Alexi Otrakji MD, Presenter: Nothing to Disclose

Subba Rao Digumarthy MD, Abstract Co-Author: Nothing to Disclose

Roberto Lo Gullo MD, Abstract Co-Author: Nothing to Disclose

Jo-Anne O. Shepard MD, Abstract Co-Author: Consultant, Agfa-Gevaert Group

Cristy Savage RT, Abstract Co-Author: Nothing to Disclose

Mannudeep K. S. Kalra MD, Abstract Co-Author: Nothing to Disclose

To compare performance of routine dual energy chest CT (DECT) for lesion and vascular enhancement at 35 and 100 seconds scan delays following administration of intravenous iodinated contrast media.

Our study included 52 adult patients who underwent contrast enhanced routine DECT CT of the chest on dual source MDCT(Somatom Definition Flash,Siemens)or single source 64-row MDCT(GE 750HD Discovery,GE).Of these 26 patients (mean age 64±11years,M:F12:14,mean weights75 ±19 kg)received 80 ml of 370mg% iodinated intravenous contrast(2-3 cc/seconds)and were scanned at 35 second fixed delay.The remaining sex- and gender-matched 26 patients(mean age 67±12years,M:F 12:14,mean weights74 ±19 Kg) were scanned at 100 second delay following administration of the same contrast agent(370mg%,80 ml,44ml of contrast injected at 0.6ml/second followed by 36ml contrast at 1.8ml/second) using the identical DECT technique.Blended,monoenergetic(60 kev),and material decomposition image (iodine/ pulmonary blood volume and virtual non contrast (VNC)) were generated for all patients.HU (in main pulmonary artery (MPA)),CTDI vol and DLP were recorded .

There was no significant difference between weights and radiation dose of the patients undergoing DECT at 35- or 100-second scan delay (p>0.1).DECT at 100 seconds demonstrated significantly better contrast enhancement compared to prior CT examinations (in 20/53 pulmonary abnormalities) as compared to DECT at 35-second scan delay (better  in 16/20).Optimal to excellent quality was noted in DECT at 100 seconds for all image types (100% Mono60 Kev, iodine, and VNC images)With none to minimal contrast related artifacts in most patients.There was superior iodine subtraction on VNC images on DECT performed with 100 seconds delay compared to those at 35 seconds (p<0.0001). Vascular contrast enhancement in MPA at 100 second scan delay 333±137 HU.

DECT of the chest at 100 second scan delay allows better lesion enhancement,fewer artifacts and superior quality of material decomposition images as compared to standard 35 second scan delay.Pulmonary arterial enhancement is not compromised due to split bolus contrast injection technique used for longer scan delays.

Fixed delay split bolus DECT gives enough time for lung lesions to enhance which improves the diagnostic characterization of these lesions,without compromising the vascular enhancement.

Otrakji, A, Digumarthy, S, Lo Gullo, R, Shepard, J, Savage, C, Kalra, M, Comparison of 35-second and 100-second Scan Delays for Contrast Enhanced Routine Dual Energy CT of the Chest: Lesion and Vascular Enhancement.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14017785.html