Diagnostic work-up in obstructive and inflammatory salivary gland disorders

Abstract

Inflammatory and obstructive disorders of the salivary glands are caused by very different pathological conditions affecting the gland tissue and/or the excretory system. The clinical setting is essential to address the appropriate diagnostic imaging work-up. According to history and physical examination, four main clinical scenarios can be recognised: (1) acute generalised swelling of major salivary glands; (2) acute swelling of a single major salivary gland; (3) chronic generalised swelling of major salivary glands, associated or not with "dry mouth"; (4) chronic or prolonged swelling of a single major salivary gland. The algorithm for imaging salivary glands depends on the scenario with which the patient presents to the clinician. Imaging is essential to confirm clinical diagnosis, define the extent of the disease and identify complications. Imaging techniques include ultrasound (US), computed tomography (CT) and magnetic resonance (MR) with MR sialography.

Keywords: MR sialography; MRI; Salivary glands; Sialadenitis; Sialolithiasis.

Fig. 1.

Acute parotid sialadenitis (A). Enlarged, hypoechoic parotid gland (arrows), colour Doppler shows increased blood flow. Parotid gland abscess (B). US demonstrates a heterogeneous hypoechoic collection (abs) within the parotid gland: internal echoes, poorly defined borders and posterior acoustic enhancement (arrows).

Fig. 2.

Obstructive sialadenitis. On US, the submandibular gland (smg) appears enlarged and hypoechoic (A). Highly reflective echogenic focus within the Wharton's duct (arrow) with prominent posterior acoustic shadowing (arrowheads), consistent with a sialolith (B).

Fig. 3.

Obstructive sialadenitis complicated by extra-glandular abscess, contrast-enhanced CT. (A) The bone window image demonstrates a mineralised stone (arrow) within the right Wharton's duct. (B-D) The soft tissue window images show enlargement of the right submandibular gland (black asterisk), thickening of the submandibular fat tissue producing a "dirty fat" appearance. At the level of the neck swelling (arrowheads), CT demonstrates an abscess (white asterisks) in the submandibular space. The calculus is shown also the coronal plane (arrow).

Fig. 4.

Focal obstructive sialadenitis. MR axial SE T1 (A), TSE T2 (B), VIBE after contrast administration (C), DWI b1000 (D) with ADC map (E); sialo-MR (maximum intensity projection in the sagittal plane) (F). Sudden onset of painful swelling of the right parotid gland. The focal inflamed area (arrows) can be detected because of its mass-effect on the adjacent gland tissue (asterisks), greater post-contrast enhancement and diffusion restriction. The MR sialography shows a filling defect (arrowhead) and intraglandular duct ectasia.

Fig. 5.

Bilateral benign parotid lymphoepithelial cysts in a HIV-positive patient. MR TSE T2-weighted sequences on the coronal (A) and axial (B) planes. Multiple cystic lesions in the parotid glands, among which a high-protein content cyst (white asterisk) and a cyst extending in the right parapharyngeal space reaching the lateral wall of oropharynx.

Fig. 6.

Sjögren's syndrome – intermediate disease. MR TSE T2-weighted sequences on the axial (A) and coronal (B) planes. Bilateral parotid tiny ductal dilatation, particularly evident on the right.

Fig. 7.

Lymphoma of mucosa-associated lymphoid tissue (MALT) in a patient with primary Sjögren's syndrome. MR TSE T2 (A), VIBE after contrast administration (B), DWI b1000 (C) with ADC map (D). MR scan shows a lesion of the superficial portion of the parotid gland (black asterisk), displacing the remaining part of the gland (dashed line), with enhancement and high diffusion restriction. A second lesion with similar features is evident at the anterior extension of the gland (white asterisk).

Fig. 8.

Wharton's duct sialolithiasis. MR TSE T2 (A), SE T1 (B) and MR sialography (maximum intensity projection in the axial plane) (C). Hypointense mineralised stone in the left Wharton's duct, to which corresponds a filling defect on sialo-MR (arrows); moderate ducts dilatation (arrowheads).

Fig. 9.

Stensen's duct sialolithiasis. Cone-beam CT (A) and MR sialography (maximum intensity projection in the axial plane) (B). Highly mineralised stone in the left Stensen's duct, corresponding to a filling defect on MR sialography (arrow) causing a marked dilatation of the ductal system (arrowheads); dilatation of the contralateral ductal system is also evident.

Fig. 10.

Mucopyocele. MR TSE T2 (A) and post-contrast VIBE (B). Spherical lesion within the soft tissues of the lip with ring-enhancement and hypointensity on T2, corresponding to a mucopyocele of a labial gland (arrow).

Fig. 11.

Plunging ranula. TSE T2, coronal plane (A-C, anterior to posterior), TSE T2 with fat-saturation, axial plane (D). MR shows a defect of the mylohyoid muscle (arrow) with sublingual gland (white asterisk) herniation. Note the normal appearance of the contralateral and ipsilateral (in a posterior slice) mylohyoid muscle (arrowheads). Plunging ranula (black asterisks) extends posteriorly in the submandibular space.