PubMed · 10299550
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
W B Seaman. 1984. Digital radiography.. https://pubmed.ncbi.nlm.nih.gov/10299550/
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
BACKGROUND: Irregular vibrations of the vocal folds are regarded as a main reason for the common symptom of hoarseness. With real time resolution, they can only be observed using high speed recording techniques (up to 10,000 images/s). METHOD: During the last years, we have developed a recording device and image processing software dedicated to the extraction of vocal fold motion curves from the image series. Irregular vibrations can be understood by using Hirano's "body-cover-model": one vocal fold is assumed to act as a system of two coupled oscillators (the vocal muscle and the epithelium, coupled by the connective tissue of Reinke's space). RESULTS: By applying this biomechanical two-mass model and inversely solving Bernoulli's equation, the driving parameters of the vibration were computed from the high speed image series in selected cases. These parameters, like the subglottal pressure und the bilateral tension of the vocal muscle cannot, in general, be measured directly. DISCUSSION: From the model, it can be supposed that laryngeal asymmetry (either in mass or tension) is the primary reason causing irregularity. The consequence of asymmetry in the medio-lateral direction are different fundamental frequencies on each side, while asymmetry in the anterior-posterior direction leads to ap-mode vibrations.
BACKGROUND: The movement of a rigid body through space may be comprehensively described by constructing a "finite helical axis" (FHA). The rigid body carries out a rotation around this axis for discrete periods of time while at the same time moving along this axis. MATERIAL AND METHODS: The free opening and closing movement of the mouth was registered in eight asymptomatic test persons, using the CADIAX electronic axiography system (GAMMA-DENTAL, Klosterneuburg, Austria). Subsequently, the position of the FHA in space, the angle of rotation around this axis, and the amount of translation along the FHA were determined for each subject, using the coordinates of the measuring styluses. RESULTS: During the initial phase of the mouth-opening movement, the FHAs were near the condyle. Over the course of the opening movement, they moved toward downward backward, downward and downward forward, and finally to forward upward toward the condyle upon reaching maximum mouth opening. During the closing movement, the FHAs shifted back in the reverse direction. During both the opening and the closing movement, there was a slight translational movement along the FHAs, which provided an indication of mandibular deviation.
BACKGROUND: In some cases of retinopathy of prematurity (ROP), it difficult to determine with certainty whether plus disease is present or absent. We have developed a computer program that captures digital images from a video-indirect ophthalmoscope, identifies and traces the major posterior pole blood vessels, measures the dilation and tortuosity of each vessel, and calculates whether or not an eye has plus disease. Our purpose was to determine the accuracy of the computer program in comparison with two masked examiners. METHODS: A representative sample of posterior pole images from 20 premature infants, 10 normal and 10 representing various degrees of dilation and tortuosity, was extracted from our video database and analyzed by the computer program as well as by two masked examiners experienced in the diagnosis of ROP. The standard photograph from the Cryotherapy for ROP study, representing the minimum degree of dilation and tortuosity required for plus disease, was also digitized, analyzed, and used as a numeric comparison for the automated determination of plus disease. RESULTS: Of the five images determined to have plus disease by both examiners, four were calculated to have plus disease by the computer program (80% sensitivity). Of the 11 images without plus disease, 10 were calculated not to have plus disease by the computer program (91% specificity). CONCLUSIONS: Our computer program has very good sensitivity and specificity compared with masked examiners' determination of the presence or absence of plus disease. Automated analysis of dilation and tortuosity of posterior pole blood vessels has the potential to remove subjectivity from the determination of plus disease.