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

Abstract

Background and purpose: 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.

Methods: 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.

Results: 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.

Conclusion: 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.

Fig 1.

Findings in a 6-year-old girl with stage II SSPE. A, Axial T2-weighted localizer image (2875/120) shows a 2 × 2 × 2-cm voxel placed in the left FSWM. B, MR spectrum (single voxel, PRESS; 2000/31/256) shows a normal NAA/Cr ratio and increased Cho/Cr and MI/Cr ratios.

Fig 2.

Findings in an 8-year-old girl with stage II SSPE. A, Axial T2-weighted image (4530/100) shows normal brain parenchymal findings. B, Coronal T2-weighted localizer image (2875/120) shows a 2 × 2 × 2-cm voxel placed in the left POWM. C, MR spectrum (single voxel, PRESS; 2000/31/256) shows a normal NAA/Cr ratio and increased Cho/Cr and MI/Cr ratios.

Fig 3.

Findings in an 8-year-old boy with stage III SSPE. A, Coronal T2-weighted image (4530/100) shows periventricular hyperintensities and cerebral and brain stem atrophy. B, Axial T2-weighted localizer image (2875/120) shows a 2 × 2 × 2-cm voxel placed in the left POWM. C, MR spectrum (single voxel, PRESS; 2000/31/256) shows a substantially decreased NAA/Cr ratio, increased Cho/Cr, Ins/Cr ratios, and lipid and lactate peaks.

Fig 4.

Findings in a 7-year-old girl with stage III SSPE. A, CSI map of NAA shows decreased NAA signal intensity in the FSWM (straight arrows) and POWM (curved arrows). B, Axial T2-weighted localizer image (2875/120) for MVS shows periventricular hyperintensities and cerebral atrophy. C, MR spectrum (1500/136) (1) shows a normal NAA/Cr ratio and increased Cho/Cr ratios in left periventricular white matter. MR spectrum (2) shows substantially decreased NAA/Cr and increased Cho/Cr ratios in the left POWM.

Fig 5.

Findings in an 8-year-old boy with stage III SSPE. A, Coronal T2-weighted image (4530/100) shows periventricular hyperintensities and cerebral atrophy. B, CSI map of Cho shows increased Cho signal intensity in the left periventricular white matter (arrows). C, Axial T2-weighted localizer image (2875/120) for MVS shows diffuse periventricular hyperintensities and cerebral atrophy. D, MR spectrum (1500/136) (3) shows significantly decreased NAA/Cr and increased Cho/Cr ratios in the left POWM.