Fig. 3. Three-dimensional magnetic resonance imaging reconstructions of subjects with ( a, b ) positional obstructive sleep apnea syndrome (OSAS); ( c, d ) nonpositional OSAS; and ( e, f ) control subjects. ( a, c, e ) Lateral pharyngeal wall, tongue, and pharyngeal airway with outline of the face, posterosuperior view; ( b, d, f ) lateral pharyngeal wall, tongue, and craniofacial structures (mandible and lower part of maxilla), anterosuperior left oblique view. Green = lateral pharyngeal wall; red = tongue, red; yellow = upper airway space; blue web = craniofacial structures. Note that positional OSAS had relatively small volume of the lateral pharyngeal wall and the smallest craniofacial volume; nonpositional OSAS had relatively large craniofacial volume and the largest volume of the lateral pharyngeal wall; the control subjects had the largest craniofacial volume and the smallest volume of the lateral pharyngeal wall.