Differentiation of tubercular infection and metastasis presenting as ring enhancing lesion by diffusion and perfusion magnetic resonance imaging

As both tuberculoma and metastasis can manifest as solitary or multiple ring-enhancing intra-axial lesions that are difficult to differentiate by conventional magnetic resonance imaging (MRI), we hypothesized that the use of diffusion and perfusion MRI would make differentiation of these pathologies possible.

Diffusion and T2*-weighted dynamic contrast-enhanced perfusion MRI scans from 11 patients with histologically proven tuberculoma or metastasis were retrospectively reviewed by two radiologists who were blinded to the pathology. All patients had a ring-enhancing lesion on conventional MRI. Apparent diffusion coefficient (ADC) values and regional cerebral blood volume (rCBV) were calculated from the walls of the lesions.

Lesions showed different perfusion characteristics depending on whether they were due to tuberculosis or metastasis. The mean rCBV ratio between the lesion periphery and normal white matter was inferior to one for tubercular lesions and greater than five for metastases. However, ADC values were similar.

Measuring rCBV obtained by T2*-weighted dynamic contrast-enhanced perfusion MRI can help in differentiating intracranial tubercular mass lesions and metastases.