Alteration of Chronic Inflammatory Status by Trans-arterial Embolization in Frozen Shoulder Evaluated by 18F-FDG-PET/CT

To investigate changes in chronic inflammatory status before and after trans-arterial embolization (TAE) in frozen shoulder (FS) by [¹⁸F]-FDG-PET/CT as a possible mechanism of the therapeutic response to TAE.

Materials and Methods: Fifteen patients with unilateral FS underwent TAE using  imipenem/cilastatin sodium. Patients underwent PET/CT with FDG (as a biomarker of inflammation) before and 8 weeks after TAE. Regional uptake was evaluated by the maximum standardized uptake value (SUVmax). The lesion-side to (contralateral-) normal-side uptake ratio (L/C ratio) was also calculated. Pain and functional scales were evaluated.

Results:  On FDG-PET, the average SUVmax of the lesion-side was significantly greater than that of the normal-side (SUVmax before TAE: 3.11 ± 1.25 vs. 1.95 ± 1.15, p = 0.0001; 8-weeks post-TAE: 2.36 ± 0.74 vs. 1.78 ± 0.69, p = 0.0002). The mean L/C ratios before TAE (1.71 ± 0.60) decreased after TAE (1.37 ± 0.29, p = 0.011). The decrease of FDG uptake (-21.1 ± 12.2%) showed a significant correlation with the change in the pain scale score (r = -0.56, p = 0.039) and extension score (r = -0.59, p = 0.026). 

Conclusion: Chronic inflammation is likely to be an underlying mechanism that should be targeted for symptomatic improvement of frozen shoulder.