MR spectroscopy in gliomatosis cerebri

Abstract

Background and purpose: The diagnosis of gliomatosis cerebri with MR imaging is known to be difficult. We report on the value of MR spectroscopy in the diagnosis, grading, and biopsy planing in eight patients with histopathologically proved gliomatosis cerebri.

Methods: Patients underwent MR imaging and MR spectroscopy (single-voxel point-resolved spectroscopy [PRESS] at 1500/135, and chemical-shift imaging [CSI] PRESS at 1500/135) before open (n = 4) or stereotactic (n = 4) biopsy. In six patients who underwent CSI, biopsy samples were taken from regions of maximally elevated levels of choline/N-acetylaspartate (Cho/NAA).

Results: All patients showed elevated Cho/creatine (Cr) and Cho/NAA levels as well as varying degrees of decreased NAA/Cr ratios, which were most pronounced in the anaplastic lesions. In low-grade lesions, there was a maximum Cho/NAA ratio of 1.3, whereas in anaplastic tumors, the maximum Cho/NAA level was at least 2.5. Spectra in two patients with grade III lesions revealed a lactate peak; lactate and lipid signals were seen in two patients with grade IV lesions. Biopsy specimens from regions with maximally elevated levels of Cho/NAA showed dense infiltration of tumor cells.

Conclusion: MR spectroscopy might be used to classify gliomatosis cerebri as a stable or a progressive disease indicating its potential therapeutic relevance.

fig 1.

Case 4: 38-year-old woman with bifrontal hyperintensity and tumor spread via corpus callosum. A, Axial T2-weighted spin-echo localizer image (1900/80). B, Corresponding spectrum (CSI, PRESS, 1500/135, voxel size = 7.5 × 7.5 × 15 mm) shows a moderate increase in Cho/Cr and Cho/NAA and a decrease in NAA/Cr.

fig 2.

Case 5: 12-year-old boy with seizure. A, Axial T1-weighted localizer image (fast low-angle shot, 80/10) shows extensive hypointense infiltration of the right hemisphere with little mass effect. B, Corresponding spectrum (CSI, PRESS, 1500/135, voxel size = 7.5 × 7.5 × 15 mm) shows a marked increase in Cho/Cr and Cho/NAA and a pronounced decrease in NAA/Cr. Moreover, there is a lactate doublet at 1.35 ppm.

fig 3.

Case 8: 55-year-old man with diffuse involvement of both hemispheres. A, Axial T2-weighted spin-echo localizer image (1900/80). B, Corresponding spectrum. Stereotactic biopsy sample was taken from the denoted voxel, with a maximum Cho/NAA ratio of the lesion of 8.9 as well as a lactate doublet at 1.35 ppm. Histopathologic examination revealed a grade IV tumor. In other areas of the tumor there were lipid signals at 0.8 to 1.3 ppm (CSI, PRESS, 1500/135, voxel size = 7.5 × 7.5 × 15 mm). fig 4. Case 1: 10-year-old boy with seizure. Axial spin-echo T2-weighted image (1900/80) shows extensive hyperintensity of the left occipital, parietal, and temporal lobes, with infiltration of the thalamus and the insula. Both gray and white matter are affected, and there is little mass effect

fig 5.

Metabolite ratios for Cho/Cr, NAA/Cr, and Cho/NAA. The difference between the histopathologic tumor grades is most pronounced in the Cho/NAA ratio. In the group of low-grade lesions, the maximum Cho/NAA level is 1.3, whereas in anaplastic tumors, the Cho/NAA ratio is at least 2.5 with a maximum value of 8.9 in a grade IV lesion