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salivary glands radiology. Definition of Salivary Gland Disease. Dental diagnosticians have responsibility for detecting disorders of the salivary glands A familiarity with salivary gland disorders and
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Definition of Salivary Gland Disease • Dental diagnosticians have responsibility for detecting disorders of the salivary glands • A familiarity with salivary gland disorders and applicable current imaging techniques is an essential element of the clinician ’ s armamentarium .
Clinical Signs and Symptoms • Diseases of the major salivary glands may have single or multiple clinical features. • Pain and altered salivary flow may be present. • The periodicity and longevity of these symptoms are important in the differential diagnosis, • a review of the medical history and physical condition of the patient may provide important information.
Differential Diagnosis Parotid Gland Area-of Salivary Enlargements
Differential DiagnosisSubmandibular Area-of Salivary Enlargements
Applied Diagnostic Imagingof the Salivary Glands • Diagnostic imaging of salivary gland disease may be undertaken to differentiate inflammatory processes from neoplasticdisease . • diffuse disease from focal suppurative disease, identify and localize sialoliths, and demonstrate ductalmorphologyanddetermine the anatomic location of a tumor, in addition , differentiate benign from malignant tumor .
PLAIN FILM RADIOGRAPHY • Plain film radiography is a fundamental part of the examination of the salivary glands and may provide sufficient information to preclude the use of more sophisticated and expensive imaging techniques . • It has the potential to identify unrelated pathoses in the areas of the salivary glands that may be mistakenly identified as salivary gland disease, such as resorptive or osteoblastic changes in adjacent bone .
PLAIN FILM RADIOGRAPHY • Panoramic and conventional posteroanterior (PA) skull radiographs may demonstrate bony lesions, thus eliminating salivary pathosis from the differential diagnosis. • Unilateral or bilateral functional or congenital hypertrophy of the masseter muscle may clinically mimic a salivary tumor. A plain film extraoral radiograph may demonstrate a deep antegonialnotch, overdeveloped mandibular angle, and exostosison the outer surface of the angle in cases of masseter hypertrophy. • Plain film radiographs are useful when the clinical impression, supported by a compatible history, suggests the presence of sialoliths (stones or calculi).
INTRAORAL RADIOGRAPHY • Sialoliths in the anterior two thirds of the submandibular duct are typically imaged with a cross-sectional mandibularocclusalprojection • The posterior part of the duct is demonstrated with an over-the-shoulder occlusalprojection view, where the directing cone is placed on the shoulder and central ray directed in an anterior direction through the angle of the mandible, with the patient ’ s head tilted to the unaffected side and rotated back . • Parotid sialoliths are more difficult to demonstrate than the submandibular variety as a result of the tortuous course of Stensenduct around the anterior border of the masseter and through the buccinator muscle. As a rule, only sialoliths anterior to the masseter muscle can be imaged on an intraoral film.
Underexposed mandibularocclusal radiograph demonstrating radiopaquesialolith inWharton duct. Note the classic laminated appearance.
Periapical radiographs of the same case. Theradiopaque calculus can be localized lingual to the teeth by applying appropriate object localizationrules
An axial bone algorithm CT image showing a sialolith in the submandibular duct (arrow).
EXTRAORAL RADIOGRAPHY • A panoramic projection frequently demonstrates sialoliths in the posterior duct or reveals intraglandularsialoliths in the submandibular gland. • The image of most parotid sialolithsis superimposed over the ramus and body of the mandible . • To demonstrate sialoliths in the submandibular gland, the lateral projection is modified by opening the mouth, extending the chin, and depressing the tongue with the index finger.
EXTRAORAL RADIOGRAPHY • Sialoliths in the distal portion of Stensen duct or in the parotid gland are difficult to demonstrate by intraoral or lateral extraoral views. However, a PA skull projection with the cheeks puffed out may move the image of the sialolith free of the bone .
Anteroposterior skull view with cheek blownout to provide air contrast to reveal a parotidsialolith(arrow).
CONVENTIONAL SIALOGRAPHY • First performed in 1902, sialography is a radiographic technique where a radiopaque contrast agent is infused into the ductalsystem of a salivary gland before imaging with plain films, fluoroscopy, panoramic radiography, conventional tomography, or CT. Sialography remains the most detailed way to image the ductalsystem . • The parotid and submandibular glands are more readily studied with this technique. • A survey or “ scout” film is usually made before the infusion of the contrast solution into the ductalsystem . • With this technique, Lipid-soluble (e.g., Ethiodol) or non –Lipid-soluble (e.g., Sinografi n) contrast solution is then slowly infused until the patient feels discomfort (usually between 0.2 and 1.5 ml).
CONVENTIONAL SIALOGRAPHY • These iodine-containing agents render the ductal system radiopaque, The image of the ductal system appears as “ tree limbs, ” with no area of the gland devoid of ducts. With acinarfilling, the “ tree ” comes into “ bloom, ” which is the typical appearance of the parenchymalopacification phase . • Non – lipid-soluble contrast agents are preferred because of reports of inflammatory reactions subsequent to inadvertent extravasation of lipid-soluble agents . • Sialographyis indicated for the evaluation of chronic inflammatory diseases and ductalpathoses. Contraindications include acute infection, known sensitivity to iodine-containing compounds, and immediately anticipated thyroid function tests.
SialographyA, Lateral projection of the parotid demonstrating opacificationall the way to the terminal ducts and acini. B, Anteroposterior projection of the same gland demonstrating“ parenchymal blushing ” from acinaropacification.
Sialogram of Normal Submandibular Gland. This lateralview demonstrates parenchymal blushing. Normal fine branching isvisible. Lack of parenchymal blushing at the anteroinferior margin iscaused by radiographic burnout.
COMPUTED TOMOGRAPHY • CT is useful in evaluating structures in and adjacent to salivary glands; it displays both soft and hard tissues and minute differences in soft tissue densities . • CT is useful in assessing acute inflammatory processes and abscesses as well as cysts, mucoceles, and neoplasia. Calcifications such as sialoliths are also well depicted with CT.
CT Images with Soft Tissue Algorithm. A, Axial viewdemonstrating bilateral enlargement of the parotid glands (arrowheads).B, Coronal view of the same patient. The clinical/histopathologicdiagnosis was autoimmune parotitis.
MAGNETIC RESONANCE IMAGING • MRI for soft tissue mass details and localization • Differanciates : • St vs. Ht • Normal vs. abnormal tissue • Identifies facial nerve ( parotid ) • Containdications: • -pacemaker • -cochlear implant .
These magnetic resonance images reveal a lymphoepithelial cyst involving the rightparotid gland. This axial T1-weighted image reveals a well-defined circular lesion involving the rightparotid gland with an internal signal isointense to muscle, and the matching T2-weighted image
reveals that the lesion has a high internal signal because of the fluid content
SCINTIGRAPHY (NUCLEAR MEDICINE, POSITRONEMISSION COMPUTED TOMOGRAPHY) • Selective up take of techntium • Asseseessilvary gland function (not anatomy) • Expel technetium after stimulations
Scintigraphy. A, 99m Tc-pertechnetatescan of the salivary glands (right and left anterioroblique views) demonstrates increased uptake ofradioisotope in the right parotid gland (blackarrowhead). B, Scintigram taken after administrationof a sialogog (lemon juice) demonstratesretention of isotope in right parotid gland (whitearrowheads). This is a typical presentation of salivarystasis, Warthin tumor, or oncocytoma.
ULTRASONOGRAPHY • For superficial , soft tissue swilling • Differentioates cystic vs. solid • Us-guide FNA
Ultrasonography (US) Image of Right Parotid Gland. Awell-delineated solid mass is suggested by echo returns within thelesion (arrows). US appearance is typical of a benign salivary tumor
Obstructive and inflammatory disorders • Sialolithiasis • Bacterial sialadenitis • Sialodochitis • Autoimmune sialadenitis
sialolithiasis ** calculus and salivary stones ** Formation of calcified obstruction within salivary gland duct ** Clinical features : Chronic retrograde infection Swelling and pain with eating Major or minor S.G Usually one S.G involved Submandibular S.G >> 83% of the cases
**Raiographic features : • Radiopaque : * Vary from cigar to oval or round shape * Homogeneous radiopaque internal structure • Radiolucent : ductal filling defect ** sialography is helpful when obstruction is undetectable on plain RG . ** CT may also detect minimally calcified sialoliths not visible on plain films.
Sialography should not be performed if a radiopaque stone has been shown by plain radiography to be in the distal portion of the duct • More than 90% of stones larger than 2 mm are detected as echo-dense spots in US images
D/D: phleboliths dystrophic calcification of LN palatine tonnsiliths Tx: • sialogogs to stimulate saliva secretion. • Sialography may also stimulate discharge . • Surgical removal of the sialolith • Removal of the whole involved S.G
Bacterial sialadentis • Parotitis and sabmandibulitis • Acute or chronic bacterial infection of terminal acini or parenchyma of S.G
Acute bacterial infections • most commonly affect the parotid gland • Most cases are unilateral • may occur at any age Clinical features : • swelling • redness • Tenderness • Malaise • Enlarged regional lymph nodes • suppuration may also be noted Untreated acute suppurative infections typically form abscesses.
Chronic bacterial infection : can affect any of major S.G causing extensive swelling and culminating in fibrosis may be a consequence of un-Tx acute sialadenitis or some types of obstruction . intermittent swelling, pain when eating, and superimposed infection resulting from salivary stasis
RG features : Sialography is contraindicated in acute infections • Epithelial flattening may lead to mildly dilated terminal ducts and saclike acini, which is demonstrable with sialography. • even distribution throughout the gland is seen in recurrent parotitis and autoimmune disorders US may distinguish between diffuse inflammation and suppuration • MRI is an appropriate alternative • examination in cases which sialography is contraindicated
Treatment • attention to oral hygiene • local massage • increased fluid intake • oral sialogogs (sour citrus fruit wedges or salivary stimulants). • antibiotic regimen may also be indicated. • surgical remedies ranging from partial to total excision of the gland
Sialodochitis • Ductalsialadenitis • inflammation of the ductal system of the salivary glands. • Clinical features : ** sialectasia or dilation of ductal system ** sausage-string appearance of the main duct and its major branches Tx : as tx of sialadenitis