Objective: To evaluate the reliability of suprahyoid and infrahyoid electromyography (EMG) measurement during swallowing. Methods: In all, 10 healthy volunteers were evaluated for the following surface EMG (sEMG) parameters in the suprahyoid and infrahyoid muscles during swallowing: onset latency, offset latency, duration, peak latency, maximal amplitude during swallowing, and the area under curve (AUC) of the rectified EMG signal. The sEMG was recorded while the participants swallowed five times each of the four fluid volumes (saliva, 2 ml, 5 ml, and 20 ml of water), totaling to 20 swallows. Moreover, the intra-participant variability per parameter was evaluated using the coefficient of variation (CV). Results: Suprahyoid muscles were activated 0.095 s (95% CI, 0.062-0.128) earlier than the infrahyoid muscles.Maximal amplitudes during the 20 ml swallow were 17.484 (−1.543-36.512) and 13.490 (1.254-25.727) μV higher than values obtained during the 2 ml swallow in the suprahyoid and infrahyoid muscles, respectively. Furthermore, the AUC of the rectified EMG signal increased with the volume of swallow in both muscle groups (P=0.003, suprahyoid; P＜0.002, infrahyoid). The intra-individual variabilities of offset latency, duration, and maximal amplitude were relatively low (＜30% CV) in both muscle groups with respect to other parameters. The assessment of each parameter using EMG was highly reliable, with an intraclass correlation coefficient of ＞0.8. Conclusion Among the variable sEMG parameters assessed, the offset latency, duration, and maximal amplitude were the least variable. Although reliability on the rater side showed good results, the swallow-to-swallow variability of the parameters need to be considered in swallowing studies using sEMG.

Objective: To evaluate the reliability of suprahyoid and infrahyoid electromyography (EMG) measurement during swallowing. Methods: In all, 10 healthy volunteers were evaluated for the following surface EMG (sEMG) parameters in the suprahyoid and infrahyoid muscles during swallowing: onset latency, offset latency, duration, peak latency, maximal amplitude during swallowing, and the area under curve (AUC) of the rectified EMG signal. The sEMG was recorded while the participants swallowed five times each of the four fluid volumes (saliva, 2 ml, 5 ml, and 20 ml of water), totaling to 20 swallows. Moreover, the intra-participant variability per parameter was evaluated using the coefficient of variation (CV). Results: Suprahyoid muscles were activated 0.095 s (95% CI, 0.062-0.128) earlier than the infrahyoid muscles.Maximal amplitudes during the 20 ml swallow were 17.484 (−1.543-36.512) and 13.490 (1.254-25.727) μV higher than values obtained during the 2 ml swallow in the suprahyoid and infrahyoid muscles, respectively. Furthermore, the AUC of the rectified EMG signal increased with the volume of swallow in both muscle groups (P=0.003, suprahyoid; P＜0.002, infrahyoid). The intra-individual variabilities of offset latency, duration, and maximal amplitude were relatively low (＜30% CV) in both muscle groups with respect to other parameters. The assessment of each parameter using EMG was highly reliable, with an intraclass correlation coefficient of ＞0.8. Conclusion Among the variable sEMG parameters assessed, the offset latency, duration, and maximal amplitude were the least variable. Although reliability on the rater side showed good results, the swallow-to-swallow variability of the parameters need to be considered in swallowing studies using sEMG.

Purpose: To evaluate the clinical reliability of the Topolyzer Vario (Wavelight-Alcon, Erlangen, Germany), we compared threedifferent corneal topographers in terms of corneal refractive power. Methods: The medical records of patients who visited Severance Hospital for corneal refractive surgery were retrospectivelyreviewed. Keratometric data of patients who underwent evaluations using the Pentacam HR (Oculus, Wetzlar, Germany),ORBscan II (Bausch & Lomb, Rochester, NY, USA), and Topolyzer Vario instruments on the same day were obtained. Flat keratometry(Kf), steep keratometry (Ks), mean keratometry (Km), astigmatism keratometry (Kastig), Cartesian astigmatism (J0), andoblique astigmatism (J45) values were calculated. The measurement values of the three devices were subjected to Pearson’scorrelation analysis and repeated measures analysis of variance (with Bonferroni correction); a Bland-Altman plot was alsocreated. Results: The keratometric data of 80 eyes were included in the analysis and all of the keratometric measurements obtained bythe three devices showed significant correlations, i.e., good agreement. The Kf and Km measurements of the Pentacam HR wereflatter than those of the ORBscan II, and the Kf, Km, Ks, and J45 measurements were flatter than those of the Topolyzer Vario.However, there was no significant difference in keratometric values between the ORBscan II and Topolyzer Vario. Furthermore,the difference in corneal refractive power between the Pentacam HR and Topolyzer Vario was not clinically significant. Conclusions When measuring the corneal refractive power of patients without any history of corneal disorder or ocular surgery,the Topolyzer Vario is a clinically reliable device that shows similar performance to the ORBscan II and Pentacam HR.

Purpose: To compare the polishing characteristics and their influence on Candida albicans adhesion to the recently introduced polyetherketoneketone (PEKK) and the conventional polymethylmethacrylate (PMMA) denture resin material. Materials and methods: Specimens from PEKK (Group E) and PMMA (Group M) were made in dimensions of 8 mm in diameter and 2 mm in thickness. The specimens were further divided into sub-groups according to the extent of polishing (ER, MR: rough; EP, MP: polished, N = 12 each). The specimens were polished using polishing machine and SiC foil. ER and MR group specimens were polished with 600 grit SiC foil only. EP and MP groups were further polished with 800, 1,000, 1,200 grit SiC foils sequentially. To measure the surface roughness values (Sa) of specimens, atomic force microscope (AFM) was used and scanning electron microscope (SEM) observation under 1,000, and 20,000 magnifications was performed to investigate surface topography. The polished specimens were soaked in C. albicans suspension for 2 hours with shaking to promote adhesion. The attached C. albicans were detached from the surface with 10 times of pipetting. The suspension of detached C. albicans was performed by serial dilution to 103 times, and the diluted suspensions were inoculated on Sabouraud dextrose agar plates using spread plate method. After incubating the plate for 48 hours, colony forming unit (CFU)/plate of C. albicans was counted. Statistical analysis was performed using one-way ANOVA and Tukey HSD test to confirm significant difference between the groups (α=.05). Results: Average Sa value was significantly higher in MR group compared to other groups (P<.05), meaning that additional polishing steps reduced surface roughness effectively only in the PMMA specimens. There was no significant difference in Sa values between MP and EP groups. In SEM images, PEKK specimens showed numerous spikes of abraded material protruding from the surface and this phenomenon was more significant in EP group. The mean CFU/plate value was the highest in EP group and this was significant when it was compared to MP group (P<.05) which was the lowest. Conclusion Polishing PEKK using serial SiC abrasive foil may result in higher adhesion of C. albicans. In clinic, this should be considered carefully.

OBJECTIVES: Augmented reality (AR) technology has become rapidly available and is suitable for various medical applications since it can provide effective visualization of intricate anatomical structures inside the human body. This paper describes the procedure to develop an AR app with Unity3D and Vuforia software development kit and publish it to a smartphone for the localization of critical tissues or organs that cannot be seen easily by the naked eye during surgery. METHODS: In this study, Vuforia version 6.5 integrated with the Unity Editor was installed on a desktop computer and configured to develop the Android AR app for the visualization of internal organs. Three-dimensional segmented human organs were extracted from a computerized tomography file using Seg3D software, and overlaid on a target body surface through the developed app with an artificial marker. RESULTS: To aid beginners in using the AR technology for medical applications, a 3D model of the thyroid and surrounding structures was created from a thyroid cancer patient's DICOM file, and was visualized on the neck of a medical training mannequin through the developed AR app. The individual organs, including the thyroid, trachea, carotid artery, jugular vein, and esophagus were localized by the surgeon's Android smartphone. CONCLUSIONS: Vuforia software can help even researchers, students, or surgeons who do not possess computer vision expertise to easily develop an AR app in a user-friendly manner and use it to visualize and localize critical internal organs without incision. It could allow AR technology to be extensively utilized for various medical applications.
Carotid Arteries ; Education, Medical ; Esophagus ; Human Body ; Humans ; Imaging, Three-Dimensional ; Jugular Veins ; Manikins ; Methyltestosterone ; Neck ; Smartphone ; Surgeons ; Thyroid Gland ; Thyroid Neoplasms ; Thyroidectomy ; Trachea