Keywords:
Performed at one institution, Cross-sectional study, Retrospective, Quality assurance, Acute, Diagnostic procedure, CT-Angiography, Thorax, Pulmonary vessels, Emergency Imaging
Authors:
M. M. Abdullah, U. S. Umer, A. Nawaz Khan, S. Alam, H. Abid, S. Ghulam ghaus, S. Rughafi, S. Nawaz; Peshawar/PK
DOI:
10.26044/ecr2020/C-13152
Methods and materials
The study was done in the Radiology department with the permission of the ethical committee. All these studies are performed with a 128 row Toshiba Aquilion CT scanner. Iodine based contrast media is used as contrast media through a 18 to 20 G IV catheter in the right ante-cubital vein. Contrast is injected though a double chamber power injector with a flow rate of 4-5ml/sec12 followed by a saline chaser. Bolus tracking method is used using ROI on the main pulmonary artery. Randomly 100 cases were selected, who underwent CTPA with suspicion of pulmonary embolism. The images were viewed through PACS workstation using Synapse® (FUJI DICOME VIEWER), because it increase the accuracy as compared to hard-copy films9. The images are viewed using different setting like Lung window(w:1500 HU, c:-600HU), mediastinal window( w:350HU, c:40HU) and pulmonary artery specific window(w: 700HU, c:100HU) settings, because an embolus can be missed only on mediastinal window2. Multiplanar reformation images through the longitudinal axis of a vessel can be used to overcome some of the problems faced with axial-orientated images of obliquely or axially orientated arteries11. Also, reformatted images can help to differentiate between some anatomic, patient, technical, and pathologic factors that mimic pulmonary embolism and true pulmonary embolism10.
In each study different parameter were selected like age, gender, HU of the main pulmonary trunk, and the diagnosis. A circular region of interest should be measured in the largest axial image of the main pulmonary artery with a diameter of approximately 50% of the vessel. The minimum enhancement of main pulmonary trunk should be 211HU. Above than 211 will be satisfactory, below 211HU is not satisfactory. According to RCR no more that 10.8% of CTPAs have less than 211 HU enhancement of main pulmonary trunk. The data was analyzed using SPSS 21.