Utility of maximum perfusion sity as an ultrasonographic marker of intraneural blood flow

We quantified intraneural blood flow (INBF) using a perfusion measurement software (PixelFlux), and compared it to the qualitative method of counting blood vessels (vessel score) in a cohort of carpal tunnel syndrome (CTS) patients. METHODS: 47 patients (67 wrists) with clinical and electrophysiological diagnosis of CTS, and 20 healthy controls (40 wrists) were enrolled. Median nerve ultrasound (US) was performed at the carpal tunnel inlet to measure the cross-sectional area (CSA) and vessel score. Power Doppler sonograms from nerves with detectable INBF were processed with PixelFlux, to obtain the maximum perfusion intensity (MPI). RESULTS: Forty-nine percent of CTS patients had detectable INBF compared to none in the control group (P<0.0001). MPI correlated significantly with vessel score (r=0.945, P<0.0001), CSA (r=0.613, P<0.0001), and electrophysiological severity (r=0.440, P<0.0001). MPI had higher intra/inter-observer reliability compared to vessel score (0.95 vs 0.47). CONCLUSION: MPI is a better method for quantification of INBF.