Assessment of Degenerative Joint Disease with NaF PET

Objectives Degenerative joint disease, also known as osteoarthritis, is a chronic disease characterized by loss of articular cartilage, subchondral bone changes, and osteophyte formation. Risk factors include obesity, joint injury and genetic predisposition. Most commonly seen in older patients with joint pain, swelling, and limited joint motion, it is usually diagnosed clinically or with the help of X-ray. Increased MDP activity is often noted in these affected joints on bone scans. Now with the availability of NaF PET/CT, we are able to assess this reactive bone formation activity quantitatively. In this study, we evaluated the association between NaF uptake activity and the severity of affected joints.

Methods Data were collected retrospectively from 11 NaF PET/CT studies performed at our institute, scanned 60 minutes after tracer injection. Each patient was male with a history of prostate cancer, aging 60 - 86 years old. PET images were analyzed using an adaptive thresholding algorithm (ROVER software, ABX, Radeberg, Germany), allowing for the delineation and quantification of increased NaF uptake in regions of interest (ROI). The following values were calculated for each ROI and for each patient: maximum standard uptake value (SUVmax), mean standard uptake value (SUVmean), metabolically active volume (MAV), total lesion glycolysis (TLG = SUVmean[asterisk]MAV), partial volume corrected SUVmean (pvcSUVmean), and partial volume corrected total lesion glycolysis (pvcTLG   =   pvcSUVmean[asterisk]MAV). The severity of arthritis of the 11 patients were scored as having mild, moderate, or severe by an experienced radiologist, for statistical analysis.

Results Statistical analysis revealed no association between SUVmax, SUVmean, or PVC SUVmean and the severity of arthritis, with R squared values close to 0 and p values of more than 0.7. A weak association between MAV and arthritis severity was noted (R squared of 0.3) but was not statistically significant, likely due to the small sample size of this study. However, our data demonstrated significant association between TLG (R squared of 0.559, p 0.008) or PVC TLG (R squared of 0.658, p 0.002) and arthritis severity.

Conclusions Our study demonstrated a quantification association between 18F-NaF uptake and the severity of degenerative joint disease, most sensitively detected by TLG and PVC TLG. The findings demonstrate that 18F-NaF uptake may serve as an indicator of the severity and progression of degenerative joint disease.

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