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AJNR - American Journal of Neuroradiology

Publication Preview: Published September 12, 2009

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American Journal of Neuroradiology
DOI 10.3174/ajnr.A1756

BRAIN

Enhanced Detection of Diffusion Reductions in Creutzfeldt-Jakob Disease at a Higher B Factor

H. Lee, C. Hoffman, P.B. Kingsley, A. Degnan, O. Cohen and I. Prohovnik

From the Departments of Psychiatry (H.L., A.D., I.P.) and Radiology (I.P.), Mount Sinai School of Medicine, New York; Departments of Radiology (C.H.) and Neurology (O.C.), Sheba Medical Center, Tel Hashomer, Israel; and Department of Radiology (P.B.K.), North Shore University Hospital, Manhasset, New York.

Please address correspondence to I. Prohovnik, PhD, Department of Psychiatry, Mount Sinai School of Medicine, One Gustave Levy Pl, New York, NY 10029; e-mail: Isak.Prohovnik{at}mssm.edu

BACKGROUND AND PURPOSE: Diffusion-weighted imaging (DWI) is sensitive to the cerebral manifestations of human prion diseases. The magnitude of diffusion weighting, termed "b factor," has only been evaluated at the standard b = 1000 s/mm². This is the first rigorous evaluation of b = 2000 s/mm² in Creutzfeldt-Jakob Disease (CJD).

MATERIALS AND METHODS: We compared DWI characteristics of 13 patients with CJD and 15 healthy controls at b = 1000 s/mm² and b = 2000 s/mm². Apparent diffusion coefficients (ADC) were computed and analyzed for the whole brain by voxel-wise analysis (by SPM5) as well as in anatomically defined volumes of interest (by FSL FIRST).

RESULTS: Measured ADC was significantly lower (by approximately 5%–15%) at b = 2000 s/mm² than at b = 1000 s/mm² and significantly lower in patients than in controls. The differences between patients and controls were greater and more extensive at b = 2000 s/mm² than at b = 1000 s/mm² in the expected regions (thalamus, putamen, and caudate nucleus).

CONCLUSIONS: Because higher b factors change the absolute value of observed ADC, as well as lesion detection, care should be taken when combining studies using different b factors. While the clinical application of high b factors is currently limited by a low signal intensity–to-noise ratio, it may offer more information in questionable cases, and our results confirm and extend the central role of diffusion imaging in human prion diseases.