Visual Grading Characteristics Research Articles

Visualization of wrist anatomy\u2014a comparison between 7T and 3T MRI

ObjectiveInjuries to the wrist are, due to its small size and complex anatomical structures, difficult to assess by MR, and surgical interventions such as diagnostic arthroscopy are often necessary. Therefore, improved visualization using non-invasive methods could be of clinical value. As a first step of improvement, the purpose of this study was to evaluate visualization of anatomical structures at 7T compared with 3T MR.MethodsEighteen healthy volunteers (three males and three females from each age decade between 20 and 49 years) were examined with 7T and 3T MR. Four musculoskeletal radiologists graded 2D and 3D images on a five-level grading scale for visibility of ligaments, cartilage, nerves, trabecular bone, and tendons, as well as overall image quality (i.e., edge sharpness, perceived tissue contrast, and presence of artefacts). Statistical analysis was done using a visual grading characteristics (VGC) analysis.ResultsVisibility of cartilage, trabecular bone, tendons, nerves, and ligaments was graded significantly higher at 7T with an area under the curve (AUCVGC) of 0.62–0.88 (95% confidence interval [CI] 0.50–0.97, p = < 0.0001–0.03) using either 2D or 3D imaging. Imaging with 3T was not graded as superior to 7T for any structure. Image quality was also significantly superior at 7T, except for artefacts, where no significant differences were found.ConclusionsTendons, trabecular bone, nerves, and ligaments were all significantly better visualized at 7T compared to 3T.Key Points• MRI of the wrist at 7T with a commercially available wrist coil is feasible at similar acquisition times as for 3T MRI.• The current study showed 7T to be superior to 3T in the visualization of anatomical structures of the wrist, including ligaments, tendons, nerves, and trabecular bone.• Image quality was significantly superior at 7T, except for artefacts, where no significant differences were found.

Effect of x-ray energy on the radiological image quality in propagation-based phase-contrast computed tomography of the breast.

Purpose: Breast cancer is the most common cancer in women in developing and developed countries and is responsible for 15% of women's cancer deaths worldwide. Conventional absorption-based breast imaging techniques lack sufficient contrast for comprehensive diagnosis. Propagation-based phase-contrast computed tomography (PB-CT) is a developing technique that exploits a more contrast-sensitive property of x-rays: x-ray refraction. X-ray absorption, refraction, and contrast-to-noise in the corresponding images depend on the x-ray energy used, for the same/fixed radiation dose. The aim of this paper is to explore the relationship between x-ray energy and radiological image quality in PB-CT imaging. Approach: Thirty-nine mastectomy samples were scanned at the imaging and medical beamline at the Australian Synchrotron. Samples were scanned at various x-ray energies of 26, 28, 30, 32, 34, and 60keV using a Hamamatsu Flat Panel detector at the same object-to-detector distance of 6m and mean glandular dose of 4mGy. A total of 132 image sets were produced for analysis. Seven observers rated PB-CT images against absorption-based CT (AB-CT) images of the same samples on a five-point scale. A visual grading characteristics (VGC) study was used to determine the difference in image quality. Results: PB-CT images produced at 28, 30, 32, and 34keV x-ray energies demonstrated statistically significant higher image quality than reference AB-CT images. The optimum x-ray energy, 30keV, displayed the largest area under the curve of 0.754 ( ). This was followed by 32keV ( , ), 34keV ( , ), and 28keV ( , ). Conclusions: An optimum energy range (around 30keV) in the PB-CT technique allows for higher image quality at a dose comparable to conventional mammographic techniques. This results in improved radiological image quality compared with conventional techniques, which may ultimately lead to higher diagnostic efficacy and a reduction in breast cancer mortalities.

How does a non-optimal tube potential influence radiation dose to the patient in lumbar spine radiography?

IntroductionWhen comparing the radiation dose to the patient, the lumbar spine has one of the highest dose values in general radiography, therefore the procedure needs to be optimised. The aim of this study was to investigate the effect of a non-optimal tube potential (66 kV) during anteroposterior (AP) lumbar spine radiography on the radiation dose received by the patient compared with the radiation dose when an optimal tube potential (79 kV) is used, in accordance with European guidelines. MethodsThis retrospective study involved 100 patients referred for lumbar radiography in two different diagnostic departments. Half of the patients were admitted to a department which used optimal tube potential and the other half to the department which used non-optimal tube potential for AP lumbar spine radiography protocols. The height and weight of the patients were collected to calculate the body mass index (BMI) of the patients. The image field size and dose area product (DAP) values were collected after each imaging session. The effective dose and selected organ dose were calculated using the PCXMC 2.0 program. ResultsThe results showed that a non-optimal tube potential resulted in a significant increase in the DAP value by 360% (p < 0.001) and a significant increase in the effective dose by 160% (p < 0.001). Dose to selected organs due to non-optimal tube potential increased from 107% (breasts) up to 631% (prostate) (p < 0.001). The images were not assessed using visual grading characteristics (VGC) analysis, but the radiologists evaluated all the images appropriate for diagnostic reading. ConclusionBased on our study's stated results, we can conclude that optimal tube potential use is essential to achieve the ALARA principle. Implications for practiceThe study shows the effect of a non-optimal tube potential on the radiation dose received by the patient during radiography of the lumbar spine. This could influence possible diagnostic departments to consider protocol optimisation due to the high radiation dose received by the patient.

EVALUATION OF VGC ANALYZER BY COMPARISON WITH GOLD STANDARD ROC SOFTWARE AND ANALYSIS OF SIMULATED VISUAL GRADING DATA

The purpose of the present work was to evaluate the use of resampling statistical methods for analysis of visual grading data—implemented in the software VGC Analyzer—by comparing the reanalyzed results from previously performed visual grading studies with the results calculated by gold standard receiver operating characteristic (ROC) methodology, Obuchowski-Rockette (OR)-Dorfman–Berbaum–Metz (DBM) multiple-readers and multiple-case (MRMC) and by analysis of simulated visual grading data where the true distribution was presumed to be known. The reanalysis was performed on two multiple-reader studies with non-paired data and paired data, respectively. The simulation study was performed by simulating a large number of visual grading characteristics (VGC) studies and by analyzing the statistical distribution of null hypothesis (H0) rejection rate. The comparison with OR-DBM MRMC showed good agreement when analyzing non-paired data for both fixed-reader and random-reader settings for the calculated area under the curve values and the confidence intervals (CIs). For paired data analysis, VGC Analyzer showed significantly lower CIs compared with the ROC software. This effect was also illustrated by the simulation study, where the VGC Analyzer, in general, showed good accuracy for simulated studies with stable statistical basis. For simulated studies with unstable statistics, the accuracy in the H0 rejection rate decreased. The present study has shown that resampling methodology can be used to accurately perform the statistical analysis of a VGC study, although the resampling technique used makes the method sensitive to small data sets.

Validation of a candidate instrument to assess image quality in digital mammography using ROC analysis

PurposeTo validate a candidate instrument, to be used by different professionals to assess image quality in digital mammography (DM), against detection performance results. MethodsA receiver operating characteristics (ROC) study was conducted to assess the detection performance in DM images with four different image quality levels due to different quality issues. Fourteen expert breast radiologists from five countries assessed a set of 80 DM cases, containing 60 lesions (40 cancers, 20 benign findings) and 20 normal cases. A visual grading analysis (VGA) study using a previously-described candidate instrument was conducted to evaluate a subset of 25 of the images used in the ROC study. Eight radiologists that had participated in the ROC study, and seven expert breast-imaging physicists, evaluated this subset. The VGA score (VGAS) and the ROC and visual grading characteristics (VGC) areas under the curve (AUCROC and AUCVGC) were compared. ResultsNo large differences in image quality among the four levels were detected by either ROC or VGA studies. However, the ranking of the four levels was consistent: level 1 (partial AUCROC: 0.070, VGAS: 6.77) performed better than levels 2 (0.066, 6.15), 3 (0.061, 5.82), and 4 (0.062, 5.37). Similarity between radiologists’ and physicists’ assessments was found (average VGAS difference of 10 %). ConclusionsThe results from the candidate instrument were found to correlate with those from ROC analysis, when used by either observer group. Therefore, it may be used by different professionals, such as radiologists, radiographers, and physicists, to assess clinically-relevant image quality variations in DM.

Comparison of simultaneous multi-slice single-shot DWI to readout-segmented DWI for evaluation of breast lesions at 3T MRI

PurposeTo compare diffusion-weighted imaging of the breast performed with a conventional readout-segmented echo-planar imaging (rs-EPI) sequence to when using a prototype simultaneous multi-slice single-shot EPI (SMS-ss-EPI) acquisition. MethodFrom September 2017 to December 2018, 26 women with histologically proven breast cancer were scanned with the conventional rs-EPI and the SMS-ss-EPI at 3 T during the same imaging examination. Four breast radiologists (4–13 years of experience) independently scored both acquired series of 25 women (one case was used for training) for overall image quality (1: extremely poor to 9: excellent) and artifacts (1: very disturbing to 5: not present). All lesions (n = 52; 40 malignant, 12 benign) were also evaluated for visibility (1: not visible, 2: visible if location is given, 3: visible). In addition, lesion characteristics were rated, and a BI-RADS score was given. Results were analyzed using visual grading characteristics and the resulting area under the curve (AUCVGC), weighted kappa, McNemar test, and dependent-samples t-test when appropriate. ResultsOverall, radiologists significantly preferred the image quality in rs-EPI over that of SMS-ss-EPI (AUCVGC: 0.698, P = 0.002). Infolding and ghosting, and distortion artifacts were significantly less apparent in the rs-EPI (AUCVGC: 0.660, P = 0.022 and AUCVGC: 0.700 P = 0.002, respectively). Lesions were, however, significantly better visible on the SMS-ss-EPI images (AUCVGC: 0.427, P = 0.016). Malignant lesions had significantly higher visibility with SMS-ss-EPI (P = 0.035). Sensitivity and specificity were comparable between both sequences (P = 0.760 and P = 0.549, respectively). ConclusionsDespite the perceived lower image quality and the increased presence of artifacts in the SMS-ss-EPI sequence, malignant lesions are better visualized using this sequence.

EVALUATION OF MODEL-BASED ITERATIVE RECONSTRUCTION IN ABDOMINAL COMPUTED TOMOGRAPHY IMAGING AT TWO DIFFERENT DOSE LEVELS.

The purpose of this study was to qualitatively evaluate recently introduced Model-based iterative reconstruction method (IMR) and routinely used iterative reconstruction algorithm iDose4 to investigate future dose reduction possibilities for abdominal CT exams. The study contained data from 34 patients who underwent abdominal CT in SkåneUniversityHospital Lund, Sweden. A low-dose scan (CTDIvol3.4 mGy) reconstructed with both iDose4 and IMR and a standard-dose scan (CTDIvol 5.3 mG) reconstructed with iDose4 alone were visually graded in ViewDEX v2.0 by four radiologists using modified EU image criteria. The visual grading characteristics analysis for the evaluation comparing iDose4 standard dose with IMR low dose did not show any statistically significant difference in five of six criteria. In one of the criteria, iDose4 was superior to IMR. The result show promising possibilities are introduced for substantial radiation dose reduction (35%) in abdominal CT imaging when replacing iDose4 with IMR. Still, care should be taken when considering the reproduction of adrenal glands.

Visibility of significant prostate cancer on multiparametric magnetic resonance imaging (MRI)\u2014do we still need contrast media?

ObjectivesTo assess the visibility of clinically significant prostate cancer (PCA) lesions on the sequences multiparametric MRI of the prostate (mpMRI) and to evaluate whether the addition of dynamic contrast–enhanced imaging (DCE) improves the overall visibility.MethodsWe retrospectively evaluated multiparametric MRI images of 119 lesions in 111 patients with biopsy-proven clinically significant PCA. Three readers assigned visual grading scores for visibility on each sequence, and a visual grading characteristic analysis was performed. Linear regression was used to explore which factors contributed to visibility in individual sequences.ResultsThe visibility of lesions was significantly better with mpMRI when compared to biparametric MRI in visual grading characteristic (VGC) analysis, with an AUCVGC of 0.62 (95% CI 0.55–0.69; p < 0.001). This benefit was seen across all readers. Multivariable linear regression revealed that a location in the peripheral zone was associated with better visibility on T2-weighted imaging (T2w). A higher Prostate Imaging-Reporting and Data System (PI-RADS) score was associated with better visibility on both diffusion-weighted imaging (DWI) and DCE. Increased lesion size was associated with better visibility on all sequences.ConclusionsVisibility of clinically significant PCA is improved by using mpMRI. DCE and DWI images independently improve lesion visibility compared to T2w images alone. Further research into the potential of DCE to impact on clinical decision-making is suggested.Key Points• DCE and DWI images independently improve clinically significant prostate cancer lesion visibility compared to T2w images alone.• Multiparametric MRI (DCE, DWI, T2w) achieved significantly higher visibility scores than biparametric MRI (DWI, T2w).• Location in the transition zone is associated with poor visibility on T2w, while it did not affect visibility on DWI or DCE.

Image quality of bedside chest radiographs in intensive care beds with integrated detector tray: A phantom study

IntroductionVendors offer intensive care beds with integrated detector trays for bedside radiography, promoting better ergonomics and patient comfort. However, no documentation of the effects on diagnostic image quality has been located. This study examines measured and subjective image quality of supine bedside chest radiographs with and without use of such a detector tray. MethodsA contrast-detail phantom (CDRAD 2.0) was exposed using standard supine chest exposure parameters. Plexiglass plates of 16 and 21 cm were placed in front to simulate patient attenuation for standard and adipose patients. Exposures were repeated with the detector placed in tray and directly in bed. Images were analysed using dedicated software giving a figure-of-merit IQFinv. Results were compared using ANOVA. Then an anthropomorphic chest phantom (Lungman) was exposed using the same parameters, and the same placements of the detector. Exposures were done with and without extra conformal tissue to simulate varying patient sizes, and with and without added typical intensive care equipment. Images were analysed by two radiologists using a three-point scale, on five image quality criteria. Radiologist also stated whether the images were sufficient for diagnosis. Results were compared using Visual Grading Characteristics, using dedicated software, resulting in Areas Under the Curve (AUC-VGC) for each combination and criteria. Inter- and intra-rater reliability were assessed with kappa statistics. Composite Visual Grading Analysis (VGAS) scores were calculated for each image. Both IQFinv and were normalized and compared. ResultsFor all criteria both IQFinv and AUC-VGC was significantly better when exposing the detector directly in bed, than with the detector placed in the tray across all exposures. When stratified into thin and adipose patients, IQFinv decreased significantly for thin patients, while VGAS-scores did not. For adipose patients, both figures were significantly lower with the detector in the tray. ConclusionUse of detector tray for bedside chest imaging decreases image quality. Implications for practiceRadiographers should critically evaluate image quality and experimentally determine optimal exposure factors, when taking equipment with integrated trays into use.

Comparison of Magnetic Resonance Angiography and Digital Subtraction Angiography for the Assessment of Infrapopliteal Arterial Occlusive Lesions, Based on the TASC II Classification Criteria

This paper aimed to study the agreement and repeatability, both intra- and interobserver, of infrapopliteal lesion assessment with magnetic resonance angiography (MRA), using the TransAtlantic Inter-Society Consensus (TASC) II criteria, with perioperative digital subtraction angiography (DSA) as a reference. Sixty-eight patients with an MRA preceding an endovascular infrapopliteal revascularization were included. Preoperative MRAs and perioperative DSAs were evaluated in random order by three independent observers using the TASC II classification. The results were analyzed using visual grading characteristics (VGC) analysis and Krippendorff’s α. No systematic difference was found between modalities: area under the VGC curve (AUCVGC) = 0.48 (p = 0.58) or intraobserver; AUCVGC for Observer 1 and 2 respectively, 0.49 (p = 0.85) and 0.53 (p = 0.52) for MRA compared with 0.54 (p = 0.30) and 0.49 (p = 0.81) for DSA. Interobserver differences were seen: AUCVGC of 0.63 (p < 0.01) for DSA and 0.80 (p < 0.01) for MRA. These results were confirmed using Krippendorff’s α for the three observers showing 0.13 (95% confidence interval (CI) −0.07–0.31) for MRA and 0.39 (95% CI 0.23–0.53) for DSA. Poor interobserver agreement was also found in the choice of a target vessel on preoperative MRA: Krippendorff’s α = 0.19 (95% CI 0.01‒0.36). In conclusion, infrapopliteal lesions can be reliably determined on preoperative MRA, but interobserver variability regarding the choice of a target vessel is a major concern that appears to affect the overall TASC II grade.

To repeat or not to repeat: Radiologists demonstrated more decisiveness than their fellow radiographers in reducing the repeat rate during mobile chest radiography

IntroductionRadiologists and radiographers play a complementary role in providing an optimal image quality with decrease radiation dose and proper diagnosis during chest radiographs. We aim Investigate years of experience among radiologists and radiographers on perception of image quality and its impact on repeat rate when evaluating portable pediatric chest radiographs. MethodsIRB approved retrospective study consisted of randomly selected images (n = 131) of pediatric portable chest radiographs. Images were blindly assessed by four radiologists and four radiographers. Readers were asked to assess qualitative and quantitative image quality by rating: image quality, decision to repeat and image technique. All data was compared employing Pearson's Correlation, Visual grading characteristic (VGC) and Cohens' kappa analyses. ResultsImage quality: Radiologists (88.4%) rated images as excellent significantly more than radiographers (11.6%), and radiographers (90.1%) as poor significantly more than radiologists (9.9%) (p < 0.05). Repeat: Radiologists (57%) decided not to repeat images significantly more than radiographers (43%) (p < 0.05). Image technique: Radiologists rated images as acceptable (65%) and excellent (97.7%) significantly more than radiographers (35% and 2.3% respectively) (p < 0.05), whereas radiographers (84%) assessed image technique as poor significantly more than radiologists (16%) (p < 0.05). VGC: radiographers had slightly better qualitative evaluation of image quality than radiologists. An association between image quality (p < 0.002) and repeat decision (p < 0.044) with years of experience was established when comparing years of experience with image assessment rubric, while no association was noted with image technique (p < 0.9). ConclusionRadiologists demonstrated more decisiveness than their fellow radiographers in reducing the repeat rate of portable pediatric chest radiographs. Interestingly, years of experience only seem to affect image technique and image quality assessment among radiologists. Implications for practiceContinuous education of radiographers and close collaboration with radiologists is crucial to achieve optimal image quality and low radiation doses.

The Effect of Dose Reduction on Overall Image Quality in Clinical Chest Tomosynthesis

To evaluate the effect of reduction in effective dose on the reproduction of anatomical structures in chest tomosynthesis (CTS). Twenty-four CTS examinations acquired at exposure settings resulting in an effective dose of 0.12 mSv for an average sized patient were included in the study. The examinations underwent simulated dose reduction to dose levels corresponding to 32%, 50%, and 70% of the original dose using a previously described and validated method. The image quality was evaluated by five thoracic radiologists who rated the fulfillment of specified image quality criteria in a visual grading study. The ratings for each image quality criterion in the dose-reduced images were compared to the corresponding ratings for the full-dose examinations using visual grading characteristics (VGC) analysis. The area under the resulting VGC curve (AUCVGC) provides a measure of the difference between the ratings, where an AUCVGC of 0.5 indicates no difference. The dose reductions resulted in inferior reproduction of structures compared to the original dose level (AUCVGC <0.5). Structures in the central region of the lung obtained the lowest AUCVGC for each dose level whereas the reproduction of structures in the parenchyma was least affected by the dose reduction. Although previous studies have shown that dose reduction in CTS is possible without affecting the performance of certain clinical tasks, the reproduction of normal anatomical structures is significantly degraded even at small reductions. It is therefore important to consider the clinical purpose of the CTS examinations before deciding on a permanent dose reduction.

Impact of various iodine concentrations of iohexol and iodixanol contrast media on image reconstruction techniques in a vascular-specific contrast media phantom: quantitative and qualitative image quality assessment.

The aim of our study is to investigate the impact of iodine quantification on image reconstruction when employing a vascular-specific contrast media phantom with varying iodine concentrations. A 30-cm phantom simulating arterial and venous blood vessel diameters was manufactured. Small (9mm) and medium (12mm) cylinders contained iodine concentrations from 10 to 100% while large (21mm) cylinders were in quartiles from 25 to 100% diluted in blood equivalent medium. Each phantom was filled with either iohexol 350 mgI/mL (Group A) or iodixanol 320 mgI/mL (Group B) and then scanned separately. For each group, tube potential (80-140 kVp) and current (50-400mAs) were changed and all image series were reconstructed with filtered back projection (FBP), hybrid-based iterative reconstruction (HBIR) and model-based iterative reconstruction (MBIR). Mean opacification was measured in all groups. All data were compared employing an independent t test and Pearson's correlation. Visual grading characteristic (VGC) and Cohens' kappa analyses were performed. At 80 kVp, mean opacification using HBIR was significantly higher in Group B (2165 ± 1108 HU) than in Group A (2040 ± 1036 HU) (p < 0.009). At 140 kVp, MBIR and HBIR were greater in Group A (1704 ± 1033 HU and 1685 ± 1023 HU) versus Group B (1567 ± 1036 HU and 1567 ± 1034 HU) (p < 0.022). CNR using FBP, HBIR and MBIR was higher in Group B (46 ± 42 HU, 70 ± 163 HU and 83 ± 74 HU, respectively) than in Group A (43 ± 39 HU, 174 ± 130 HU and 80 ± 65 HU, respectively) (p < 0.0001-0.035). Qualitative image analysis demonstrated no difference in Cohen's kappa analysis. VGC was higher in Group A at all image reconstruction groups. Iohexol outperforms iodixanol in observer performance when assessing image reconstruction techniques and iodine concentrations in a vascular-specific contrast media phantom.

Contrast media volume is significantly related to patient lung volume during CT pulmonary angiography when employing a patient-specific contrast protocol

Aim: The purpose of this study is to investigate the relationship between contrast media volume and patient lung volume when employing a patient-specific contrast media formula during pulmonary computed tomography angiography (CTA).&#x0D; Materials and methods: IRB approved this retrospective study. CTA of the pulmonary arteries was performed on 200 patients with suspected pulmonary embolism (PE). The contrast media volume (CMV) was calculted by employing a patient-specific contrast formula. Lung volume was quantified employing semi-automated lung software that calculated lung volumes (intellispace -Philips). The mean cross-sectional opacification profile of central and peripheral pulmonary arteries and veins were measured for each patient and arteriovenous contrast ratio (AVCR) calculated for each lung segment. Mean body mass index (BMI) and lung volume were quantified. Receiver operating (ROC) and visual grading characteristics (VGC) measured reader confidence in emboli detection and image quality respectively. Inter and intra-observer variations were investigated employing Cohen’s kappa methodology.&#x0D; Results: Results showed that the mean pulmonary arterial opacification of the main pulmonary circulation (343.88±73HU), right lung; upper (316.51±23HU), middle (312.5±39HU) and lower (315.23±65HU) lobes and left; upper (318.76±83HU), and lower (321.91±12HU) lobes. The mean venous opacification of all pulmonary veins was below 182±72HU. AVCR was observed at all anatomic locations (p&lt;0.0002) where this ratio was calculated. Moreover, larger volumes of contrast significantly correlated with larger lung volumes (r=0.89, p&lt;0.03) and radiation dose (p&lt;0.03). VGC and ROC analysis demonstrated increased area under the curve: 0.831 and 0.99 respectively (p&lt;0.02). Inter-observer variation was observed as excellent (κ = 0.71).&#x0D; Conclusion: We conclude that increased CMV is significantly correlated to increased patient lung volume and radiation dose when employing a patient-specific contrast formula. The effects patient habitus is highlighted.

Comparison of two Meglumine-Diatrizoate based bowel preparations for computed tomography colonography: Comparison of patient symptoms and bowel preparation quality

IntroductionTo investigate the impact of two Meglumine-Diatrizoate based bowel preparation regimes for computed tomography colonography (CTC) on the patient experience and image quality. Methods100 patients consumed Meglumine-Diatrizoate at 24 h and 12 h prior to the CTC examination. 50 patients followed regime 1 (50:50), 50 ml of Meglumine-Diatrizoate at both 24 and 12 h prior to the examination. 50 patients followed regime 2 (75:25), 75 ml of Meglumine-Diatrizoate at 24 h prior to the examination and 25 ml of Meglumine-Diatrizoate at 12 h prior to the examination. All patients completed a questionnaire to indicate the time of onset of adverse effects and when they were most severe. Five advanced practitioners assessed the image quality in a visual grading study. Visual grading characteristic (VGC) analysis was applied with regime 1 as the reference condition and regime 2 and test condition; test alpha was set at 0.05. ResultsImage quality was assessed with successful bowel cleansing as the scoring criteria for the visual grading study. The bowel cleansing as provided by the two Meglumine-Diatrizoate regimes was revealed not to be statistically different, with the area under the VGC curve and 95% confidence intervals 0.487 (0.287, 0.701), p = 0.887. Patients taking the 75:25 bowel preparation experienced a shorter median time to the onset of adverse effects. ConclusionThere was no observed difference in Image quality criteria score for the two Meglumine-Diatrizoate based bowel preparation with more predictable adverse effects of Meglumine-Diatrizoate with the 75:25 preparation. Implications for practiceProviding patients with a higher contrast burden 24 h prior to CTC may have a positive impact on the patient experience without compromising image quality.

Balancing act between quantitative and qualitative image quality between nonionic iodinated dimer and monomer at various vessel sizes during computed tomography: a phantom study

Purpose: Investigate the impact of nonionic dimer and monomer on iodine quantification in different vessel sizes when employing a vascular specific phantom and varying iodinated contrast media (ICM) concentrations during computed tomography (CT). Materials and Methods: We created a vascular specific phantom (30 cm) to simulate human blood vessel diameters (25 cylinders of different diameters: 10 × 9mm, 10 × 12mm and 5 × 21mm). The phantom was filled with two ICM separately: Group: Iohexol(monomer)350 mg ml−1 and B: Iodixanol(Dimer)320 mg ml−1. Cylinders of same size were filled with increasing ICM concentration(10%–100%) while large cylinders were filled in quartiles(25%–100%). Phantom was scanned with different tube potential (80–140kVp), current (50–400mAs), reconstruction method [filtered back projection (FBP), hybrid-based iterative reconstruction (HBIR) and model-based iterative reconstruction (MBIR)] for each ICM. Chi-square was employed to compare mean opacification, contrast/noise ratio (CNR) and noise. Qualitative analysis was assessed by Visual grading characteristic (VGC) and Cohens-kappa analyses. Results: At 80 and140kVp significant difference in opacification between Group A (2054 ± 1040HU and 1696 ± 1027HU) and B (2169 ± 1105HU and 1568 ± 1034HU) was demonstrated (p < 0.001). However, at 100 and 120kVp no difference was noted (p > 0.05). When comparing image noise, it was higher in Group A compared to B (p < 0.05). CNR was higher in Group B (119.99 ± 126.10HU) than A (107.09 ± 102.56HU) (p < 0.0001). VGC: Group A outperformed B in image opacification in all vessel sizes and ICM concentrations except at medium vessels with concentration group 2(0.4–0.6 mg ml−1). Cohens’-kappa: agreement in opacification between each ICM group and iodine concentration 1(0–0.3 mg ml−1): κ = 0.253 and 0.014 respectively, concentration 2(0.4–0.6 mg ml−1):κ = −0.017 and −0.005 respectively and concentration 3(0.7–1 mg ml−1):κ = 0.031 and 0.115 respectively. Conclusion: Nonionic dimer (Iodixanol) surpasses monomer (Iohexol) in quantitative image quality assessment by having lower image noise and higher CNR during CT.

Image quality and radiation dose reduction in chest CT in pulmonary infection

To evaluate the effect of dose reduction with iterative reconstruction (IR) on image quality of chest CT scan comparing two protocols. Fifty-nine patients were enrolled. The two CT protocols were applied using Iterative Reconstruction (ASIR™) 40% but different noise indexes, recording dose-length product (DLP) and volume computed tomography dose index (CTDIvol). The subjective IQ was rated based on the distinction of anatomic details using a 4-point Likert scale based on the European Guidelines on Quality Criteria for CT. For each patient, two single CTs, at enrollment (group 1) and at follow-up after lowering the dose (group 2), were evaluated by two radiologists evaluating, for each examination, five different lung regions (central zone-CZ; peripheral zone-PZ; sub-pleural region-SPR; centrilobular region-CLR; and apical zone-AZ). An inter-observer agreement was expressed by weighted Cohen's kappa statistics (k) and intra-individual differences of subjective image analysis through visual grading characteristic (VGC) analysis. An average 50.4% reduction in CTDIvol and 51.5% reduction in DLP delivered were observed using the dose-reduced protocol. An agreement between observers evaluating group 1 CTs was perfect (100%) and moderate to good in group 2 examinations (k-Cohen ranging from 0.56 for PZ and AZ to 0.70 for SPR). In the VGC analysis, image quality ratings were significantly better for group 1 than group 2 scans for all regions (AUCVGC ranging from 0.56 for CZ to 0.62). However, disagreement was limited to a score 4 (excellent)-to-score 3 (good) IQ transition; apart from a single case in PZ, both the observers scored the IQ at follow-up as 2 (sufficient) starting from a score 4 (excellent). Dose reduction achieved in the follow-up CT scans, although a lower IQ still allows a good diagnostic confidence.

Propagation-Based Phase-Contrast CT of the Breast Demonstrates Higher Quality Than Conventional Absorption-Based CT Even at Lower Radiation Dose

Propagation-based phase-contrast CT (PB-CT) is an advanced X-ray imaging technology that exploits both refraction and absorption of the transmitted X-ray beam. This study was aimed at optimizing the experimental conditions of PB-CT for breast cancer imaging and examined its performance relative to conventional absorption-based CT (AB-CT) in terms of image quality and radiation dose. Surgically excised breast mastectomy specimens (n = 12) were scanned using both PB-CT and AB-CT techniques under varying imaging conditions. To evaluate the radiological image quality, visual grading characteristics (VGC) analysis was used in which 11 breast specialist radiologists compared the overall image quality of PB-CT images with respect to the corresponding AB-CT images. The area under the VGC curve was calculated to measure the differences between PB-CT and AB-CT images. The highest radiological quality was obtained for PB-CT images using a 32 keV energy X-ray beam and by applying the Homogeneous Transport of Intensity Equation phase retrieval with the value of its parameter γ set to one-half of the theoretically optimal value for the given materials. Using these optimized conditions, the image quality of PB-CT images obtained at 4 mGy and 2 mGy mean glandular dose was significantly higher than AB-CT images at 4 mGy (AUCVGC = 0.901, p = 0.001 and AUCVGC = 0.819, p = 0.011, respectively). PB-CT achieves a higher radiological image quality compared to AB-CT even at a considerably lower mean glandular dose. Successful translation of the PB-CT technique for breast cancer imaging can potentially result in improved breast cancer diagnosis.

Optimisation of the lateral lumbar spine projection using an air-gap technique

IntroductionLumbar spine radiography is considered as having a high radiation dose compared to other planar radiography examinations. The aim of this study was to investigate the feasibility of replacing an antiscatter grid with an air gap technique to achieve dose reduction for lateral lumbar spine radiography while maintaining image quality on a direct digital radiography (DDR) system. MethodsIn phase 1, an experimental study using an anthropomorphic phantom identified the optimal airgap technique. In phase 2, lateral projections of the lumbar spine were performed on 50 patients randomly assigned equally into a control group (using the antiscatter grid) and an experimental group (using the airgap technique). The dose area product (DAP) was recorded, keeping other variables constant. Image quality evaluation was performed by 5 radiologists performing Absolute Visual Grading Analysis (VGA) using an image quality score tool, with resultant scores analysed using Visual Grading Characteristics (VGC). ResultsA 10 cm airgap in conjunction with a source to image distance (SID) of 121 cm was found as the optimal airgap technique. The clinical application of this technique resulted in a statistically significant (p < 0.05) reduction in DAP of 72%. Image quality scores were higher for the antiscatter grid but variation between the two techniques was not significant (p > 0.05). ConclusionReplacing the antiscatter grid with an airgap technique in lateral lumbar spine digital radiography, provides a significant dose reduction whilst still maintaining diagnostic image quality. Implications for practiceThe airgap technique is a simple and easy technique to implement and radiographers should find no difficulties in applying it, as It involves no additional cost and no additional equipment.

4D perfusion CT of prostate cancer for image-guided radiotherapy planning: A proof of concept study

PurposeAdvanced forms of prostate cancer (PCa) radiotherapy with either external beam therapy or brachytherapy delivery techniques aim for a focal boost and thus require accurate lesion localization and lesion segmentation for subsequent treatment planning. This study prospectively evaluated dynamic contrast-enhanced computed tomography (DCE-CT) for the detection of prostate cancer lesions in the peripheral zone (PZ) using qualitative and quantitative image analysis compared to multiparametric magnet resonance imaging (mpMRI) of the prostate.MethodsWith local ethics committee approval, 14 patients (mean age, 67 years; range, 57–78 years; PSA, mean 8.1 ng/ml; range, 3.5–26.0) underwent DCE-CT, as well as mpMRI of the prostate, including standard T2, diffusion-weighted imaging (DWI), and DCE-MRI sequences followed by transrectal in-bore MRI-guided prostate biopsy. Maximum intensity projections (MIP) and DCE-CT perfusion parameters (CTP) were compared between healthy and malignant tissue. Two radiologists independently rated image quality and the tumor lesion delineation quality of PCa using a five-point ordinal scale. MIP and CTP were compared using visual grading characteristics (VGC) and receiver operating characteristics (ROC)/area under the curve (AUC) analysis.ResultsThe PCa detection rate ranged between 57 to 79% for the two readers for DCE-CT and was 92% for DCE-MRI. DCE-CT perfusion parameters in PCa tissue in the PZ were significantly different compared to regular prostate tissue and benign lesions. Image quality and lesion visibility were comparable between DCE-CT and DCE-MRI (VGC: AUC 0.612 and 0.651, p>0.05).ConclusionOur preliminary results suggest that it is feasible to use DCE-CT for identification and visualization, and subsequent segmentation for focal radiotherapy approaches to PCa.