Musculoskeletal conditions are the most common causes of disability in the United States. Among these, arthritis (osteoarthritis and rheumatoid arthritis) and back or spinal problems are the first and second leading causes of disability among adults. As the U.S. adult population ages, the prevalence of these conditions appears to be increasing, resulting in concomitant increases in health care resource utilization. Musculoskeletal complaints are some of the most common reasons for doctor visits and are significant sources of lost productivity. According to the American Productivity Audit, pain of musculoskeletal origin (including back-pain, arthritis related pain, and pain due to other musculoskeletal conditions ) was reported by 7.2 percent of the workforce as having occurred over the previous two weeks. In the same cross-sectional study, back pain was the second most common cause of missed days at work (after headache). Importantly, pain of musculoskeletal origin was also a leading cause of total lost productive time, a measurement that takes into account the pain-related reduction in productivity while at the workplace. Similar patterns are observed in other industrialized countries. Clinically, the differential diagnosis of nonspecific musculoskeletal complaints is challenging, and the use of imaging modalities is often required to establish a diagnosis, guide treatment, or monitor disease progression. Magnetic resonance imaging (MRI) is a widely used medical technology, and is often employed as the preferred imaging tool for disorders of the musculoskeletal system (rheumatologic and orthopedic) and neurologic conditions, as it can better delineate soft tissue structures than either plain x rays or computerized tomography (CT). Although more costly and with a longer procedural time compared with CT, MRI has emerged as the imaging modality of choice for complex musculoskeletal disorders. Unlike radiographs and CT, MRI uses no ionizing radiation to produce images. Rather, this imaging technique employs a strong magnetic field to exploit the magnetic properties of hydrogen atoms in the water and lipid content of the body. This Technical Brief aims to answer the following Guiding Questions that were developed in collaboration with the Agency for Healthcare Research and Quality and input from Key Informants (KIs). The terminology used in the guiding questions to describe magnetic resonance imaging (MRI) technologies that were included in this Technical Brief was changed from "positional MRI" to current "stress-loading MRI" after the literature review determined that stress-loading MRI more accurately described the principle underlying the technologies of interest. Throughout the report, we use "stress-loading MRI" or "MRI technologies under loading stress" to cover all MRI modalities and applications that allow imaging under stress loading or weight-bearing conditions, which include positional or upright MRI devices. Guiding Question 1: What are the operating principles of stress-loading MRI, and what are the potential benefits and harms associated with its use? Guiding Question 2: What is the current availability and cost of stress-loading MRI testing, and what are the special requirements that stress-loading MRI facilities have to fulfill? Guiding Question 3: What published studies have reported on the diagnostic performance, efficacy/effectiveness, or safety of stress-loading MRI? Organize them according to the Fryback and Thornbury scheme, and provide a synthesis of the following information as applicable: Guiding Question 4: What is the projected uptake of stress-loading MRI technology in the near future? What are the potential areas for future research that are most meaningful given the current state of the evidence and the projected uptake of the technology?