Quantitative MR spectroscopic imaging of brain lesions in patients with AIDS: Correlation with [¹¹C-methyl]thymidine pet and thallium-201 SPECT

Rationale and Objectives. The purpose of this study was to examine the metabolic basis for magnetic resonance (MR) spectroscopic imaging findings in focal brain lesions of patients with acquired immunodeficiency syndrome (AIDS). Materials and Methods. The authors combined MR spectroscopic imaging with [¹¹C-methyl]thymidine positron emission tomography (PET) and thallium-201 single photon emission computed tomography (SPECT) in 10 patients. They sought a characteristic metabolite profile that would enable differentiation of benign lesions from primary central nervous system lymphoma and determined whether PET and SPECT results supported the MR spectroscopic imaging findings. Results. Metabolite compositions of the lesions were similar, likely because the lesions were late stage and tended to be necrotic. Brain lesions in patients with AIDS were nonspecific regarding metabolic profile as determined with MR spectroscopic imaging. All patients with positive PET and SPECT studies had primary central nervous system lymphoma. Conclusion. PET and SPECT may be more reliable than MR spectroscopic imaging for differentiating benign lesions from primary central nervous system lymphoma in patients with AIDS.