Automated 3-dimensional quantification of noncalcified and calcified coronary plaque from coronary CT angiography
ABSTRACT We aimed to develop an automated algorithm (APQ) for accurate volumetric quantification of non-calcified (NCP) and calcified plaque (CP) from coronary CT angiography (CCTA).
APQ determines scan-specific attenuation thresholds for lumen, NCP, CP and epicardial fat, and applies knowledge-based segmentation and modeling of coronary arteries, to define NCP and CP components in 3D. We tested APQ in 29 plaques for 24 consecutive scans, acquired with dual-source CT scanner. APQ results were compared to volumes obtained by manual slice-by-slice NCP/CP definition and by interactive adjustment of plaque thresholds (ITA) by 2 independent experts.
APQ analysis time was <2 sec per lesion. There was strong correlation between the 2 readers for manual quantification (r = 0.99, p < 0.0001 for NCP; r = 0.85, p < 0.0001 for CP). The mean HU determined by APQ was 419 +/- 78 for luminal contrast at mid-lesion, 227 +/- 40 for NCP upper threshold, and 511 +/- 80 for the CP lower threshold. APQ showed a significantly lower absolute difference (26.7 mm(3) vs. 42.1 mm(3), p = 0.01), lower bias than ITA (32.6 mm(3) vs 64.4 mm(3), p = 0.01) for NCP. There was strong correlation between APQ and readers (R = 0.94, p < 0.0001 for NCP volumes; R = 0.88, p < 0.0001, for CP volumes; R = 0.90, p < 0.0001 for NCP and CP composition).
We developed a fast automated algorithm for quantification of NCP and CP from CCTA, which is in close agreement with expert manual quantification.
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ABSTRACT: We study how to provide end-to-end QoS (quality of service) between nodes in a mobile ad hoc network and a fixed IP network that supports differentiated services (DiffServ). The ad hoc network incorporates a stateless wireless ad hoc networks (SWAN) scheme to support service differentiation. SWAN uses local rate control for best-effort traffic and sender-based admission control for real-time traffic. Best-effort traffic and real-time flows that have not yet been admitted as real-time sessions are delayed by a best-effort traffic shaper. In this paper, we propose FA-SWAN (fast admission-SWAN), a modified version of the SWAN QoS scheme. In contrast to SWAN, FA-SWAN enables the real-time flows to bypass the traffic shaper during the admission control process. Only after a real-time session is rejected as such, will the traffic be considered as best-effort and will have to be rate controlled. The results indicate that the modifications improve the performance of the voice application in comparison with the original SWAN.Vehicular Technology Conference, 2004. VTC2004-Fall. 2004 IEEE 60th; 10/2004
- Journal of cardiovascular computed tomography 11/2009; 3(6):383-5. DOI:10.1016/j.jcct.2009.09.005 · 4.51 Impact Factor
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ABSTRACT: The quantification of non-calcified coronary plaques using multidetector computed tomography has not been extensively investigated. To evaluate the ability of dual-source computed tomography (DSCT) to quantify non-calcified plaque volumes using intravascular ultrasound (IVUS) as the standard of reference. The datasets of 70 patients with suspected or known coronary artery disease who underwent DSCT (330 ms gantry rotation, 2 x 64 x 0.6 mm collimation, 60-90 ml contrast agent) were analysed before invasive coronary angiography, with IVUS performed as part of the diagnostic procedure. 100 individual non-calcified coronary atherosclerotic plaques (one to three plaques per patient) with suitable fiducial markers were matched and selected for plaque volume measurements using manual segmentation. Only DSCT datasets with good or excellent image quality were considered for analysis. Intra and interobserver variability for plaque volume measurements by DSCT were 6+/-5% and 11+/-7%, respectively. Mean total plaque volume by DSCT was 89+/-66 mm(3) (range 14-400 mm(3)). Mean total plaque volume by IVUS was 90+/-73 mm(3) (range 16-409 mm(3)). The mean difference between DSCT and IVUS was 1+/-34 mm(3) (range -131-85 mm(3)). Despite the good correlation for plaque volume measurements (r=0.89, p<0.001), agreement between the two methods was only modest (Bland-Altman limits of agreement -67 to +65 mm(3)). CONCLUSIONS ; Non-calcified plaque volumes as determined by DSCT yielded good correlation but only modest agreement in comparison with IVUS.Heart (British Cardiac Society) 11/2009; 96(8):610-5. DOI:10.1136/hrt.2009.184226 · 6.02 Impact Factor