Multivoxel proton magnetic resonance spectroscopy of inflammatory and neoplastic lesions of the canine brain at 3.0 t

Objective—To describe findings of 3.0-T multivoxel proton magnetic resonance spectros-copy (¹H-MRS) in dogs with inflammatory and neoplastic intracranial disease and to determine the applicability of¹H-MRS for differentiating between inflammatory and neoplastic lesions and between meningiomas and gliomas.

Animals—33 dogs with intracranial disease (19 neoplastic [10 meningioma, 7 glioma, and 2 other] and 14 inflammatory).

Procedures—3.0-T multivoxel¹H-MRS was performed on neoplastic or inflammatory intra-cranial lesions identified with conventional MRI. N-acetylaspartate (NAA), choline, and cre-atine concentrations were obtained retrospectively, and metabolite ratios were calculated. Values were compared for metabolites separately, between lesion categories (neoplastic or inflammatory), and between neoplastic lesion types (meningioma or glioma) by means of discriminant analysis and 1-way ANOVA.

Results—The NAA-to-choline ratio was 82.7% (62/75) accurate for differentiating neo-plastic from inflammatory intracranial lesions. Adding the NAA-to-creatine ratio or choline-to-creatine ratio did not affect the accuracy of differentiation. Neoplastic lesions had lower NAA concentrations and higher choline concentrations than inflammatory lesions, resulting in a lower NAA-to-choline ratio, lower NAA-to-creatine ratio, and higher choline-to-creatine ratio for neoplasia relative to inflammation. No significant metabolite differences between meningiomas and gliomas were detected.

Conclusions and Clinical Relevance—¹H-MRS was effective for differentiating inflammatory lesions from neoplastic lesions. Metabolite alterations for¹H-MRS in neoplasia and inflammation in dogs were similar to changes described for humans. Use of¹H-MRS provided no additional information for differentiating between meningiomas and gliomas. Proton MRS may be a beneficial adjunct to conventional MRI in patients with high clinical suspicion of inflammatory or neoplastic intracranial lesions.