IMAGING OF BRAIN-TUMORS IN AIDS PATIENTS BY MEANS OF DUAL-ISOTOPE TL-201 AND TC-99M SESTAMIBI SINGLE-PHOTON EMISSION TOMOGRAPHY

Our aim was to evaluate the use of dual-isotope thallium-201 (Tl) and technetium-99m sestamibi (sestamibi) simultaneous acquisition in brain single-photon emission tomography (SPET) for the differentiation betw een brain lymphoma and benign central nervous system (CNS) lesions in AIDS patients. Thirty-six consecutive patients with enhancing mass les ions on magnetic resonance (MR) imaging were included in the study. SP ET of the brain was performed to obtain simultaneous Tl and sestamibi images. Regions-of-interest were drawn around the lesion and on the co ntralateral side to calculate uptake ratios. The final diagnosis was r eached by pathologic findings in 17 patients and clinical and/or MR fo llow-up in 19 patients. Of the 36 patients, 11 had brain lymphoma, 1 g lioblastoma multiforme, 15 toxoplasmosis and 9 other benign CNS lesion s. Correlation between SPET and the final diagnosis revealed in 10 tru e-positive, 23 true-negative, 1 false-positive and 2 false-negative st udies. All patients with toxoplasmosis had negative scans. A patient w ith a purulent infection had positive scans. Tl and sestamibi scans we re concordant in every lesion. The same lesions that took up Tl were a lso visualized with sestamibi, However, sestamibi scans showed higher lesion-to-normal tissue uptake ratios (3.7+/-1.8) compared with those of Tl (2.3+/-0.8, P<0.002). Simultaneous acquisition of Tl and sestami bi can help differentiate CNS lymphoma from benign brain lesions in AI DS patients.