The impact of CT radiation dose reduction and iterative reconstruction algorithms from four different vendors on coronary calcium scoring

To analyse the effects of radiation dose reduction and iterative reconstruction (IR) algorithms on coronary calcium scoring (CCS). Fifteen ex vivo human hearts were examined in an anthropomorphic chest phantom using computed tomography (CT) systems from four vendors and examined at four dose levels using unenhanced prospectively ECG-triggered protocols. Tube voltage was 120 kV and tube current differed between protocols. CT data were reconstructed with filtered back projection (FBP) and reduced dose CT data with IR. CCS was quantified with Agatston scores, calcification mass and calcification volume. Differences were analysed with the Friedman test. Fourteen hearts showed coronary calcifications. Dose reduction with FBP did not significantly change Agatston scores, calcification volumes and calcification masses (P > 0.05). Maximum differences in Agatston scores were 76, 26, 51 and 161 units, in calcification volume 97, 27, 42 and 162 mm(3), and in calcification mass 23, 23, 20 and 48 mg, respectively. IR resulted in a trend towards lower Agatston scores and calcification volumes with significant differences for one vendor (P <0.05). Median relative differences between reference FBP and reduced dose IR for Agatston scores remained within 2.0-4.6 %, 1.0-5.3 %, 1.2-7.7 % and 2.6-4.5 %, for calcification volumes within 2.4-3.9 %, 1.0-5.6 %, 1.1-6.4 % and 3.7-4.7 %, for calcification masses within 1.9-4.1 %, 0.9-7.8 %, 2.9-4.7 % and 2.5-3.9 %, respectively. IR resulted in increased, decreased or similar calcification masses. CCS derived from standard FBP acquisitions was not affected by radiation dose reductions up to 80 %. IR resulted in a trend towards lower Agatston scores and calcification volumes. aEuro cent In this ex vivo study, radiation dose could be reduced by 80 % for coronary calcium scoring aEuro cent Iterative reconstruction resulted in a trend towards lower Agatston scores and calcification volumes aEuro cent Caution should be taken for coronary calcium scoring with iterative reconstruction

Computed Tomography Radiation Dose Reduction: Effect of Different Iterative Reconstruction Algorithms on Image Quality

We evaluated the effects of hybrid and model-based iterative reconstruction (IR) algorithms from different vendors at multiple radiation dose levels on image quality of chest phantom scans.A chest phantom was scanned on state-of-the-art computed tomography scanners from 4 vendors at 4 dose levels (4.1 mGy, 3.0 mGy, 1.9 mGy, and 0.8 mGy). All data were reconstructed with filtered back projection (FBP) and reduced-dose data also with IR (iDose4, Adaptive Iterative Dose Reduction 3D, Adaptive Statistical Iterative Reconstruction, Sinogram-Affirmed Iterative Reconstruction, prototype Iterative Model Reconstruction, and Veo). Computed tomography numbers and noise were measured in the spine and lungs. Signal-to-noise ratios (SNR) and contrast-to-noise ratios (CNR) were calculated and differences were analyzed with the Friedman test.For all vendors, radiation dose reduction with FBP resulted in significantly increased noise levels (?148%) as well as decreased SNR (?57%) and CNR (?58%) (P <0.001). Conversely, IR resulted in decreased noise levels (?48%) as well as increased SNR (?94%) and CNR (?94%). The SNRs and CNRs of the model-based algorithms at 80% reduced dose were similar to reference-dose FBP.Hybrid IR algorithms have the potential to reduce radiation dose with 27% to 54% and model-based IR algorithms with up to 80%

Coronary Artery Calcification Scoring with State-of-the-Art CT Scanners from Different Vendors Has Substantial Effect on Risk Classification

Purpose: To determine the intervendor variability of Agatston scoring determined with state-of-the-art computed tomographic (CT) systems from the four major vendors in an ex vivo setup and to simulate the subsequent effects on cardiovascular risk reclassification in a large populationbased cohort. Materials and Methods: Research ethics board approval was not necessary because cadaveric hearts from individuals who donated their bodies to science were used. Agatston scores obtained with CT scanners from four different vendors were compared. Fifteen ex vivo human hearts were placed in a phantom resembling an average human adult. Hearts were scanned at equal radiation dose settings for the systems of all four vendors. Agatston scores were quantified semiautomatically with software used clinically. The ex vivo Agatston scores were used to simulate the effects of different CT scanners on reclassification of 432 individuals aged 55 years or older from a population-based study who were at intermediate cardiovascular risk based on Framingham risk scores. The Friedman test was used to evaluate overall differences, and post hoc analyses were performed by using the Wilcoxon signed-rank test with Bonferroni correction. Results: Agatston scores differed substantially when CT scanners from different vendors were used, with median Agatston scores ranging from 332 (interquartile range, 114-1135) to 469 (interquartile range, 183-1381; P <.05). Simulation showed that these differences resulted in a change in cardiovascular risk classification in 0.5%-6.5% of individuals at intermediate risk when a CT scanner from a different vendor was used. Conclusion: Among individuals at intermediate cardiovascular risk, state-of the-art CT scanners made by different vendors produced substantially different Agatston scores, which can result in reclassification of patients to the high-or low-risk categories in up to 6.5% of cases. (C) RSNA, 201

Heart rate lowering treatment leads to a reduction in vulnerable plaque features in atherosclerotic rabbits - Fig 4

<p>Histological sections of atherosclerotic plaque for a non-treated (panels A-C) and Ivabradine treated (panels D-F) rabbit. Panel A and D show HE sections and panel B and E a slide stained for macrophages using RAM11 antibody (red), with magnifications in panel C and F.</p

Presence of macrophages in the proximity of the vascular lumen using a semi-quantitative three point scale for non-treated (eight animals, two sections per animal) and Ivabradine-treated animals (seven animals, 2 sections per animal).

<p>Histological sections are divided into three categories ranging from 0 (no luminal macrophages; example image shown in panel B) via 1 (partially luminal macrophages; example in panel C) to 2 (predominantly luminal macrophages; example in panel D). Macrophages in the histological images are indicated by an arrow head (^). The displayed scale bar is applicable for all histological images and the luminal side is indicated by an asterisk (*) in all histological images.</p

Study parameters for the present study.

<p>Parameters are reported as mean values ± standard error. Number of successful experiments that were performed is indicated (^§n = 9, ^lln = 8, ^¶n = 7, ^#n = 6). AUC 7 min and K^trans represent DCE-MRI parameters of the plaque microvasculature. The percentage of RAM11 is a measure of the plaque macrophage content. Used abbreviations: heart rate (HR); blood pressure (BP); Elastica von Gieson (EvG); area-under-the-curve (AUC); ^*p<0.05.</p

Number of successfully performed procedures in the present study.

<p>Number of successfully performed procedures in the present study.</p

The experimental design.

<p>Two weeks after initiation of 1.0% cholesterol-enriched diet, the animals receive a balloon injury. At week 10, they are switched from 1.0% to 0.3% cholesterol-enriched diet. Fourteen weeks after diet initiation the animals undergo measurement of the HR and US and MR imaging before euthanisation.</p