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Proceedings Paper

Dynamic myocardial perfusion in a porcine balloon-induced ischemia model using a prototype spectral detector CT
Author(s): Rachid Fahmi; Brendan L. Eck; Anas Fares M.D.; Jacob Levi; Hao Wu; Mani Vembar; Amar Dhanantwari; Hiram G. Bezerra M.D.; David L. Wilson
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Paper Abstract

Myocardial CT perfusion (CTP) imaging is an application that should greatly benefit from spectral CT through the significant reduction of beam hardening (BH) artifacts using mono-energetic (monoE) image reconstructions. We used a prototype spectral detector CT (SDCT) scanner (Philips Healthcare) and developed advanced processing tools (registration, segmentation, and deconvolution-based flow estimation) for quantitative myocardial CTP in a porcine ischemia model with different degrees of coronary occlusion using a balloon catheter. The occlusion severity was adjusted with fractional flow reserve (FFR) measurements. The SDCT scanner is a single source, dual-layer detector system, which allows simultaneous acquisitions of low and high energy projections, hence enabling accurate projection-based material decomposition and effective reduction of BH-artifacts. In addition, the SDCT scanner eliminates partial scan artifacts with fast (0.27s), full gantry rotation acquisitions. We acquired CTP data under different hemodynamic conditions and reconstructed conventional 120kVp images and projection-based monoenergetic (monoE) images for energies ranging from 55keV-to-120keV. We computed and compared myocardial blood flow (MBF) between different reconstructions. With balloon completely deflated (FFR=1), we compared the mean attenuation in a myocardial region of interest before iodine arrival and at peak iodine enhancement in the left ventricle (LV), and we found that monoE images at 70keV effectively minimized the difference in attenuation, due to BH, to less than 1 HU compared to 14 HU with conventional 120kVp images. Flow maps under baseline condition (FFR=1) were more uniform throughout the myocardial wall at 70keV, whereas with 120kVp data about 12% reduction in blood flow was noticed on BH-hypoattenuated areas compared to other myocardial regions. We compared MBF maps at different keVs under an ischemic condition (FFR < 0.7), and we found that flow-contrast-to-noise-ratio (CNRf ) between LAD ischemic and remote healthy territories attains its maximum (2.87 ± 0.7) at 70keV. As energies diverge from 70keV, we noticed a steady decrease in CNRf and an overestimation of mean-MBF. Flow overestimation was also noticed for conventional 120kVp images in different myocardial regions.

Paper Details

Date Published: 19 March 2015
PDF: 10 pages
Proc. SPIE 9417, Medical Imaging 2015: Biomedical Applications in Molecular, Structural, and Functional Imaging, 94170Y (19 March 2015); doi: 10.1117/12.2081547
Show Author Affiliations
Rachid Fahmi, Case Western Reserve Univ. (United States)
Brendan L. Eck, Case Western Reserve Univ. (United States)
Anas Fares M.D., Univ. Hospitals Case Medical Ctr. (United States)
Jacob Levi, Case Western Reserve Univ. (United States)
Hao Wu, Case Western Reserve Univ. (United States)
Mani Vembar, Philips Healthcare (United States)
Amar Dhanantwari, Philips Healthcare (United States)
Hiram G. Bezerra M.D., Univ. Hospitals Case Medical Ctr. (United States)
David L. Wilson, Case Western Reserve Univ. (United States)

Published in SPIE Proceedings Vol. 9417:
Medical Imaging 2015: Biomedical Applications in Molecular, Structural, and Functional Imaging
Barjor Gimi; Robert C. Molthen, Editor(s)

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