Magnetic Resonance Imaging

MRI may be the best current mode of imaging for assessment of the upper airway and surrounding soft tissue and craniofacial structures (Figs. 1-4) (13-25). Advantages of MRI include that it: (i) achieves high resolution images of the upper airway and soft tissue; (ii) provides precise and accurate measurements of the upper airway and surrounding tissue; (iii) obtains multiplanar images in the axial, sagittal, and coronal planes; (iv) permits volumetric data analysis including three-dimensional reconstruction images of the upper airway and surrounding structures; (v) permits state-dependent imaging; and (vi) avoids radiation exposure allowing for repeat measurements. The shortcomings of MRI include that it: (i) is costly and not widely available; (ii) cannot be performed on patients with metallic implants such as pacemakers; (iii) has noise related to the machine that can be disturbing to sleep; and (iv) is difficult to perform in patients with claustrophobia and morbid obesity. Nonetheless, MRI studies have advanced our understanding of the pathophysiology of OSA as well as the mechanisms underlying effective treatments such as weight loss, CPAP, oral appliances, and upper airway surgery (13-16,18-20,23-27). The advent of ultrafast MRI techniques has

FIGURE 3 Mid-sagittal magnetic resonance imaging of a normal subject (left) and a patient with sleep apnea (right). The upper airway is smaller in both the retropalatal and retroglossal region in the apneic patient. The soft palate is longer in the apneic patient. The amount of subcutaneous fat (white area at the back of the neck) is greater in the apneic. Source: From Ref. 23.

FIGURE 3 Mid-sagittal magnetic resonance imaging of a normal subject (left) and a patient with sleep apnea (right). The upper airway is smaller in both the retropalatal and retroglossal region in the apneic patient. The soft palate is longer in the apneic patient. The amount of subcutaneous fat (white area at the back of the neck) is greater in the apneic. Source: From Ref. 23.

provided multiple images at multiple sites with sufficient image quality and temporal resolution to allow a dynamic assessment of the pharyngeal musculature (14,16,28).

Volumetric MRI appears to be a powerful tool to assess and measure anatomic risk factors for OSA. Schwab et al. (29) demonstrated that the volume of upper airway soft tissue structures is enlarged in patients with sleep apnea, even after controlling for volume of the parapharyngeal fat pads (Fig. 5). Furthermore, the volume of the tongue and lateral pharyngeal walls were shown to be particularly important independent risk factors for sleep apnea (29).

Sleep Apnea

Sleep Apnea

Have You Been Told Over And Over Again That You Snore A Lot, But You Choose To Ignore It? Have you been experiencing lack of sleep at night and find yourself waking up in the wee hours of the morning to find yourself gasping for air?

Get My Free Ebook


Post a comment