Background: The appropriate monitoring of union following the treatment of scaphoid nonunion is essential. However, there is no consensus regarding the optimal imaging modality for this evaluation. 
Objectives: Here, we compared the reliability of plain radiographs with computed tomography (CT) scanning in determining the union of scaphoid following the scaphoid nonunion.
Methods: In this retrospective study, 25 patients, who underwent the surgical treatment of scaphoid nonunion and had both plain radiographs and CT images, were included. The surgical procedure included open reduction, illiac crest bone graft, and K-wire fixation. Two different observers assessed the healing of scaphoid nonunion by both imaging modalities and graded as healed or non-healed.
Results: The mean±SD age of the patients was 29.1±6.8 years. The mean±SD time interval from the operation to imaging was 6.5±2.5 months. Based on the plain radiographs, all patients achieved the scaphoid union. However, in the CT evaluation, 23(92%) patients showed the scaphoid union. Accordingly, CT images and plain radiographs agreed in 23 cases and disagreed in two cases. This difference was not statistically significant (P=0.5).
Conclusion: In a subset of patients, who underwent the operation for the treatment of scaphoid nonunion, plain radiographs might falsely confirm a scaphoid union. In these patients, a complementary CT evaluation might be helpful in the accurate assessment of scaphoid healing. 

Background: Previous studies have shown a moderate correlation between bone mineral density (BMD) measured by dual-energy x-ray absorptiometry (DEXA) and Hounsfield units (HU) assessed on diagnostic computed tomography (CT) scans in the lumbar spine. 
Objectives: In this study, we aimed to evaluate the correlation between DEXA scores and HU values for different bones and several anatomical landmarks.
Methods: In this retrospective study, 214 patients underwent DEXA and diagnostic CT scans of different bones, including the proximal humerus (n=96), distal tibia (n=56), distal femur (n=34), and proximal tibia (n=28). HU values of five anatomic landmarks, including the medulla, anteromedial cortex, anterolateral cortex, posteromedial cortex, and posterolateral cortex, were measured, and their correlation with the lowest T-score of the patients was assessed.
Results: The HU of the center of the medulla was significantly correlated with the lowest T-score in the proximal (r=0.486, P=0.04) and distal tibia (r=0.458, P=0.01). In the proximal humerus, the HU of the anteromedial cortex was significantly correlated with the lowest T-score (r=0.0353, P=0.01). The mean HU of the posterolateral cortex in the proximal humerus was significantly smaller in the osteoporotic patients (P=0.003). The mean HU of the center of the medulla in the proximal tibia was significantly lower in patients with ‎osteoporotic (P=0.036). The mean HU values of the posteromedial cortex and center of the medulla in the distal tibia were significantly larger in patients with normal BMD (P=0.04 both). 
Conclusion: A moderately significant correlation is observed between the lowest T-score and specific anatomical landmarks of the different bones.