Adequate imaging capacity is required to enable clinicians make timely patient management decisions and ultimately to reduce inpatient length of stay [9]. MRI waiting lists are typically the longest of any inpatient imaging modality as scan times are relatively long compared to other imaging modalities such as CT and the number of MRI scanners are limited [4]. In Ireland, most public hospitals operate a weekday-only MRI service with minimal or no out-of-hours capacity. Our study demonstrates that a limited routine weekend inpatient MRI service significantly reduces the waiting times for inpatient scans which is most pronounced for less urgent scans.

The commencement of a weekend MRI service resulted in a relatively modest increase in the overall inpatient MRI activity during the study period (6%). Prior to the weekend MRI lists, the scanners operated for 45 h per week, the weekend lists resulted in an extra 9 h per week of scanning time (20% increase). We did not convert all the potential extra time in to inpatient scanning capacity due to service pressures elsewhere. The ability to scan at weekends allowed the department to slightly reduce the number of inpatient scans performed during weekdays enabling us to scan complex cardiac MRIs and MRIs under general anaesthesia during normal weekday working hours. Despite the relatively modest increase in inpatient scanning numbers from 2022 to 2023 (6%), a 33% reduction in the waiting time for urgent scans was seen and a 40% reduction in the waiting time for routine MRI scans underlining the vast improvement in patient flow through the department. As expected, there was no significant change in the waiting time for scans categorised as immediate. We did not assess the quality of weekend MRI reporting compared to weekday; however, it has previously been shown to be safe [10].

Increased use of MRI for inpatients has been shown to reduce length of stay and lower mortality [8, 9] while early access to MRI is important as it significantly reduces a patient’s overall length of stay [7]. Patients admitted over weekends have been shown to wait significantly longer for MRI when compared to those admitted during the week which likely relates to limited access to routine MRI [11]. MRI scanners that operate on a weekday-only service are underutilised; a scanner operating from 0800 to 1700 each weekday will result in 2250 h of scanning per year (based on 250 working days per annum). If a scanner operated on a 24-h basis for 365 days per annum (24/7 service), this would give 8760 scanner hours. Most MRI scanners in the public health system in Ireland run for approximately 26% of their potential operational hours. Our study demonstrated that a modest increase in inpatient scanning capacity can result in a very significant reduction in inpatient waiting times. If scanners operated at full capacity, inpatient waiting lists could potentially be eliminated.

There are many barriers to establishing a 24/7 MRI service in a publicly funded health system, primarily the lack of MRI trained staff, limited reporting capacity and strict labour laws [12]. Training an MRI radiographer to work independently can take up to 1 year after commencement of MRI placement. Once trained, retention of MRI radiographers is problematic. The private sector can attract staff with preferential on-call rates including fee-per-item scanning payments. Many younger staff also seek opportunities to work abroad where MRI-trained radiographers are in high demand. Our hospital is also based in an urban centre where rents and house prices are very challenging for staff. There is also a national shortage of radiologists in Ireland with consultant numbers of 5.8 per 100,000 population, significantly below the OECD average of 8 radiologists per 100,000 [13,14,15]. Low consultant numbers limit the reporting capacity to take on initiatives such as weekend MRI. Despite these challenges, most large academic hospitals have established CT on call rosters which enable 24/7 scanning, and we should aim to expand this to MRI.

The study has several limitations. It was a single-centre study and the findings may not be applicable to other sites where the case mix and subspecialty practice is different. We made no attempt to assess the direct impact of weekend MRI on length of stay as this is a complex and multifactorial issue not entirely dependent on radiology imaging turnaround; we plan to study this further during the continued roll-out of the service. The additional imaging capacity was not solely used to improve patient flow, and routine inpatient waiting time improvements may have been underestimated as we used some of the additional capacity to increase our capacity for complex outpatient imaging.

In conclusion, routine weekend inpatient MRI significantly shortens waiting times, improves patient flow and may shorten length of stay despite only modestly increasing the overall number of MRIs performed.