High speed glottographic diagnostics in laryngology

Introduction. High speed imaging (HSI) allows thousands of pictures to be taken of the vibrating vocal folds per second. Although already developed in 1939 in the USA, this method only became clinically useful a few years ago as the amount of data exceeded the capacity of physical memory. Materials and Methods. Rigid endoscopes are normally used for high speed glottography. After clinical investigation of the patient, kymographic analysis can be carried out off-line. Up to 8,000 grayscale images of 256x256 pixels can be stored by the Wolf HS Endocam 5560 that we used in our study. A maximum of 4,000 images/s can be taken by the high speed camera. Results. In high speed glottography, analysis and documentation of single vocal fold movements within the vibratory cycle is possible. In contrast to stroboscopic investigations, aperiodic movements of the vocal folds can be visualized. The duration of a recording differs from 2 to 4 s depending on the capture speed. The data transfer to the computer for archiving and analysing the images takes a few minutes. Conclusion. HSI has advantages and disadvantages compared to videoendoscopy and videostroboscopy. The main advantage is the visualisation of aperiodic movements, the disadvantages are the transfer time for the data and the poorer image quality compared to conventional videoendoscopy. Nevertheless HSI is a very promising technique in laryngological investigation.