Rapid differential diagnosis of cerebral toxoplasmosis and primary central nervous system lymphoma by thallium-201 SPECT

Mordechai Lorberboym, Lois Estok, Josef Machac, Isabelle Germano, Michael Sacher, Richard Feldman, Fran Wallach, David Dorfman

Research output: Contribution to journalArticlepeer-review

78 Scopus citations

Abstract

This study sought to assess whether 201Tl brain SPECT can significantly reduce the time required for the differential diagnosis of primary central nervous system (CNS) lymphoma and cerebral toxoplasmosis in patients with AIDS. Methods: Eighteen patients who presented with focal lesions on CT or MRI, or both, underwent 201Tl brain SPECT shortly after admission and before a CT-guided stereotactic brain biopsy. Early and delayed 201Tl uptake ratios were obtained for patients with positive 201Tl study results, and the retention index of 201Tl was calculated. Results: Ten patients had 11 loci of significantly increased 201Tl uptake in regions of corresponding CT/MRI lesions. Five of these patients had biopsy- proven lymphomas, one of them in two separate foci. Another patient was found to have metastatic adenocarcinoma. Three patients had a clinical course and response to radiation therapy consistent with lymphoma, and study results in another patient were considered falsely positive. Of nine patients with no 201Tl uptake in regions of CT/MRI lesions, two had biopsy findings consistent with a benign etiology, and the other seven improved clinically on antitoxoplasmosis medications alone. The overall sensitivity of 201Tl brain SPECT was 100%, and specificity was 90%. The 201Tl retention index in patients with lymphomas was significantly higher than that in patients with adenocarcinomas and nonmalignant lesions (1.35 ± 0.16 versus 0.24 and 0.56, respectively). Conclusion: Thallium-201 brain SPECT is a sensitive and specific method for rapid differential diagnosis of CNS lymphoma and toxoplasmosis in patients with AIDS. The 201Tl retention index is useful in differentiating CNS lymphomas from other malignant and nonmalignant pathologies.

Original languageEnglish
Pages (from-to)1150-1154
Number of pages5
JournalJournal of Nuclear Medicine
Volume37
Issue number7
StatePublished - Jul 1996

Keywords

  • acquired immunodeficiency syndrome
  • central nervous system lymphoma
  • retention index
  • thallium-201
  • toxoplasmosis

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