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

Purpose: To evaluate and delineate the characteristics of cerebral toxoplasmosis lesions using a combination of magnetic resonance (MR) spectroscopy, diffusion, and perfusion studies. Material and Methods: 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 135ms and 270ms. Perfusion studies were carried out using the dynamic contrast-enhanced technique, and the relative cerebral blood volume maps were qualitatively and quantitatively analyzed. Results: 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±.7). All the lesions revealed a predominant lipid peak on MR spectroscopy and were extremely hypovascular on perfusion MR studies. Conclusion: 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.