Challenges in delivering computed tomography coronary angiography as the first-line test for stable chest pain

Objective The National Institute for Health and Care Excellence (NICE) clinical guidelines ‘chest pain of recent onset: assessment and diagnosis’ (update 2016) state CT coronary angiography (CTCA) should be offered as the first-line investigation for patients with stable chest pain. However, the current provision in the UK is unknown. We aimed to evaluate this and estimate the requirements for full implementation of the guidelines including geographical variation. Ancillary aims included surveying the number of CTCA-capable scanners and accredited practitioners in the UK. Methods The number of CTCA scans performed annually was surveyed across the National Health Service (NHS). The number of percutaneous coronary interventions performed for stable angina in the NHS in 2015 was applied to a model based on SCOT-HEART (CTCA in patients with suspected angina due to coronary heart disease: an open-label, parallel-group, multicentre trial) data to estimate the requirement for CTCA, for full guideline implementation. Details of CTCA-capable scanners were obtained from manufacturers and formally accredited practitioner details from professional societies. Results An estimated 42 340 CTCAs are currently performed annually in the UK. We estimate that 350 000 would be required to fully implement the guidelines. 304 CTCA-capable scanners and 198 accredited practitioners were identified. A marked geographical variation between health regions was observed. Conclusions This study provides insight into the scale of increase in the provision of CTCA required to fully implement the updated NICE guidelines. A small specialist workforce and limited number of CTCA-capable scanners may present challenges to service expansion

Sex-based inequalities in contemporary UK hospital management of stable chest pain

ObjectiveWe surveyed UK practice of National Institute for Health and Care Excellence (NICE) “Recent onset chest pain” guidance (CG95, 2016), stratified by sex. We looked for sex-related differences in referral to computed tomographic coronary angiography (CTCA) and subsequent functional imaging (FI), invasive coronary angiography (ICA) and revascularisation.MethodsThis was a prospective analysis of CTCA practice in 8 UK centres between 2018 and 2020. Coronary artery disease (CAD) was recorded with the CAD-reporting and data system. Local electronic records/archiving/communication systems were used to collect data regarding subsequent FI, ICA and revascularisation.Results2301 women, 2326 men underwent CTCA; women were older (58±11 vs 55±12 years, p&lt;0.001) but more likely to have normal coronary arteries (46% (1047) vs 29% (685); p&lt;0.001) and less likely to have severe stenosis (7% (169) vs 13% (307); p&lt;0.001). FI was used less for 4% (93) women, 5% (108) men; ICA was also used less for women (8% (182) vs 14% (321)), as was revascularisation (4% (83) vs 8% (177), p&lt;0.001 for all), including those with ≥moderate CTCA stenosis undergoing ICA (53% (79) vs 61% (166); p&lt;0.001).ConclusionsWomen referred for a NICE CG95 (2016) CTCA are more likely to have normal coronary arteries and men more likely to have CAD. More men than women will then undergo ICA and revascularisation even after adjustments for CTCA disease severity. Raised awareness of these inequalities may improve contemporary chest pain care.</jats:sec

The State of the Art of Medical Imaging Technology: from Creation to Archive and Back

Medical imaging has learnt itself well into modern medicine and revolutionized medical industry in the last 30 years. Stemming from the discovery of X-ray by Nobel laureate Wilhelm Roentgen, radiology was born, leading to the creation of large quantities of digital images as opposed to film-based medium. While this rich supply of images provides immeasurable information that would otherwise not be possible to obtain, medical images pose great challenges in archiving them safe from corrupted, lost and misuse, retrievable from databases of huge sizes with varying forms of metadata, and reusable when new tools for data mining and new media for data storing become available. This paper provides a summative account on the creation of medical imaging tomography, the development of image archiving systems and the innovation from the existing acquired image data pools. The focus of this paper is on content-based image retrieval (CBIR), in particular, for 3D images, which is exemplified by our developed online e-learning system, MIRAGE, home to a repository of medical images with variety of domains and different dimensions. In terms of novelties, the facilities of CBIR for 3D images coupled with image annotation in a fully automatic fashion have been developed and implemented in the system, resonating with future versatile, flexible and sustainable medical image databases that can reap new innovations

Feasibility study of low-dose CT colonography using model-based iterative reconstruction: preliminary findings in 20 patients

Purpose: To compare image quality on computed tomographic (CT) images acquired at standard dose (SD) and low dose (LD) using adaptive statistical iterative reconstruction (ASIR) and model-based iterative reconstruction (MBIR) techniques. Methods and Materials: 20 patients were prospectively recruited for the study with informed consent. They underwent standard dose (SD) and low-dose (LD) CT colonography. Low-dose parameters were based on our phantom study with using vendor-specific automatic tube current modulation known as noise index. Both sets of scans were reconstructed with ASIR and MBIR. Objective and subjective image qualities were assessed as well as diagnostic accuracies for significant lesions (e.g. polyps, cancer, etc). Effective doses for each scans were recorded. Results: Objective image analysis supports significant noise reduction and superior contrast-to-noise ratio with low-dose scans using MBIR technique (p < 0.05) despite being acquired at lower doses. Subjective image parameters were equivalent for LD MBIR and SD ASIR for both colonic and extra-colonic findings. Diagnostic accuracies for polyp detection and other significant lesions were comparable. Dose recorded were substantially lower for MBIR (range 45-75% reduction compared with ASIR) with mean average being 4.2 mSv in our population group. Conclusion: MBIR shows superior reduction in noise whilst maintaining image quality and most importantly substantial dose reduction can be achieved. More patients are being recruited to substantiate diagnostic accuracies data with full results to be presented at the ECR 2013.link_to_subscribed_fulltex

Assessment of image quality on effects of varying tube voltage and automatic tube current modulation with hybrid and pure iterative reconstruction techniques in abdominal/pelvic CT: A phantom study

OBJECTIVES: The objective of this study was to compare image quality on abdominal/pelvic computed tomographic images acquired with filtered back projection (FBP), adaptive statistical iterative reconstruction (ASIR), and novel model-based iterative reconstruction (MBIR) techniques with varying levels of automatic tube current modulation and tube voltages. METHODS: A 2-phase study was performed. In phase 1, a torso phantom was scanned at 17 different noise levels of automatic current modulation (selected using noise index [NI]) at 120 kilovolt (peak) (kVp). Images reconstructed with FBP, ASIR, and MBIR underwent objective analysis. In phase 2, additional scans were performed at 3 different kVp (80, 100, and 120 kVp at 3 different NIs (33, 50, and 70). Objective and subjective image qualities were assessed. Computed tomography dose index and dose-length products were recorded. RESULTS: The objective image analysis supports significant noise reduction with MBIR compared with ASIR and FBP (P < 0.05) at all 17 NI tested at 120 kVp. When lowering the kVp, the subjective image quality was improved, but when this is performed in conjunction with increasing NI, image quality was maintained only at moderately high NI of 50 but was degraded at higher NIs despite improving contrast-to-noise ratio. CONCLUSIONS: Our results represent the first exploration in the utility of MBIR technique with alteration of kVp in conjunction with tube current modulation in comparison with traditional methods. Objective image noise for MBIR is superior. Subjective image quality is only moderately improved. Scanning at low kVp and moderately high NI with MBIR can ensure that a balance of improved image noise and contrast can be achieved as well as reducing dose. Copyright © 2013 by Lippincott Williams &Wilkins.link_to_subscribed_fulltex

CT chest using standard and 2 ultra-low dose scans with Model-Based Iterative Reconstruction – Preliminary Objective Analysis in 20 patients

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Adaptive Statistical Iterative Reconstruction (ASIR): Re-defining CT dose reduction strategies

Advances in Technology Poster: P104KEY LEARNING OBJECTIVES: (1) Brief description of ASIR (Adaptive Statistical Iterative Reconstruction) physics. (2) Compare diagnostic quality of CT scan images performed without and with ASIR. (3) Demonstrate various clinical applications of ASIR. DESCRIPTION: Diagnostic x-rays account for the largest artificial source of exposure to ionizing radiation and CT represents the greater proportion. Traditionally, reducing CT dose result in an increase in image noise and a compromise on image quality. ASIR, on the other hand utilizes complex algebraic calculations to lower image noise and CT dose without loss of anatomical detail. ASIR has been shown to reduce CT doses by up to 50%. A study conducted in our institution comparing the Dose Length Products (DLPs) of CT pulmonary angiogram scans performed in the same patients without and with ASIR showed statistically significant reduction in dose of up to 42% without compromising diagnostic accuracy (445.87 vs 257.59). This educational poster provides a brief description of how ASIR works. It also shows the diagnostic quality of images obtained with ASIR by comparing similar images of the same patients without ASIR. Thirdly, the various ways in which ASIR can be utilized will be discussed. CONCLUSION: ASIR effectively lowers CT doses without compromising diagnostic quality. Radiologists need to be conversant with recent developments in CT dose lowering strategies such as ASIR and various ways in which it can be utilized clinically

Image comparative assessment using iterative reconstructions: Clinical comparison of low-dose abdominal/pelvic computed tomography between adaptive statistical, model-based iterative reconstructions and traditional filtered back projection in 65 patients

OBJECTIVES: The objective of this study was to compare image quality (objective and subjective parameters) and confidence in lesion detection between 3 image reconstruction algorithms in computed tomographic (CT) examinations of the abdomen/pelvis. MATERIALS AND METHODS: This prospective institutional review board-approved study included 65 patients (mean [SD] age, 71.3 ± 9 years; mean [SD] body mass index, 24.4 [4.8] kg) who underwent routine CT examinations of the abdomen/pelvis followed immediately by 2 low-dose scans. Raw data sets were reconstructed by using filtered back projection (FBP), adaptive statistical iterative reconstruction (ASIR), and a model-based iterative reconstruction (MBIR). Measurements of objective noise and CT numbers were compared using repeated-measures analysis of variance. Six subjective image quality parameters were scored. Diagnostic confidence and accuracy in detection of various elementary lesions were performed. RESULTS: Objectively, mean image noise for MBIR was significantly superior at all dose levels (P < 0.001). Subjectively, standard-dose ASIR and low-dose MBIR scans were better than standard-dose FBP scan in all parameters assessed (P < 0.05). Low-dose MBIR scans were comparable with standard-dose ASIR scans in all parameters except at noise index of 70 (approximately 85% dose reduction), where, in this case, the detection of liver lesions less than 5 mm were rated inferior (P < 0.05) with diagnostic accuracy reducing to 77.4%. CONCLUSIONS: Low-dose MBIR scan shows superior objective noise reduction compared with standard-dose FBP and ASIR. Subjectively, low-dose MBIR scans at 76% dose reduction were also superior compared with standard-dose FBP and ASIR. However, at dose reductions of 85%, small liver lesions may be missed. Copyright © 2014 Lippincott Williams & Wilkins.link_to_subscribed_fulltex

Image quality assessment of standard-and low-dose chest ct using filtered back projection, adaptive statistical iterative reconstruction, and novel model-based iterative reconstruction algorithms

OBJECTIVE. The purpose of this article is to compare image quality between filtered back projection (FBP), adaptive statistical iterative reconstruction (ASIR), and model-based iterative reconstruction (MBIR) at standard dose and two preselected low-dose scans. SUBJECTS AND METHODS. Thirty patients (16 men and 14 women; mean age, 67 years) were prospectively recruited. Patients underwent three scans (one standard-dose scan and two low-dose scans at noise indexes [NIs] of 33, 60, and 70, respectively). All three scans were reconstructed with FBP, ASIR, and MBIR. Objective and subjective image qualities were compared. Dose-length products and effective doses for each scans were recorded. Mean image noise and attenuation values were compared between different reconstruction algorithms using repeated-measures analysis of variance and paired Student t tests. The interobserver variation between the two radiologists for subjective image quality and lesion assessment was estimated by using weighted kappa statistics. RESULTS. Objective image analysis supports significant noise reduction with low-dose scans using the MBIR technique (p 0.05). Subjective analysis reveals no significant difference between image quality and diagnostic confidence between low-dose MBIR scans compared with standard-dose scans reconstructed using ASIR (p > 0.05). Average effective doses were 3.7, 1.2, and 0.9 mSv for standard scans at NIs of 33, 60, and 70, respectively. CONCLUSION. MBIR shows superior noise reduction and improved image quality. Substantial dose reduction can be achieved by increasing the NI parameters as tested in this study without affecting image quality and diagnostic confidence. © American Roentgen Ray Socoety.link_to_subscribed_fulltex