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17.45 · China Medical University (PRC)+ 1Show
more authorsAbstractAim:
To investigate the potential dose reduction in cardiovascular computed tomography angiography (CTA) in a swine model using 320-detector volume CT with adaptive iterative dose reduction in three dimensions (AIDR 3D) reconstruction to maintain a comparable image quality (IQ) to that reconstructed by a conventional filtered back projection (FBP) algorithm.
Methods and materials:
Twenty-four mini-pigs underwent cardiovascular CTA four times at 80 KVp and different tube currents. An automatic exposure control (AEC) system was used and the noise index (NI) was predetermined at a standard deviation (SD) of 20 (Method A, routine dose), and 25, 30, 35 (Methods B-D) to reduce the dose gradually. Method A was reconstructed with FBP. Methods B-D were reconstructed using AIDR 3D (strong). Two radiologists graded IQ by reviewing both cardiac and vascular structures using a five-point scale. Quantitative IQ parameters of image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were measured and compared. A receiver-operating characteristic (ROC) analysis was performed to select a radiation reduction threshold and maintain comparable IQ (score ≥4).
Method B and C had significantly lower image noise (p&0.0001), higher CNR and SNR than Method A (p&0.0001). Compared with Method A (noise: 52.7±8.3; SNR: 11.7±2.8; and CNR: 9.9±2.7), Method C had comparable subjective IQ and higher objective IQ (noise: 38.9±6.1; SNR: 16.3±3.5; and CNR: 13.5±3.3). The results of the ROC curve showed that Method C (SD30) was the optimal dose threshold to maintain a comparable subjective IQ (AUC: 0.85, 95% confidence interval [CI]: 0.80-0.90). The effective dose (ED) of Method C was reduced by 49%, compared to that of Method A (0.33±0.08 mSv versus 0.65±0.15 mSv).
Conclusion:
AIDR 3D at a strong level combined with an AEC system can potentially reduce the ED by 49% and maintain an IQ comparable to that achieved using a routine-dose and FBP reconstruction in mini-pig cardiovascular CTA.Do you want to read the rest of this article?
CitationsCitations0ReferencesReferences24ABSTRACT: To investigate the potential of reducing the radiation dose in prospectively electrocardiogram-triggered coronary computed tomography angiography (CCTA) while maintaining diagnostic image quality using an iterative reconstruction technique (IRT).
Prospectively-gated CCTA were first performed on a phantom using 256-slice multi-detector CT scanner at 120 kVp, with the tube output gradually reduced from 210 mAs (Group A) to 125, 105, 84, and 63 mAs (Group B-E). All scans were reconstructed using filtered back projection (FBP) algorithm and five IRT levels (L2-6), image quality (IQ) assessment was performed. Based on the IQ assessment, Group D(120 kVp, 84 mAs) reconstructed with L5 was found to provide IQ comparable to that of Group A with FBP. In the patient study, 21 patients underwent CCTA using 120 kV, 210 mAs with FBP reconstruction (Group 1) followed by 36 patients scanned with 120 kV, 84 mAs with IRT L5 (Group 2). Subjective and objective IQ and effective radiation dose were compared between two groups.
In the phantom scans, there were no significant differences in image noise, contrast-to-noise ratio (CNR) and modulation transfer function (MTF) curves between Group A and the 84 mAs, 63 mAs groups (Groups D and E). Group D (120 kV, 84 mAs and L5) provided an optimum balance, producing equivalent image quality to Group A, at the lowest possible radiation dose. In the patient study, there were no significant difference in image noise, signal-to-noise ratio (SNR) and CNR between Group 1 and Group 2 (p = 0.71, 0.31, 0.5, respectively). The effective radiation dose in Group 2 was 1.21±0.14 mSv compared to 3.20±0.58 mSv (Group 1), reflecting dose savings of 62.5% (p&0.05).
iterative reconstruction technique used in prospectively ECG-triggered 256-slice coronary CTA can provide radiation dose reductions of up to 62.5% with acceptable image quality. Full-text · Article · Feb 2013 +1 more author...ABSTRACT: To compare the image quality of coronary CT angiography (CTA) studies between standard filtered back projection (FBP) and adaptive iterative dose reduction in three-dimensions (AIDR3D) reconstruction using CT noise additional software to simulate reduced radiation exposure. Images from 93 consecutive clinical coronary CTA studies were processed utilizing standard FBP, FBP with 50 % simulated dose reduction (FBP50 %), and AIDR3D with simulated 50 % dose reduction (AIDR50 %). Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were measured within 5 regions-of-interest, and image quality for each reconstruction strategy was assessed by two independent readers using a 4-point scale. Compared to FBP, the SNR measured from the AIDR50 % images was similar or higher (airway: 38.3 ± 12.7 vs. 38.5 ± 14.5, p = 0.81, fat: 5.5 ± 1.9 vs. 5.4 ± 2.0, p = 0.20, muscle: 3.2 ± 1.2 vs. 3.1 ± 1.3, p = 0.38, aorta: 22.6 ± 9.4 vs. 20.2 ± 9.7, p & 0.0001, liver: 2.7 ± 1.0 vs. 2.3 ± 1.1, p & 0.0001), while the SNR of the FBP50 % images were all lower (p values & 0.0001). The CNR measured from AIDR50 % images was also higher than that from the FBP images for the aorta relative to muscle (20.5 ± 9.0 vs. 18.3 ± 9.2, p & 0.0001). The interobserver agreement in the image quality score was excellent (κ = 0.82). The quality score was significantly higher for the AIDR50 % images compared to the FBP images (3.6 ± 0.6 vs. 3.3 ± 0.7, p = 0.004). Simulated radiation dose reduction applied to clinical coronary CTA images suggests that a 50 % reduction in radiation dose can be achieved with adaptive iterative dose reduction software with image quality that is at least comparable to images acquired at standard radiation exposure and reconstructed with filtered back projection. Full-text · Article · Feb 2013 +1 more author...ABSTRACT: Twelve infants (body weight, 3.59±1.36 kg) with congenital heart disease underwent a clinically indicated cardiovascular computed tomography angiography (CTA) study. Retrospectively, we investigated the feasibility and diagnostic capability of different non-electrocardiogram-triggered CTA protocols and assessed radiation doses. Scans were performed on a 256-multislice CT (MSCT) scanner with the vendor-preset helical protocol at 120 kV for babies, with axial single-shoot scans at 120 kV and 80 kV. The 80-kV protocol led to significantly reduced mean effective doses of 0.29±0.08 mSv (P=.017) and renders diagnostic image quality. All major cardiovascular defects were detected on MSCT, and all images were of diagnostic quality.Article · Nov 2012 +1 more author...ABSTRACT: To assess the image quality of coronary CT angiography (CCTA) of 640-slice CT reconstructed by Adaptive Iterative Dose Reduction (AIDR) three-dimensional (3D) in comparison with the conventional filtered back-projection (FBP). CCTA images of 51 patients were scanned at the lowest tube voltage possible on condition that the built-in automatic exposure control system could suggest the optimal tube current. They were, then, reconstructed with FBP and AIDR 3D (standard). Objective measurements including CT density, noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were performed. Subjective assessment was done by two radiologists, using a 5-point scale (0:nondiagnostic-4:excellent) based on the 15-coronary segment model which was grouped into three parts as the proximal, mid, and distal segmental classes. Radiation dose was also measured. AIDR images showed lower noise than FBP images (45.0 ± 9.4 vs. 73.4 ± 14.6 HU, p & 0.001) without any significant difference in CT density (665.5 ± 131.7 vs. 668 ± 136.3 HU, p = 0.8). Both SNR (15.0 ± 2.1 vs. 9.2 ± 1.7) and CNR (16.8 ± 2.3 vs. 10.4 ± 1.8) were significantly higher for AIDR than FBP (p & 0.001). Total subjective image quality score was also significantly improved in AIDR compared with FBP (3.1 ± 0.6 vs. 1.6 ± 0.4, p & 0.001), with better interpretability of the mid and distal segmental classes (100 vs. 95 % for the mid, p & 0.001; 100 vs. 90 % for the distal, p & 0.001). Mean effective radiation dose was 2.0 ± 1.0 mSv. The AIDR 3D reconstruction algorithm reduced image noise by 39 % compared with the FBP without affecting CT density, thus improving SNR and CNR for CCTA. Its advantages in interpretability were also confirmed by subjective evaluation by experts.Article · Aug 2012 +1 more author...ABSTRACT: Pediatric cardiac patients often undergo repeat diagnostic testing, resulting in relatively high cumulative medical radiation exposure. Low-dose CT scanning techniques used to decrease radiation exposure may result in reduced image quality.
This study evaluates a prototype iterative reconstruction algorithm, sinogram-affirmed iterative reconstruction (SAFIRE), to determine the effect on qualitative and quantitative measures of image quality in pediatric cardiac CT datasets, compared with a standard weighted filtered back projection (wFBP) algorithm.
Seventy-four datasets obtained on a 128-slice dual-source CT system were evaluated for image quality using both the wFBP and the prototype iterative reconstruction algorithm. Contrast, noise, contrast-to-noise ratio, signal-to-noise ratio, and qualitative image quality were compared between groups. Data were analyzed as medians and 25th and 75th percentiles, and groups were compared with the use of the Wilcoxon singed-rank test or k sample equality of medians test.
There was a 34% decrease in noise, a 41% increase in contrast-to-noise ratio, and a 56% increase in signal-to-noise ratio in the prototype iterative reconstruction, compared with wFBP. All differences were statistically significant (P & 0.001). Qualitative measures of image noise and noise texture were also improved in the iterative reconstruction group (P & 0.001 for both). Diagnostic confidence was similar between reconstruction techniques. Median scan dose length product was 15.5 mGy · cm.
The prototype iterative reconstruction algorithm studied significantly reduces image noise and improves qualitative and quantitative measures of image quality in low-dose pediatric CT datasets, compared with standard wFBP.Article · May 2012 +1 more author...ABSTRACT: This work aimed at assessing the doses delivered in Switzerland to paediatric patients during computed tomography (CT) examinations
of the brain, chest and abdomen, and at establishing diagnostic reference levels (DRLs) for various age groups. Forms were
sent to the ten centres performing CT on children, addressing the demographics, the indication and the scanning parameters:
number of series, kilovoltage, tube current, rotation time, reconstruction slice thickness and pitch, volume CT dose index
(CTDIvol) and dose length product (DLP). Per age group, the proposed DRLs for brain, chest and abdomen are, respectively, in terms
of CTDIvol: 20, 30, 40, 60mGy; 5, 8, 10, 12mGy; 7, 9, 13, 16mGy; and in terms of DLP: 270, 420, 560, 1,000mG 110, 200, 220,
460mG 130, 300, 380, 500mGy cm. An optimisation process should be initiated to reduce the spread in dose recorded in
this study. A major element of this process should be the use of DRLs. Full-text · Article · Sep 2008 +1 more author...ArticleMarch 2015 · PLoS ONE · Impact Factor: 3.23+3 more authors…To determine the optimal dose reduction level of iterative reconstruction technique for paediatric chest CT in pig models.
27 infant pigs underwent 640-slice volume chest CT with 80kVp and different mAs. Automatic exposure control technique was used, and the index of noise was set to SD10 (Group A, routine dose), SD12.5, SD15, SD17.5, SD20 (Groups from B to E) to reduce dose respectively.... ArticleOctober 2012 · European journal of radiology · Impact Factor: 2.37+1 more author…Aim:
To assess the image quality (IQ) of an iterative reconstruction (IR) technique (iDose(4)) from prospective electrocardiography (ECG)-triggered coronary computed tomography angiography (coronary CTA) on a 256-slice multi-detector CT (MDCT) scanner and determine the optimal dose reduction using IR that can provide IQ comparable to filtered back projection (FBP).
Method and materials:
110... ArticleJanuary 2017 · Medicine · Impact Factor: 5.72+3 more authors…The instantaneous wave-free ratio (iFR) closely related to fractional flow reserve (FFR) is a adenosine-independent physiologic index of coronary stenosis severity. We sought to evaluate whether iFR derived from coronary computed tomographic angiography (iFRCT) can be used as a novel noninvasive method for diagnosis of ischemia-causing coronary stenosis.
We retrospectively enrolled 33 patients... ArticleJuly 2013 · European Radiology · Impact Factor: 4.01+3 more authors…To evaluate the accuracy of low-dose coronary CTA with iterative reconstruction (IR) in the diagnosis of coronary artery disease (CAD) in patients with suspected CAD.
Ninety-six patients with suspected CAD underwent low-dose prospective electrocardiogram-gated coronary CTA, with images reconstructed using IR. Image quality (IQ) of coronary segments were graded on a 4-point scale (4,... Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.This publication is from a journal that may support self archiving.