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Purpose We compare the effect of tube current modulation (TCM) and fixed tube current (FTC) on size‐specific dose estimates (SSDE) and image quality in lung cancer screening with low‐dose CT (LDCT) for patients of all sizes. Methods Initially, 107 lung screening examinations were performed using FTC, which satisfied the Centers for Medicare & Medicaid Services' volumetric CT dose index (CTDIvol) limit of 3.0 mGy for standard‐sized patients. Following protocol modification, 287 examinations were performed using TCM. Patient size and examination parameters were collected and water‐equivalent diameter (Dw) and SSDE were determined for each patient. Regression models were used to correlate CTDIvol and SSDE with Dw. Objective and subjective image quality were measured in 20 patients who had consecutive annual screenings with both FTC and TCM. Results CTDIvol was 2.3 mGy for all FTC scans and increased exponentially with Dw (range = 0.96–4.50 mGy, R2 = 0.73) for TCM scans. As patient Dw increased, SSDE decreased for FTC examinations (R2 = 1) and increased for TCM examinations (R2 = 0.54). Image quality measurements were superior with FTC for smaller sized patients and with TCM for larger sized patients (R2 > 0.5, P

Background and Aim: Data on prevalence of portopulmonary shunts (PPS) are quite limited. Most studies have used cineportography or echocardiography for diagnosis. Only few recent case reports have reported the use of computed tomography (CT) for identifi- cation of PPS. This study tried to determine the prevalence of PPS in patients with cirrhosis using contrast-enhanced CT of the abdomen, and to determine their association with demographic and clinical characteristics. Methods: A total of 150 subjects with cirrhosis who had previously undergone triple- phase CT were analyzed. PPS was diagnosed when at least one esophageal varix met all of the following criteria: (i) it could be followed cephalad into the chest to the level of the inferior pulmonary vein or left atrium; (ii) it abutted the wall of either of these structures; (iii) it had luminal continuity with one of these structures; and (iv) it was no longer seen one slice above the level of contact. Results: Of 150 subjects, 18 were excluded for incomplete data. The prevalence of PPS was found to be 26/132 (19.7%). Of these, 14 (53.8%) patients had PPS draining into the left atrium and 12 (46.2%) had those draining into one of the pulmonary veins. Presence of PPS was associated with the presence of varices at endoscopy, ascites, thrombocytope- nia and splenomegaly. Conclusion: In our study, the largest study on PPS to date, the prevalence of PPS in cirrhotic patients using triple phase CT was found to be 19.7%. CT may be a useful technique to study PPS and their clinical implications.