We reviewed 12,526 computer-generated text reports of dual-isotope perfusion SPECT studies from a 6-year period for NCFs. NCFs were categorized by organ and by probability of malignancy: high (eg, focal breast or lung uptake of MIBI or TET), intermediate (eg, lymph node uptake or thyroid abnormalities), or low (eg, filling defects in liver, kidney, spleen, or gall bladder; ascites; or pleural effusions). Confirmatory imaging studies or clinical confirmation for each NCF was sought. There were a total of 207 NCFs identified in 180 reports (1.7 % of reports, ranging from 0 % to 2.8 % of reports of individual interpreters). Of these, 107 NCFs were unsuspected before SPECT; 24 % were considered at high probability for malignancy, and 24 % were considered intermediate in likelihood of malignancy. Follow-up data were available for 178 NCFs, confirming 88 % of these findings, including 82 % of breast foci, 62 % of lung foci, 86 % of hepatobiliary/spleen abnormalities, and 94 % of renal abnormalities. The probability of malignancy was highest (82 % ) in breast or lung foci in which uptake of both Tl-201 and the Tc-99m–labeled agent was present.
In patients referred for evaluation of myocardial perfusion, NCFs are unusual and require systematic and careful inspection of projection images for their detection. With Tl-201, TET, MIBI, or dual-isotope imaging, detecting and reporting NCFs may occasionally result in life-saving early cancer identification.