Carole A. Ridge MD, FFRRCSI, Presenter: Nothing to Disclose

Jennifer Nimhuircheartaigh MBBCh, Abstract Co-Author: Nothing to Disclose

Jonathan Dodd MD, Abstract Co-Author: Nothing to Disclose

Stephen John Skehan MBBCh, Abstract Co-Author: Nothing to Disclose

This retrospective study compared the performance of a standard pulmonary CT angiography (CTA) protocol with a CTA protocol optimized for use in pregnancy in a group of pregnant patients with suspected pulmonary embolism (PE).

Forty two pregnant patients with suspected PE were retrospectively included in the study: Twenty six patients were imaged using a standard pulmonary CTA protocol (group A) and sixteen different patients were subsequently imaged using a protocol modified for pregnancy (group B) involving a shallow inspiration breath-hold following adequate coaching from a technologist and a high concentration, rate of injection and volume of contrast material. Patient characteristics and diagnostic adequacy were recorded from the radiology information system. Measurements of pulmonary arterial enhancement were performed on all CTA studies at specific sites including the main pulmonary artery, right and left pulmonary arteries and right and left lower lobe arteries proximal to their segmental divisions. The relative contribution of the inferior vena cava to the right side of the heart (KIVC) was calculated to detect an artifact due to transient interruption of the contrast bolus by unopacified blood from the inferior vena cava which is thought to happen more frequently in pregnant patients.

The pulmonary CTA protocol modified for use in pregnancy (group B) produced better quality images than the standard pulmonary CTA protocol (group A): the rate of diagnostic adequacy was higher in group B than in group A (88% vs 64%), mean pulmonary arterial enhancement was higher in group B than in group A (339 HU vs 178 HU, p = 0.001) and transient interruption of contrast material by unopacified blood from the inferior vena cava was observed less frequently in group B than in group A (13% vs 39%).

A pulmonary CTA protocol optimized for use in pregnancy significantly impacts on image quality by increasing the rate of diagnostic adequacy, improving pulmonary arterial opacification and decreasing the incidence of transient interruption of the contrast bolus by unopacified blood from the inferior vena cava.

This optimized pulmonary CTA protocol significantly improves image quality and is a reliable investigation for the investigation of suspected PE in pregnancy.

Ridge, C, Nimhuircheartaigh, J, Dodd, J, Skehan, S, Optimizing Pulmonary CTA in Pregnancy: Evaluation of a Modified CTA Protocol.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9002439.html