Can Proton MR Spectroscopic and Perfusion Imaging Differentiate Between Neoplastic and Nonneoplastic Brain Lesions in Adults?

Abstract

BACKGROUND AND PURPOSE: Noninvasive diagnosis of brain lesions is important for the correct choice of treatment. Our aims were to investigate whether 1) proton MR spectroscopic imaging (¹H-MRSI) can aid in differentiating between tumors and nonneoplastic brain lesions, and 2) perfusion MR imaging can improve the classification.

MATERIALS AND METHODS: We retrospectively examined 69 adults with untreated primary brain lesions (brain tumors, n = 36; benign lesions, n = 10; stroke, n = 4; demyelination, n = 10; and stable lesions not confirmed on pathologic examination, n = 9). MR imaging and ¹H-MRSI were performed at 1.5T before biopsy or treatment. Concentrations of N-acetylaspartate (NAA), creatine (Cr), and choline (Cho) in the lesion were expressed as metabolite ratios and were normalized to the contralateral hemisphere. Dynamic susceptibility contrast-enhanced perfusion MR imaging was performed in a subset of patients (n = 32); relative cerebral blood volume (rCBV) was evaluated. Discriminant function analysis was used to identify variables that can predict inclusion in the neoplastic or nonneoplastic lesion groups. Receiver operator characteristic (ROC) analysis was used to compare the discriminatory capability of ¹H-MRSI and perfusion MR imaging.

RESULTS: The discriminant function analysis correctly classified 84.2% of original grouped cases (P < .0001), on the basis of NAA/Cho, Cho_norm, NAA_norm, and NAA/Cr ratios. MRSI and perfusion MR imaging had similar discriminatory capabilities in differentiating tumors from nonneoplastic lesions. With cutoff points of NAA/Cho ≤0.61 and rCBV ≥1.50 (corresponding to diagnosis of the tumors), a sensitivity of 72.2% and specificity of 91.7% in differentiating tumors from nonneoplastic lesions were achieved.

CONCLUSION: These results suggest a promising role for ¹H-MRSI and perfusion MR imaging in the distinction between brain tumors and nonneoplastic lesions in adults.