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E2162. The Magnet is Sometimes “Off”: Practical Strategies for Optimizing Challenging Musculoskeletal MR Imaging
Authors
  1. Jesse Bashford; Mayo Clinic Arizona
  2. Anshuman Panda; Mayo Clinic Arizona
  3. Jeremiah Long; Mayo Clinic Arizona
  4. Samuel Fahrenholtz; Mayo Clinic Arizona
  5. Alix Hopp; Mayo Clinic Arizona
  6. Douglas Katz; NYU Winthrop Radiology Associates
  7. Jonathan Flug; Mayo Clinic Arizona
Background
Diagnostic quality MSK MR imaging must overcome unique challenges which are not present in other subspecialties. These specific challenges include imaging of joints with varying shapes and sizes off isocenter, imaging of very small structures with obliquely oriented anatomy, imaging around extensive hardware and surgical material. The decision to operate often relies on small/subtle findings which rely on accurate, high-quality imaging, however missed diagnoses can lead to long-term morbidity. Over time, specialized imaging equipment, specialized imaging sequences, and optimizing techniques have been identified to overcome these challenges. Overcoming these diagnostic obstacles involves collaboration between radiologists, physicists, technologists, and vendors. The combined skills of this multidisciplinary group can take advantage of the tools described in this exhibit to optimize your MSK MR imaging.

Educational Goals / Teaching Points
We highlight the five most common MSK MRI challenges and provide practical startegies on scanning these challenging cases: 1) Off-Center imaging 2) Patient motion 3) Metal imaging 4) Small FOV imaging 5) Scan angles and slice positioning

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Off-Center imaging: Challenging because of inhomogeneous fat suppression at the edges or sides of the bore due to magnetic field inhomogeneity. Patient motion: Voluntary or involuntary motion will lead to loss of spatial resolution and blurriness in the image. This can limit shoulder imaging or be problematic when imaging small structures. Metal imaging: Orthopedic arthroplasties and surgical implants are very common. The hardware causes susceptibility artifact, limiting MR imaging capabilities. Small FOV imaging: Imaging of small structures, such as hand, fingers, and wrist with a small field of view (FOV) requires imaging parameters which maximize signal to noise ratio (SNR). Scan angles and slice positioning: Certain injuries require specific patient positions (e.g. ‘superman’ position) or slice prescriptions (‘Fabs’ view of bicep tendon) for accurate diagnosis. Balancing patient comfort with ability to prescribe scan to capture the images in right angle presents unique challenges.

Conclusion
Diagnostic quality MSK MR imaging must overcome unique challenges which are not present in other subspecialties. These specific challenges include imaging of joints with varying shapes and sizes off isocenter, imaging of very small structures with obliquely oriented anatomy, imaging around extensive hardware and surgical material. We review the common issues, describing the pertinent physics principles contributing to these issues and address practical tips and tricks to overcome this artifact. Overcoming these diagnostic obstacles involves collaboration between radiologists, physicists, technologists, and vendors. The combined skills of this multidisciplinary group can take advantage of the tools described in this exhibit to optimize your MSK MR imaging.