Mark E Wagshul PhD, Presenter: Nothing to Disclose

Sanghun Sin PhD, Abstract Co-Author: Nothing to Disclose

Michael L. Lipton MD, PhD, Abstract Co-Author: Nothing to Disclose

Keivan Shifteh MD, Abstract Co-Author: Nothing to Disclose

Raanan Arens MD, Abstract Co-Author: Nothing to Disclose

Obstructive sleep apnea syndrome (OSAS) is a growing public health problem affecting children and adolescents, linked to the rapidly rising prevalence of obesity in these age groups. Transient upper airway obstruction during sleep as well as during wakefulness leads to a host of physiological, cognitive and social problems in OSAS patients. We have developed a novel approach to capture the dynamics of airway anatomy across the respiratory cycle toward fully understanding this disorder.

We employed 3D gradient echo imaging (TE/TR = 3.5/7.5 ms, FA = 8o, 10 cine frames), with 1.1 mm isotropic voxel resolution, to cover the entire extent of the upper airway. Dynamic respiratory information, with 300 ms temporal resolution, was achieved with retrospective gating on the flow waveform, collected from a pressure transducer coupled to a nasal cannula. A novel gating scheme was developed, transforming the arrhythmia rejection feature normally used for retrospective cardiac gating into a rejection method for respiratory cycles based on a flow tidal volume. We demonstrated the feasibility of the technique on a 3T Philips Achieva in twelve healthy controls and one OSAS patient.

Using the 3D retrospective gating approach, we obtained excellent signal-to-noise ratio images, with isotropic resolution which will allow arbitrary direction 3D reconstruction, an important feature for future work in finite element analysis of upper airway dynamics. Motion of the epiglottis and soft palate are clearly seen in the cine images. Quantitative information of airway size and shape over the respiratory cycle was easily obtained from single-slice, 1 mm thick axial reconstructions.

OSAS is a major health problem. Our novel gating technique based on real-time tidal volume measurement will allow future studies of airway dynamics during abnormal or apnic respiratory periods. The ability to monitor airway dynamics will provide information about the underlying pathophysiology of this syndrome.

High contrast, dynamic visualization of upper airway motion is feasible and will help uncover the functional mechanisms responsible for airway obstruction in sleep apnea patients.

Wagshul, M, Sin, S, Lipton, M, Shifteh, K, Arens, R, Respiratory-gated 3D Dynamic Imaging of the Upper Airway and Applications to Sleep Apnea.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11005775.html