[Value of magnetic resonance in the diagnostic definition of neurotoxoplasmosis and in the assessment of the response to pharmacological treatment].

Purpose: We investigated the role of Magnetic Resonance Imaging (MRI) in the diagnosis of neurotoxoplasmosis and in the evaluation of drug treatment response.

Material And Methods: Twenty-six AIDS patients (22 men and 4 women, mean age 26.7 years) with clinical suspicion of neurotoxoplasmosis were examined. A patient was considered to have neurotoxoplasmosis if there were signs of focal neurologic impairment and a positive/questionable response to the serum test for Toxoplasma gondii. MR images were acquired with T1-weighted spin-echo (SE) and inversion recovery (IR) sequences and with T2-weighted SE sequences. Gd-DTPA was administered in all cases. After the beginning of therapy with sulfadiazine and pyrimethamine all patients were submitted to clinical and neuroradiologic follow-up for 60 days.

Results: MR examinations on admission demonstrated at least one brain lesion in all patients and multifocal involvement in 70% of cases. Enhancing lesions were found in 90% of patients (83% ring enhancement, 4% focal enhancement, 3% mixed patterns). The most frequent lesion sites were the basal ganglia and thalami (70%). The brain lesions were subdivided into 4 groups by their morphology and signal patterns.

Discussion: The time course of clinical and neuroradiologic responses demonstrates a rapid improvement after the first week of therapy, which stabilized after the second week. Pearson correlation between clinical and neuroradiologic treatment responses showed a nearly linear correlation (r = .97; p < .001). The diagnosis was then confirmed in all patients based on the positive response to the serum test for Toxoplasma gondii (IgG > 12 UI/mL) and/or clinical and neuroradiologic improvement after therapy.

Discussion And Conclusions: This study demonstrates the accuracy of MRI in the detection of toxoplasmosis brain lesions and in the evaluation of treatment response.