Tuberculosis and diffusion MR imaging and spectroscopy

Abstract

Central nervous system tuberculosis remains a major problem in developing countries, where an increasing incidence can be seen among immunocompromised patients. Cerebral tubercular granulomas with central necrosis are usually seen as rim-enhancing lesions on magnetic resonance imaging (MRI), and on T2weighted images the center may be of variable signal intensity. The time it takes to obtain a diffusionweighted image (DWI) is short, and in many institutions it is a routine part of any MRI of the brain. DWI MRI has revolutionized the imaging of acute infarction in the brain. The value of DWI in cerebral infections and in the differentiation of abscesses from necrotic tumors has been widely reported. Yet, little has been written about DWI on tubercular lesions. Medical journals publish positive results, but radiologists should also be familiar with the limitations of modern imaging techniques. In this issue of Acta Radiologica, Drs Arun Batra and Brig R. P. Tripathi present their experience on diffusion MRI and MR spectroscopy in the evaluation of focal tubercular lesions. This is so far the largest material on this topic and it shows that DWI and MR spectroscopy help in determining the nature of tubercular lesions; however, since the findings vary, they do not help in specific characterization. This article is highly recommended reading.