Yoshinori Funama PhD, Presenter: Nothing to Disclose

Katsuyuki Taguchi PhD, Abstract Co-Author: Research grant, Siemens AG Research grant, Koninklijke Philips Electronics NV

Seitaro Oda MD, Abstract Co-Author: Nothing to Disclose

Daisuke Utsunomiya MD, Abstract Co-Author: Nothing to Disclose

Yasuyuki Yamashita MD, Abstract Co-Author: Nothing to Disclose

Kazuo Awai MD, Abstract Co-Author: Research grant, Toshiba Corporation Research grant, Hitachi, Ltd Research grant, Bayer AG

Dhruv Mehta MS, Abstract Co-Author: Employee, Koninklijke Philips Electronics NV

Hiroo Murasaki, Abstract Co-Author: Nothing to Disclose

Toshiaki Shimonobo, Abstract Co-Author: Nothing to Disclose

Assessment of coronary artery stent patency is limited by blooming artifact. Potential improvements in spatial resolution with hybrid iterative reconstruction techniques may help overcome this limitation. The purpose of this study was to evaluate in-stent lumen visualization on an anthropomorphic moving heart phantom. Assessments were performed at multiple heart rates and reconstruction technique combinations.

An anthropomorphic moving heart phantom with inner luminal diameter of 3.0mm was implanted with coronary stents. CT acquisitions were performed on a 64-slice MDCT at multiple effective current-time product (mAs): routine dose - 120kVp, 900mAs; low-dose - 120kVp, 450mAs. Acquisitions were performed at multiple heart rates (0, 50, 80 bpm). All acquisitions were reconstructed with conventional filtered back projection (FBP). The low-dose acquisitions were additionally reconstructed with a hybrid iterative reconstruction technique (iDose4, Philips Healthcare). For both reconstruction techniques standard cardiac kernel(CB) and high-resolution cardiac kernel (CD) were applied. The settings of iDose4 were targeted to offset the increase in noise resulting from lowering radiation dose(iDose4Level / noise-reduction%: iDose4Level4 / 29% , iDose4Level7 / 55%). The extent of blooming artifact was quantified by the kurtosis, which was computed from the attenuation line-profiles obtained across identical cross-sections of the stent for the different reconstructions.

The kurtosis for FBP, iDose4Level4 and iDose4Level7 were 0.13, 1.56, and 1.58 respectively, for the study performed at 450 mAs, 50 bpm and CB kernel. The kurtosis further increased for iDoseLevel4 & iDoseLevel7 to 2.47 and 2.46 respectively, with the use of CD kernel. For heart rates of 0 and 80 bpm, a similar trend in increase of kurtosis was observed. Blooming artifact reduction and improved in-stent lumen visualization correlated well with the increasing kurtosis.Image noise for FBP at 900 mAs and iDose4Level7 at 450 mAs were 15.4, 10.8 HU with CB kernel and 41. 6, 24.6 HU with CD kernel.

iDose4 combined with high-resolution kernels can help dramatically reduce coronary stent blooming artifact. Hence, providing improved in-stent lumen visualization.

Iterative reconstruction techniques and high-resolution kernels may help increase the diagnostic confidence for assessment of coronary artery stent patency.

Funama, Y, Taguchi, K, Oda, S, Utsunomiya, D, Yamashita, Y, Awai, K, Mehta, D, Murasaki, H, Shimonobo, T, Investigation of a Hybrid Iterative Reconstruction Technique for Reduction of Coronary Stent Blooming Artifact in Coronary CT Angiography.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11005439.html