Radiation doses and image quality of abdominal CT scans at different patient sizes using spectral detector CT scanner: a phantom and clinical study

Radiologic technologists face various types of patients during multi-detector computed tomography (CT) examinations. In emergency departments, it is common to have patients who cannot follow instructions for the examinations. The asymmetric axial view of the head CT might affect the correctness of the clinician’s diagnosis. This study aimed to assess the impact of head positioning on the image quality of head CT using two phantoms. All scans were performed on a 16-slice CT scanner. In the control group, the tilted angle of the phantoms was 0[Formula: see text], and no multiplanar reconstruction (MPR) was performed. In the experimental groups, the tilted angles of the phantoms were 5[Formula: see text], 10[Formula: see text] and 15[Formula: see text], respectively, and MPR was performed afterwards. The results showed that if the head was tilted during the head CT examinations, image asymmetry and artifacts appeared without MPR. After MPR, one phantom showed that there were significant differences and the other phantom showed no significant differences quantitatively in image symmetry and artifacts between experimental groups and the control group, while both phantoms showed no significant differences qualitatively in image symmetry and artifacts between experimental groups and the control group. Although MPR can correct the image asymmetry and artifacts caused by tilted head positioning to some extent, it consumes time. Therefore, technologists should position the head as exactly as possible when performing head CT examinations.

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Evaluation of three-dimensional iterative image reconstruction in virtual monochromatic imaging at 40 kilo-electron volts: phantom and clinical studies to assess the image noise and image quality in comparison with other reconstruction techniques

British Journal of Radiology ◽

10.1259/bjr.20190675 ◽

2020 ◽

Vol 93 (1110) ◽

pp. 20190675

Author(s):

Takuya Ishikawa ◽

Shigeru Suzuki ◽

Yoshiaki Katada ◽

Tomoko Takayanagi ◽

Rika Fukui ◽

...

Keyword(s):

Clinical Study ◽

Image Reconstruction ◽

Image Quality ◽

Three Dimensional ◽

Image Noise ◽

Reconstruction Technique ◽

Iterative Image Reconstruction ◽

Virtual Monochromatic Imaging ◽

Monochromatic Imaging

Objective: The purpose of this study was to evaluate the image quality in virtual monochromatic imaging (VMI) at 40 kilo-electron volts (keV) with three-dimensional iterative image reconstruction (3D-IIR). Methods: A phantom study and clinical study (31 patients) were performed with dual-energy CT (DECT). VMI at 40 keV was obtained and the images were reconstructed using filtered back projection (FBP), 50% adaptive statistical iterative reconstruction (ASiR), and 3D-IIR. We conducted subjective and objective evaluations of the image quality with each reconstruction technique. Results: The image contrast-to-noise ratio and image noise in both the clinical and phantom studies were significantly better with 3D-IIR than with 50% ASiR, and with 50% ASiR than with FBP (all, p < 0.05). The standard deviation and noise power spectra of the reconstructed images decreased in the order of 3D-IIR to 50% ASiR to FBP, while the modulation transfer function was maintained across the three reconstruction techniques. In most subjective evaluations in the clinical study, the image quality was significantly better with 3D-IIR than with 50% ASiR, and with 50% ASiR than with FBP (all, p < 0.001). Regarding the diagnostic acceptability, all images using 3D-IIR were evaluated as being fully or probably acceptable. Conclusions: The quality of VMI at 40 keV is improved by 3D-IIR, which allows the image noise to be reduced and structural details to be maintained. Advances in knowledge: The improvement of the image quality of VMI at 40 keV by 3D-IIR may increase the subjective acceptance in the clinical setting.

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Improvement of image quality and diagnostic confidence using Smart MAR – a projection-based CT protocol in patients with orthopedic metallic implants in hip, spine, and shoulder

Acta Radiologica ◽

10.1177/0284185120903446 ◽

2020 ◽

Vol 61 (10) ◽

pp. 1421-1430

Author(s):

Felix W Feldhaus ◽

Georg Böning ◽

Johannes Kahn ◽

Uli Fehrenbach ◽

Martin Maurer ◽

...

Keyword(s):

Image Quality ◽

Soft Tissues ◽

Signal To Noise Ratio ◽

Multislice Ct ◽

Orthopedic Implants ◽

Ct Scans ◽

Ct Scanner ◽

Diagnostic Confidence ◽

Metallic Implants ◽

Ct Protocol

Background In computed tomography (CT) scans, artifacts caused by metallic orthopedic implants still hamper the visualization of important, periprosthetic tissues. Smart MAR metal artifact reduction tool is a promising three-stage, projection-based, post-processing algorithm. Purpose To determine whether the Smart MAR tool improves subjective and objective image quality and diagnostic confidence in patients with orthopedic implants of the hip, spine, and shoulder. Material and Methods Seventy-two patients with orthopedic screws, hip/shoulder replacement, or spine spondylodesis were included. CT scans were performed on a single-source multislice CT scanner, raw data were post-processed using Smart MAR. Image quality was evaluated both quantitatively (ROI-based) and qualitatively (rater-based) and compared to iterative reconstructions (ASIR V). As comparative standard for artificial prosthetic breaks or loosening, follow-up examinations were used. Results Smart MAR reconstructions of the hip (n = 23), spine (n = 26), and shoulder (n = 23) showed a significantly reduced attenuation and noise of regions adjacent to metallic implants ( P<0.002). Subjective image quality ( P<0.005, shoulder P = 0.038/ P = 0.046) and overall diagnostic confidence were higher in Smart MAR (all regions P<0.002). Signal-to-noise ratio (SNR; P = 0.72/ P = 0.96) was not improved. Compared to standard ASIR V new, artificial metal extinctions (up to 50%) or periprosthetic hem lines (48%–73%) were introduced by Smart MAR. Conclusion Smart MAR improved image quality of the hip, spine, and shoulder CT scans resulting in higher diagnostic confidence in evaluation of periprosthetic soft tissues. As shown for spine implants, it should be used with caution and as a complementary tool for evaluation of periprosthetic loosening or integrity of metal implant, as in many cases it introduced new artifacts.

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Comparison of image quality of atrial fibrillation and normal sinus rhythm ratients on single beat volumetric CT scanner, initial experience with a new CT scanner

Journal of Cardiovascular Computed Tomography ◽

10.1016/j.jcct.2015.12.036 ◽

2016 ◽

Vol 10 (2) ◽

pp. e13

Author(s):

Muhammad A. Latif ◽

Abner D. Wilding ◽

Kadeem Walker ◽

Emir Veledar ◽

Juan C. Batlle ◽

...

Keyword(s):

Atrial Fibrillation ◽

Image Quality ◽

Sinus Rhythm ◽

Normal Sinus Rhythm ◽

Initial Experience ◽

Ct Scanner ◽

Normal Sinus ◽

Volumetric Ct

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Total Bolus Extraction Method Improves Arterial Image Quality in Dynamic CTAs Derived from Whole-Brain CTP Data

BioMed Research International ◽

10.1155/2014/603173 ◽

2014 ◽

Vol 2014 ◽

pp. 1-6

Author(s):

Elyas Ghariq ◽

Adriënne M. Mendrik ◽

Peter W. A. Willems ◽

Raoul M. S. Joemai ◽

Eidrees Ghariq ◽

...

Keyword(s):

Image Quality ◽

Ct Perfusion ◽

Ct Scanner ◽

Whole Brain ◽

Acute Cerebral Ischemia ◽

Dynamic Ct Angiography ◽

Information Dynamic ◽

Hemodynamic Information ◽

Ophthalmic Arteries

Background and Purposes. The 320-detector row CT scanner enables visualization of whole-brain hemodynamic information (dynamic CT angiography (CTA) derived from CT perfusion scans). However, arterial image quality in dynamic CTA (dCTA) is inferior to arterial image quality in standard CTA. This study evaluates whether the arterial image quality can be improved by using a total bolus extraction (ToBE) method.Materials and Methods. DCTAs of 15 patients, who presented with signs of acute cerebral ischemia, were derived from 320-slice CT perfusion scans using both the standard subtraction method and the proposed ToBE method. Two neurointerventionalists blinded to the scan type scored the arterial image quality on a 5-point scale in the 4D dCTAs in consensus. Arteries were divided into four categories: (I) large extradural, (II) intradural (large, medium, and small), (III) communicating arteries, and (IV) cerebellar and ophthalmic arteries.Results. Quality of extradural and intradural arteries was significantly higher in the ToBE dCTAs than in the standard dCTAs (extraduralP=0.001, large intraduralP<0.001, medium intraduralP<0.001, and small intraduralP<0.001).Conclusion. The 4D dCTAs derived with the total bolus extraction (ToBE) method provide hemodynamic information combined with improved arterial image quality as compared to standard 4D dCTAs.

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