Evaluating Contrast-Enhancing Brain Lesions in Patients with AIDS by Using Positron Emission Tomography

15 October 1995 | Volume 123 Issue 8 | Pages 594-598

Objective: To determine whether a noninvasive method for evaluating contrast-enhancing brain lesions in patients with the acquired immunodeficiency syndrome (AIDS) can accurately differentiate between lymphoma and nonlymphoma diagnoses. This method is based on Toxoplasma serologic testing and positron emission tomography.

Design: Prospective, nonrandomized, criterion standard clinical study.

Setting: An academic center in the mid-southeastern United States.

Patients: 20 patients with AIDS and contrast-enhancing brain lesions.

Interventions: Positron emission tomographic scanning and Toxoplasma serologic testing.

Main Outcome Measure: Diagnoses were confirmed by clinical response, autopsy, or brain biopsy.

Results: Eight patients had a confirmed diagnosis of toxoplasmosis, six had lymphoma, four had other diagnoses, and two were not evaluable. Seven of eight patients with toxoplasmosis had positron emission tomographic scans; all of these scans showed hypometabolic lesions consistent with a nonlymphoma diagnosis. The six patients with lymphoma all had hypermetabolic lesions on positron emission tomographic scans. The difference between these two sets of results was statistically significant (P < 0.001, Fisher exact test, two-tailed). The anti-Toxoplasma titer was 1:4 in all patients with confirmed toxoplasmosis who had serologic testing and in three of six patients with lymphoma.

Conclusions: Evaluating contrast-enhancing brain lesions in patients with AIDS by using Toxoplasma serologic testing and positron emission tomography can accurately guide therapy and obviate the need for most brain biopsies in these patients. A larger, national, multicenter study is needed to confirm our findings and to determine the effect of earlier diagnosis and treatment on morbidity and mortality in patients with AIDS and primary central nervous system lymphoma.

Author and Article Information

From Vanderbilt University School of Medicine, Nashville, Tennessee.
Grant Support: In part by a grant from the National Institutes of Health (5M01RR00095, General Clinical Research Center).
Requests for Reprints: Mark Pierce, MD, Division of Infectious Diseases, Vanderbilt University Medical Center, 1211 21st Avenue South, Medical Arts Building, Suite 539, Nashville, TN 37232-8302.
Current Author Addresses: Dr. Pierce: Division of Infectious Diseases, Vanderbilt University Medical Center, 1211 21st Avenue South, Medical Arts Building, Suite 539, Nashville, TN 37232-8302.