BackgroundUK Biobank’s ambitious aim is to perform cardiovascular magnetic resonance (CMR) in 100,000 people previously recruited into this prospective cohort study of half a million 40-69 year-olds.Methods/designWe describe the CMR protocol applied in UK Biobank’s pilot phase, which will be extended into the main phase with three centres using the same equipment and protocols. The CMR protocol includes white blood CMR (sagittal anatomy, coronary and transverse anatomy), cine CMR (long axis cines, short axis cines of the ventricles, coronal LVOT cine), strain CMR (tagging), flow CMR (aortic valve flow) and parametric CMR (native T1 map).DiscussionThis report will serve as a reference to researchers intending to use the UK Biobank resource or to replicate the UK Biobank cardiovascular magnetic resonance protocol in different settings.

Two-dimensional (2D) breath-hold cine MRI is used to assess cardiac anatomy and function. However, this technique requires cooperation from the patient, and in some cases the scan planning is complicated. Isotropic nonangulated threedimensional (3D) cardiac MR can overcome some of these problems because it requires minimal planning and can be reformatted in any plane. However, current methods, even those that use undersampling techniques, involve breath-holding for periods that are too long for many patients. Free-breathing respiratory gating sequences represent a possible solution for realizing 3D cine imaging. A real-time respiratory self-gating technique for whole-heart cine MRI is presented. Key words: whole-heart imaging; respiratory gating; cine MRI; free breathing; self navigation Two-dimensional (2D) cine imaging has been shown to be an accurate method of assessing cardiac anatomy and function (1). Unfortunately, it requires multiple breathholds and the scan planning requires operator knowledge of cardiac anatomy. Isotropic nonangulated three dimensional (3D) cardiac MR can overcome some of these problems because it requires minimal planning and can be reformatted in any plane (2,3). However, such scans lack the temporal information needed to assess cardiac function. A more optimal solution would be a time-resolved (cine) 3D technique. A fundamental problem with this approach is the length of acquisition and the attendant difficulties with respiratory compensation. Parallel imaging techniques (4,5) and other undersampled techniques (6) have been used to acquire 3D cine data sets in a single breath-hold (7-10). However, it is desirable to achieve better combinations of spatiotemporal resolution for an accurate functional and anatomical analysis. Respiratory compensation for static 3D whole-heart imaging can be achieved with the use of navigator beams (11). Unfortunately, navigator techniques interrupt the acquisition and thus are difficult to combine with steady-state free precession (SSFP) cine sequences (12). Furthermore, interleaving of navigators in a cine acquisition can limit the temporal resolution.To address these limitations, it would be useful to develop 3D acquisition techniques that incorporate respiratory self-gating. Such techniques would enable improvements in both spatial and temporal resolution. Respiratory self-navigated techniques have been proposed for 2D radial cine MRI (13), 3D whole-heart coronary MR angiography (MRA) (14) using radial trajectories, and 2D multislice spiral imaging (15). A recent study performed respiratory self-navigated coronary MRA (16) using Cartesian trajectories with a projection calculated from a center k-space profile. In such studies motion compensation is performed retrospectively. The main problem with retrospective correction schemes is that it is difficult to ensure that all necessary data are acquired at the correct respiratory position. It would therefore be preferable to use respiratory self-navigation in a real-time manner such that data corrupted b...

BackgroundT1 mapping and extracellular volume (ECV) have the potential to guide patient care and serve as surrogate end-points in clinical trials, but measurements differ between cardiovascular magnetic resonance (CMR) scanners and pulse sequences. To help deliver T1 mapping to global clinical care, we developed a phantom-based quality assurance (QA) system for verification of measurement stability over time at individual sites, with further aims of generalization of results across sites, vendor systems, software versions and imaging sequences. We thus created T1MES: The T1 Mapping and ECV Standardization Program.MethodsA design collaboration consisting of a specialist MRI small-medium enterprise, clinicians, physicists and national metrology institutes was formed. A phantom was designed covering clinically relevant ranges of T1 and T2 in blood and myocardium, pre and post-contrast, for 1.5 T and 3 T. Reproducible mass manufacture was established. The device received regulatory clearance by the Food and Drug Administration (FDA) and Conformité Européene (CE) marking.ResultsThe T1MES phantom is an agarose gel-based phantom using nickel chloride as the paramagnetic relaxation modifier. It was reproducibly specified and mass-produced with a rigorously repeatable process. Each phantom contains nine differently-doped agarose gel tubes embedded in a gel/beads matrix. Phantoms were free of air bubbles and susceptibility artifacts at both field strengths and T1 maps were free from off-resonance artifacts. The incorporation of high-density polyethylene beads in the main gel fill was effective at flattening the B1 field. T1 and T2 values measured in T1MES showed coefficients of variation of 1 % or less between repeat scans indicating good short-term reproducibility. Temperature dependency experiments confirmed that over the range 15–30 °C the short-T1 tubes were more stable with temperature than the long-T1 tubes. A batch of 69 phantoms was mass-produced with random sampling of ten of these showing coefficients of variations for T1 of 0.64 ± 0.45 % and 0.49 ± 0.34 % at 1.5 T and 3 T respectively.ConclusionThe T1MES program has developed a T1 mapping phantom to CE/FDA manufacturing standards. An initial 69 phantoms with a multi-vendor user manual are now being scanned fortnightly in centers worldwide. Future results will explore T1 mapping sequences, platform performance, stability and the potential for standardization.Electronic supplementary materialThe online version of this article (doi:10.1186/s12968-016-0280-z) contains supplementary material, which is available to authorized users.

BackgroundFor late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) assessment of atrial scar to guide management and targeting of ablation in atrial fibrillation (AF), an objective, reproducible method of identifying atrial scar is required.ObjectiveTo describe an automated method for operator-independent quantification of LGE that correlates with colocated endocardial voltage and clinical outcomes.MethodsLGE CMR imaging was performed at 2 centers, before and 3 months after pulmonary vein isolation for paroxysmal AF (n = 50). A left atrial (LA) surface scar map was constructed by using automated software, expressing intensity as multiples of standard deviation (SD) above blood pool mean. Twenty-one patients underwent endocardial voltage mapping at the time of pulmonary vein isolation (11 were redo procedures). Scar maps and voltage maps were spatially registered to the same magnetic resonance angiography (MRA) segmentation.ResultsThe LGE levels of 3, 4, and 5SDs above blood pool mean were associated with progressively lower bipolar voltages compared to the preceding enhancement level (0.85 ± 0.33, 0.50 ± 0.22, and 0.38 ± 0.28 mV; P = .002, P < .001, and P = .048, respectively). The proportion of atrial surface area classified as scar (ie, >3 SD above blood pool mean) on preablation scans was greater in patients with postablation AF recurrence than those without recurrence (6.6% ± 6.7% vs 3.5% ± 3.0%, P = .032). The LA volume >102 mL was associated with a significantly greater proportion of LA scar (6.4% ± 5.9% vs 3.4% ± 2.2%; P = .007).ConclusionsLA scar quantified automatically by a simple objective method correlates with colocated endocardial voltage. Greater preablation scar is associated with LA dilatation and AF recurrence.