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Emerging Magnetic Resonance Imaging Technologies for Musculoskeletal Imaging Under Loading Stress: Scope of the Literature

Issa J. Dahabreh, MD, MS; Nira Hadar, MS; and Mei Chung, PhD, MPH
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From Center for Clinical Evidence Synthesis, Institute for Clinical Research and Health Policy Studies, Tufts Medical Center, Boston, Massachusetts.

Disclaimer: This article is based on a technical brief prepared by the Tufts Medical Center Evidence-based Practice Center under contract to the AHRQ (contract 290-2007-100551). The findings and conclusions in this article are those of the authors, who are responsible for its contents; the findings and conclusions do not necessarily represent the views of the AHRQ. Therefore, no statement in this report should be construed as an official position of the AHRQ or of the U.S. Department of Health and Human Services.

Acknowledgment: The authors thank Dr. Iovin Ramon and Ms. Srila Sen, who served as medical editors for the technical brief.

Financial Support: By contract 290-2007-100551 from the AHRQ.

Potential Conflicts of Interest: Drs. Dahabreh and Chung and Ms. Hadar: Grant (money to institution): AHRQ. Disclosures can also be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=M11-1239.

Requests for Single Reprints: Mei Chung, PhD, MPH, Center for Clinical Evidence Synthesis, Institute for Clinical Research and Health Policy Studies, Tufts Medical Center, 800 Washington Street, Box 63, Boston, MA 02111; e-mail, mchung1@tuftsmedicalcenter.org.

Current Author Addresses: Drs. Dahabreh and Chung and Ms. Hadar: Center for Clinical Evidence Synthesis, Institute for Clinical Research and Health Policy Studies, Tufts Medical Center, 800 Washington Street, Box 63, Boston, MA 02111.

Author Contributions: Conception and design: I.J. Dahabreh, N. Hadar, M. Chung.

Analysis and interpretation of the data: I.J. Dahabreh, M. Chung.

Drafting of the article: I.J. Dahabreh.

Critical revision of the article for important intellectual content: N. Hadar, M. Chung.

Final approval of the article: I.J. Dahabreh, N. Hadar, M. Chung.

Provision of study materials or patients: I.J. Dahabreh.

Statistical expertise: I.J. Dahabreh.

Administrative, technical, or logistic support: M. Chung.

Collection and assembly of data: I.J. Dahabreh, N. Hadar, M. Chung.

Ann Intern Med. 2011;155(9):616-624. doi:10.7326/0003-4819-155-9-201111010-00009
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Imaging under loading stress is hypothesized to improve the diagnostic value of magnetic resonancel imaging (MRI) for musculoskeletal conditions. This article reviews 57 studies about MRI under physiologic loading stress performed in an upright or sitting position or under axial loading by using a compression device. The most commonly imaged regions were the spine (33 studies) and knee (13 studies). Most studies had a cross-sectional (n = 37) or case–control (n = 13) design and reported on anatomical measurements rather than patient-relevant end points. Studies were generally small: The median (25th, 75th percentile) number of case patients was 26 (17, 45), and the median (25th, 75th percentile) number of control participants was 13 (12, 20 for case–control studies). Fifteen of 57 studies used at least 2 imaging tests and reported on diagnostic or patient-relevant outcomes but did not report meaningful information on the relative performance of the tests. In 10 studies that included information on adverse effects, 5% to 15% of participants reported new-onset or worsening pain and neuropathy during MRI under loading stress. Overall, evidence is insufficient to support the clinical utility of MRI under loading stress for musculoskeletal conditions.


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Figure 1.
Computer illustrations of MRI scanners.

Illustrations reproduced with permission from I-Pei Chung. MRI = magnetic resonance imaging. Top. Simplified schematic of an open, upright, weight-bearing MRI device, modeled on the FONAR Upright multipositional MRI (FONAR, Melville, New York). The device allows positional (flexion and extension), weight-bearing (upright and sitting) imaging and has an open configuration. A tilting table placed at right angles between the magnet coils can be positioned at any angle between −20 and 90 degrees vertically, which allows supine and standing imaging. An MRI-compatible seat can be added for imaging in a sitting position, as shown. Bottom. Simplified schematic of an axial-loading device used to simulate gravity in the supine position, modeled on the DynaWell L-Spine device (DynaWell Diagnostics, Las Vegas, Nevada). The device consists of a harness attached to a nonmagnetic compression part by straps, which are tightened to axially load the lumbar spine. Tightening or loosening the adjustment knobs on the footplates can regulate and equally distribute the load on the legs.

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Appendix Figure 1.
Evidence map of shared authorship patterns in studies of stress-loading magnetic resonance imaging.

This figure shows that 32 teams of investigators produced 56 publications that reported on 57 studies. It does not necessarily imply overlap of patient populations but represents a method to identify the most active research groups in the field by showing overlap among author lists in included studies. Each publication is represented by a box, and studies that share at least 1 author are shown as a group of boxes linked with lines. The Methods section describes how the figure was generated. One team that published 6 articles, which constitute approximately 10% of all of the studies that we considered eligible, included Drs. Danielson and Willén (inventors of the DynaWell axial-loading MRI device [DynaWell Diagnostics, Las Vegas, Nevada]) as coauthors.

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Appendix Figure 2.
Summary of evidence search and selection.

MRI = magnetic resonance imaging.

* Reviews, letters, or editorials.

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Figure 2.
Map of available evidence, stratified by study design and anatomical location.

The green circles represent studies and are proportional to the number of enrolled patients; the black circles represent studies that reported diagnostic or patient-relative outcomes and compared at least 2 tests. Placement of studies within each box is random. Two studies did not report sample size and are not shown. Two studies monitoring changes before and minutes after an orthopedic intervention or physical activity are plotted along with longitudinal studies.

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