Presentation
Headache for 6 months.
Patient Data
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There is an abnormal poorly enhancing well defined intra-axial lesion in the subcortical white matter of left high parietal lobe. The lesion is seen as hypointense on T1W, hyperintense on T2W and FLAIR, showing no blooming on GRE or restriction on DWI.
No perilesional edema is noted. No evidence of necrosis, hemorrhage or calcification are seen in the lesion. Mild mass effect is seen in the form of effacement the underlying cortical sulci in the parafalcine area.
Mild elevation in choline with decrease in the NAA and creatine levels are seen within the lesion. Increased Choline / Creatine ratio of 2.04 is seen. No lactate/lipid peak is seen.
Imaging and spectoscopic findings are suggestive of low grade glioma.
Incidentally noted a subgaleal sebaceous cyst in the right occipital region.
Case Discussion
Low-grade gliomas are generally characterized by a relatively high concentration of N-acetylaspartate (NAA), low level of choline and absence of lactate and lipids. The increase in creatine concentration indicates low-grade gliomas with earlier progression and malignant transformation.
Progression in grade of a glioma is reflected in the progressive decrease in the NAA and myo-inositol levels on the one hand, and elevation in choline level up to grade III on the other. Malignant transformation of the glial tumors is also accompanied by the presence of lactate and lipids in MR spectra of grade III but mainly grade IV gliomas.
It follows that MRS is a helpful method for detection of glioma regions with aggressive growth or upgrading due to favorable correlation of the choline and NAA levels with histopathological proliferation index Ki-67. Thus, magnetic resonance spectroscopy is also a suitable method for the targeting of brain biopsies.
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