The usefulness of power Doppler ultrasonography in differentiating primary and secondary Raynaud's phenomenon

The objectives of this study were to assess a usefulness of power Doppler ultrasonography (PDU) and compare the diagnostic value of PDU to nailfold capillaroscopy (NFC) in the patients with clinically diagnosed Raynaud's phenomenon (RP) and healthy controls. Forty-one patients with primary (n=19), secondary RP (n=22), and ten healthy controls underwent PDU and NFC examinations on the same day. Microvascularity was evaluated using PDU before and after cold challenges, and the PDU signals were qualitatively graded on a scale of 1-4. According to the change of microvascularity before and after cold challenges, the findings of PDU were classified into three groups: (1) 'pattern I' (normal microvascularity over grade 3 both before and after cold challenges), (2) 'pattern II' (decreased microvascularity to grade 1 or 2 only after cold challenge), and (3) 'pattern III' (decreased microvascularity of grade 1 or 2 both before and after cold challenges). PDU confirmed the presence of RP in all patients with clinically diagnosed RP and yielded a correct classification in 88.9% of the all persons analyzed (normal=100%, primary RP=89.5%, secondary RP=77.3%). The analysis was performed to assess the degree of agreement between the final diagnoses obtained by PDU and NFC. A good correlation rate was observed between PDU and NFC examinations in differentiating primary from secondary RP (Kappa=0.658, p<0.01). In conclusion, PDU examination with a cold challenge is a useful and reliable method to diagnose RP and discriminate between primary and secondary RP.