Article

A novel volumetric magnetic resonance imaging paradigm to study upper airway anatomy.

Center for Sleep and Respiratory Neurobiology, University of Pennsylvania Medical Center, Philadelphia 19104-4283, USA.
Sleep (Impact Factor: 5.06). 09/2002; 25(5):532-42.
Source: PubMed

ABSTRACT We utilized novel three-dimensional volumetric analysis techniques with magnetic resonance imaging (MRI) to study the upper airway and surrounding soft-tissue structures. These MRI techniques allowed us to objectively quantify the volume of the tongue, soft palate, parapharyngeal fat pads, and lateral pharyngeal walls.
We first validated our volumetric imaging techniques on a phantom and then demonstrated that our results were reliable and reproducible in normal subjects who did not lose weight. Finally, we studied 12 obese, nonapneic women during wakefulness before and after weight loss. We hypothesized that our novel magnetic-resonance computer-reconstruction techniques would allow us to detect small reductions in the volume of the tongue, soft palate, lateral pharyngeal walls, and parapharyngeal fat pads and increases in the volume of the upper airway with weight loss.
University medical center.
Normal controls and 12 obese nonapneic women.
Weight loss.
Following a mean 17.1+/-8.62 kg (17.3%) reduction in weight, upper airway volume increased (p = 0.06) in both the retropalatal and retroglossal regions. This increase in upper airway volume was mediated by significant reductions in the volume of the lateral pharyngeal wall (p = 0.0001) and parapharyngeal fat pads (p = 0.001). However, the volume of the tongue (p = 0.35) and soft palate (p = 0.39) were not reduced significantly with weight loss.
These data indicate that volumetric MRI is a powerful tool to study anatomic changes in the upper airway and surrounding soft-tissue structures and is sensitive enough to detect changes in these structures.

2 Bookmarks
 · 
145 Views
  • 48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition; 01/2010
  • [Show abstract] [Hide abstract]
    ABSTRACT: Study Objectives: (1) To determine whether facial phenotype, measured by quantitative photography, relates to underlying craniofacial obstructive sleep apnea (OSA) risk factors, measured with magnetic resonance imaging (MRI); (2) To assess whether these associations are independent of body size and obesity. Design: Cross-sectional cohort. Setting: Landspitali, The National University Hospital, Iceland. Participants: One hundred forty patients (87.1% male) from the Icelandic Sleep Apnea Cohort who had both calibrated frontal and profile craniofacial photographs and upper airway MRI. Mean +/- standard deviation age 56.1 +/- 10.4 y, body mass index 33.5 +/- 5.05 kg/m(2), with on-average severe OSA (apnea-hypopnea index 45.4 +/- 19.7 h(-1)). Interventions: N/A. Measurements and Results: Relationships between surface facial dimensions (photos) and facial bony dimensions and upper airway softtissue volumes (MRI) was assessed using canonical correlation analysis. Photo and MRI craniofacial datasets related in four significant canonical correlations, primarily driven by measurements of (1) maxillary-mandibular relationship (r = 0.8, P < 0.0001), (2) lower face height (r = 0.76, P < 0.0001), (3) mandibular length (r = 0.67, P < 0.0001), and (4) tongue volume (r = 0.52, P = 0.01). Correlations 1, 2, and 3 were unchanged when controlled for weight and neck and waist circumference. However, tongue volume was no longer significant, suggesting facial dimensions relate to tongue volume as a result of obesity. Conclusions: Significant associations were found between craniofacial variable sets from facial photography and MRI. This study confirms that facial photographic phenotype reflects underlying aspects of craniofacial skeletal abnormalities associated with OSA. Therefore, facial photographic phenotyping may be a useful tool to assess intermediate phenotypes for OSA, particularly in large-scale studies.
    Sleep 05/2014; 37(5):959-968. DOI:10.5665/sleep.3670 · 5.06 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Study Objective: Obstructive sleep apnea is prevalent among people with asthma, but underlying mechanisms remain unknown. Inhaled corticosteroids may contribute. We tested the effects of orally inhaled fluticasone propionate (FP) on upper airway (UAW) during sleep and wakefulness. Study design: 16-week single-arm study. Participants: 18 (14 females, mean [+/- SD] age 26 +/- 6 years) corticosteroid-naive subjects with mild asthma (FEV1 89 +/- 8% predicted). Interventions: High dose (1,760 mcg/day) inhaled FP. Measurements: (1) UAW collapsibility (passive critical closing pressure [Pcrit]); (2) tongue strength (maximum isometric pressure-Pmax, in KPa) and endurance-time (in seconds) able to maintain 50% Pmax across 3 trials (Ttot)-at anterior and posterior locations; (3) fat fraction and volume around UAW, measured by magnetic resonance imaging in three subjects. Results: Pcrit overall improved (became more negative) (mean +/- SE) (-8.2 +/- 1.1 vs. -12.2 +/- 2.2 cm H2O, p = 0.04); the response was dependent upon baseline characteristics, with older, male gender, and worse asthma control predicting Pcrit deterioration (less negative). Overall, Pmax increased (anterior p = 0.02; posterior p = 0.002), but Ttot generally subsided (anterior p = 0.0007; posterior p = 0.06), unrelated to Pcrit response. In subjects studied with MRI, fat fraction and volume increased by 20.6% and 15.4%, respectively, without Pcrit changes, while asthma control appeared improved. Conclusions: In this study of young, predominantly female, otherwise healthy subjects with well-controlled asthma and stiff upper airways, 16-week high dose FP treatment elicited Pcrit changes which may be dependent upon baseline characteristics, and determined by synchronous and reciprocally counteracting local and lower airway effects. The long-term implications of these changes on sleep disordered breathing severity remain to be determined.
    Journal of clinical sleep medicine: JCSM: official publication of the American Academy of Sleep Medicine 01/2014; 10(2):183-93. DOI:10.5664/jcsm.3450 · 2.93 Impact Factor

Full-text

Download
381 Downloads
Available from
May 21, 2014