Paper Info
Title
Effect of beam hardening on transmural myocardial perfusion quantification in myocardial CT imaging
Abstract
The detection of subendocardial ischemia exhibiting an abnormal transmural perfusion gradient (TPG) may help identify ischemic conditions due to micro-vascular dysfunction. We evaluated the effect of beam hardening (BH) artifacts on TPG quantification using myocardial CT perfusion (CTP). We used a prototype spectral detector CT scanner (Philips Healthcare) to acquire dynamic myocardial CTP scans in a porcine ischemia model with partial occlusion of the left anterior descending (LAD) coronary artery guided by pressure wire-derived fractional flow reserve (FFR) measurements. Conventional 120 kVp and 70 keV projection-based mono-energetic images were reconstructed from the same projection data and used to compute myocardial blood flow (MBF) using the Johnson-Wilson model. Under moderate LAD occlusion (FFR similar to 0.7), we used three 5 mm short axis slices and divided the myocardium into three LAD segments and three remote segments. For each slice and each segment, we characterized TPG as the mean "endo-to-epi" transmural flow ratio (TFR). BH-induced hypoenhancement on the ischemic anterior wall at 120 kVp resulted in significantly lower mean TFR value as compared to the 70 keV TFR value (0.29 +/- 0.01 vs. 0.55 +/- 0.01; p<le-05). No significant difference was measured between 120 kVp and 70 keV mean TFR values on segments moderately affected or unaffected by BH. In the entire ischemic LAD territory, 120 kVp mean endocardial flow was significantly reduced as compared to mean epicardial flow (15.80 +/- 10.98 vs. 40.85 +/- 23.44 ml/min/100g; p<1e-04). At 70 keV, BH was effectively minimized resulting in mean endocardial MBF of 40.85 +/- 15.3407 ml/min/100g vs. 74.09 +/- 5.07 ml/min/100g (p=0.0054) in the epicardium. We also found that BH artifact in the conventional 120 kVp images resulted in falsely reduced MBF measurements even under non-ischemic conditions.
Year
DOI
Venue
2016
10.1117/12.2217447
Proceedings of SPIE
Keywords
Field
DocType
Myocardial CT perfusion,beam hardening,transmural perfusion gradient,myocardial blood flow,spectral detector CT,dual energy CT
Perfusion scanning,Nuclear medicine,Artery,Occlusion,Blood flow,Fractional flow reserve,Optics,Ischemia,Beam hardening,Perfusion,Physics
Conference
Volume
ISSN
Citations 
9788
0277-786X
0
PageRank 
References 
Authors
0.34
0
9
Name
Order
Citations
PageRank
Rachid Fahmi1335.16
Brendan L. Eck212.37
Jacob Levi302.37
Anas Fares400.68
Hao Wu59238.83
M Vembar6517.27
A. Dhanantwari793.27
Hiram G. Bezerra8106.64
David L. Wilson917436.04