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Objective To investigate the feasibility of subtraction coronary computed tomography angiography (Sub-CCTA) for the diagnosis of coronary heart disease in the segment with severe calcification.Methods A retrospective analysis was performed on 27 patients who underwent clinically indicated digital subtraction angiography (DSA) and CCTA using a 320-detector row CT.Compared with the results of DSA,sensitivity,specificity,positive predictive value,negative predictive value and accuracy of Con-CCTA and Sub-CCTA were calculated.The clinical diagnostic accuracy of the two imaging methods was evaluated using the receiver operating characteristic (ROC) curve.The stenosis of coronary segments was divided into four grades (Ⅰ,Ⅱ,Ⅲ,Ⅳ).Kappa coefficient was used to measure agreement between two imaging methods.Image quality of 4-scale grade scoring method was used and t test was conducted.Results A total of 52 segments with severe calcification were evaluated.The scores of image quality in Con-CCTA and Sub-CCTA were 2.8 ± 0.5 and 3.4 ± 0.7,respectively.There was significant difference between them (t =5.9,P ＜ 0.05).Compared with the result of DSA as the golden standard,the Kappa coefficients were 0.55 and 0.81 respectively in Con-CCTA and Sub-CCTA for the quantitative evaluation of the severe calcified segments.The sensitivity,specificity,positive predictive value and negative predictive value and accuracy of Con-CCTA were 81.0％,63.1％,63.1％,81.1％ and 70.8 ％;and for Sub-CCTA they were 90.5 ％,85.2％,82.1 ％,92.0％ and 87.5 ％ respectively.Compared with Con-CCTA,the area under the ROC curve of Con-CCTA and Sub-CCTA were 0.84 (95％CI:0.70-0.93) and 0.96 (95％ CI:0.86-1.00),respectively,and the difference was statistically significant (P =0.03).Conclusions Sub-CCTA can improve the diagnostic accuracy of coronary artery stenosis in severe calcified segment.Application of subtraction technique in CCTA can reduce or even eliminate the artifacts caused by severe calcified plaque,and has a good clinical application prospect.
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Objective To investigate rare and atypical imaging manifestations of abdominal lesions associated with IgG4-related disease (IgG4-RD).Methods Forty-one patients with IgG4-RD proved histopathologically or clinically were investigated retrospectively.All the patients underwent precontrast and dynamic enhancement scan of the abdomen.CT was performed in 32 patients and MR imaging in 27 patients (including both of CT and MRI in 18 patients).Whether tissue and organs of the abdomen were involved was observed,especially rare and atypical imaging manifestations including focal pancreatic lesion,pseudocyst and (or) abscess as well as calcification of pancreas,peripheral blood vessels of pancreas involvement and mass-like lesions were existed.Involvement of the organs including liver,gallbladder,spleen,gastrointestinal tract,mesentery and their manifestations were also observed.Results One to four abdominal organs were involved,the numbers of involved organs were as follows:one organ in 13 patients (31.7％),two organs in 12 patients (29.3％),three organs in 13 patients (31.7％),and four organs in 4 patients (7.3％).The most commonly involved organ of the abdomen was the pancreas which was found in 35 patients.Abdominal extrapancreatic lesions were found in 33 patients.Focal involvement of pancreas as a rare manifestation showed in 11 cases (11/35,31.4％).The patterns were focal and multifocal.Rare cases showed pseudocysts (3/35,8.6％) and abscess was found in 1 case.Capsule-like rim was present around the pancreas lesions in 25 cases.Ten cases showed thick and wide rim with unclear boundaries with adjacent blood vessels,and 7 of them showed the peripheral blood vessels surrounded.Bile duct involvement was observed in 26 patients,and gallbladder involvement was observed in only 2 of them.Rare renal involvement patient has mass-like lesion,with hypointensity on T2WI,then showed decreased enhancement and gradually delayed enhancement.One retroperitoneal fibrosis patient also showed mass-like lesion as an atypical and rare manifestation.Three IgG4-related liver inflammatory pseudotumors were found in 2 patients.Lesions showed iso or hypointensity on T2WI,continuously enhancement,with abnormal edge ring.Mesentery involvement was found in 1 patient.Conclusion Several abdominal lesions associated with IgG4-RD have rare and atypical imaging manifestations.There are specific imaging characteristics,which are helpful for most accurate diagnosis of IgG4-RD.
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Objective To investigate the methods and effects of abdominal and pelvic shielding for pediatric chest CT examinations.Methods The 705-D phantom made by Computerized Imaging Reference Systems (CIRS) was used to replace a 5-year-old child,thermoluminescent dosimeters were set in the abdomen and pelvis to measure the organ and tissue doses.Chest scans were conducted with the routine protocol for pediatric chest CT examinations.Doses to main organs and tissues in the abdomen and pelvis were measured after chest CT scans without lead apron,with lead apron covering anterior of the abdomen and pelvis and with apron wrapping same part,respectively.Results Absorbed doses to some abdominal organs near the irradiation field were up to several mGy in a procedure of pediatric chest CT examination.There were statistically significant differences among the dose values for three different scans at the same location (x2 =16.00,P ＜ 0.05).Statistically significant difference was also found between the dose values for scans,which were measured with wrapping and covering approaches (Z =-2.52,P ＜ 0.05).Compared to the doses in the condition of no shielding,the doses in testis and colon reduced by 71.2％ and 42.3％,respectively,if the abdomen and pelvis was wrapped with a lead apron (0.35 mm Pb),and reduced by 55.9％ and 26.1％,respectively,if the same lead apron was used to cover the anterior of the abdomen and pelvis.Conclusions In pediatric chest CT examinations,the use of a lead apron can effectively shield the abdomen and pelvis,and plays an important role in protection of the gonad and colon.The wrapping measure is worth being recommended.