Two cases of ringlike enhancement on MRI mimicking malignant brain tumors

The present study was performed to investigate two cases with ringlike enhanced lesions mimicking malignant tumors on magnetic resonance imaging (MRI) and to determine the utility of thallium-201 single-photon emission tomography (201Tl-SPECT) and diffusion-weighted MR imaging (DWI) for differential diagnosis between neoplastic and nonneoplastic lesions. One patient was a 50-year-old man who presented with a right caudate lesion. The 201Tl-SPECT study revealed no uptake in the lesion. Stereotactic biopsy was performed, and pathological findings indicated cerebral infarction. The other patient was a 58-year-old woman who presented with a right frontal lesion with edema. DWI showed a hypointense signal, and the apparent diffusion coefficient (ADC) revealed a hyperintense signal in the lesion. Stereotactic biopsy with endoscopy was performed, and the pathological findings suggested a demyelinating disease. Combined 201Tl-SPECT and DWI studies may be useful for differential diagnosis between neoplastic and nonneoplastic lesions. However, stereotactic biopsy should be performed for the final pathological diagnosis.