Thallium-201 SPECT and Technetium-99m-Phytate Subtraction Liver Imaging in the Evaluation of Pancreatic Cancers

We preliminarily evaluated the usefulness of 201Tl SPECT in the investigation of pancreatic cancers. The subjects included 32 patients with malignant tumors, 16 with benign disorders and 10 controls. SPECT was performed 10 min after the injection of 148-222 MBq of 201Tl; subjects had fasted to minimize intestinal activity. In addition, subtracted SPECT using 99mTc-phytate to separate the boundary of abnormal uptake from liver activity was carried out in 14 patients. Thallium-201 did not accumulate in the pancreatic bed of the controls. In contrast, 29 of the 32 patients with malignant tumors showed positive phytate uptake with a sensitivity of 90.6% in the detection of malignancy. Of the 16 benign disorders, only four patients showed abnormal uptake; however, the mean value of the lesion-to-hepatic ratio (0.43 +/- 0.06; range, 0.35-0.51), as an index of the degree of uptake, was lower than that in positive malignant tumors (0.72 +/- 0.16; range, 0.53-1.28). Thallium-201 activity per milligram of resected cancer tissue in two patients was 2-3 times greater than in normal tissue. Follow-up 201Tl SPECT in the five treated patients demonstrated similar alterations between 201Tl uptake and tumor markers. Our results suggest that 201Tl SPECT may have clinical potential in the investigation of pancreatic cancers.