Accuracy of measurements on digital videostroboscopic images of the vocal folds.
OBJECTIVE
The reliability of objective measurements on digital laryngeal images was investigated.


METHODS
The magnitude of the error of measurement of surface areas by visually tracing the outline was determined for three different areas: the area of the lesion and, during vibration, the glottal area on maximal opening of the vocal folds and the glottal area on maximal closing of the vocal folds.


RESULTS
The errors in these areas were 10% to 30%. The results suggest that the error is mainly due to the uncertainty of the real outline of areas with a vague boundary. Correction for differences in magnification between two images (posttherapy and pretherapy) is of importance in about 25% to 65% of cases, depending on the area measured.


CONCLUSIONS
Only when the magnification ratio is small (less than about +/- 10% from 1.0) may a correction not be necessary.
Speyer
Renée
R
Institute of Phoniatrics, University Medical Center Utrecht, Utrecht, the Netherlands.
Wieneke
George H
GH
Kersing
Willem
W
Dejonckere
Philippe H
PH
D006801:Humans; D007091:Image Processing, Computer-Assisted; D007828:Laryngoscopy; D015588:Observer Variation; D010699:Phonation; D015203:Reproducibility of Results; D014741:Video Recording; D014827:Vocal Cords / Q000473:pathology* / Q000503:physiopathology; D014832:Voice Disorders / Q000503:physiopathology / Q000628:therapy