Yung Hsin Chen MD, Presenter: Nothing to Disclose

David I Weltman MD, Abstract Co-Author: Nothing to Disclose

Thinh Huy Vu MD, Abstract Co-Author: Nothing to Disclose

Kathryn Ann Robinson MD, Abstract Co-Author: Nothing to Disclose

Sameer Goyal MD, Abstract Co-Author: Nothing to Disclose

Katheryn Draves MD, Abstract Co-Author: Nothing to Disclose

Edward Kim MD, Abstract Co-Author: Nothing to Disclose

Ceayee Mak MD, Abstract Co-Author: Nothing to Disclose

Ivan Ramirez MD, Abstract Co-Author: Nothing to Disclose

Brian James Webber DO, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

We evaluate the potential for improving bolus CT pulmonary angiography in patients with physiologic flow artifacts using expiration imaging.

We performed expiration CT angiography in 12 consecutive patients in whom the contrast enhancement of the main pulmonary artery was suboptimal. Image acquisition was performed on 16-multislice CT with injection rate of 3cc/s. Bolus trigger for scanning was set at 120 HU at pulmonary arterial trunk and initiated post respiration instruction. All CT images were graded for contrast quality with respect to sufficient enhancement of pulmonary arteries (3 grades) at 5 anatomic levels: pulmonary trunk, right and left main and lobar, segmental and subsegmental branches. All CT angiographic images were evaluated concerning the diagnosis of pulmonary embolism (PE). Mean attenuation values of inferior vena cava (IVC), superior vena cava, right atrium (RA) and each of the 5 pulmonary artery levels were compared between the inspiration and expiration imaging by means of the two-tailed Student t test for paired data.

At each level anatomic level of the pulmonary artery there was significant difference in enhancement (P<0.001) when comparing inspiration and expiration imaging. The percent increase in contrast enhancement between inspiration and expiration scan ranged from 113 HU -/+ 73 (pulmonary trunk) to 104 HU +/- 53 (subsegmental arteries). During expiration, enhancement of pulmonary trunk was excellent (83%) and adequate (17%) as compared to adequate (67%) and poor (33%) for pulmonary trunk during inspiration. No PE was detected on inspiration imaging while lobar, and bilateral segmental and subsegmental partial occlusion is seen with expiration imaging (n=1). Comparing inspiration and expiration image, there was significant increase enhancement in IVC (P<0.001) and RA (P < 0.05).

Expiration phase CT angiography reduces unopacified venous systemic return and increases enhancement of the pulmonary vasculature. Using expiratory technique can reduce the number of indeterminant pulmonary CT angiogram and increase diagnostic yield.

Chen, Y, Weltman, D, Vu, T, Robinson, K, Goyal, S, Draves, K, Kim, E, Mak, C, Ramirez, I, Webber, B, et al, , Waiting to Exhale: Improving Contrast Dynamic during CT Pulmonary Angiogram Using Expiratory Imaging.  Radiological Society of North America 2005 Scientific Assembly and Annual Meeting, November 27 - December 2, 2005 ,Chicago IL. http://archive.rsna.org/2005/4406047.html