Impact of iterative reconstruction on CNR and SNR in dynamic myocardial perfusion imaging in an animal model.

To evaluate a new iterative reconstruction (IR) algorithm for radiation dose, image quality (IQ), signal-to-noise-ratio (SNR), and contrast-to-noise-ratio (CNR) in multidetector computed tomography (MDCT) dynamic myocardial perfusion imaging (MPI).ECG-gated 256-slice MDCT dynamic MPI was performed in six pigs after subtotal balloon occlusion of one artery. Two 100 kVp protocols were compared: high dose (HD): 150 mAs; low dose (LD): 100 mAs. HD images were reconstructed with filtered back projection (FBP), LD images with FBP and different strengths of IR (L1, L4, and L7). IQ (5-point scale), SNR, and CNR (ischemic vs. normal myocardium) values derived from the HD (FBP) images and the different LD images were compared.Mean SNR values for myocardium were 16.3, 11.3, 13.1, 17.1, and 28.9 for the HD, LD (FBP), LD (L1), LD (L4), and LD (L7) reconstructions, respectively. Mean CNR values were 8.9, 6.3, 7.8, 9.3, and 12.8. IQ was scored as 4.6, 3.3, 4.4, 4.7, and 3.4, respectively. A significant loss of IQ was observed for the LD (L7) images compared to the HD (FBP) images (P < 0.05).Appropriate levels of iterative reconstruction can improve SNR and CNR, facilitating radiation dose savings in CT-MPI without influencing diagnostic quality.Iterative reconstruction (IR) can reduce radiation dose in myocardial perfusion CT. Our study also demonstrated improvements in image quality (noise, SNR, and CNR). Dynamic CT-MPI could help determine the hemodynamic significance of coronary artery disease. With dynamic CT MPI, myocardial blood flow can be determined quantitatively

256-slice CT angiographic evaluation of coronary artery bypass grafts: effect of heart rate, heart rate variability and Z-axis location on image quality.

The objective of this study is to assess the effect of heart rate, heart rate variability and z-axis location on coronary artery bypass graft (CABG) image quality using a 256-slice computed tomography (CT) scanner.A total of 78 patients with 254 CABG (762 graft segments) were recruited to undergo CABG assessment with 256-slice CT and prospective ECG-gating. Two observers rated graft segments for image quality on a 5-point scale. Quantitative measurements were also made. Logistic and cumulative link mixed models were used to assess the predictors of graft image quality.Graft image quality was judged as diagnostic (scores 5 (excellent), 4 (good) and 3 (moderate)) in 96.6% of the 762 segments. Interobserver agreement was excellent (kappa>=0.90). Graft image quality was not affected by heart rate level. However, high heart rate variability was associated with an important and significant image quality deterioration (odds ratio 4.31; p = 0.036). Distal graft segments had significantly lower image quality scores than proximal segments (p<= 0.02). Significantly higher noise was noted at the origin of the mammary grafts (p = 0.001), owing to streak artifacts from the shoulders.CABG imaging with 270-msec rotation 256-slice CT and prospective ECG-gating showed an adequate image quality in 96.6% of graft segments, and an excellent interobserver agreement. Graft image quality was not influenced by heart rate level. Image quality scores were however significantly decreased in patients with high heart rate variability, as well as in distal graft segments, which are closer to the heart

Coronary virtual intravascular endoscopy

© Springer International Publishing Switzerland 2016.Virtual endoscopy is a 3-dimensional (3D) visualization tool that provides unique intraluminal information of hollow organs and anatomical structures by utilising volumetric dataset. Coronary virtual intravascular endoscopy (VIE) represents a specifi c application of virtual endoscopy in the diagnostic evaluation of coronary anatomy, coronary artery disease including plaque assessment, coronary stents, and coronary artery bypass grafting. This chapter presents information about coronary VIE generation, intraluminal appearances of normal coronary artery, coronary plaques with regard to different types of plaques, coronary stents in terms of normal patent stents and in-stent restenosis, and coronary artery bypass grafting