Non-opaque soft tissue foreign body: sonographic findings

We evaluated 47 patients with suspected foreign body retention in soft tissues by 10 MHz linear array transducer. A single radiologist performed all examinations with 6 years' experience in musculoskeletal Sonography. We detected and localized the presence of the foreign body in the soft tissue as guidance for facilitating the surgery.We detected soft tissue foreign body in 45 cases as hyperechoic foci. Posterior acoustic shadowing was seen in 36 cases and halo sign was seen in 5 cases due to abscess or granulation tissue formation. Surgery was performed in 39 patients and 44 foreign bodies were removed.Sonography is a useful modality in detection and localization of radiolucent foreign bodies in soft tissue which can avoid misdiagnosis during primary emergency evaluation.Penetrating object injuries are a common problem in the emergency department, and retained foreign bodies in soft tissues complicate many such injuries. Because a retained foreign body may cause severe infection or inflammatory reaction, detection and removal of foreign bodies are necessary [1].Punctured wounds and soft tissue lacerations are inspected, palpated and explored to rule out the presence of a foreign body, and radiographic evaluations are routinely obtained to confirm radio-opaque foreign bodies such as glass, metal, and stone within the soft tissue [2,3], However 38% of such foreign bodies are overlooked at initial examination in the emergency room [4].A radiolucent foreign body such as wood frequently remains undetected [3]. In such situations, other imaging modalities are needed for diagnosis. Sonography plays an important role in the evaluation of these patients [5].Sonography has a reported sensitivity of 95% for detection of foreign bodies [6,7].In previous reports the positive predictive value of Conventional Radiography (CR) and Sonography (US) were 100% and 95% respectively and for Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) were 95% and 93.8% respectively. CT