Subtraction Map Pipeline to Assess Longitudinal Changes in Multiple Sclerosis at Portable Ultra-Low-Field MRI

Motivation: Ultra-low-field (ULF) MRI is more patient-accessible due to its cost effectiveness and portability and could in principle allow more frequent follow-up in disabling neurological diseases like multiple sclerosis (MS). However, using ULF MRI to track longitudinal changes is challenging due to reduced SNR and CNR. Goal(s): To develop an ULF longitudinal subtraction pipeline. Approach: We developed a subtraction pipeline for ULF images and assessed longitudinal changes in 14 scans from 12 MS participants. Results were compared with an MS neurologist’s impression of high-field images. Results: Our pipeline was able to detect new lesions and longitudinal changes in MS on par with high-field MRI. Impact: A longitudinal subtraction pipeline, implemented on ultra-low field MR images, was useful for monitoring interval changes in patients with MS, augmenting the clinical utility of follow-up MRI.