Clinical impact of MR spectroscopy when MR imaging is indeterminate for pediatric brain tumors.

OBJECTIVE: We undertook this study to determine if single-voxel proton (hydrogen) MR spectroscopy could have clinical impact on the management of pediatric brain tumors when MR findings were indeterminate. SUBJECTS AND METHODS: Eleven children (mean age, 9 years) being examined for brain tumors underwent MR imaging that revealed indeterminate criteria of enhancement, mass effect, and prolonged T1 and T2 signal. MR spectroscopy was then used to distinguish radiation necrosis from tumor in one patient, differentiate residual tumor from scarring in two patients, document early treatment response in three patients, and discriminate benign from malignant masses in five patients. RESULTS: In 10 of the 11 patients, spectra were successfully acquired. Based on the chemical analysis of the indeterminate area shown on MR imaging, clinical impact was achieved in these 10 patients. Clinical impact included treatment modification in five patients, follow-up studies replacing further treatment in three patients, and tumor characterization in the remaining two patients. Confirmation was by histology in four patients and by follow-up MR imaging and MR spectroscopy for up to 30 months in the remaining six patients. CONCLUSION: When MR imaging is indeterminate in evaluating pediatric brain tumors, MR spectroscopy can provide objective neurochemical information, thereby altering treatment.