抄録
Salivary gland function is primarily evaluated by observing biopsy tissue and by measuring the saliva collected by gum test and saxon test. However, biopsy is an invasive method of evaluation for the salivary gland. In addition, neither the gum test nor the saxon test can specify the disordered parts, as saliva of the parotid or submandibular gland is difficult to separate from the collected saliva, meaning that function of the salivary gland other than overall saliva secretion cannot be adequately evaluated. As an imaging method, salivary scintigraphy is one method for evaluating function. However, radiation exposure is unavoidable with this modality, as radionuclides are used. Magnetic resonance imaging (MRI) is noninvasive and requires no exposure to radiation. In addition, this modality can obtain morphological, biochemical and physiological information with high spatial resolution for soft tissues using magnetism and electromagnetic waves. We examined the utility of equivalent cross-relaxation rate (ECR) imaging (ECRI) for functional evaluation of the parotid gland to detect minute changes in organization and molecular structure, offering information reflecting interactions with water molecules and biomacromolecules using MRI. A total of 15 patients with head-neck cancer underwent both salivary scintigraphy and MRI. ECR values were compared between non-and post-radiated parotid glands. In addition, ECR value was compared with maximum uptake rate (MUR), a functional parameter obtained by salivary gland scintigraphy. A correlation was detected between ECR values and MUR. Moreover, ECR values were significantly elevated in the post-radiated parotid gland. ECRI is thus useful for detecting changes in organization and molecular configuration and for evaluating function of the parotid gland after radiotherapy.
