MRI OF THE ABNORMAL PEDIATRIC HAND AND WRIST WITH PLAIN FILM CORRELATION

Based on a pool of 24 selected cases of nontraumatic pathology of the hand and wrist in patients under the age of 18 years, collected from t hree pediatric hospitals, the authors have illustrated a number of con genital, inflammatory, and infectious conditions as well as tumors of bones and soft tissues, utilizing MRI with plain film correlation Due to different MR signal characteristics, the etiology of macrodactyly m ay be recognized, e.g., vascular and/or fatty versus neurofibromatosis , etc. In septic arthritis, MR has shown abnormal marrow signal in adj acent bones denoting osteomyelitis, often unexpected from the plain fi lm appearance. Tenosynovitis has a specific MR appearance: Fluid in th e tendon sheath gives high signal on T2-weighted imaging. In arthritis -because of the associated hyperemia-there is definite synovial enhanc ement easily visible immediately after Gd-chelate injection. Gd also h elps identify viable tissues postinfection as well as viable tumor tis sue (versus scar or necrotic tissue) in tumors. Plain radiography is t he imaging method of choice for diagnosis and differential diagnosis o f most cases of bone cysts, tumors, and tumor-like conditions, e.g., s imple and aneurysmal bone cysts, enchondroma, and osteoid osteoma. In the study of masses, MRI gives excellent detail regarding tumor stagin g and the extent of soft tissue tumors as well as the soft tissue comp onent of bone tumors. In the hand and wrist, aneurysmal bone cysts are usually confined within a metacarpal or carpel bone, showing high sig nal intensity on T2-weighted imagine, often with fluid/fluid levels. I f ganglion cysts are excluded, the most commonly encountered soft tiss ue masses are the pan vascular malformations. MR angiography can demon strate the vascularity of the lesion. Some benign soft tissue lesions have a characteristic MR appearance, e.g., ganglion cysts, lipomata, a nd accessory muscles.