frontal lobe showed reduced N-acetyl compounds (-28%) and glutamate plus glutamine (-16%), suggestive of ne uron loss, and increased myo-inositol (MI) (+19%), suggestive of incre ased glial content. In three frontotemporal dementia patients, a lacta te peak was present in the frontal lobe. In Alzheimer patients, no sta tistically significant abnormalities were observed in the frontal regi on, but MI was elevated (+8%) in the temporoparietal region. With use of linear discriminant analysis of MR spectroscopy data alone, 92% of the frontotemporal dementia patients were correctly differentiated fro m the Alzheimer patients and control subjects. The overall accuracy fo r discrimination among all three groups was 84%. CONCLUSION: H-1 MR sp ectroscopy demonstrated biochemical abnormalities in patients with fro ntotemporal dementia and aided differentiation between patients with f rontotemporal dementia and Alzheimer disease.