Salivary gland disease chapter 32 .pptx

Chapter 32 white and pharoah

1. Chapter 32

2. Projection Imaging panoramic images : both parotid and submandibular sialoliths . Parotid sialoliths :over the mandibular rami superior to the occlusal plane submandibular sialoliths :superior to the hyoid bone near the antegonial notch of the mandible Cross-sectional mandibular occlusal images are best used to identify submandibular duct sialoliths projection images do fail at identifying noncalcified sialoliths , which are estimated to account for 40% of all parotid sialoliths and 20% of all submandibular sialoliths .

3. Ultrasonography initial assessment of the parotid and submandibular glands , especially when an abnormality is located superficially differentiating cysts from neoplasms benign from malignant lesions become more specific at detecting Sjögren syndrome still lacking in its ability to detect sialoliths Inability to detect deep salivary gland lesions

4. Multidetector Computed Tomography inflammation of the salivary glands Sialoliths : if they are relatively large and significantly Calcified cysts and neoplasms : but may not be reliable at distinguishing benign from malignant lesions . after intravenous administration contrast agent that renders glandular tissues hyperdense relative to the surrounding fat and muscle.

5. Magnetic Resonance Imaging imaging method of choice for assessment of space-occupying lesions (cyst and neoplasms): superior soft-tissue contrast modality of choice for evaluation of intracranial and perineural spread of disease: use of intravenous gadolinium as a contrast agent Detection of sialoliths , particularly when calcified, is problematic : signal voids

6. Nuclear Medicine functional examinations determined on the basis of variations in the rate of TPT uptake or clearance Warthin tumor distinctively demonstrates reduced TPT clearance highly sensitive : examination of all the major salivary glands at once it lacks specificity and resolution : assessment of the salivary gland morphology difficult.

7. Sialography assess both the morphology of the parotid and submandibular glands in addition their function rate of clearance of the contrast agent: indirect indicator of reduced secretory function MRI may be combined with sialography : patients’ own saliva is used as a contrast The primary indication for sialography is chronic inflammatory conditions , especially when obstruction is suspected contraindications: acute infection immediately anticipated thyroid function

8. Sialendoscopy direct visualization of the parotid and submandibular major ducts Diagnosis and management of obstructive conditions Acute inflammation is the only known contraindication

9. Conditions Affecting the Salivary Glands

10. Acute Bacterial Infections Clinical features: tender swelling of not only the infected gland but also the draining lymph nodes. A purulent discharge may also be noted at the orifice of the gland duct. Imaging features MDCT is the imaging of choice enlargement of the affected gland with peripheral enhancement streaking of the adjacent fat tissue thickening of the subcutaneous tissues Involved lymph nodes appear enlarged with a higher attenuation than normal abscesses appear as well-defined areas of low attenuation

11. Imaging features MDCT is the imaging of choice enlargement of the affected gland with peripheral enhancement streaking of the adjacent fat tissue thickening of the subcutaneous tissues Involved lymph nodes appear enlarged with a higher attenuation than normal abscesses appear as well-defined areas of low attenuation MRI is the second imaging modality of choice lower signal on T1 - weighted MRI and a higher signal on T2 -weighted images

12. Acute Viral Infections Clinical Features: malaise, myalgia, anorexia, and low-grade fever . Imaging Features: Imaging findings are nonspecific , MDCT images: enlargement of the glands and a slightly higher attenuation than normal slightly higher T2-weighted MRI signal than normal

13. Chronic Inflammation primary causes :salivary stones ( sialoliths ), ductal narrowing (strictures), and mucous plugs secondary causes : trauma to the ductal structures or spaceoccupying lesions impinging on the ductal structures . Approximately 83% of sialoliths form in the ducts of the submandibular glands: their tortuous upward path that ends in a relatively narrow orifice Viscous nature of submandibular saliva its high pH and high mineral content

14. Imaging Features Projection images: well-defined , mixed radiolucent and radiopaque or completely radiopaque entities Sialography : imaging modality of choice depict sialoliths (even small noncalcified ones ), strictures, and subtle changes in the delicate ductal structures sausage-like” appearance variably sized globular collections: abscess formation

15. Sialadenosis Sialadenosis or sialosis is a nonneoplastic , noninflammatory enlargement of primarily the parotid glands . bilateral involvement Causes of this condition include a variety of endocrine disorders such as diabetes mellitus, a number of nutritional abnormalities such asbchronic alcoholism,

16. Imaging features MDCT and MRI: nonspecific enlargements fibrous or fatty changes splaying of an otherwise normal ductal system

17. Autoimmune Sialadenitis early stages of the disease: Sialography: normal ductal system numerous punctate collections of contrast material distributed evenly throughout the gland are not evident on MDCT or MRI

18. Autoimmune Sialadenitis disease progresses: Sialography : ducts become narrow collections of contrast material become globular : pruning of the tree ” or “ leafless fruitladen tree” collections of contrast material remain MDCT: Enlarged and dense glands MRI: well-defined globular areas with low T1 signal intensity and high T2 signal intensity are seen throughout the gland

19. Postirradiation Sialadenitis bilateral swelling of the parotid glands progressive xerostomia Imaging features MDCT and MRI findings depend on the stage of the disease Early sialogram : flow voids in the parenchyma where atrophy of the acini has started to occur . Sialographic studies in late stages of the disease may not even be possible . Nuclear medicine examinations in the early stages reveal normal uptake but delayed excretion of TPT.

20. Cystic Lesions Sialocysts are true cysts retention cyst, mucous retention cyst, ductal cyst, and salivary ductal cyst. In contrast, a sialocele or mucocoele is a pseudocyst the term ranula is reserved for cysts of the sublingual glands regardless of whether the cyst is true(usually located in the oral cavity) or a pseudocyst (plunging below the mylohyoidmuscle ).

21. Imaging Features: indirectly visualized on sialography : “ ball-in-hand MDCT images: well-circumscribed nonenhancing low-attenuation areas MRI: well-circumscribed high-signal areas on T2 -weighted do not enhance after contrast administration

22. Benign Neoplasms parotid gland> minor salivary glands > submandibular gland> sublingual gland The likelihood of neoplasms of the salivary glands being benign varies directly with the size of the gland. Therefore most neoplasms of the salivary glands are benign or low-grade malignancies.

23. Imaging Features MRI : imaging modality MDCT is a reasonable imaging alternative well-defined margins and variable internal signal or attenuation, depending on the predominant tissue of the neoplasm Enhancement ball-in-hand appearance

24. Malignant Neoplasms sublingual neoplasms >minor salivary gland> submandibular> parotid glands Imaging features: Variable low-grade : similar to benign high-grade: ill-defined margins and invasion and destruction of adjacent structures