Abhinav Vij MBBS, MPH, Presenter: Nothing to Disclose

Shyla S. Saini, Abstract Co-Author: Nothing to Disclose

Mannudeep K. S. Kalra MD, Abstract Co-Author: Medical Advisory Board, General Electric Company Research grant, General Electric Company Faculty, General Electric Company Consultant, Bracco Group

Matthew David Gilman MD, Abstract Co-Author: Nothing to Disclose

Jo-Anne O. Shepard MD, Abstract Co-Author: Nothing to Disclose

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

To assess the image quality, vessel contrast and diagnostic confidence in CTPE (CTPE) studies obtained from reconstructing projection based single source dual energy CT (SS DECT) data at different keV.

In an IRB approved study, 27 CTPE studies were performed with SS DECT (GE HD 750) in 27 consecutive patients [10 M:17 F; 57 ± 17 years] using 80 and 140 kVp. 1.25mm sections were transferred to a spectral CT data processing workstation to reconstruct monochromatic images at 77, 70, 65, 60 and 50 KeV. Two experienced thoracic radiologists assessed the pulmonary trunk (MPA), right and left main (RPA and LPA), lobar (LA) and subsegmental (SSA) pulmonary arterial branches for image noise, artifacts, and vessel contrast on a scale of 1-5 (1 being the worst and 5 the best). Mean CT numbers were also measured in these vessels at each KeV. The confidence of diagnosis (COD) was scored on a 5-point scale (1 being the lowest and 5 the highest). The studies were categorized in to 3 groups based on mean CT numbers in the vessels - excellent (> 300 HU), adequate (250-300 HU) and suboptimal (< 250 HU). Friedman Anova test was used for data analysis.

There were 4 positive and 23 negative studies of PE. At 77 KeV (120kVp), contrast opacification was suboptimal in 7/23 (26%), adequate in 13/27 (48%) and excellent in 7/27 (26%). In all groups, vessels showed higher contrast and noise at lower KeV (p < 0.0001). Among suboptimal studies the artifacts decreased and COD increased at lower keV (p < 0.0001). However among the excellent studies, artifacts increased and COD decreased at ≤70 KeV (p < 0.001). Among the adequate studies the artifacts decreased and COD improved at 70 and 65 Kev but became worse at 50keV due to greater image noise. PE in suboptimal studies was better seen at ≤70 keV.

Monochromatic images (≤70 keV) acquired with SS-DECT enhance image contrast and diagnostic confidence of suboptimal CT pulmonary angiography.

SSDE CT allows image interpretation at lower keV with significant increase in vessel contrast, COD and decrease in artifacts for suboptimal studies and these studies can be potentially salvaged.

Vij, A, Saini, S, Kalra, M, Gilman, M, Shepard, J, Digumarthy, S, CT Pulmonary Embolism Study (CTPE) with Single Source Dual-Energy CT: A Pilot Study to Assess Image Quality and Diagnostic Confidence on 50-77 keV Monochromatic Images.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9014343.html