Usefulness of Reformatted CT Rib Series in Patients with Thoracic Trauma

Abstract

INTRODUCTIONBlunt thoracic trauma is a common reason for emergency room visits. Although the use of initial routine chest computed tomography (CT) is controversial, it is increasingly used for patients with traumatic injury, and has a higher diagnostic performance than that of plain radiographs (1-5).Chest CT is useful for the evaluation of rib fractures. However, rib fractures can be missed by chest CT when there is no related change due to rib fracture and the fracture line is parallel to the CT section plane. The evaluation of ribs is particularly difficult due to their peripheral location. It is problematic for many radiologists when describing the fracture site in patients with rib fracture. Some clinicians use additional plain chest radiographs to overcome the limitations of CT in symptomatic patients; however, the patients are exposed to additional radiation during this process (6, 7). Three-dimensional reformation of the chest CT is helpful, but it takes more time for the radiologist to read the CT images (6, 8).Recently, reformatting techniques have been used in many fields of radiology. These reformatting techniques make interpreting CT images more convenient and improve diagnostic performance because they provide additional information about the lesion (6, 9, 10). The reformatted images reflect the data with iso- Purpose: To assess the value of adding a reformatted computed tomography (CT) rib series to transversely reconstructed CT imaging in the evaluation of rib fractures in patients with suspected traumatic thoracic injuries. Materials and Methods: One hundred consecutive patients with suspected traumatic thoracic injuries underwent 128-section multi-detector row CT. Transverse CT images with 5-mm-thick sections were reconstructed and rib series were reformatted using isotropic voxel data. Three independent radiologists, who were blinded to the data, interpreted the CT scans at 2 sessions with a 4-week interval between the sessions. Only transverse CT images were reviewed at the first session. At the second session, the CT images were reviewed along with the reformatted CT rib series. The following parameters were analyzed: receiver operating characteristic (ROC) curve, pairwise comparisons of ROC curves, sensitivity, specificity, positive predictive value, and negative predictive value. Results: There were 153 rib fractures in 29 patients. The level of the area under the ROC curve, Az improved for all observers. The diagnostic sensitivity and specificity of each observer tended to improve in the second session. The mean confidence scores for all observers of patients with rib fractures improved significantly in the second session. Conclusion: A reformatted CT rib series together with transverse CT scan is useful for the evaluation of rib fracture. Original ArticlepISSN 1738-2637 J Korean Soc Radiol 2013;68(1):27-