Low volume contrast CTPA in patients with renal dysfunction

Introduction: The study aims to evaluate a method for and technical feasibility of performing CT pulmonary angiography (CTPA) with just 30 mL of contrast. Methods: Twenty-four patients with renal dysfunction suspected of having pulmonary embolus underwent CTPA using 30 mL of contrast. A modified acquisition protocol was employed where sequential monitoring of the central superior vena cava (SVC) was performed following injection of contrast. Scanning was triggered at the first visualised arrival of contrast within the SVC. Hounsfield unit (HU) measurements were performed at the main pulmonary artery to the subsegmental branches to determine the adequacy of each study. Results: The level of pulmonary arterial enhancement achieved was high, averaging 247 HU across all measured arteries. Average enhancement within more peripheral lobar, segmental and subsegmental arteries was also greater than 200. Only one study was considered non-diagnostic. Conclusion: Low-volume CTPA is technically feasible and provides excellent enhancement of the pulmonary arterial tree.