Portable MRI found handy, useful—just not as a full-on replacement for its immovable cousin
Point-of-care MRI is a worthwhile diagnostic option for emergency departments and ICUs concerned about wait or transport times to access fixed MRI for patients with neuroimaging needs.
However, buyers should be aware of some limitations in the category before adding POC MRI to their portfolio of advanced imaging equipment at the ready for such indications as stroke, altered mental state, suspected intracranial mass and ventricular shunt placement.
So suggest researchers at the University of California–Irvine who retrospectively compared the performance of their POC MRI with that of CT and fixed MRI as used during a five-month break-in period for the bedside MRI model.
The primary comparison points the team sought were turnaround times vs. fixed MRI and image quality vs. standard-of-care brain CT.
Corresponding author Daniel Chow, MD, MBA, and colleagues report their findings in a study published Aug. 2 in Radiology [1].
Traditional MRI Resistant to Replication
The team first found a modest slice of patients sent for noncontrast brain MRI, 35 of 638, received the scan at their bedside. One of these had two POC MRI exams.
All imaging exams reviewed for the study were performed without contrast.
Of the 36 POC brain MRIs, 13 were performed in the ED and 23 in the ICU. Of these 36, some 26 (72%) were of diagnostic quality.
Further, of 23 POC MRI exams with preceding head CT, three (13%) revealed acute infarctions that weren’t apparent or characterizable on preceding brain CT.
On the other hand, 10 of the 36 POC MRIs were not of diagnostic quality, albeit mainly due to patient motion. Eight of these required follow-up with fixed MRI and, of these eight, five came back from the follow-up with acute or subacute infarctions.
As for speed, MRI turnaround times were significantly reduced for patients in the ICU (5.3 hours at POC vs. 11.7 hours for fixed MRI)—but not for patients in the ED (3.4 hours vs. 3.7 hours).
From these and additional findings Chow and co-authors conclude their study “demonstrates that point-of-care brain MRI can serve as a diagnostic tool in emergency departments and intensive care units to provide bedside image acquisition, with some limitations in diagnostic quality.”
Bedside MRI ‘May Have a Role in Facilitating Timely Imaging of Critically Ill Patients’
Citing similar POC MRI research, the authors note their ratio of diagnostic quality scans landed considerably lower than previous showings—72% in their work vs. 85% in one prior study and 87% in another.
Chow and colleagues identify two main reasons for their more limited returns on diagnostic quality.
One, they had difficulty fitting some patients for the POC MRI head coil.
“Positioning can be improved with angulation, lowering shoulders, and using support material,” they offer. “In some instances, the habitus may ultimately inhibit the ability to acquire POC MRI. Training is necessary in proper selection of patients based on habitus. Habitus can pose an imaging dilemma not just to POC MRI but across different imaging modalities.”
Two, some patients had much trouble trying to remain still.
This problem was worsened by MRI’s relatively long scan sequences, they point out, but “is an issue across various imaging modalities.”
Acknowledging their single-site setting and small sample as limitations, Chow et al. state their results “indicate that point-of-care (POC) MRI may have a role in facilitating timely imaging of critically ill patients by providing easier bedside image acquisition.”
In instances of motion artifact or suspected subtle findings, they add, “it may be necessary to perform subsequent imaging with a 1.5-T or 3-T fixed unit MRI scanner.”
More:
Ongoing technologist training, selection of patients with appropriate body habitus who can limit motion, and further research are necessary to determine the accuracy of POC MRI, clinical indications and patients for whom it may be particularly useful. Further studies are needed to determine the real-world incremental value of POC MRI compared with noncontrast head CT and the concordance between POC MRI and traditional fixed MRI, as well as the contrast and spatial resolution to detect subtle neurologic abnormalities, to determine the appropriateness of POC MRI and guide clinical patient selection.”
The authors note their institution is one of the first five in the U.S. to adopt the technology for regular clinical use.
The POC MRI technology used in the study was the Swoop portable system marketed by Hyperfine, in which none of the authors has a financial interest.
Dave P. has worked in journalism, marketing and public relations for more than 30 years, frequently concentrating on hospitals, healthcare technology and Catholic communications. He has also specialized in fundraising communications, ghostwriting for CEOs of local, national and global charities, nonprofits and foundations.