Universität zu Köln

von Spiczak, Jochen, Mannil, Manoj, Peters, Benjamin, Hickethier, Tilman, Baer, Matthias, Henning, Andre, Schmidt, Bernhard, Flohr, Thomas, Manka, Robert, Maintz, David and Alkadhi, Hatem (2018). Photon Counting Computed Tomography With Dedicated Sharp Convolution Kernels Tapping the Potential of a New Technology for Stent Imaging. Invest. Radiol., 53 (8). S. 486 - 495. PHILADELPHIA: LIPPINCOTT WILLIAMS & WILKINS. ISSN 1536-0210

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Abstract

Objectives The aims of this study were to assess the value of a dedicated sharp convolution kernel for photon counting detector (PCD) computed tomography (CT) for coronary stent imaging and to evaluate to which extent iterative reconstructions can compensate for potential increases in image noise. Materials and Methods For this in vitro study, a phantom simulating coronary artery stenting was prepared. Eighteen different coronary stents were expanded in plastic tubes of 3 mm diameter. Tubes were filled with diluted contrast agent, sealed, and immersed in oil calibrated to an attenuation of -100 HU simulating epicardial fat. The phantom was scanned in a modified second generation 128-slice dual-source CT scanner (SOMATOM Definition Flash, Siemens Healthcare, Erlangen, Germany) equipped with both a conventional energy integrating detector and PCD. Image data were acquired using the PCD part of the scanner with 48 x 0.25 mm slices, a tube voltage of 100 kVp, and tube current-time product of 100 mAs. Images were reconstructed using a conventional convolution kernel for stent imaging with filtered back-projection (B46) and with sinogram-affirmed iterative reconstruction (SAFIRE) at level 3 (I46(3)). For comparison, a dedicated sharp convolution kernel with filtered back-projection (D70) and SAFIRE level 3 (Q70(3)) and level 5 (Q70(5)) was used. The D70 and Q70 kernels were specifically designed for coronary stent imaging with PCD CT by optimizing the image modulation transfer function and the separation of contrast edges. Two independent, blinded readers evaluated subjective image quality (Likert scale 0-3, where 3 = excellent), in-stent diameter difference, in-stent attenuation difference, mathematically defined image sharpness, and noise of each reconstruction. Interreader reliability was calculated using Goodman and Kruskal's and intraclass correlation coefficients (ICCs). Differences in image quality were evaluated using a Wilcoxon signed-rank test. Differences in in-stent diameter difference, in-stent attenuation difference, image sharpness, and image noise were tested using a paired-sample t test corrected for multiple comparisons. Results Interreader and intrareader reliability were excellent ( = 0.953, ICCs = 0.891-0.999, and = 0.996, ICCs = 0.918-0.999, respectively). Reconstructions using the dedicated sharp convolution kernel yielded significantly better results regarding image quality (B46: 0.4 0.5 vs D70: 2.9 +/- 0.3; P < 0.001), in-stent diameter difference (1.5 +/- 0.3 vs 1.0 +/- 0.3 mm; P < 0.001), and image sharpness (728 +/- 246 vs 2069 +/- 411 CT numbers/voxel; P < 0.001). Regarding in-stent attenuation difference, no significant difference was observed between the 2 kernels (151 +/- 76 vs 158 +/- 92 CT numbers; P = 0.627). Noise was significantly higher in all sharp convolution kernel images but was reduced by 41% and 59% by applying SAFIRE levels 3 and 5, respectively (B46: 16 +/- 1, D70: 111 +/- 3, Q70(3): 65 +/- 2, Q70(5): 46 +/- 2 CT numbers; P < 0.001 for all comparisons). Conclusions A dedicated sharp convolution kernel for PCD CT imaging of coronary stents yields superior qualitative and quantitative image characteristics compared with conventional reconstruction kernels. Resulting higher noise levels in sharp kernel PCD imaging can be partially compensated with iterative image reconstruction techniques.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code von Spiczak, Jochen UNSPECIFIED UNSPECIFIED UNSPECIFIED Mannil, Manoj UNSPECIFIED UNSPECIFIED UNSPECIFIED Peters, Benjamin UNSPECIFIED UNSPECIFIED UNSPECIFIED Hickethier, Tilman UNSPECIFIED UNSPECIFIED UNSPECIFIED Baer, Matthias UNSPECIFIED UNSPECIFIED UNSPECIFIED Henning, Andre UNSPECIFIED UNSPECIFIED UNSPECIFIED Schmidt, Bernhard UNSPECIFIED UNSPECIFIED UNSPECIFIED Flohr, Thomas UNSPECIFIED UNSPECIFIED UNSPECIFIED Manka, Robert UNSPECIFIED UNSPECIFIED UNSPECIFIED Maintz, David UNSPECIFIED UNSPECIFIED UNSPECIFIED Alkadhi, Hatem UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-179101
DOI:	10.1097/RLI.0000000000000485
Journal or Publication Title:	Invest. Radiol.
Volume:	53
Number:	8
Page Range:	S. 486 - 495
Date:	2018
Publisher:	LIPPINCOTT WILLIAMS & WILKINS
Place of Publication:	PHILADELPHIA
ISSN:	1536-0210
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language AFFIRMED ITERATIVE RECONSTRUCTION; IN-VITRO EXPERIENCE; CORONARY-STENTS; CT; DETECTOR; FEASIBILITY; ANGIOGRAPHY; PERFORMANCE; STRENGTH; IMAGES Multiple languages Radiology, Nuclear Medicine & Medical Imaging Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/17910