Multiparametric magnetic resonance imaging features of giant intracranial tuberculomas

To evaluate Magnetic Resonance Imaging (MRI) features of Giant Tuberculomas (GT) of the brain and deduce characteristic imaging phenotypes which may differentiate GT from higher grade glioma.

A retrospective analysis of MRI was done on Tuberculomas of size >2 cm. The diagnosis was established by histopathology or presumed from size reduction on follow-up MRI while on empirical anti-tubercular therapy (ATT). Multimodality characteristics of GT on T1/T2W, Fluid attenuation recovery (FLAIR), Diffusion-Weighted imaging (DWI), Susceptibility Weighted Imaging (SWI), Spectroscopy (MRS) and Perfusion weighted sequences were assessed. These imaging features were also evaluated in WHO Grade IV, IDH-wild type glioma (histopathologically and genetically proven) and a comparative analysis of the imaging features between GT and glioma was done.

Thirty-two GT and 20 glioma were evaluated. Pronounced intralesional T2 hypointensity (n = 8;25%), T2 hyperintense crescent beneath the periphery (n = 25, 78.1%), T2W lamellated/whorled appearance (n = 17;53.125%), hyperintense rim on T1W MT (n = 25;78.1%), peripheral rim of diffusion restriction (n = 22; 68.75%), peripheral rim of blooming on SWI (n = 20, 62.5%), prominent lipid resonance on MR spectroscopy (n = 30; 93.75%), overshoot of the signal intensity-time curve above the base line (n = 9/10; 90%) on dynamic susceptibility contrast (DSC) perfusion, were remarkable imaging characteristics. Reduction of peripheral T1 hyperintensity, compaction of T2 hypointense core, expansion of sub-marginal T2 hyperintense rim and increased peripheral susceptibility (n = 20; 62.5%) during follow-up imaging, while on ATT, were standout features. GT could be differentiated from WHO grade IV (IDH-wild type) glioma on the basis of a significantly higher proportion of GTs showing a whorled/lamellated appearance, T1 hyperintense rim, T2 hypointense core, DWI-ADC mismatch, well-defined rim on SWI, prominent lipid peak on MRS and a submarginal T2 hyperintense rim. GT showed a higher normalized ADC ratio from the core as well as the rim. Significantly higher proportion of glioma showed a T1 hypointense and T2 hyperintense core and a nodular rim enhancement. A significantly higher r CBV, Choline to creatine, choline to NAA ratio and mean thickness of the peripheral enhancing rim were defining features among gliomas.

Neuroimaging features of GT have been elucidated. Reduction of peripheral T1 hyperintensity, compaction of T2 hypointense core, expansion of sub-marginal T2 hyperintense rim, and increased peripheral susceptibility on follow-up may be considered imaging markers of response to anti-tubercular therapy. Multiparametric MRI features can differentiate GT from WHO grade IV (IDH-wild type) glioma.