scholarly journals Comparison of Iterative Model Reconstruction versus Filtered Back-Projection in Pediatric Emergency Head CT: Dose, Image Quality, and Image-Reconstruction Times

2019 ◽  
Vol 40 (5) ◽  
pp. 866-871 ◽  
Author(s):  
R.N. Southard ◽  
D.M.E. Bardo ◽  
M.H. Temkit ◽  
M.A. Thorkelson ◽  
R.A. Augustyn ◽  
...  
Keyword(s):  
Image Reconstruction ◽  
Image Quality ◽  
Pediatric Emergency ◽  
Model Reconstruction ◽  
Back Projection ◽  
Filtered Back Projection ◽  
Head Ct ◽  
Ct Dose ◽  
Iterative Model ◽  
Iterative Model Reconstruction

scholarly journals Iterative Model Reconstruction (IMR) in MDCT Below 2 mSv for the Detection of Urinary Calculi: Diagnostic Accuracy and Image Quality in Comparison to Filtered Back-Projection and 4th Generation Iterative Reconstruction (iDose4)

2018 ◽  
Vol 190 (07) ◽  
pp. 630-636 ◽  
Author(s):  
Jakob Schmidt-Holtz ◽  
Azien Laqmani ◽  
Sebastian Butscheidt ◽  
Max Kurfürst ◽  
Maxim Avanesov ◽  
...  
Keyword(s):  
Image Quality ◽  
Image Noise ◽  
Wilcoxon Test ◽  
Model Reconstruction ◽  
Back Projection ◽  
Filtered Back Projection ◽  
Iterative Model ◽  
Iterative Model Reconstruction ◽  
The Impact ◽  
Stone Detection

Purpose The purpose of the study was to assess the impact of iterative model reconstruction (IMR) on reader confidence with respect to stone detection and image quality in comparison to filtered back-projection (FBP) and iDose level 4 (iDose4) in abdominal MDCT with radiation doses below 2 mSv. Materials and Methods For 32 consecutive patients with suspected ureteral stone disease, the raw data of unenhanced 256 slice MDCT (120 kV, 40 reference mAs, mean CTDIvol: 2.7 ± 0.8 mGy, mean DLP: 126 ± 38 mGy × cm) were reconstructed using a prototype version of IMR (levels 1 – 3), iDose4 (level 4) and FBP at a 3 mm slice thickness. Image analysis was independently performed by two radiologists in a blinded fashion. The reader confidence level with respect to stone detection was recorded based on a 5-point scale (1 – certain exclusion; 5 – concrement definitely present) as well as for the evaluation of image quality regarding the depiction of anatomical details (1 – poor; 5 – excellent). A clinical reference standard for stone detection was not established. Statistical evaluation included weighted kappa analysis and Wilcoxon test. Results 17 pelvic and ureteral stones were found. 11 further concrements were located within the ostium of the urinary bladder or the bladder itself. Applying IMR, a distinct improvement in image quality was observed at every level (mean value for FBP, 2.0; iDose4, 2.9; IMR L1, 4.2; IMR L2, 4.0; IMR L3, 3.9; all p < 0.001). Applying the higher IMR levels L2 and L3, a certain level of so-called “blotchiness” of anatomical contours was observed. Reader confidence was significantly improved and was independent of IMR level (certain stone detection FBP, 69 %; iDose4, 81 %; IMR L1 to L3, 95 %; all p > 0.001). With increasing IMR levels, the reduction in streak artifacts was quantified by a decrease in image noise. A loss of anatomical information was not observed. The sensitivity rates for stone detection were equivalent for all MDCTs reconstructed with FBP, iDose4 and IMR. A mean effective dose of 1.9 ± 0.6 mSv was calculated. Conclusion In comparison to FBP and iDose4, a significant increase in mean image quality, reduction in image noise and improvement in subjective reader confidence can be achieved by applying IMR even at significantly reduced dose settings below 2 mSv. Results indicate that a further dose reduction might be possible with IMR. Key Points  Citation Format

Knowledge-based iterative model reconstruction in coronary computed tomography angiography: comparison with hybrid iterative reconstruction and filtered back projection

2017 ◽  
Vol 59 (3) ◽  
pp. 280-286 ◽  
Author(s):  
Min Jae Cha ◽  
Jae Seung Seo ◽  
Dong Soo Yoo ◽  
Semin Chong
Keyword(s):  
Image Quality ◽  
Coronary Computed Tomography Angiography ◽  
Model Reconstruction ◽  
Back Projection ◽  
Knowledge Based ◽  
Hybrid Iterative Reconstruction ◽  
Iterative Model ◽  
Iterative Model Reconstruction ◽  
Group A ◽  
Group B

Background Knowledge-based iterative model reconstruction (IMR) is known to allow radiation dose reduction while preserving image quality. Purpose To investigate the effect of IMR on coronary computed tomography angiography (CCTA) by comparing it with filtered back projection (FBP) and hybrid iterative reconstruction (HIR). Material and Methods Forty-five patients (group A) who underwent CCTA with prospective electrocardiogram (ECG) triggering at 80 kVp were included. All images were reconstructed using three algorithms: FBP, HIR, and IMR. The control group comprised 45 patients (group B) who underwent CCTA at 100 kVp; their images were reconstructed with HIR alone. Objective and subjective image quality was assessed by two radiologists. Results In group A, the signal-to-noise and contrast-to-noise ratios were significantly higher for images reconstructed with IMR than with HIR or FBP ( P < 0.001). IMR was also superior to HIR and FBP in subjective image quality analyses, including image noise, vessel sharpness, beam-hardening artifact, and overall quality ( P < 0.001). Moreover, the images reconstructed using IMR in group A had superior image quality with less radiation exposure than those reconstructed using HIR in group B on both objective and subjective analyses ( P < 0.001). The mean attenuation values were also significantly higher in group A than in group B ( P < 0.001). Conclusion Compared with HIR and FBP, IMR provided higher quality images with less radiation exposure in CCTA, using low kilovoltage and prospective ECG triggering.

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