Magnetization transfer MR imaging correlation with histopathology in intracranial tuberculomas

Objective: The purpose of this study was to correlate the differences in the magnetization transfer (MT) ratios of different components of the tuberculoma with histopathology and to see whether MT or conventional MR imaging correlates better with histopathology. Methods: MT T1 and conventional spin echo MR imaging was performed in six patients with intracranial tuberculomas. The tuberculomas were excised as a single mass and ex vivo MR imaging was performed using the same protocol. The gross histopathology was compared with in vivo imaging with respect to the MR signal intensity (MT ratio) in all six specimens. Results: The size of the tuberculomas was larger on MT T1-weighted images compared to T2-weighted images and matched the gross measurements of each specimen. The MT hyperintense rim matched the cellular component of the tuberculoma that was masked on T2-weighted images because of the associated perifocal oedema. The cellular component had a lower MT ratio compared to the necrotic components. Conclusion: The outer hyperintense rim and hyperintense strands are due to the cellular infiltrate, noncaseating granulomas, and gliosis while the hypointense core represents solid caseation. The cellular outer rim shows lower MT ratio compared to the core of the tuberculoma. Histological correlation of the cellular and necrotic components of tuberculomas is best shown with MT T1 imaging.