Shota Yamamoto BS, Presenter: Nothing to Disclose

Justin Pryce McWilliams MD, Abstract Co-Author: Nothing to Disclose

Cesar Arellano MD, Abstract Co-Author: Nothing to Disclose

Wanda Marfori MD, Abstract Co-Author: Nothing to Disclose

Stefan Georg Ruehm MD, Abstract Co-Author: Nothing to Disclose

To evaluate dual energy CT bone subtraction (DEBS) in patients with peripheral artery disease (PAD).

Twenty patients (mean age 73, range 54 to 91, 11 male, 9 female) with known or suspected PAD underwent peripheral artery CTA using a dual energy CT scanner (Somatom Definition, Siemens Medical Solutions) with commercially available software (syngo Multi-Modality workplace software version VE31B, Siemens). Images were evaluated by two board certified radiologists in consensus. A total of 558 non-occluded vessels were evaluated with two methods of image processing: a) automated dual-energy subtraction, and b) conventional manual software based subtraction. Images from each tube detector pair (140 kV and 80 kV), reconstructed at 1 mm slice thickness and 0.75 mm increment with a D30f soft tissue kernel, were combined and loaded into the program. CT acquisition was performed with the following parameters: 0.5 sec gantry rotation time, 32x2x0.6-mm collimation and 165 ms temporal resolution. One tube of the dual source CT system was operated with 95 mAs/rotation at 140 kV and the second tube with 405 mAs/rotation at 80 kV. A merged dataset, generated from the dual energy datasets mimicking a 120 kVp single energy scan (30% 140 kV and 70% 80 kV), was used for comparative MBS. The DEBS software automatically removed bone segments using the dual energy algorithm. Bone segments were removed in MBS using a region growing algorithm by a skilled technician. Using source images and MPR, visibility of each segment was evaluated on a three-point grading scale (0=non diagnostic, 3= vessel is clearly visible) by two radiologists in a consensus reading. A paired Wilcoxon signed rank test was used to determine statistical significance.

Dual energy bone removal provided far superior vessel visibility to MBS (2.74 DEBS vs. 2.56 MBS p=0.011). Following DEBS, 5 of 558 non-occluded vessel segments (0.89%) could not be visualized due to bone remnants, while 42 of 558 non-occluded vessel segments were obscured by bone remnants following MBS (7.5%).

Dual energy CTA is a promising new technique which enables facilitated visualization of peripheral vessels in patients with PAD.

Automated dual energy bone subtraction of the peripheral artery is a relatively new algorithm which offers the potential to increase efficiency of CT angiographic data interpretation by facilitated po

Yamamoto, S, McWilliams, J, Arellano, C, Marfori, W, Ruehm, S, Dual-Energy CT Angiography of the Peripheral Arteries: Dual-Energy Based vs Conventional Bone Subtraction.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8003020.html