This is the first national survey examining the provision of CMR in the United Kingdom. We have established that 60 centres provide CMR services and 53 of these (88%) responded to our detailed survey.
The number of CMR scans performed annually per centre has increased rapidly over two years, by 44% or 38% comparing mean or median numbers respectively. It is likely that demand for this imaging technique will continue to rise as cardiologists increasingly appreciate the clinical benefits of CMR. There was a marked variation in the number of scans performed in different centres. Twelve high volume centres performed 66% of all CMR scans nationally, while 28 centres in combination accounted for only 13% (Figure 2). CMR is recognised as a highly complex imaging modality and both the National Imaging Board and BSCMR/BSCI recommend a minimum number of scans per centre of 300 . In 2010, 22 centres in the survey performed less than this. The survey did not address whether clinicians in these small volume centres have links to larger units. These findings certainly raise concerns regarding whether smaller volume centres have the necessary clinicians with appropriate training and volume of work to run a high quality independent CMR service.
There is a striking geographical variation in CMR use. High volume centres are concentrated in and around London with the rest of the country being populated by either low or moderate volume centres. The geographical imbalance is likely to reflect underuse outside London rather than excessive use in the capital given the large number of recognised indications for CMR. The BCS working group forecast a need to deliver 400 CMR scans per million adults by 2010, and 2275 scans per million adults by 2015 . Underuse of CMR is particularly evident in centres without a scanner on site. These centres refer a mean of only 5 patients per month despite catchment areas in some cases of over 300,000.
Optimal use of CMR scanners in each centre should be ensured. Processes are required to minimise time for acquisition and intervals between patients. Clearly some protocols (for example for congenital heart disease) necessitate more time. Despite this, waiting times are generally low by UK standards, which likely reflects under-utilisation of the technique given the discrepancy between anticipated number of scans needed and the number performed. Only 15% of centres have an inpatient waiting time of greater than 5 days. Outpatient waiting lists are similarly short, with only 3 CMR centres having a waiting list in excess of 8 weeks. It is likely that rapidly increasing numbers of CMR scans nationally will be reflected in increased waiting times in the coming years unless adequate forward planning is put in place. Only 38% of services are specifically funded for CMR, the most common source being primary care trusts. Changes to commissioning systems in the National Health Service will make CMR funding a contentious issue in forthcoming years.
Cardiologists and radiologists operate CMR in isolation in 33% and 33% of hospitals respectively and collaborate to run services in 33%. Radiologists alone report twice as many scans as cardiologists alone (36% v 15%). The BSCMR advocate a joint speciality approach, as both disciplines bring complementary knowledge to CMR. Cardiologists are trained in all aspects of cardiac diagnosis and treatment, including other cardiac imaging modalities. Radiologists have formal training in extra-cardiac imaging as well as the heart. The finding that 86% of trainees are cardiologists and 14% are radiologists reflects current training patterns in CMR. Initiatives to engage radiology trainees in CMR are required to address this imbalance.
Our data suggest that 30% of centres rely on trainees to report CMR scans. We do not have information on the level of accreditation (if any) that these trainees have, although it is likely that some will have SCMR Level 2 or 3 accreditation. Current guidelines suggest that CMR scans be reported by SCMR Level 2 or 3 accredited practitioners, with no stipulation that the practitioner should be a consultant (the lead doctor in charge of patient care in the UK). This seems reasonable given that imaging modalities such as echocardiography are reported by technicians and trainees, typically supervised by a consultant cardiologist who provides advice with difficult cases and quality control. A similar arrangement was observed in all responding centres, with trainees always reporting CMR scans under consultant supervision, and consultants countersigning final reports.
The most common indications for CMR are heart failure and cardiomyopathy, coronary artery disease, and congenital heart disease. As all cardiac departments manage these conditions, it is necessary for clear referral pathways for recognised indications between district general (regional community hospital) cardiologists and regional CMR services.
Only 64% of centres have quality control processes in place, while audit is infrequent when performed at all. We regard quality control and audit as an essential component of any service. A departmental meeting should also be a feature of all CMR centres, especially for those with a commitment to training . While 58% of centres have trainees, only 53% have a formal training programme, and only 42% have a level 3 mentor. We propose that centres that train should be high volume (the BSCMR stipulates 500 scans per year),  be supervised by a level 3 Mentor, have a formal training programme and perform regular quality control and audit. The geographical variation in CMR volume is also seen in the numbers of trainees. Sixty-one per cent of trainees are trained in only 6 centres. Indeed, three of these centres train 42% of all those trained nationally.
A number of limitations merit consideration. Our findings only capture CMR activity from 88% of UK CMR centres. Private hospitals were not included in the current survey. Our primary contact in each centre was a cardiologist or a clinical director in cardiology. Although this potentially introduces bias, we expect clinical directors or cardiologists would be aware of the presence of CMR within their institution. There is no national collection of CMR scanning figures and we have no means to determine whether the figures returned are accurate. No data was collected regarding stress imaging, or the specific number of scans performed for research as opposed to clinical indications. The provision of clinical CMR is therefore likely to be underestimated given the high academic output of several centres in the UK. The current survey informs us about UK CMR practice only. It is likely that diverse patterns would be found in other countries. Some are likely to be similar to the UK (e.g. Germany) but provision in others markedly at variance. We propose that national and international surveys should be performed using the same methodology as in the current manuscript. A trade-off exists between questionnaire length and response rate, with more questions risking increasing non-response, loss of precision and possible bias [12, 13]. Only questions that were necessary to achieve the study objectives were included.