Читать книгу Salivary Gland Pathology - Группа авторов - Страница 73

Ultrasound is performed infrequently for head and neck imaging relative to CT and MRI. Although US can depict normal anatomy and pathology in the major salivary glands, it is limited in evaluation of the deep lobe of the parotid and submandibular gland (Figures 2.16 and 2.17). US is operator dependent and takes significantly longer to perform on bilateral individual salivary glands when compared to contrast‐enhanced CT of the entire neck. US is quite effective at delineating cystic from solid masses, and determining degree of vascularity. US can be used to image calculi and observe the resulting ductal dilatation. Normal lymph nodes and lymphadenopathy can also be reliably distinguished. US can be used to initially stage disease. It is not, however, optimal for post‐therapy follow‐up, be it radiation or surgery. When compared with CT or MRI, US significantly lacks in soft‐tissue resolution and contrast. Because of its real‐time imaging capability and ease of handheld imaging, US is quite good at image‐guided fine needle aspiration and biopsy. The application of color Doppler or power Doppler US can distinguish arteries from veins, which are critical for image‐guided biopsy (Figures 2.18 and 2.19). Eighteen‐gauge core biopsies of the parotid may be safely performed under US guidance (Wan et al. 2004).

Figure 2.16. Ultrasound of the submandibular gland (black arrow) adjacent to the mylohyoid muscle (white arrow).

Figure 2.17. Ultrasound of the parotid gland demonstrating a normal intraparotid lymph node on a hyperechoic background. The lymph node is round and has a hypoechoic rim but demonstrates a fatty hyperechoic hilum (arrow).

Figure 2.18. Ultrasound of the parotid gland in longitudinal orientation demonstrating the Doppler signal of the external carotid artery.

Figure 2.19. Ultrasound of the parotid gland in longitudinal orientation demonstrating the Doppler signal of the retromandibular vein.