Magnetic resonance evaluation of cerebral toxoplasmosis in patients with the acquired immunodeficiency syndrome

Abstract

To evaluate and delineate the characteristics of cerebral toxoplasmosis lesions using a combination of magnetic resonance (MR) spectroscopy, diffusion, and perfusion studies. A total of 8 patients with 23 lesions were evaluated on a 1.5-T MR system. Diffusion-weighted imaging (DWI) was performed with three 'b' values of 50, 500, and 1000 s/mm2, and the apparent diffusion coefficient maps were calculated. The diffusion-weighted appearances and the T2-weighted MR appearances of the lesions were compared. MR spectroscopy was performed using the point-resolved single-voxel technique with two TE values of 135 ms and 270 ms. Perfusion studies were carried out using the dynamic contrast-enhanced technique, and the relative cerebral blood volume maps were qualitatively and quantitatively analyzed. DWI revealed the majority of the lesions as having increased diffusion within their necrotic centers, with the ADC ranging from 0.5 to 3.01 (mean +/- SD: 1.49 +/- 0.7). All the lesions revealed a predominant lipid peak on MR spectroscopy and were extremely hypovascular on perfusion MR studies. MR diffusion, spectroscopy, and perfusion studies help in characterizing toxoplasmosis lesions and, in most cases, can be used in combination to help establish the diagnosis of toxoplasmosis.