Diagnostic criteria of complex regional pain syndrome considering image patterns and quantitation on three-phase bone scan

Objectives Patients with Complex Regional Pain Syndrome(CRPS) present various signs and symptoms, and it is hard to make a confirmatory histopathologic diagnosis. The Three-phase Bone Scan(TPBS) can be useful for diagnosis, but TPBS shows various finding according to clinical course of CRPS. We investigate the diagnostic criteria of CRPS considering image patterns and quantitation on TPBS.

Methods 142 patients with clinically suspected CRPS patients were enrolled in this study (M:F=82:60, Age=39 ± 15 years). Each patient underwent TPBS and was diagnosed by IASP 2004 modified criteria (CRPS 80, no CRPS 62, time interval between event and scan 14.7±18.6 months). Three nuclear medicine physicians visually evaluated TPBS images according to uptake symmetricity, degree and pattern. We hypothesize that TPBS shows serial change in accordance with affected duration and classify patients based on TPBS pattern (acute, chronic). Count ratio of affected limb/contralateral limb was measured.

Results Increased radioactivity on delayed image suggest CRPS (73.8%). The majority of patients showing symmetric TPBS is not CRPS (71.8%). Most of the patients showing acute pattern have CRPS (69.8%), and count ratio 1.4 can be useful in differential diagnosis (se 82.8%, sp 69.2%, AUC 0.73). Most of the patients showing chronic pattern have also CRPS (72%). Suggestive diagnostic criteria based on symmetricity and count ratio is useful for differential diagnosis in total patients (se 80%, sp 71%)

Conclusions Pattern and quantitative analysis of TPBS can be useful in optimized CRPS diagnosis. And high sensitivity and specificity are achieved in suggestive of diagnostic criteria