Quantitating the superiority of pinhole relative to parallel hole collimator images in detecting foci of radioiodine uptake in the thyroid bed/neck in patients with well-differentiated thyroid cancer

1015 Objectives: The objective of this study was to quantitatively determine how many more foci of radioiodine (RAI) uptake could be detected with individual images (IIs) using pinhole collimator (PiHC) relative to IIs or whole body images (WBIs) obtained with parallel-hole collimator (PaHC) of the thyroid neck/bed in patients with well-differentiated thyroid cancer (WDTC). Methods: A retrospective review was conducted of all RAI scans performed at Wash Hosp Ctr from Jun 2000 to Dec 2006 in patients who had (1) WDTC, (2) a RAI scan of the thyroid bed/neck prior to their first RAI ablation, (3) IIs performed with PiHC and PaHC, and (4) WBIs performed with PaHCs. The specifics of the procedure/cameras will be presented. Each type of image was evaluated blindly. A two-tail student t-test was used. Results: Of the 325 patients meeting the above criteria, the mean (range) age was 46 y.o. (15-83). The mean (range) number of foci identified on WBI-PaHC, II-PaHC, and II-PiHC images were 2.14 (0-8), 2.82 (0-11), and 3.32 (0-14), respectively. The means (ranges) [p values] of the differences in the number foci detected with II-PiHC vs II-PaHC and II-PiHC vs WBI-PaHC were 0.502 (-3 to 6) [p Conclusions: II-PiHCs demonstrated statistically more foci of RAI uptake in the thyroid bed/neck than II-PaHC or WBI-PaHC. This offers the potential to better identify cervical metastases, modify empiric prescribed activity of RAI, and/or provide a better baseline for future comparison.