MR imaging: arthropathies and infectious conditions of the elbow, wrist, and hand

Magnetic Resonance Imaging of the Hand and Wrist: Techniques and Spectrum of Disease

“…Diffuse increased signal intensity involving the deep fascial tissues on T2-weighted imaging is the hallmark feature. This condition differs from cellulitis, which shows diffuse signal abnormality and enhancement limited to the subcutaneous fat 46 .…”

“…Soft-tissue abscesses have intermediate to low signal intensity on T1-weighted images but high signal intensity on T2-weighted images. Gadolinium contrast agent reveals a thick, peripherally enhancing wall surrounding nonenhancing fluid and/or debris centrally 46 .…”

“…Osteomyelitis appears on MRI as an area of confluent low signal intensity replacing the normal high-signal-intensity marrow fat on T1-weighted imaging 46 . Periosteal elevation, which appears as a linear signal abnormality paralleling the cortex in all sequences, can occur as infectious material accumulates subperiosteally 46 . As the infection progresses, cortical destruction appears as a focal interruption of the cortical line.…”

“…As the infection progresses, cortical destruction appears as a focal interruption of the cortical line. Next, an opening through the periosteum that permits decompression of pus from infected bone into surrounding tissues can form 46 . On STIR images, this opening appears as a high-signal-intensity defect traversing a low-signalintensity cortex 46 and may mature into an abscess to ultimately form a sinus tract to the skin.…”

“…T2-weighted sequences can easily detect inflammation of the synovial lining of joints and tendon sheaths 46 . It should be noted, however, that intravenous contrast agent administration is often helpful in such cases because both fluid and hypertrophied synovium will appear bright on standard T2-weighted images, whereas only the latter will enhance on postcontrast T1-weighted images.…”