The discovery of a solitary hot spot of the rib on bone scintigraphy is a common occurrence. In this setting, differentiation between benign rib fracture and metastatic disease is clinically important. Baxter et al. [1] found that in patients with known extraskeletal malignancy, solitary rib lesions are frequently malignant in origin (41%). Standard radiographs, including spot radiographs, are usually obtained. CT of the chest using transverse sections also is often performed. In our experience, however, differentiating benign and malignant conditions on the basis of these investigations is often difficult. MRI of the rib is not routinely performed, and with MRI sequences adapted for the visualization of bone structures, artifacts related to breathing usually pose a problem. In addition, breath-hold sequences used in body MRI offer insufficient detail for visualization of bone rib abnormalities.
Because the transverse sections obtained with standard CT technique are oblique with regard to both the long and the short axes of the rib, interpretation may be difficult (Fig. 1). Hence, we sought to develop an improved CT technique for the evaluation of rib lesions. The use of angulated thin-section helical CT offers the possibility to obtain several CT sections of any selected rib and to analyze the rib as if one were looking at a long tubular bone. After the completion of this project, MDCT became routinely available at our department. Hence, instead of angulating the gantry, we obtain reconstructions along the long axis of the rib; this approach yields a similar appearance of the rib as described in this article. With this technique, evaluating the cortical and intramedullary areas of the rib is possible. Adjacent soft-tissue masses also can be assessed in detail. In this article, we describe a pattern-based approach based on the lesions we encountered in 50 patients.