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Purpose@#We assessed the lesion detection performance of the dual-tracer parathyroid SPECT imaging using the joint reconstruction method. @*Materials and Methods@#Thirty-six noise realizations were created from SPECT projections collected from an in-house neck phantom to emulate 99mTc-pertechnetate/99mTc-sestamibi parathyroid SPECT datasets. Difference images representing parathyroid lesions were reconstructed using the subtraction and the joint methods whose corresponding optimal iteration was defined as the iteration which maximized the channelized Hotelling observer signal-to-noise ratio (CHO-SNR). The joint method whose initial estimate was derived from the subtraction method at optimal iteration (the joint-AltInt method) was also assessed. In a study of 36 patients, a human-observer lesion-detection study was performed using difference images from the three methods at optimal iteration and the subtraction method with four iterations. The area under the receiver operating characteristic curve (AUC) was calculated for each method. @*Results@#In the phantom study, both the joint-AltInt method and the joint method improved SNR compared to the subtraction method at their optimal iteration by 444% and 81%, respectively. In the patient study, the joint-AltInt method yielded the highest AUC of 0.73 as compared with 0.72, 0.71, and 0.64 from the joint method, the subtraction method at optimal iteration, and the subtraction method at four iterations. At a specificity of at least 0.70, the joint-AltInt method yielded significantly higher sensitivity than the other methods (0.60 vs 0.46, 042, and 0.42; p < 0.05). @*Conclusions@#The joint reconstruction method yielded higher lesion detectability than the conventional method and holds promise for dual-tracer parathyroid SPECT imaging.
RESUMO
BACKGROUND/AIMS: To report gastric emptying scintigraphy, normal values should be established for a specific protocol. The aim of this study was to provide normal gastric emptying values and determine factors affecting gastric emptying using Asian rice-based meal in healthy volunteers. METHODS: One hundred and ninety-two healthy volunteers were included at 7 tertiary care centers across Thailand. Gastric emptying scintigraphy was acquired in 45 degree left anterior oblique view immediately after ingestion of a 267 kcal steamed-rice with technetium-99m labeled-microwaved egg meal with 100 mL water for up to 4 hours. RESULTS: One hundred and eighty-nine volunteers (99 females, age 43 +/- 14 years) completed the study. The medians (5-95th percentiles) of lag time, gastric emptying half time (GE T1/2) and percent gastric retentions at 2 and 4 hours for all volunteers were 18.6 (0.5-39.1) minutes, 68.7 (45.1-107.8) minutes, 16.3% (2.7-49.8%) and 1.1% (0.2-8.8%), respectively. Female volunteers had significantly slower gastric emptying compared to male (GE T1/2, 74 [48-115] minutes vs. 63 (41-96) minutes; P < 0.05). Female volunteers who were in luteal phase of menstrual cycle had significantly slower gastric emptying compared to those in follicular phase or menopausal status (GE T1/2, 85 [66-102] mintes vs. 69 [50-120] minutes or 72 [47-109] minutes, P < 0.05). All of smoking volunteers were male. Smoker male volunteers had significantly faster gastric emptying compared to non-smoker males (GE T1/2, 56 [44-80] minutes vs. 67 [44-100] minutes, P < 0.05). Age, body mass index and alcohol consumption habits did not affect gastric emptying values. CONCLUSIONS: A steamed-rice with microwaved egg meal was well tolerated by healthy volunteers. Gender, menstrual status and smoking status were found to affect solid gastric emptying.
