Value of power Doppler imaging and the hypoechoic halo in the sonographic detection of foreign bodies: correlation with histopathologic findings.

OBJECTIVE: To present the power Doppler findings and evaluate the hypoechoic rim in increasing the conspicuity of foreign bodies detected on sonography and to correlate the sonographic and histopathologic findings. METHODS: Between 1998 and 2001, all sonographic examinations for evaluation of possible foreign bodies were reviewed retrospectively. Patients who had surgical exploration and pathologic evaluation were included in the study. Gray scale and power Doppler examinations were performed with high-frequency linear array transducers. Histologic evaluation was then correlated with the sonographic findings. RESULTS: Twenty-five patients were referred for evaluation of possible foreign bodies. Twelve patients underwent surgery and had pathologic correlation. Sonography had sensitivity of 92% for the overall detection of foreign bodies. There were 2 false-positive findings in which discrete foreign bodies were not seen at gross inspection, but inflammation and scar tissue were present at histologic examination. Pathologic findings were thought to represent chronic foreign body reactions. Hypervascularity immediately surrounding the foreign bodies was shown on power Doppler imaging in all cases, correlating with granulation tissue and neovascularity on pathologic examinations. The hypoechoic halo was shown in all but 2 cases and correlated with fibrinous exudate, granulation tissue, and collagenous capsule formation. CONCLUSIONS: Sonography is an effective and sensitive tool for the detection of soft tissue foreign bodies. The use of power Doppler imaging may aid in detection of possible foreign bodies by increasing the conspicuity of both the hypoechoic halo and the foreign body itself.