Alexi Otrakji MD, Presenter: Nothing to Disclose

Efren Jesus Flores 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

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

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

Margaret Kave BS, RT, Abstract Co-Author: Nothing to Disclose

To assess if “contrast enhanced routine chest dual energy CT protocol” (DECT-RC) can provide acceptable vascular enhancement and additional parenchymal information compared to “single energy CT pulmonary angiography” protocol (SECT-PA).

Our IRB approved retrospective study included 200 adult patients who underwent either DECT-RC (n= 100 patients, M: F 47:53,mean age 62±15years, mean weight 76±19kg) or SECT-PA (n=100 patients, M:F 43:57, mean age 59±17years, mean weight 84±24kg). All CT examinations were performed on dual source MDCT (Siemens Definition Flash) or single source 64-row MDCT (GE 750HD Discovery). For DECT-RC, we generated images 60kev, pulmonary blood volume images (PBV) and virtual non-contrast images (VNC) images in transverse plane at 2.5mm thickness. Transverse SECT-PA images were reconstructed at both 1.25 and 2.5mm thicknesses. Two thoracic radiologists assessed main, lobar, segmental and subsegmental pulmonary arterial enhancement and filling defects in addition to diagnostic confidence, pulmonary and mediastinal abnormalities on 60 kev, PBV and VNC images. CTDI vol, and DLP were recorded for each patient.

Radiation dose for DECT-RC (7.2 ± 2.1mGy,260.4 ± 83.2 mGy.cm,3.6 ± 1.2 mSv) was significantly lower than SECT-PA protocol (15 ± 7.9 mGy,499.3±276.4 mGy.cm,7 ± 3.9 mSv) (p=0.0040). Optimal to excellent enhancement in pulmonary arteries was noted with DECT-PA (85%, 85/100 patients) and in 82% of SECT-PA (82/100 patients) (p>0.05). Limited to unacceptable pulmonary arterial enhancement was noted in % (15/100 patients) with DECT-RC and % (18/100 patients) with SECT-PA protocols. PBV images were deemed to provide helpful incremental value in making the diagnosis in 72% of patients (72/100) mostly in patients with perfusion defects from air trapping (better seen on PBV), consolidation, atelectasis, and pulmonary embolism.  The incremental value of VNC images were helpful in 4/100 patients only with high attenuation lung nodules (n=1) and mediastinal lymph nodes (n=3).

Contrast enhanced routine chest protocol with DECT has the potential to replace SECT pulmonary angiography protocol for providing required pulmonary arterial enhancement as well as helpful additional information for evaluation of lung lesions.

Routine chest CT with DECT can provide similar or better information compared to single energy CT pulmonary angiography without incurring any radiation penalty.

Otrakji, A, Flores, E, Lo Gullo, R, Shepard, J, Kalra, M, Digumarthy, S, Kave, M, Comparison of Routine Chest Dual Energy CT Protocol with Single Energy CT Pulmonary Angiography Protocol: Vascular Enhancement and Incremental Value.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14017402.html