The frequency of insufficient contrast enhancement of the pulmonary artery in routine contrast-enhanced chest CT and its improvement with an increased injection rate: A prospective study

Purpose: To evaluate the frequency of insufficient contrast enhancement of the pulmonary artery (PA) during chest computed tomography (CT) and its improvement by an increased injection rate. Materials and Methods: Two hundred and eighty-eight (group A) and 278 (group B) consecutive patients underwent chest CT with the administration of 100 mL of a 300-mgI/mL nonionized contrast material through the antecubital vein using a power injector. The flow rate was 2 mL/s in group A and 3 mL/s in group B, and 50 mL saline was administered simultaneously using a dual injector. The scan delay was 30 s in both groups. The CT numbers in the pulmonary trunk, bilateral main PA, left atrium, and ascending and descending aortas were measured. Insufficient enhancement of the PA was defined as a CT number of the pulmonary trunk ≤180 HU. Results: Insufficient enhancement of the PA was observed in 21 of 288 patients (7.3%) in group A, whereas it was seen in only 9 of 278 patients (3.2%) in group B (P=0.038). Conclusions: The use of a flow rate of 3 mL/s is associated with a significantly lower frequency of insufficient contrast enhancement of the PA, compared with the use of a lower flow rate of 2 mL/s with the same total volume of contrast.