MS UMB/2001/107 Revision NONINVASIVE ASSESSMENT OF VOCAL FOLD MUCOSAL WAVE VELOCITY USING COLOR DOPPLER IMAGING

The vibratory movement of the vocal folds (VF) plays an important role in normal function of phonation. We developed a noninvasive technique to quantify the human MWV in vivo using color Doppler imaging (CDI). During phonation the motion of mucosa-air interface generates a unique pattern of US color artifacts which assist the identification of true VF location. An in vitro study using vibrating string phantom was conducted to investigate how the CDI displayed a vibrating soft tissue at high frequency. The vibrating amplitude, frequency, mass density and the acoustic impedance of the soft tissues were found to dominate the formation of color artifacts. Based on the model of finite string with fixed ends, we estimated the mean mucosal wave velocity (MWV) for ten adult volunteers (6M 4F, age 34±5) with normal VF function. The mean MWVs for the male subjects were found vary from 2.1 to 10 m/s in frequency range of 85-310 Hz at their comfortable pitch and intensity, while the females typically had higher MWV that varied from 5.0 to 16.5 m/s in frequency range of 180-480 Hz. The MWV increased linearly with the frequency and there was no observable difference in mucosa stiffness due to the effect of gender. The variation in MWV as it propagates vertically can be seen from the color and shape of the artifacts. The VF polyp resulted in abnormal MWV and different CDI vibratory artifacts. The CDI artifacts provide the insight of the dynamics of mucosa structure during phonation, and the method presented is promising for noninvasive monitoring of laryngeal functions clinically

Effects of Surgery on the Phonation Threshold Pressure in Patients With Vocal Fold Polyps

There are few objective measurements to assess the results of surgery for vocal fold polyps. This study investigated the effects of surgery on the phonation threshold pressure (PTP) in patients with vocal fold polyps. Methods: Prospectively, 32 consecutive patients with vocal fold polyps were enrolled. PTP was measured 1 day before and 6 weeks after laryngomicrosurgery, by means of an airflow interruption method. An accelerometer was used to detect the vocal fold vibration instead of using an acoustic signal. Results: In all 32 patients, the average preoperative PTP was 0.51 ± 0.23 kPa, and 6 weeks after surgery, it was 0.28 ± 0.17 kPa; this difference was statistically significant (p < 0.001). Individually, PTP decreased in 31 patients after surgery. PTP increased after surgery in only one patient, from 0.74 to 0.75 kPa. Subjectively, all patients could phonate with less effort after surgery. Use of an accelerometer to sense vocal fold vibration was feasible and made it easier to identify the time point of cessation of vocal fold vibration, which is important for PTP measurement. Conclusion: Laryngomicrosurgery can lower PTP in patients with vocal fold polyps and improve the ease of phonation. PTP is one of the objective measurements for assessing the effects of surgery in patients with vocal fold polyps. Use of an accelerometer to detect vocal fold vibration improved the measurement of PTP

A Distributed Continua AHD System with ZigBee/PAN-IF Gateway and Continua QoS Control Mechanism

In a residential or nursing home environment, using ZigBee/802.15.4 wireless network specifically to collect and gather various types of personal health data proves to be a feasible choice. The Continua Guidelines has defined both the sensor-LAN IF (sensor Local Area Network Interface) PHD (Personal Health Device) and PAN IF (Personal Area Network Interface) PHD, but only a Continua certified sensor-LAN IF PHD with Zigbee HC (Health Care) profile can connect with Continua AHD (Application Hosting Device) through Zigbee/802.15.4 network and allows data communicating between AHD and PHDs. In this paper, we present a distributed Continua AHD system design that divides the AHD device containing Continua PAN IF into Continua AHD Host and Continua AHD Gateway with communication through ZigBee/802.15.4 network. Under this structure, a Continua PHD connects with a Continua AHD Host through Continua AHD Gateway within ZigBee/802.15.4 network. One immediate advantage of the proposed system is that both of the Continua sensor-LAN IF and PAN IF PHDs can connect with Continua AHD (Host) through ZigBee/802.15.4 network. To further address the QoS (Quality of Service) issue for Continua PAN IF message transmission in a ZigBee network, we present a software approach to automatically determine the types of packet transmitted and execute Continua QoS control. Together with the QoS mechanism in the enhanced ZigBee MAC Layer, this approach realizes a complete Continua QoS control mechanism for the distributed AHD system