Citations

Stereoscopic particle image velocimetry (SPIV) is a variant of particle image velocimetry (PIV) that allows for the measurement of three components of velocity along a plane in a flow field. In PIV, particles in the flow field are tracked by reflecting laser light from tracer particles into two angled cameras, allowing for the velocity field to be determined. Particle shadow velocimetry (PSV) is an inherently less expensive velocity measurement method since the method images shadows cast by particles from an LED backlight instead of scattered light from a laser. Previous studies have shown that PSV is an adequate substitute for PIV for many two-dimensional, two-component velocimetry measurements. In this work, the viability of the two-dimensional, three-component stereoscopic particle shadow velocimetry (SPSV) is demonstrated by using SPSV to examine a simple jet flow. Results obtained using SPIV are also used to provide benchmark comparison for SPSV measurements. Results show that in-plane and out-of-plane velocities measured using SPSV are comparable to those measured using SPIV.

ObjectiveAssess interrater agreement of endoscopic assessment of velopharyngeal (VP) function before and after viewing the video instruction tool (VIT). We hypothesized improvement in interrater agreement using the Golding‐Kushner scale (GKS) after viewing the VIT.Study DesignProspective study.SettingMulti‐institutional.MethodsSixteen fellowship‐trained pediatric otolaryngologists who treat velopharyngeal insufficiency (VPI) rated 50 video segments using the GKS before and after watching the VIT. Raters assessed gap size percentage and lateral pharyngeal wall (LPW), soft palate (SP), and posterior pharyngeal wall (PPW) movement. Intraclass correlation coefficient was estimated for these continuous measures. Raters also indicated the presence of a palatal notch, Passavant's ridge, and aberrant pulsations (categorical variables). Fleiss κ coefficient was used for categorical variables. Wilcoxon signed‐rank test was performed on the difference between the pre/post individual video ratings.ResultsReliability improved for all continuous variables after watching the instructional video. The improvement was significant for PPW (0.22‐0.30, P <. 001), SP (left: 0.63‐0.68, P <. 001 and right: 0.64‐0.68, P =. 001), and LPW (left: 0.49‐0.54, P =. 01 and right: 0.49‐0.54, P =. 09) but not significant for gap size (0.65‐0.69, P =. 36). Among categorical variables, agreement on Passavant's ridge significantly improved (0.30‐0.36, P =. 03).ConclusionExposure to a video instruction tool improves interrater agreement of endoscopic assessment of VP function. Significant improvement was observed in our primary end points, specifically posterior pharyngeal wall movement, soft palate movement, and lateral pharyngeal wall movement. There was less impact of the VIT on the interrater agreement of the categorical variables, palatal notch, Passavant's ridge, and aberrant pulsations.