Musculoskeletal ultrasonography: Nomenclature, technical considerations, validation, and standardization
- George AW Bruyn, MD, PhD
George AW Bruyn, MD, PhD
- Department of Rheumatology
- MC IJsselmeerziekenhuizen, Lelystad
- The Netherlands
Ultrasonography (US), also referred to as ultrasound imaging or sonography, is an imaging modality that utilizes reflected pulses of high-frequency (ultrasonic) sound waves to assess soft tissues, cartilage, bone surfaces, and fluid-containing structures. US imaging, at one time the sole province of radiologists, has become now widely available in rheumatology clinics and other ambulatory and emergency settings. However, the widespread use of US by clinicians who diagnose and treat musculoskeletal disorders has been hampered by questions related to the reliability, validity, standardization, methodology, and ability to detect changes over time. These issues and technical aspects of musculoskeletal US are addressed in detail separately. (See "Musculoskeletal ultrasonography: Clinical applications".)
The use of US to assess patients with rheumatic diseases in the clinic was fostered by the development of compact real-time US systems in the 1980s. Synovitis of the knee was the earliest musculoskeletal disorder assessed ultrasonographically in the clinic . US assessment of synovitis of the small joints of the hands in patients with rheumatoid arthritis (RA) followed by a decade . Availability in the 1990s of high-resolution transducers made detailed assessment of superficial structures feasible.
The nomenclature, technical considerations, validity, and reliability of musculoskeletal US are discussed here. Imaging modalities generally used to diagnose disorders of the musculoskeletal system and guidelines for selecting imaging studies (eg, plain film radiography, computed tomography [CT scan], magnetic resonance imaging [MRI], and US) for selected musculoskeletal problems are presented separately. (See "Imaging techniques for evaluation of the painful joint" and "Radiologic evaluation of the painful hip in adults" and "Radiologic evaluation of the painful shoulder".)
The use of US to screen for, diagnose, and monitor the response of osteoporosis to treatment requires dedicated, special-purpose devices rather than US imaging systems to assess bone mineral content. (See "Screening for osteoporosis", section on 'Ultrasound'.)
NOMENCLATURE AND CONVENTIONS
Various terms are used to describe ultrasonographic (US) equipment, transducer and image orientation, normal and abnormal features in acquired images, and artifacts.
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- NOMENCLATURE AND CONVENTIONS
- Types of ultrasonography
- - B-mode US
- - Grayscale US
- - Doppler US
- - Color Doppler US
- - Duplex US
- - Power Doppler US
- Transducer orientation and image presentation
- - Bone surface
- - Cartilage
- - Synovium
- - Synovial fluid
- - Joint capsule
- - Tendons
- - Nerves
- - Muscles
- - Bursae
- - Ligaments
- - Axial resolution
- - Lateral resolution
- Time or B gain correction
- Edge shadows
- Comet tail
- Acoustic shadowing
- TECHNICAL CONSIDERATIONS
- VALIDATION, RELIABILITY, AND STANDARDIZATION