Imaging signs and the qualitative diagnosis of solitary rib lesions using (99m)technetium-methylene diphosphonate whole-body bone imaging in patients with a malignant tumor

BACKGROUND: The aim of this study was to summarize the valuable information for qualitative diagnosis by investigating the imaging signs from the whole-body bone imaging of solitary rib lesions. METHODS: A retrospective analysis was conducted of the data from 313 patients with malignant tumors and solitary rib lesions identified using whole-body bone imaging in Department of Nuclear Medicine of Central South University Xiangya School Affiliated Haikou Hospital between January 2015 and December 2017. Based on the final comprehensive diagnosis of the rib lesions, the patients were divided into a bone metastasis group, fracture group, other benign lesions group, and an uncertain group, and the characteristic imaging changes in rib lesions in each group were explored. RESULTS: (I) Significant differences were identified among the 4 groups (P<0.001) in the distribution of lesions in the anterior, posterior, and lateral ribs and proximal costal cartilage. The fracture group had the highest proportion of lesions in the anterior ribs (99/121, 81.8%) and proximal costal cartilage (74.4%, 90/121). (II) Significant differences were detected in morphology, concentration, boundaries, and radioactivity distribution among the 4 groups of patients (P<0.001). The bone metastasis group had the highest proportion of lesions appearing as stripes (35/67, 52.2%), and the fracture group had the highest proportion of lesions appearing as spots (94.2%, 114/121) and the lowest proportion appearing as stripes (3/121, 2.5%). (III) Significant differences were found in the longitudinal diameter, transverse diameter, aspect ratio, and tumor-to-normal tissue ratio between the 4 groups (P<0.001). The longitudinal diameter (27.8±16.0 mm) and aspect ratio (1.9±1.0) of the bone metastasis group were the highest, whereas the longitudinal diameter (15.2±3.9 mm) and aspect ratio (1.0±0.2) of the fracture group were the smallest. CONCLUSIONS: This study revealed that different types of solitary rib lesions had relatively characteristic imaging signs in whole-body bone imaging.