Abstract
Objective: To determine the diagnostic efficiency of thallium-201 single photon emission computed tomography (SPECT) and Epstein-Barr virus (EBV) polymerase chain reaction (PCR) in the differentiation of primary central nervous system lymphoma (PCNSL) from other central nervous system processes in patients with HIV/AIDS.Design/Methods: Over 10 years, 68 thallium-201 SPECT scans were performed on neurologically symptomatic HIV+ patients with focal lesions on CT or MRI at the Johns Hopkins Hospital. Diagnoses were then established by either autopsy, biopsy, or clinical response to anti-toxoplasmosis therapy. Patients were categorized prior to a prospective clinical reading of the SPECT scans by nuclear medicine physicians.Results: In our patient sample overall, the diagnostic efficiency of thallium-201 SPECT was 79%. The diagnostic accuracy of EBV PCR testing alone in a subset of 22 patients in our study that had CSF analyzed was 73%. However, when both positive EBV PCR and positive thallium-201 SPECT results were used together, the diagnostic accuracy improved to 100% based on a sample of 13 patients where EBV PCR and SPECT imaging results were concordant. Conclusion: Thallium-201 SPECT has a relatively high positive predictive value with regards to the diagnosis of PCNSL, which suggests that patients with positive results could undergo empiric radiation treatment without resorting to brain biopsy. However, the predictive value can be increased by testing for CSF EBV using PCR. Alternatively, if CSF cannot be safely obtained because of mass effect, we believe that these data still suggest that empiric radiation treatment should be considered when discussing treatment options with patients with a positive thallium-201 SPECT.
Highlights
In our patient sample overall, the diagnostic efficiency of thallium-201 single photon emission computed tomography (SPECT) was 79%
The diagnostic accuracy of Epstein-Barr virus (EBV) polymerase chain reaction (PCR) testing alone in a subset of 22 patients in our study that had cerebrospinal fluid (CSF) analyzed was 73%. When both positive EBV PCR and positive thallium201 SPECT results were used together, the diagnostic accuracy improved to 100% based on a sample of 13 patients where EBV PCR and SPECT imaging results were concordant
When both EBV PCR and thallium-201 SPECT results were used together, the diagnostic accuracy improved to 100% based on a sample of 13 patients where the EBV PCR and SPECT imaging results were concordant
Summary
The alternative diagnoses included toxoplasmosis, progressive multifocal leukoencephalopathy, septic emboli, stroke, meningitis, brain abscess, and tuberculosis. Twenty out of 26 patients with PCNSL had focal areas of thallium uptake corresponding to CT/MRI lesions. Eight out of 42 patients with other diagnoses had false-positive scans. Thirtyfour out of 42 patients without PCNSL showed no thallium uptake on scanning. Six out of 26 patients with PCNSL had false-negative scans. The diagnostic accuracy of EBV PCR testing alone in a subset of 22 patients in our study that had CSF analyzed was 73%. When both EBV PCR and thallium-201 SPECT results were used together, the diagnostic accuracy improved to 100% based on a sample of 13 patients where the EBV PCR and SPECT imaging results were concordant
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