Keywords:
Embolism / Thrombosis, Contrast agent-intravenous, CT-Angiography, Pulmonary vessels
Authors:
A. S. Menon, J. A. Abdulkarim; Nuneaton/UK
DOI:
10.1594/ecr2018/C-1402
Methods and materials
Patient parameters
The CTPA images were retrospectively evaluated for 65 patients that included 40 females and 25 males,
aged 29-90years.
Scan Parameters
Reduced dose of intravenous contrast 45 ml of 350 mg iodine/ml Omnipaque was injected at 5 ml/s tapering to 4.2 ml/s by a power injector through an 18guage cannula.
The degree of opacification in the proximal pulmonary arteries was measured in Hounsfield units.
The scan initiation was controlled using bolus tracking method,
placing a region of interest (ROI) in the main pulmonary artery.
The scans were triggered when the threshold reached 80 HU in main pulmonary artery.
Measurement and Diagnostic quality
The three regions of interest measured were main,
right/left pulmonary arteries.
Threshold value of 250 HU in main pulmonary artery was considered to be diagnostic.
This particular value was chosen from past literature and authors own clinical experience that emboli cannot be usually ruled out if the main pulmonary artery opacification is less than 250Hu.