Cine MR Imaging Research On Upper Airway In Children Without Respiratory Symptoms During Sleep

Background and Objective：With the development of Sleep Medicine in rencent years, sleepdisorder has been increasingly recognized as a serious problem which mayaffect the growth and development of children. Obstructive sleep apneahypoventilation syndrome(OSAHS) is the most common and serious sleepdisorder in children. The diagnosis of OSAHS usually relies on thepolysomnography during the whole night, nasopharyngolaryngoscope,traditional cervical radiography in lateral view, and computed tomography.These methods have more or less disadvantages, including invasion,radiations, and obscurity. Recently, with the development of magneticresonance imaging, cine MR imaging has been applied in the evaluatin ofOSAHS. In reviewing the domestic literature, no report about cine MRimaging applied to evaluate the upper airway in children were found.The purpose of this study is to establish the normal reference range ofupper airway in asymptomatic children from2to7years during sleep byusing Cine MR imaging, and make a foundation for further study of airwayand related diseases in children. Methods：One hundred and twelve subjects were recruited from a population ofpatients from2to7years (mean age,4-year-old) who were referred for MRimaging of the brain in the Department of Radiology of Chong QingChildren’s Hospital. All of these children were screened by questionnairesurvey and clinical interview about sleep, and112subjects including69boys and43girls without respiratory symptoms were included in this study.A sagittal and transverse midline cine MR sequence and fast SE IRsequence were performed. Motion of the nasopharynx, oropharynx, andhypopharynx was characterized as static patent, dynamic patent,intermittent collapse, or static collapsed, and maximal diameter andgreatest change in size were calculated. Mouth position(open or closed)was determined, and the parameters of each segment of upper airway intwo mouth positions were compared. Meanwhile, the most commonunderlying anatomic causes of obstructive sleep apnea, including adenoidtonsils, palatine tonsils and abnormalities of the soft palate, wasdetermined.Results：1In112subjects, dynamic motion was detected in the hypopharynxin50(44.6%), in the nasopharynx in44(39.3%), and in the oropharynx onlyin8（7.2%）. The mean dynamic motion is2.5mm（ranged from0.5mm to 7.1mm） in hypopharynx，2.1mm（ranged from0.5mm to4.6mm）innasopharynx，and2.8mm（ranged from0.5mm to5.0mm） in oropharynx.2In the50subjects who showed dynamic patent of the hypopharynx,The main manifestation included isolated posterior motion of the tongue in5(10%), motion of the posterior wall of the pharynx in26(52%), andposterior motion of the tongue combined with motion of pharyngealposterior wall in19(38%).3In the112subjects, there was no difference in the frequency ofdynamic motion of the hypopharynx between those with open mouths andthose with closed mouths. Yet, there was a statistically significantcorrelation between mouth position and dynamic motion in thenasopharynx(p=0.0005) and in the oropharynx(p=0.00024).4The size of adenoid tonsils was10.6+2.1mm，in which7(6.3%)were larger than12mm. The signal of soft palate was similar to that oftongue. The soft palate was found adjacent to the tongue in9(8.0%), and noone was detected extending inferiorly beyond the middle level of thetongue.Conclusion:1MRI and cine MR imaging can be used as an ideal modality toevaluate and measure the upper airway and sleep-related airway diseases inchildren.2Dynamic motion of the upper airway is commonly encountered in children without sleep disorder，and it should be considered as a normalfinding. The dynamic motion of the upper airway is less than5mm.3The main manifestation of the hypopharynx include isolatedposterior motion of the tongue, motion of the posterior wall of the pharynxand in conjunction with posterior motion of the tongue. Isolated posteriormotion of the tongue should be considered with greater suspicion aspossibly indicating an abnormality.4The frequency of dynamic motion of the nasopharynx andoropharynx in those with open mouths is higher than in those with closedmouths.