The Frequency of Insufficient Contrast Enhancement of the Pulmonary Artery in Routine Contrast-enhanced Chest CT and Its Improvement With an Increased Injection Rate

Abstract

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. 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. 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). 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.