Pulmonary embolism: Low dose contrast MSCT pulmonary angiography with modified test bolus technique.

PURPOSE: This study aims to prove that the test bolus technique provides a better selective imaging study of the pulmonary arterial system in comparison to the automatic bolus-tracking technique.

METHOD: A prospective study included 600 patients, classified into 2 groups where each group consisted of 300 patients. In group A, we used the bolus tracking technique with 80-100 ml of contrast while in group B test bolus technique was used with 50 mL of contrast.

RESULTS: It was clear that the Main PA average density was 260.5 HU in group A and increased to 320 HU in group B with P value < 0.002. The Ascending aorta average density decreased from 250 HU in group A to 130 HU in group B with P value <.001. The average score was increased by 35 % (from 1.75 in group A to 2.8 in group B with P value < .001). The Volume of IV contrast needed decreased by 40 % in group B compared to group A.

CONCLUSION: MSCTPA using test bolus method reduces the amount of the contrast used with better opacification of the pulmonary artery and its sub segmental branches in addition to reduced artifact.