Real‐time multislice MRI during continuous positive airway pressure reveals upper airway response to pressure change

Abstract

Purpose To determine if real-time MRI (RT-MRI) method during continuous positive airway pressure (CPAP) can be used to measure neuromuscular reflex and/or passive collapsibility of the upper airway in individual obstructive sleep apnea (OSA) subjects. Materials and Methods We conducted experiments on 4 adolescents with OSA and 3 healthy controls, during natural sleep and during wakefulness. Data were acquired on a clinical 3T scanner using simultaneous multi-slice (SMS) RT-MRI during CPAP. CPAP pressure level was alternated between therapeutic and sub-therapeutic levels. Segmented airway area changes in response to rapid CPAP pressure drop and restoration were used to estimate 1) upper airway loop gain (UALG) and 2) anatomical risk factors, including fluctuation of airway area (FAA). Results FAA significantly differed between OSA patients (2–4x larger) and healthy controls (Student’s t-test, P<0.05). UALG and FAA measurements indicate that neuromuscular reflex and passive collapsibility varied among the OSA patients, suggesting the presence of different OSA phenotypes. Measurements had high intra-subject reproducibility (intra-class correlation coefficient r > 0.7). Conclusion SMS RT-MRI during CPAP can reproducibly identify physiological traits and anatomical risk factors that are valuable in the assessment of OSA. This technique can potentially locate the most collapsible airway sites. Both UALG and FAA possess large variation among OSA patients.

Critical to Know Pcrit: A Review on Pharyngeal Critical Closing Pressure in Obstructive Sleep Apnea

“…These models have been validated for the human pharyngeal airway (42), and employing them helps to better understand the anatomical and physiological behavior of the pharyngeal airway. Pcrit and the changes related to it under different loads were evaluated with this model (16,(43)(44)(45)(46).…”

Real‐Time Magnetic Resonance Imaging

“…Especially, controlled aliasing in parallel imaging results in higher acceleration, also known as CAIPIRINHA (33,34), has shown substantially reduced aliasing artifacts. This technique has recently been explored in some RT-MRI studies (35)(36)(37). 3D imaging has also been explored by extending 2D acquisition schemes to 3D or by using novel 3D sampling trajectories.…”

“…Figure 6 and Supplemental Movies 7-9 illustrate representative research areas in speech production (23,141), sleep apnea (36,37,142) and swallowing (143). Imaging is often performed along with synchronized recordings of physiological signals such as audio signals in speech (144), polysomnography signals used in sleep studies (36), and intraoral pressure sensor used in swallowing (145) to aid real-time or retrospective analysis.…”

Children with Upper Airway Dysfunction: At Risk of Obstructive Sleep Apnea

“…Finally, the endoscope should be introduced through the nasal cavity, allowing visualization of the retrovelar, oropharyngeal, retrobasilingual, retroepiglottic, and glottic regions. 54 If done correctly under optimal anesthesia to mimic natural sleep, DISE procedure can provide a comprehensive evaluation of the multisite obstruction in the upper airway. The site and the severity of the upper airway obstruction can be assessed based on the VOTE classification mentioned previously.…”