Nobody likes having to repeat a task, and nowhere is that more evident than in MRI. A new study in JACR quantifies the operational toll of MRI scans that have to be repeated due to patient motion, revealing both good news and bad news.
Despite its unquestioned diagnostic power, MRI is the imaging modality most susceptible to motion artifacts.
- That’s because patients have to lie motionless for long periods of time in a confined, noisy metal tube – an environment tailor-made to induce claustrophobia.
MRI vendors have introduced a variety of new technologies and pulse sequences to speed up exams, but patient motion is still a nagging problem.
- To investigate the issue further, researchers from NYU Grossman School of Medicine collaborated with Siemens Healthineers to document MRI exam repeat rates over six months at NYU.
In all, 85.3k MRI exams were included in the analysis, with the following findings…
- 4.8% of all MRI exams (4k) included at least one repeated sequence.
- The highest repeat rate occurred in pediatrics and the lowest in breast MRI (9.9% and 3.5%, respectively).
- Repeat acquisitions added up to 115 hours of scanner time, equivalent to 268 lost MRI scanning slots.
To take the study deeper, researchers more closely analyzed brain MRI and MR cholangiopancreatography (MRCP) studies, finding…
- For 77 patients undergoing brain MRI, repeat acquisitions had better image quality and diagnostic confidence, but 20% of repeat sequences did not improve.
- For 27 patients undergoing MRCP, repeat acquisitions were less successful, as they didn’t improve image quality or diagnostic confidence.
So that’s the bad news. What’s the good news? The study’s 4.8% repeat rate was actually lower than those reported in previous research into motion-related repeats, which have ranged from 7.5% to 30%.
- One reason for the discrepancy is that the current study relied on exams labeled as repeats by technologists, which could have resulted in an underestimation.
But another reason is the fact that MRI practices have adopted a wide range of techniques and technologies that reduce the impact of patient motion, like shorter protocols, parallel imaging, compressed sensing, and deep learning reconstruction.
The Takeaway
The new findings into the operational toll of MRI motion artifacts provide useful insights into the extent of the problem. But they also include a silver lining – that the modality’s relentless pace of technological innovation could make repeat exams less of an issue in the future.