Improved diagnostic accuracy for polymyalgia rheumatica using FDG-PET/CT with clinical diagnosis or 2012 ACR/EULAR classification criteria.

OBJECTIVE

In routine care, clinicians may employ 2-[18F]fluoro-2-deoxy-D-glucose (FDG)-PET/CT to validate their initial clinical diagnosis of PMR. Nevertheless, the diagnostic utility of combining FDG-PET/CT findings with clinical presentation has not been explored. Therefore, this study aimed to investigate whether the diagnostic accuracy for PMR could be enhanced by combining FDG-PET/CT findings with the clinical baseline diagnosis or the 2012 ACR/EULAR clinical classification criteria for PMR.

METHODS

An investigation and a validation cohort were included from two countries, encompassing 66/27 and 36/21 PMR/non-PMR patients, respectively. The cohorts comprised treatment-naïve patients suspected of PMR, who initially received a clinical baseline diagnosis and underwent FDG-PET/CT scans. The FDG-PET/CT Leuven score was applied to classify patients as either PMR or non-PMR and combined with the clinical baseline diagnosis. Final diagnoses were established through clinical follow-up after 12 or six months in the investigation and validation cohorts, respectively.

RESULTS

In the investigation cohort, a clinical baseline diagnosis yielded a sensitivity/specificity of 94%/82%, compared with 78%/70% using the ACR/EULAR criteria. Combining the clinical baseline diagnosis with a positive Leuven score showed a sensitivity/specificity of 80%/93%, compared with 80%/82% for an ACR/EULAR-Leuven score. In the validation cohort, the baseline diagnosis revealed a sensitivity/specificity of 100%/91%, compared with 92%/76% using the ACR/EULAR criteria. Combining FDG-PET/CT with the baseline diagnosis demonstrated a sensitivity/specificity of 83%/95% compared with 89%/81% for the ACR/EULAR-Leuven score.

CONCLUSION

Combining FDG-PET/CT findings with the clinical baseline diagnosis or ACR/EULAR clinical classification criteria can improve the diagnostic specificity for PMR.