Role of diffusion weighted imaging in differentiation of intracranial tuberculoma and tuberculous abscess from cysticercus granulomas-a report of more than 100 lesions

Restricted diffusion is noted in a large number of non-stroke conditions including tuberculoma. The purpose of this study was to demonstrate spectrum of diffusion weighted imaging (DWI) abnormalities in tuberculomas and tuberculous abscess and to distinguish these from degenerating neurocysticercosis. Seventy tuberculomas and tuberculous abscesses in 30 patients were categorized in three groups depending on the intensity in the core of the lesion on T2 weighted images. Mean apparent diffusion coefficient (ADC) was calculated from the core as well as from the wall of the lesions. Forty-five lesions of neurocysticercosis in different stage of evolution in 12 patients were also included for comparison. The mean ADC value from the core of the T2 hypointense lesions was significantly higher compared to the wall ((1.24 ± 0.32) × 10−3 and (1.06 ± 0.15) × 10−3 mm2/s, respectively), while mean ADC value from the core of mildly T2 hyperintense lesions was significantly lower compared to the wall ((0.80 ± 0.08) × 10−3 and (1.08 ± 0.13) × 10−3 mm2/s, respectively). Truly T2 hyperintense lesions were divided into two subgroups, tuberculomas and tuberculous abscesses; ADC values from the core and the wall of these lesions were (0.74 ± 0.13) × 10−3, (0.61 ± 0.08) × 10−3 and (1.03 ± 0.14) × 10−3, (1.08 ± 0.14) × 10−3 mm2/s, respectively, and was significantly lower in core as compared to the wall. However, there was no significant difference between ADC values of the tuberculous abscess and the hyperintense tuberculomas. Vesicular and degenerating stages of cysticercus cysts from the core showed ADC values of (1.66 ± 0.29) × 10−3 and (1.51 ± 0.23) × 10−3 mm2/s, respectively, and were significantly higher than the core of all groups of tuberculomas and tuberculous abscess. We conclude that addition of DWI to routine imaging protocol may help in differentiation of tuberculous lesions from degenerating cysticercus granuloma.