Comparison of histopathology and preoperative 18F-FDG-PET/CT of osteomyelitis aiming for image guided surgery: A preliminary trial.

Objective: There are currently no robust methods for accurately localizing the infection focus of osteomyelitis. Accumulation of fluorodeoxyglucose (FDG) is nonspecific, and it is well-known that it can indicate inflammatory cells and sites of inflammation, and its effectiveness in detecting osteomyelitis has been reported recently. However, the optimal cut-off value for the Standardized Uptake Value (SUV) in detecting the focus of osteomyelitis through 18F-FDG-PET/CT is not known. We investigated the optimal SUV cut-off values using 18F-FDG positron emission tomography (PET)computed tomography (CT) to visualize the infection focus of osteomyelitis accurately.

Patients And Methods: Initially, we investigated a case where osteomyelitis was bacteriologically detected after orthopedic surgery on lower limb. Based on the surgical pathology, we explored the optimal SUV cut-off value of the 18F-FDG PET/CT image taken before surgery. The SUV cut-off value was varied, using the GE Rainbow Color Scale on a dedicated workstation. We searched for the most accurate visualization of the extent of the infectious lesion. Subsequently, using the SUV cut-off value decided on the basis of the first case studied, we investigated the accuracy for diagnosing osteomyelitis. A total of sixteen patients underwent 18F-FDG PET/CT for suspected osteomyelitis (one case involved the upper extremity and 15 cases the lower one). All patients underwent surgery. The final diagnosis was made by means of bacteriologic culture of surgical specimens and histopathologic analysis. We compared surgical pathology and preoperative 18F-FDG PET/CT.

Results: In the first case studied, the infection was most accurately localized with a SUV with a lower level of 2.00 and an upper of 8.00. Upon comparing the pathological findings and the 18F-FDG PET/CT, we set a SUV with a lower level of 2.00 and an upper level of 8.00. In thirteen cases, infection was detected with positive pathological findings. Preoperative 18F-FDG PET/CT showed high accumulation in these cases. In the remaining three cases, no infection was detected on either pathological findings nor 18F-FDG PET/CT findings.

Conclusions: The infection focus of osteomyelitis was accurately visualized by setting the SUV cut-off lower level to 2.00 and upper level to 8.00. We believe that this 18F-FDG PET/CT technique is helpful for image guided surgery of osteomyelitis.