Study of low dose and dynamic multi-slice CT about obstructive sleep apnea syndrome in sleeping

Objective: To perform Low dose dynamic MSCT(multi-slice CT) in sleeping obstructive sleep apnea syndrome (OSAS) patients correcting the imprecise measure values in waking state, and to exactly analyse the location and extension of the dynamic changes about the condition. Methods: Sixteen OSAS patients were scanned both in waking and naturally sleeping period (end phase of inspiration and expiration). Measured at the narrowest part of the retropalatal (RP) and retroglossal (RG) and 5 mm under the tip of epiglottis at the epiglottal (EPG)at the end period of inspiration in sleeping, respectively, and compared the accurate position of the narrowest or occlusive level in 3 phases. All patients were also scanned using cine mode at the narrowest level at the end period of inspiration in sleeping to show the pharyngeal cavity changes during sleep. Results: The smallest XSA of RP region (Mw=47.50 mm2, Me=73.00 mm2, Mi=2.00 mm2; Zwe=2.897, Pwe=0.003; Zwi=4.192, Pwi<0.01; Zie=4.538, Pie<0.01) were statistical difference among three phases, furthermore, the AP(the anteroposterior diameter) of RP(Mw=8.00 mm, Me=9.50 mm, Mi=1.50 mm; Zwe=1.933, Pwe=0.056; Zwi=3.720, Pwi<0.01; Zie=4.230, Pie<0.01) and LR(the left-right diameter) of RP region (Mw=8.00 mm, Me=9.00 mm, Mi=1.00 mm; Zwe=1.210, Pwe=0.246; Zwi=4.203, Pwi<0.01; Zie=4.557, Pie<0.01) and the volume of RP (Mw=4.00 mm3, Me=5.50 mm3, Mi=1.50 mm3; Zwe=1.576, Pwe=0.125; Zwi=3.532, Pwi<0.01; Zie=4.077, Pie< 0.01) and the distance between the posterior wall and anterior vertebra of RP (Mw=7.00 mm, Me=6.00 mm, Mi=10.50 mm; Zwe=0.557, Pwe=0.603; Zwi=2.541, Pwi=0.011; Zie=2.852, Pie=0.004) and RG regions (Mw=5.00 mm, Me=3.00 mm, Mi=9.50 mm; Zwe=0.747, Pwe=0.482; Zwi=2.657, Pwi=0.007; Zie=3.075, Pie=0.001), were different between inspiration and expiration of sleeping or awake. The dynamic cine CT scan during sleeping could show pharyngeal change, clearly. Conclusion: At the end period of inspiration in sleeping, the location of narrow or obstructive of airway is the most precise and sensitive and the false negative at the waking could be obviously reduced. Low dose MSCT scan reduced exposure and expense. (authors)