The diagnostic accuracy of power Doppler ultrasonography for differentiating secondary from primary Raynaud's phenomenon in undifferentiated connective tissue disease

This study was conducted to evaluate the diagnostic accuracy of power Doppler ultrasonography (PDU) for differentiating secondary from primary Raynaud’s phenomenon (RP), and also compared PDU with nailfold capillaroscopy (NFC) for the assessment of microvascularity in undifferentiated connective tissue disease (UCTD) patients with RP. Microvascularity in the nailfold and finger tip was evaluated using PDU with cold challenge, and the findings of PDU were classified according to the qualitative grading system before and after cold challenge. NFC was performed at the same day in all persons. The results of PDU were compared with the clinical, laboratory data, and the findings of NFC. The 14 UCTD patients with RP were included in our study. Seven patients were suspected of secondary RP in NFC examination, thus NFC yielded a correct classification into secondary RP in 50% of the UCTD patients. The PDU finding of pattern II, which is regarded as the finding of secondary RP, was observed in 12 UCTD patients with RP. Thus, PDU yielded a correct classification into secondary RP in 86% of UCTD patients. In conclusion, we confirmed that PDU has a higher correct classification rate than NFC for the diagnosing of secondary RP in UCTD patients. Our results suggest that PDU has better accuracy than NFC in differentiating secondary from primary RP, and PDU is more useful in assessing microvascular abnormalities in UCTD patients with RP.