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Prospective evaluation of the influence of iterative reconstruction on the reproducibility of coronary calcium quantification in reduced radiation dose 320 detector row CT.

ABSTRACT: BACKGROUND:Coronary artery calcium (CAC) predicts coronary heart disease events and is important for individualized cardiac risk assessment. This report assesses the interscan variability of CT for coronary calcium quantification using image acquisition with standard and reduced radiation dose protocols and whether the use of reduced radiation dose acquisition with iterative reconstruction (IR; "reduced-dose/IR ") allows for similar image quality and reproducibility when compared to standard radiation dose acquisition with filtered back projection (FBP; "standard-dose/FBP") on 320-detector row computed tomography (320-CT). METHODS:200 consecutive patients (60 ± 9 years, 59% male) prospectively underwent two standard- and two reduced-dose acquisitions (800 total scans, 1600 reconstructions) using 320 slice CT and 120 kV tube voltage. Automated tube current modulation was used and for reduced-dose scans, prescribed tube current was lowered by 70%. Image noise and Agatston scores were determined and compared. RESULTS:Regarding stratification by Agatston score categories (0, 1-10, 11-100, 101-400, >400), reduced-dose/IR versus standard-dose/FBP had excellent agreement at 89% (95% CI: 86-92%) with kappa 0.86 (95% CI: 0.81-0.90). Standard-dose/FBP rescan agreement was 93% (95% CI: 89-96%) with kappa = 0.91 (95% CI: 0.86-0.95) while reduced-dose/IR rescan agreement was similar at 91% (95% CI: 87-94%) with kappa 0.88 (95% CI: 0.83-0.93). Image noise was significantly higher but clinically acceptable for reduced-dose/IR (18 Hounsfield Unit [HU] mean) compared to standard-dose/FBP (16 HU; p < 0.0001). Median radiation exposure was 74% lower for reduced- (0.37 mSv) versus standard-dose (1.4 mSv) acquisitions. CONCLUSION:Rescan agreement was excellent for reduced-dose image acquisition with iterative reconstruction and standard-dose acquisition with filtered back projection for the quantification of coronary calcium by CT. These methods make it possible to reduce radiation exposure by 74%. CLINICAL TRIAL REGISTRATION:URL: https://clinicaltrials.gov/ct2/show/NCT01621594. UNIQUE IDENTIFIER:NCT01621594.

SUBMITTER: Choi AD

PROVIDER: S-EPMC7458582 | biostudies-literature | 2016 Sep-Oct

REPOSITORIES: biostudies-literature

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Prospective evaluation of the influence of iterative reconstruction on the reproducibility of coronary calcium quantification in reduced radiation dose 320 detector row CT.

Choi Andrew D AD Leifer Eric S ES Yu Jeannie J Shanbhag Sujata M SM Bronson Kathie K Arai Andrew E AE Chen Marcus Y MY

Journal of cardiovascular computed tomography 20160727 5

<h4>Background</h4>Coronary artery calcium (CAC) predicts coronary heart disease events and is important for individualized cardiac risk assessment. This report assesses the interscan variability of CT for coronary calcium quantification using image acquisition with standard and reduced radiation dose protocols and whether the use of reduced radiation dose acquisition with iterative reconstruction (IR; "reduced-dose/IR ") allows for similar image quality and reproducibility when compared to stan ...[more]

PMID: 27591767

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Project description:PurposeTo (a) use a new second-generation wide-volume 320-detector row computed tomographic (CT) scanner to explore optimization of radiation exposure in coronary CT angiography in an unselected and consecutive cohort of patients referred for clinical purposes and (b) compare estimated radiation exposure and image quality with that from a cohort of similar patients who underwent imaging with a previous first-generation CT system.Materials and methodsThe study was approved by the institutional review board, and all subjects provided written consent. Coronary CT angiography was performed in 107 consecutive patients with a new second-generation 320-detector row unit. Estimated radiation exposure and image quality were compared with those from 100 consecutive patients who underwent imaging with a previous first-generation scanner. Effective radiation dose was estimated by multiplying the dose-length product by an effective dose conversion factor of 0.014 mSv/mGy ⋅ cm and reported with size-specific dose estimates (SSDEs). Image quality was evaluated by two independent readers.ResultsThe mean age of the 107 patients was 55.4 years ± 12.0 (standard deviation); 57 patients (53.3%) were men. The median body mass index was 27.3 kg/m(2) (range, 18.1-47.2 kg/m(2)); however, 71 patients (66.4%) were overweight, obese, or morbidly obese. A tube potential of 100 kV was used in 97 patients (90.6%), single-volume acquisition was used in 104 (97.2%), and prospective electrocardiographic gating was used in 106 (99.1%). The mean heart rate was 57.1 beats per minute ± 11.2 (range, 34-96 beats per minute), which enabled single-heartbeat scans in 100 patients (93.4%). The median radiation dose was 0.93 mSv (interquartile range [IQR], 0.58-1.74 mSv) with the second-generation unit and 2.67 mSv (IQR, 1.68-4.00 mSv) with the first-generation unit (P < .0001). The median SSDE was 6.0 mGy (IQR, 4.1-10.0 mGy) with the second-generation unit and 13.2 mGy (IQR, 10.2-18.6 mGy) with the first-generation unit (P < .0001). Overall, the radiation dose was less than 0.5 mSv for 23 of the 107 CT angiography examinations (21.5%), less than 1 mSv for 58 (54.2%), and less than 4 mSv for 103 (96.3%). All studies were of diagnostic quality, with most having excellent image quality. Three of four image quality indexes were significantly better with the second-generation unit compared with the first-generation unit.ConclusionThe combination of a gantry rotation time of 275 msec, wide volume coverage, iterative reconstruction, automated exposure control, and larger x-ray power generator of the second-generation CT scanner provides excellent image quality over a wide range of body sizes and heart rates at low radiation doses.Supplemental materialhttp://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.13122621/-/DC1.

Project description:ObjectivesTo investigate the interdisciplinary interobserver reproducibility of Hertel-exophthalmometry-like protrusion measurements on multidetector-row-computed-tomography- (MDCT-) images of the orbit to facilitate structured evaluation of the orbit and mid-face.MethodsRespective reproducibility of base-length along the interfronto-zygomatic line, right and left ocular protrusion, and deriving interocular difference was measured in this retrospective (04/2009-03/2020) single-centre observational study. MDCT-series and slice-positions were selected independently, using picture-archiving-and-communication-system- (PACS-) tools on tilt-corrected axial MDCT-images (slice-thickness 0.6-3.0 mm, window/centre 350/50 HU) in 37 selected adult patients (24 female, age 57 ± 13 years, average±standard-deviation) with clinical indication for Hertel-exophthalmometry, by one radiology-attending, two ophthalmology-attendings, one critical-care-attending, and one ear-nose-throat-surgery resident, respectively. Bland-Altman plots and Wilcoxon-matched-pairs-signed-rank-tests compared interobserver results.ResultsMean and median interobserver and intraobserver (radiology-attending) deviations were within 1 mm of respective averages of base-length (98 ± 4 mm), right and left ocular protrusion (21 ± 4 mm) and interocular difference (2 ± 1 mm). Relative interobserver deviations were within 2.0% of average (all patients) for base-length, and 5.0% (>80% of patients) for ocular protrusion. Pairwise interobserver comparison showed no significant differences between interocular differences of protrusion.ConclusionsRespective measurements of base-length, ocular protrusion, and deriving interocular difference show high interdisciplinary interobserver reproducibility in tilt-corrected axial MDCT-images of the orbit or mid-face.Advances in knowledgeHertel-exophthalmometry-like protrusion measurements did not depend on the years of experience or the medical subspecialty of the observer. Measurements are objective, well reproducible and important for multiple medical disciplines and should thus be included in pertinent radiology reports.

Project description:BackgroundTo analyze the imaging features of coronary artery-to-pulmonary artery fistula (CPAF) on coronary computed tomography angiography (CCTA).MethodsThis was a retrospective study of 3,975 patients who underwent 320 row detector CCTA examinations in our hospital from May 2015 to July 2020. A total of 22 patients who diagnosed with CPAF were reviewed for CCTA imaging characteristics, including the origin, number, blood volume, opening size, and course of fistula vessels, and the drainage site, size, and imaging features of the fistula. All cases were analyzed for the presence of coronary atherosclerotic plaque and that of deficient left ventricular myocardial perfusion.ResultsA total of 22 CPAF cases detected by CCTA were collected (men, 11; women, 11; median age, 59.6±10.1 years). There were 7, 10, and 5 cases detected with 1, 2, and 3 fistula vessels, respectively, among which 4 originated from the left coronary artery, 4 from the right coronary artery, and 14 had bilateral origins. There were 10 cases in which the fistula vessels presented as a worm-like tortuous dilation with (n=5) or without (n=5) aneurysm, while 12 cases showed malformed vascular networks with (n=8) or without (n=4) aneurysm, respectively. The calculated incidence of aneurysm formation was 59.09%, and fistula vessels with an aneurysm had larger blood volume than those without. All fistula showed a single drainage site, with an average diameter of 2.81±1.48 mm where the diameter of fistula with aneurysm was larger than that without. The fistula vessels drained into the left anterolateral and anterior walls of main pulmonary artery and the proximal left inferior PA, respectively. Typical jet sign, smoke sign, and isodensity sign were presented in 22, 14 and 1 case, respectively. For the coexistent abnormalities analyzed in 22 cases, 17 participants with CPAF demonstrated hypoperfusion of the fistula vessels, and 11 demonstrated calcified plaque accompanied with luminal stenosis to different degrees.ConclusionsThe 320-row detector CCTA can comprehensively characterize the morphological features of CPAF, which is an optimal choice for physicians to make an accurate assessment before formulating patient management strategies.

Project description:Background Results of recent phantom studies show that variation in CT acquisition parameters and reconstruction techniques may make radiomic features largely nonreproduceable and of limited use for prognostic clinical studies. Purpose To investigate the effect of CT radiation dose and reconstruction settings on the reproducibility of radiomic features, as well as to identify correction factors for mitigating these sources of variability. Materials and Methods This was a secondary analysis of a prospective study of metastatic liver lesions in patients who underwent staging with single-energy dual-source contrast material-enhanced staging CT between September 2011 and April 2012. Technique parameters were altered, resulting in 28 CT data sets per patient that included different dose levels, section thicknesses, kernels, and reconstruction algorithm settings. By using a training data set (n = 76), reproducible intensity, shape, and texture radiomic features (reproducibility threshold, R2 ≥ 0.95) were selected and correction factors were calculated by using a linear model to convert each radiomic feature to its estimated value in a reference technique. By using a test data set (n = 75), the reproducibility of hierarchical clustering based on 106 radiomic features measured with different CT techniques was assessed. Results Data in 78 patients (mean age, 60 years ± 10; 33 women) with 151 liver lesions were included. The percentage of radiomic features deemed reproducible for any variation of the different technical parameters was 11% (12 of 106). Of all technical parameters, reconstructed section thickness had the largest impact on the reproducibility of radiomic features (12.3% [13 of 106]) if only one technical parameter was changed while all other technical parameters were kept constant. The results of the hierarchical cluster analysis showed improved clustering reproducibility when reproducible radiomic features with dedicated correction factors were used (ρ = 0.39-0.71 vs ρ = 0.14-0.47). Conclusion Most radiomic features are highly affected by CT acquisition and reconstruction settings, to the point of being nonreproducible. Selecting reproducible radiomic features along with study-specific correction factors offers improved clustering reproducibility. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Sosna in this issue.

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Prospective evaluation of the influence of iterative reconstruction on the reproducibility of coronary calcium quantification in reduced radiation dose 320 detector row CT.

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Prospective evaluation of the influence of iterative reconstruction on the reproducibility of coronary calcium quantification in reduced radiation dose 320 detector row CT.

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