Portable ultra-low-field MRI for progressive multifocal leukoencephalopathy: Case studies, sensitivity, and potential applications.

Background And Objective: Progressive multifocal leukoencephalopathy (PML) is a severe, disabling infection caused by JC virus reactivation. PML-related disability complicates the MRI monitoring needed to assess treatment interventions in clinical trial or compassionate use settings. Portable ultra-low-field MRI (pULF-MRI) offers a convenient approach when such frequent imaging is needed.