#3 salivary gland imaging.pdf

Salivary Gland Imaging Dr. Rebuar Fadhil Radiology- 411 First semester Week No.4 INTRODUCTION Salivary glands: are composed of 4 major glands, in addition to minor glands. Major: •2 parotid glands. •2subman d-ibular gland Minor: •Sublingual. •Multiple minor glands PAROTID GLAND • The parotid gl...

Salivary Gland Imaging Dr. Rebuar Fadhil Radiology- 411 First semester Week No.4 INTRODUCTION Salivary glands: are composed of 4 major glands, in addition to minor glands. Major: •2 parotid glands. •2subman d-ibular gland Minor: •Sublingual. •Multiple minor glands PAROTID GLAND • The parotid gland is the largest salivary gland and is composed of adipose and glandular tissues in nearly equal proportions, making it appear nearly isodense/isointense to fat on computed tomography/magnetic resonance imaging (CT/MR) images. Important structure that run through the parotid gland: 1. Branch of facial nerve. 2. Terminal branch of external carotid artery that divided into maxillary & superficial temporal artery. 3. The retromandibular vein ( post. Facial ). 4. Intraparotid lymph node. THE PAROTID DUCT: • Stensen’s duct is 5 cm long. •open opposite the second upper molar tooth • It’s paired of gland that lie below the mandible on either side. • Has 2 lobes, superficial & deep. • Warthon’s duct, drained submandibular gland that opens into anterior floor of mouth. Anatomical relationship: 1. Lingual nerve. 2. Hypoglossal nerve. 3. Anterior facial vein. 4. Facial artery. 5. Marginal mandibular branch of facial nerve. • The submandibular gland is the second largest salivary gland and is located in the floor of the mouth adjacent to the posterior body of mandible along the free edge of the mylohyoid muscle. The amount of adipose tissue is relatively lower than that of parotid gland. SUBLINGUAL GLAND • Lie on the superior surface of the mylohyoid muscle and are separated from the oral cavity by a thin layer of mucosa. • The ducts of the sublingual glands are called Bartholin’s ducts. Sublingual Gland • Sublingual gland is the smallest major salivary gland. It lies submucosally adjacent to the anterior mandible in parasymphyseal location. The Wharton's duct and lingual nerve separate the sublingual gland from the medial genioglossus muscle. Sublingual Gland • It opens via multiple ducts usually 20 in number (known as ducts of Rivinus) directly into the floor of mouth along sublingual papillae and folds. 4. MINOR SALIVARY GLAND • About 450 lie under the mucosa • They are distirbuted in the mucosa of the lips, cheeks, palate, floor of mouth & retromolar area • Also appear in oropharyanx, larynx & trachea INDICATIONS OF IMAGING • The common clinical indications of salivary gland imaging are pain and swelling. Imaging is useful in identifying the masses of salivary glands and also in differentiating them from the masses/pathologies of adjacent cervical spaces, especially parapharyngeal, masticator, and submental spaces and mandibular lesions. • The disease of major salivary gland can be broadly categorized into the inflammatory, neoplastic, systemic, and congenital condition. IMAGING ARMAMENTARIUM FOR SALIVARY GLAND : • • • • • • Plain radiography Sialography High-resolution ultrasonography (HRUS) Computed tomography (CT) Magnetic resonance imaging (MRI) Radionuclide scintigraphy PLAIN RADIOGRAPHY • It is useful in detecting ductal calculi, calcifications (as in hemangioma and lymph nodes), and adjacent osseous lesions. • Parotid gland radiography requires posteroanterior projection with extended chin, open mouth, and cheeks blown out to delineate Stenson's duct lesion. Submandibular gland radiography requires posteroanterior and ipsilateral oblique projection with extended chin, open mouth, and tongue depressed by patients’ finger PLAIN RADIOGRAPHY Plain radiograph of the submandibular region in AP (A) and lateral oblique (B) projection showing soft tissue swelling associated with a small calculus (arrow) visible on lateral oblique view taken with depressed tongue PLAIN OCCLUSAL FILM • Effective for intraductal stones, while…. • intraglandular, radiolucent or small stones may be missed. SIALOGRAPHY • It refers to the evaluation of the ductal system of the salivary glands. It is considered the gold standard technique for studying the ductal morphology. It is commonly used for parotid and submandibular glands and its main indication is chronic sialadenitis unrelated to sialolithiasis SIALOGRAPHY Conventional sialography of submandibular (A) and parotid glands (B) showing ductal system • Sialography is rarely used for sublingual imaging because of numerous small ducts opening directly into the floor of mouth HIGH-RESOLUTION ULTRASONOGRAPHY • It is a quick and noninvasive method of evaluating parotid and submandibular glands • It helps in differentiating cystic from solid lesions and also aids in guiding the exact site of Fine Needle Aspiration Cytology (FNAC) in suspected salivary gland lesions. • Operator dependent, can detect small stones • (>2mm), inexpensive, non-invasive HRUS images showing normal parotid and submandibular glands (top row) and retromandibular vein in the parotid gland (arrow) CT AND MRI • These cross-sectional studies help in true and near complete imaging of the salivary glands • MRI, because of its multiplanar capability and higher soft tissue resolution, has an upper hand over CT in demonstrating the extent of lesion and their perineural/meningeal spread. However, CT (especially cone-beam CT) demonstrates the osseous lesions/extension and calcification/calculus better than MRI. Noncontrast CT may be enough in cases of sialolithiasis. • Large stones or small CT slices done Non-contrast axial CT image showing submandibular sialolithiasis on right side (white arrow) and normal gland on left side Non-contrast T2W axial & coronal images (top row) and T1W axial and coronal images showing parotid (thick white arrows) and submandibular glands (thin white arrow) Non-contrast axial CT image show normal appearing parotid (white arrows) gland in a young subject • These studies are often performed after intravenous injection of the contrast media for better delineation of the anatomy and the extent of lesion. Diffusion-weighted (DW) images and gadolinium-enhanced dynamic MR (Gd-MRI) imaging have proven to be very useful in differentiating benign from malignant tumors. Radionuclide Imaging • is useful preoperatively to determine if gland is functional. Inflammatory Diseases of Salivary Glands • Sialolithiasis • Sialolithiasis is the medical term for salivary gland stones. These stones, or calculi, are mostly composed of calcium, but they also contain magnesium, potassium, and ammonium.. • Conventional sialography, HRUS, and CT can detect sialolithiasis with a high degree of sensitivity. Sialadenitis • is a condition characterized by inflammation and enlargement of one or more of the salivary glands, the glands that secrete saliva into the mouth. There are both acute and chronic forms. Sialadenitis is often associated with pain, tenderness, redness, and gradual, localized swelling of the affected area. • Sialadenitis manifests as moderate to intensely enhancing, diffusely enlarged salivary gland with or without abscess formation, and intraparenchymal/regional lymphadenopathy on CT/MR imaging Contrast-enhanced axial CT image shows hypodense, enlarged right submandibular gland with calculus (thick white arrow) and thickening of adjacent fascia (thin white arrow) References • • Whaites, E. and Drage, N(2020). Essentials of Dental Radiography and Radiology(6th ed.). Elsevier Health Sciences. White, S.C. and Pharoah, M.J(2019). Oral Radiology Principles and Interpretation(8th ed.). Elsevier Health Sciences.