Brain imaging with portable low-field MRI

Managing Patients With Unlabeled Passive Implants on MR Systems Operating Below 1.5 T

“…Patients with passive implants that do not have labeling for scanners operating below 1.5 T are often prevented from undergoing MRI exams on those scanners. With the vital knowledge of the MRI‐related issues that include magnetic field interactions (force and torque) and RF field‐induced heating, the supervising physician can implement a written policy to safely scan patients with passive implants labeled MR Conditional at 1.5 and 3 T. A similar strategy may be applied when performing MRI in study subjects on scanners operating below 1.5 T in a research setting 19–21 …”

“…22,36,37 MR systems with lower static magnetic fields inherently produce lower translational attraction and torque and, as such, create reduced magnetic field interactions for metallic implants. 8,10,[19][20][21][22]36,37 While certain head-only, extremityonly, and whole-body scanners operating below 1.5 T have transverse magnetic fields with concomitant directional alterations for translational attraction and torque, the orientation of the magnetic field is of no importance for passive implants labeled MR Conditional at 1.5 or 3 T. Notably, there has been no report of a magnetic field-related injury to a patient with a passive implant labeled MR Conditional at 1.5 and/or 3 T.…”

“…8,[12][13][14][15][16][17][18] Substantial improvements in hardware and software have resulted in a resurgence in MR systems operating below 1.5 T. An array of different scanner geometries, field strengths, and different use-cases are found in this realm including an open-architecture, vertical (transverse) field 1.2 T scanner and the lower field strength (generally defined as MR systems operating in the range of 0.25 to 1.0 T) MR systems that have horizontal (longitudinal) or vertical (transverse) field magnets. 10,11,[19][20][21][22] Also operating below 1.5 T are scanners with unique features or designed for specialized applications such as a very-low-field (0.064 T), point-of-care MR system, 23,24 dedicated extremity scanners, 25,26 an upright MR system, 27 a neonatal scanner, 28 an MRI-guided, radiotherapy system, 29 and a single-sided, interventional MR scanner. 30,31 The growing worldwide utilization of these MR systems combined with the increasing incidence of patients with metallic implants that need MRI creates undesirable circumstances that include patients potentially being subjected to unsafe imaging conditions or being denied access to MRI because physicians often lack the knowledge to conduct a proper assessment of risk vs. benefit.…”

“…Substantial improvements in hardware and software have resulted in a resurgence in MR systems operating below 1.5 T. An array of different scanner geometries, field strengths, and different use‐cases are found in this realm including an open‐architecture, vertical (transverse) field 1.2 T scanner and the lower field strength (generally defined as MR systems operating in the range of 0.25 to 1.0 T) MR systems that have horizontal (longitudinal) or vertical (transverse) field magnets 10,11,19–22 . Also operating below 1.5 T are scanners with unique features or designed for specialized applications such as a very‐low‐field (0.064 T), point‐of‐care MR system, 23,24 dedicated extremity scanners, 25,26 an upright MR system, 27 a neonatal scanner, 28 an MRI‐guided, radiotherapy system, 29 and a single‐sided, interventional MR scanner 30,31 …”

Robust EMI elimination for RF shielding‐free MRI through deep learning direct MR signal prediction

“…Consequently, there has been a growing interest and urgency to address the unmet clinical needs and global health-care disparities by developing ultralow-field (ULF) MRI scanners that operate below 0.1 T for low-cost and/or portable imaging applications. [5][6][7][8][9][10][11][12][13][14] Recent ULF MRI technology developments in both system engineering [15][16][17][18][19] and computing [20][21][22][23] have yielded promising results and have led to diagnostically useful information especially in intensive care. 19,[24][25][26][27] MR signals are susceptible to electromagnetic interference (EMI) signals at frequencies close to Larmor frequency.…”