Reliability and validity testing of automated scoring in obstructive sleep apnea diagnosis with the Embletta X100.

OBJECTIVES/HYPOTHESIS: To verify the reliability and validity of automated scoring and compare it to that of manual scoring for diagnosing obstructive sleep apnea using an Embletta X100 level 2 portable device. STUDY DESIGN: Retrospective study. METHODS: A total of 116 patients with suspected obstructive sleep apnea who had successfully received portable polysomnography with the Embletta X100 were examined. All polysomnography data were analyzed by automated and manual methods. Manual scoring was performed according to the revised American Academy of Sleep Medicine 2012 criteria. Automated scoring was analyzed using the automatic algorithm, which was updated with the American Academy of Sleep Medicine 2012 criteria. All parameters were evaluated statistically using correlation analysis and paired t tests. RESULTS: The apnea-hypopnea index for automated scoring and manual scoring with the Embletta X100 were moderately correlated (r = 0.76, P < .001). However, there was poor agreement (Bland-Altman plot, κ = 0.34, 0.33, and 0.26; cutoff value = 5, 15, and 30), and the apnea-hypopnea index data were generally excessively underestimated based on diagnostic agreement and disagreement criteria. Furthermore, the apnea-hypopnea index severity (Kendall tau-b = 0.62) between automated and manual scoring lacked good concordance. CONCLUSIONS: Automated scoring using the Embletta X100 was statistically moderately related to the manual scoring results. However, automated scoring tended to excessively underestimate the apnea-hypopnea index data compared to manual scoring. Thus, manual scoring by a sleep expert is essential for obstructive sleep apnea diagnosis with the Embletta X100. LEVEL OF EVIDENCE: 4.

Changes in ultrasonic properties of liver tissue in vitro during heating-cooling cycle concomitant with thermal coagulation.

The present work considers the ultrasonic properties of porcine liver tissue in vitro measured during heating concomitant with thermal coagulation followed by natural cooling, so as to provide information about changes in the ultrasonic properties of the tissue after thermal coagulation. The excised liver samples were heated in a degassed water bath up to 75°C and naturally cooled down to 30°C. The tissue was observed to begin thermally coagulating at temperatures lower than 75°C. The ultrasonic parameters considered include the speed of sound, the attenuation coefficient, the backscatter coefficient and the nonlinear parameter of B/A. They were more sensitive to temperature when heating than during natural cooling. All of the parameters were shown to rise significantly on completion of the heating-cooling cycle. At 35°C after thermal coagulation, the B/A value was increased by 96%, the attenuation and backscatter coefficients were increased by 50%∼68% and 33%∼37%, respectively, in the typical frequency ranges of 3 MHz∼5 MHz used for ultrasonic imaging and the speed of sound was increased by 1.4%. The results of this study added to the evidence that tissue characterization, in particular, based on the B/A could be valuable for ultrasonically imaging the thermal lesions following high-intensity focused ultrasound (HIFU) surgery.