Proton magnetic resonance spectroscopic imaging to differentiate between nonneoplastic lesions and brain tumors in children

Purpose: To investigate whether in vivo proton magnetic resonance spectroscopic imaging (MRSI) can differentiate between 1) tumors and nonneoplastic brain lesions. and 2) high- and low-grade tumors in children. Materials and Methods: Thirty-two children (20 males and 12 females, mean age = 10 5 years) with primary brain lesions were evaluated retrospectively. Nineteen patients had a neuropathologically confirmed brain tumor, and 13 patients had a benign lesion. Multislice proton MRSI was per-formed at TE = 280 msec. Ratios of N-acetyl aspartate/ choline (NAA/Cho), NAA/creatine (Cr), and Cho/Cr were evaluated in the lesion and the contralateral hemisphere. Normalized lesion peak areas (Cho(norm), Cr-norm, and NAA(norm)) expressed relative to the contralateral hemisphere were also calculated. Discriminant function analysis was used for statistical evaluation. Results: Considering all possible combinations of metabolite ratios, the best discriminant function to differentiate between nonneoplastic lesions and brain tumors was found to include only the ratio of Cho/Cr (Wilks'lambda, P = 0.0 12: 78. 1% of original grouped cases correctly classified). The best discriminant function to differentiate between high- and low-grade tumors included the ratios of NAA/Cr and Cho(norm) (Wilks' lambda. P = 0.001: 89.5% of original grouped cases correctly classified). Cr levels in low-grade tumors were slightly lower than or comparable to control regions and ranged from 53% to 165% of the control values in high-grade tumors. Conclusion: Proton MRSI may have a promising role in differentiating pediatric brain lesions. and an important diagnostic value. particularly for inoperable or inaccessible lesions.