Sonography of the finger.

Abstract

1451 he development of high-frequency sonography probes has allowed the imaging of small superficial structures at resolutions of 300 μ m. Small “footprint” probes have improved the ability of radiologists to scan small curved surfaces such as a finger. Our purpose is to show the value of sonography in the evaluation of finger pathology. Sonography was performed with a broadband 7.5to 10-MHz linear array scan head with the transducer placed directly on the skin using abundant coupling gel. A 3-mm-thick standoff gel pad may be useful for assessment of superficial (e.g., cutaneous) lesions. We describe the main sonographic findings in a variety of lesions. Traumatic Lesions Foreign bodies that may be radiolucent on radiography, such as nonopaque glass fragments, wood splinters, and palm spikes, are accurately detected on sonography [1]. Wooden foreign bodies as small as 2.5 mm in length can be effectively localized [2]. They appear as hyperechoic structures with variable acoustic shadowing. If they have been present for more than a week, they develop a hypoechoic rim of variable thickness that represents a foreign body reaction or abscess formation (Fig. 1). Injuries to the ulnar collateral ligament (UCL) of the first metacarpophalangeal joint are common. The injury is often referred to as gamekeeper’s thumb or skier’s thumb. Sonography can identify a tear of the UCL and differentiate displaced and nondisplaced tears. Injuries in which the UCL is displaced superficially to the adductor aponeurosis (Stener lesion) may require surgical intervention, whereas nondisplaced tears can be treated conservatively [3]. With complete tears, the displaced UCL is seen as a linear echogenic structure that is redundant and retracted with a hypoechoic hematoma surrounding the redundant margin (Fig. 2). An avulsed fragment, if present, is seen as a small hyperechoic structure. With incomplete tears, the UCL may be markedly thickened but in a normal position. Previous studies have found that sonographic findings correspond to surgical findings in up Sonography of the Finger Girolamo Moschilla 1 and William Breidahl