Portable, ultralow-field MRI technology could significantly enhance stroke care by making imaging more accessible, according to research presented on December 2 at the Radiological Society of North America (RSNA) annual meeting.
Dr. Nandor Kolos Pinter, from the University of Buffalo, highlighted the potential of low-field MRI to improve acute ischemic stroke detection, particularly in settings where access to conventional MRI is limited. “Neuroimaging is essential for stroke triage, and diffusion-weighted MRI is highly sensitive to acute ischemic stroke compared with CT,” said Dr. Pinter. “However, traditional MRI systems are bulky, stationary, and require extensive infrastructure, posing accessibility challenges. Portable, low-field MRI can address these barriers and revolutionize stroke care.”
Unlike conventional MRI systems with magnetic field strengths ranging from 1.5 to 3 tesla, the low-field MRI system used in the study operates at 64 millitesla. It is lightweight, portable, requires only a standard power outlet, and does not need specialized shielding.
As reported by auntminnie, the study, titled ACuTe Ischemic Stroke Detection with Portable MR (ACTION PMR), evaluated the performance of the low-field MRI system (Hyperfine Swoop 64) in diagnosing stroke. Conducted at three U.S. hospitals, the research included 66 patients presenting with suspected stroke. Each underwent diffusion-weighted imaging (DWI) using the portable scanner, with a scan time of approximately 17 minutes. Three experienced radiologists assessed the images for stroke lesions and their locations.
The study revealed the following performance metrics for low-field MRI:
| Measure | Value |
| Sensitivity | 67.5% |
| Specificity | 96.2% |
| Positive predictive value | 96.4% |
| Negative predictive value | 65.8% |
Additionally, interrater agreement was strong, with a kappa score of 0.80 for lesion detection and 0.95 for identifying the affected hemisphere.
While the system’s sensitivity and negative predictive value were relatively low, its high specificity and positive predictive value make it a promising tool for stroke diagnosis. Dr. Pinter noted that the lower sensitivity might stem from factors such as lesion size and single-direction DWI limitations. He emphasized the need for further research to improve spatial resolution and explore multidirectional DWI techniques.
Despite its current limitations, low-field MRI represents a significant advancement in making stroke imaging accessible to broader populations, offering a portable and cost-effective alternative to traditional MRI systems.