Early- and late-state subacute sclerosing panencephalitis: chemical shift imaging and single-voxel MR spectroscopy

Subacute sclerosing panencephalitis (SSPE) is a rare, progressive, inflammatory neurodegenerative disease. Our aim was to determine the metabolic abnormalities of brain in early- and late-stage SSPE by using MR spectroscopy and to assess areas of involvement in the early stages when MR imaging findings were normal.

Children with stage II (n = 3) or III (n = 3) SSPE and 10 healthy, age-matched children underwent MR imaging, multivoxel MR spectroscopy, and short-echo single-voxel MR spectroscopy (SVS). Areas of involvement in the brain were determined with chemical shift imaging. For SVS, 2 x 2 x 2-cm voxels were placed in the frontal subcortical white matter (FSWM) and parieto-occipital white matter (POWM). N-acetylaspartate (NAA)/creatine (Cr), choline (Cho)/Cr, myo-inositol (Ins)/Cr, and NAA/Cho ratios were calculated.

Comparisons of NAA/Cr, Cho/Cr, Ins/Cr and NAA/Cho ratios between patients and control subjects showed significant differences in FSWM and POWM (P <.01). In patients with SSPE, NAA/Cr ratios in POWM were significantly less than those in FSWM (P <.01). NAA/Cr ratios in patients with stage II SSPE and those in the control group were not significantly different; this may reflect the absence of neuronal loss. Decreased NAA/Cr, increased Cho/Cr and Ins/Cr ratios, and increased lactate and lipid peaks were found in patients with stage III SSPE.

MR spectroscopy showed findings suggestive of inflammation in stage II and findings of demyelination, gliosis, cellular necrosis, and anaerobic metabolism in stage III. MR spectroscopy could be a promising technique for early diagnosis and treatment planning in cases of SSPE.