Thesis (M.Sc.) - Cairo University - Faculty of Medicine - Department of Nuclear Medicine

Objectives: To compare the early and delayed images of whole body post therapy scans in detection of residual thyroid tissues and iodine avid distant metastases. Methods: This ongoing prospective study recruited 30 patients known to have differentiated thyroid carcinoma with history of near total thyroidectomy referred for receiving RAI ablative{u0338}therapeutic doses. Patients underwent dual imaging after receiving 131-I doses; early post therapy whole body imaging was performed on the third to fifth day post treatment and delayed whole body imaging was performed on the seventh to tenth day after treatment. Studies were read independently by two nuclear medicine physicians. Thyroid residues, distant iodine avid lesions, left shoulder (for background correction) and liver counts were taken by drawing a fixed region of interest (ROI) around each in both early and delayed imagesthen calculating ratios between residual tissue to background (RBR), residual tissue to liver (RLR) and distant lesion to background ratio (LBR) and comparing the mean of each ratio in early and delayed imagesand calculating a P value for each. Mean number of overall lesions in early and delayed imaging and mean liver countswere compared as well. Results: The uptake ratios from 27 thyroid remnants in 27 patients and 19 distant lesions in 6 patients were compared. The mean RBR on the early scan (17.1±18) was significantly higher than that on the delayed scan (16.1±18.9; p=0.002).furthermore, the mean RLR on the early scan (7.6±17.7) was significantly higher than that on the delayed scan (6.4±14.9; p=0.001) the mean liver count on the early scan .meanwhile, the mean LBR on the early scan (13.25±7) compared to that on the delayed scan (11.99±7.3; p=scan (13.25±7) compared to that on the delayed scan (11.99±7.3; p=0.4) showed no statistical significant difference

Issued also as CD