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- Title
Diffusion-weighted imaging and proton MR spectroscopy in the characterization of acute disseminated encephalomyelitis.
- Authors
Balasubramanya, K.; Kovoor, J.; Jayakumar, P.; Ravishankar, S.; Kamble, R.; Panicker, J.; Nagaraja, D.
- Abstract
Acute disseminated encephalomyelitis (ADEM) is usually a monophasic illness characterized by multiple lesions involving gray and white matter. Quantitative MR techniques were used to characterize and stage these lesions. Eight patients (seven males and one female; mean age 19 years, range 5 to 36 years) were studied using conventional MRI (T2- and T1-weighted and FLAIR sequences), diffusion-weighted imaging (DWI) and proton magnetic resonance spectroscopy (MRS). Apparent diffusion coefficient (ADC) values and MRS ratios were calculated for the lesion and for normal-appearing white matter (NAWM). Three patients were imaged in the acute stage (within 7 days of the onset of neurological symptoms) and five in the subacute stage (after 7 days from the onset of symptoms). ADC values in NAWM were in the range 0.7–1.24×10−3 mm/s2 (mean 0.937 ± 0.17 mm/s2). ADC values of ADEM lesions in the acute stage were in the range 0.37–0.68×10−3 mm/s2 (mean 0.56 ± 0.16 mm/s2) and 1.01–1.31×10−3 mm/s2 (mean 1.24 ± 0.13 mm/s2) in the subacute stage. MRS ratios were obtained for all patients. NAA/Cho ratios were in the range 1.1–3.5 (mean 1.93 ± 0.86) in the NAWM. NAA/Cho ratios within ADEM lesions in the acute stage were in the range 0.63–1.48 (mean 1.18 ± 0.48) and 0.29–0.84 (mean 0.49 ± 0.22) in the subacute stage. The ADC values, NAA/Cho and Cho/Cr ratios were significantly different between lesions in the acute and subacute stages ( P < 0.001, P < 0.027, P < 0.047, respectively). ADC values were significantly different between lesions in the acute ( P < 0.009) and subacute stages ( P < 0.005) with NAWM. In addition, NAA/Cho and Cho/Cr ratios were significantly different between lesions in the subacute stage and NAWM ( P < 0.006, P < 0.007, respectively). ADEM lesions were characterized in the acute stage by restricted diffusion and in the subacute stage by free diffusion and a decrease in NAA/Cho ratios. Restricted diffusion and progressive decrease in NAA/Cho ratios may help in staging the disease.
- Subjects
CENTRAL nervous system diseases; MEDICAL imaging systems; PROTON magnetic resonance spectroscopy; CEREBROVASCULAR disease; ENCEPHALOMYELITIS; CHRONIC encephalitis
- Publication
Neuroradiology, 2007, Vol 49, Issue 2, p177
- ISSN
0028-3940
- Publication type
Article
- DOI
10.1007/s00234-006-0164-2