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Abstract: Objective: This study aimed to determine a contrast medium injection rate that ensures both accuracy for data and safety for operation by comparing hemodynamic parameters of brain CT perfusion imaging with varied injection rates. Methods: Twenty-four healthy volunteers were divided into three groups based on contrast medium injection rates (4.5, 6.0, and 7.5 ml/s). For all subjects, CT perfusion scanning was started at 4 s after antecubital venous bolus of contrast media injection. A perfusion-analyzing software package was used to produce a time–density curve in the anterior cerebral artery and the superior sagittal sinus and calculate the regional cerebral blood flow (rCBF) in the gray matter and the white matter. The hemodynamic indices were compared among the three groups, and statistical analysis was carried out using the F test. Results: The time for the arterial rise to reach the peak value for the 7.5-ml/s group was only 0.2 s ahead of the initiation time for the rise of the superior sagittal sinus. The differences of rCBF in the gray matter and the white matter among the three groups were statistically significant. rCBF in the gray matter and the white matter for the 7.5-ml/s group was 52.8 ml · min−1 100 g−1 · (±3.1) and 21.9 ml · min−1 · 100 g−1 (±2.4), respectively. Conclusions: The use of the 7.5-ml/s injection rate can meet the prerequisite of the maximum slope model, and the resulting rCBF can be very close to that measured by positron emission tomography. Therefore, 7.5 ml/s was an ideal contrast medium injection rate. [Copyright &y& Elsevier]

Abstract: Objective: To investigate the improvement in postprocessing time and image quality of 3D negative-contrast CT cholangiography (nCTC) with minimum intensity projection (minIP). Methods: Thirty-eight patients with suspected biliary obstruction who underwent portal phase helical CT were retrospectively studied. Three-dimensional nCTC was generated using 3D tools with manual cut function in three methods: one-slice, two-slice, and vari-slice cut slab, respectively. After adjusting the threshold level to about −20 HU, the erosion function with a value of one voxel was employed each time for further cleaning up hypodense interfering voxels such as fat and air that remained and the procedure was stopped before the biliary and pancreatic ducts were overeroded. Results: Mean values of the total postprocessing time of the three manual cut methods for 3D nCTC were 57.8, 29.9, and 20.6 min, respectively. After the first erosion, interfering voxels were removed in more than half of the cases and they could be primarily eliminated following the second erosion. Meanwhile, the pancreaticobiliary ducts showed obvious erosion findings at the third erosion. Conclusions: The vari-slice manual cut method was shown to be the most timesaving postprocessing method and the image quality for 3D nCTC can be improved when one to two frequencies of erosion are applied. [Copyright &y& Elsevier]

Abstract: Objective: To retrospectively assess the diagnostic efficacy of dual-source CT angiography (DSCTA) in detecting and grading coronary stenosis. Methods: Institutional review board approval and informed consent were obtained. One hundred ten patients were performed with both DSCTA and conventional coronary angiography (CCA) without heart rate or rhythm control in 1 week. Regarding CCA as the gold standard, the assessable rate of coronary arteries and diagnostic value of coronary stenosis using DSCTA were analyzed, respectively. The intermodality agreement between DSCTA and CCA in grading coronary stenosis was assessed using κ test. The value of DSCTA in diagnosing >50% coronary stenoses was also assessed. Results: The overall assessable rate of DSCTA was 98.6% in detecting coronary arteries; there was no significant difference between assessable rates from different groups of heart rate (χ 2=0.45, P > .05). The efficacy of DSCTA was of 97.9% sensitivity, 97.3% specificity, 90.4% positive predictive value, and 99.4% negative predictive value for coronary stenosis; and 94.7% sensitivity, 96.8% specificity, 83.7% positive predictive value, and 99% negative predictive value for >50% stenoses. The intermodality agreement in diagnosing coronary stenosis was satisfactory (k=0.87, u=58.46, P<.01). Conclusions: As an effective noninvasive diagnostic tool, DSCTA yields a promising accuracy and reliability in assessing coronary stenosis. It may be recommended as a valuable screening tool for coronary artery disease, and a potential challenge to CCA as well. [Copyright &y& Elsevier]