Assessment of post-radiotherapy salivary glands

Abstract

Salivary glands are usually irradiated during radiotherapy for head and neck cancers, which can lead to radiation-induced damage. Radiation-induced xerostomia (oral dryness) is the most common post-radiotherapy complication for head and neck cancer patients and can reduce the patient's quality of life. Accurate and efficient salivary gland assessment methods provide a better understanding of the cause and degree of xerostomia, and may help in patient management. At present, there are different methods for the assessment of salivary gland hypofunction; however, none of them are considered to be standard procedure. This article reviews the value of common methods in the assessment of post-radiotherapy salivary glands.

Figure 1

Schematic diagram shows the relative position of parotid gland (P) and submandibular gland (S) in the head and neck region. The parotid gland is located in the retromandibular fossa while the submandibular gland is located under the mandible and in the floor of the oral cavity.

Figure 2

Sonogram shows a transverse scan of a normal parotid gland (arrowheads), which is hyperechoic compared with the adjacent masseter muscle (arrows).

Figure 3

Sonogram shows a longitudinal scan of a normal parotid gland with homogeneous echotexture. The intraglandular ducts (arrows) are marginally seen.

Figure 4

Sonogram shows a transverse scan of a normal submandibular gland (arrowheads) with homogeneous echotexture. The gland is hyperechoic compared with the adjacent mylohyoid muscle (black arrows) and the intraglandular ducts (white arrows) are marginally seen.

Figure 5

Sonogram shows a longitudinal scan of a parotid gland in a patient treated with conventional radiotherapy. There are multiple hypoechoic areas (arrows) within the gland, and the intraglandular ducts (arrowheads) are obviously seen.

Figure 6

(a) Axial CT scan of skull in a nasopharyngeal carcinoma patient before radiotherapy. The image density of the parotid gland (P) is about the same as the adjacent masseter muscle (M). (b) Axial CT scan of a skull in the same patient after radiotherapy. There is an increased image density of the parotid gland (P) when compared with the pre-radiotherapy scan. The image density of the parotid gland is greater than that of the adjacent masseter muscle (M).