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Background The trend towards large-scale studies including population imaging poses new challenges in terms of quality control (QC). This is a particular issue when automatic processing tools such as image segmentation methods are employed to derive quantitative measures or biomarkers for further analyses. Manual inspection and visual QC of each segmentation result is not feasible at large scale. However, it is important to be able to automatically detect when a segmentation method fails in order to avoid inclusion of wrong measurements into subsequent analyses which could otherwise lead to incorrect conclusions. Methods To overcome this challenge, we explore an approach for predicting segmentation quality based on Reverse Classification Accuracy, which enables us to discriminate between successful and failed segmentations on a per-cases basis. We validate this approach on a new, large-scale manually-annotated set of 4800 cardiovascular magnetic resonance (CMR) scans. We then apply our method to a large cohort of 7250 CMR on which we have performed manual QC. Results We report results used for predicting segmentation quality metrics including Dice Similarity Coefficient (DSC) and surface-distance measures. As initial validation, we present data for 400 scans demonstrating 99% accuracy for classifying low and high quality segmentations using the predicted DSC scores. As further validation we show high correlation between real and predicted scores and 95% classification accuracy on 4800 scans for which manual segmentations were available. We mimic real-world application of the method on 7250 CMR where we show good agreement between predicted quality metrics and manual visual QC scores. Conclusions We show that Reverse classification accuracy has the potential for accurate and fully automatic segmentation QC on a per-case basis in the context of large-scale population imaging as in the UK Biobank Imaging Study.

Background Systemic lupus erythematosus (SLE) is a systemic autoimmune disorder that commonly affects the heart, resulting in a 7 to 9 times greater incidence of cardiovascular disease (CVD) in SLE patients compared to healthy controls. Female patients with SLE between 35 and 44 years old have an incidence of myocardial infarction over 50 times greater than that observed in the Framingham cohort. Diffuse myocardial fibrosis can be detected non-invasively by extracellular volume (ECV) mapping based on pre- and postcontrast T1 measurements using cardiovascular magnetic resonance (CMR). We aimed to detect subclinical diffuse myocardial fibrosis in SLE using CMR T1 mapping. Methods 23 SLE patients (22 female, mean age 41 ± 9 years) and 23 matched controls (22 female, mean age 42 ± 9 years) without previously known cardiovascular disease underwent CMR at 1.5T. CMR evaluation included late gadolinium enhancement (LGE) [IV gadoterate meglumine at 0.15 mmol/kg], T1 mapping pre- and postcontrast, cine, tagging, and T2-weighted imaging. Results Regional fibrosis on LGE imaging was found in 5 SLE patients (22%) compared to none of controls. Presence of diffuse myocardial fibrosis in SLE was confirmed by significantly higher precontrast T1 values (981 ± 31 vs. 960 ± 21 ms, p = 0.010), decreased postcontrast T1 values (445 ± 31 vs. 470 ± 24 ms, p = 0.005) and expansion of ECV (31.8 ± 4.1 vs. 28.9 ± 2.0 %, p = 0.004). Diffuse myocardial fibrosis was evident in SLE regardless of the presence of any regional fibrosis. Left ventricular volumes, mass and ejection fraction were similar between SLE patients and controls. However, peak systolic circumferential strain (-17.0 ± 1.6 vs. -19.3 ± 1.1, p < 0.001) and peak diastolic strain rate (79 ± 26 vs. 119 ± 15 s-1, p < 0.001) were impaired in SLE. Presence of diastolic dysfunction is SLE was further supported by larger left atrial diameters (31 ± 5 vs. 26 ± 4 mm, p < 0.001). Abnormal myocardial systolic strain and diastolic strain rate correlated with diffuse myocardial fibrosis indices. There was no evidence of myocardial edema in SLE. Conclusions Cardiac involvement is common in SLE patients with no cardiovascular symptoms, and includes both focal and diffuse myocardial fibrosis, which is associated with impaired systolic and diastolic strain parameters. CMR is a robust non-invasive tool for the assessment of diffuse myocardial fibrosis and subclinical cardiac involvement in inflammatory heart disease.

Background Systemic sclerosis (SSc) is characterized by widespread tissue fibrosis including the myocardium. Diffuse myocardial fibrosis can be detected non-invasively by extracellular volume (ECV) imaging based on preand postcontrast T1 measurements using cardiovascular magnetic resonance (CMR). We hypothesized that multiparametric CMR, including T1 mapping, can detect subclinical myocardial involvement and provide a comprehensive cardiac assessment in patients with SSc.

UK Biobank is a prospective cohort study with 500,000 participants aged 40 to 69. Recently an enhanced imaging study received funding. Cardiovascular magnetic resonance (CMR) will be part of a multi-organ, multi-modality imaging visit in 3 – 4 dedicated UK Biobank imaging centres that will acquire and store imaging data from 100,000 participants (subject to successful piloting). In each of UK Biobank ’ s dedicated bespoke imaging centres, it is proposed that 15 – 20 participants will undergo a 2 to 3 hour visit per day, seven days a week over a period of 5 – 6 years. The imaging modalities will include brain MRI at 3 Tesla, CMR and abdominal MRI at 1.5 Tesla, carotid ultrasound and DEXA scans using carefully selected protocols. We reviewed the rationale, challenges and proposed approaches for concise phenotyping using CMR on such a large scale. Here, we discuss the benefits of this imaging study and review existing and planned population based cardiovascular imaging in prospective cohort studies. We will evaluate the CMR protocol, feasibility, process optimisation and costs. Procedures for incidental findings, quality control and data processing and analysis are also presented. As is the case for all other data in the UK Biobank resource, this database of images and related information will be made available through UK Biobank ’ s Access Procedures to researchers (irrespective of their country of origin and whether they are academic or commercial) for health-related research that is in the public interest.

Background Rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) commonly involve the cardiovascular system and are associated with significant morbidity and mortality, driven by cardiovascular inflammation, microvascular and diastolic dysfunction and fibrosis. Cardiovascular magnetic resonance (CMR) can assess non-invasively cardiac function, strain, ischaemia, altered vascular function, perfusion, inflammation and fibrosis; magnetic resonance spectroscopy (MRS) provides further insights into the status of myocardial energetics and lipidosis. To date, there have been no cardiovascular MRS studies in RA and SLE patients. We hypothesised that RA and SLE would be associated with impaired myocardial energetics and lipidosis.

Background Rheumatoid arthritis (RA), systemic lupus erythematosus (SLE) and systemic sclerosis (SSc) commonly involve the cardiovascular system, and are associated with high morbidity and mortality. Mechanisms of cardiovascular disease (CVD) involvement in these clinical entities are not fully understood. Furthermore, little is known about myocardial structure and function in these inflammatory arthropathies. Late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) imaging is a tool for noninvasive evaluation of myocardial fibrosis that has the advantage over other imaging techniques of being able to directly visualise both ischaemic and nonischaemic patterns of injury, and has prognostic significance. The purpose of this study was to assess the frequency and pattern of LGE in RA, SLE and SSc patients without any known CVD using CMR and to determine its relation to disease duration, vascular function (aortic distensibility; pulse wave velocity) and left ventricular

Background Rheumatoid arthritis (RA) is a multi-system, autoimmune disorder and is one of the strongest known risk factors for cardiovascular disease (CVD) morbidity and mortality. Endothelial dysfunction, accelerated atherosclerosis, vascular inflammation and myocarditis are thought to contribute to this excess CVD. Cardiovascular magnetic resonance (CMR) has the capacity of simultaneously assessing non-invasively cardiac function, altered vascular distensibility, myocardial strain and fibrosis. The purpose of this study was to assess cardiac and vascular function and to determine their relation to the presence of cardiovascular risk factors (CVRFs) and RA disease duration. Methods

Background Rheumatoid arthritis (RA) is a chronic autoimmune disease of the joints, with frequent extra-articular complications including cardiovascular disease and cardiac fibrosis from multiple causes. Diffuse myocardial fibrosis can be detected non-invasively by extracellular volume (ECV) mapping based on preand postcontrast T1 measurements using cardiovascular magnetic resonance (CMR). We therefore hypothesized that CMR T1 mapping can detect subclinical diffuse myocardial fibrosis in patients with RA.