Wooden foreign bodies: Imaging appearance

OBJECTIVE. The purpose of this study was to identify the characteristic imaging features of wooden foreign bodies. MATERIALS AND METHODS. The imaging studies of 12 patients with surgically confirmed wooden foreign bodies were retrospectively reviewed. The study group consisted of seven females and five males, 10-65 years old (mean age, 36 years). All patients underwent radiography. Nine patients were evaluated with sonography, eight with MR imaging, three with CT, and one with CT arthrography. Gadolinium-enhanced MR imaging was performed in six patients. Three patients presented with a draining sinus and nine with painful swelling. Only three patients presented with a history of penetrating injury. RESULTS. Lesions were located in the foot (n = 4), hand (n = 3), thigh (n = 2), calf (n = 2), and elbow (n = 1). Radiographs failed to reveal the retained foreign bodies in all patients. With MR imaging, wooden foreign bodies displayed a variable signal intensity that was equal to or less than that of skeletal muscle on both T1- and T2-weighted images. MR imaging showed the surrounding inflammatory response in all patients. CT showed the retained wood as linear cylindric foci of increased attenuation. Wood was highly echogenic and revealed pronounced acoustic shadowing on sonography. Arthrography in one patient showed an associated reactive synovitis. CONCLUSION. The imaging appearance of wooden foreign bodies is variable; however, imaging can be quite specific, and when taken in the appropriate clinical setting, the imaging should reliably suggest the diagnosis. Sonography is frequently underused but proved most useful for the evaluation of retained wooden foreign bodies.