Salivary gland imaging

Melbia Shiny

Introduction Major salivary glandsParotidSubmandibularSublingual

Minor salivary glandsLabial glandsLingual glands Von Ebner’s gland. Glands of Blandin’s and Nuhn’s. Buccal glandsPalatine glands (weber’s gland)

Evaluation of salivary glandsMain salivary gland complaints and causes1)Acute intermittent generalized swelling.SialolithiasisStricture/stenosisRecurrent juvenile parotitis2)Acute generalized swellingInfection – Viral,Bacterial

3)Chronic generalised swellingSjogren’s syndromeSialosisCystic fibrosisSarcoidosis4)Discrete swellingIntrinsic tumor – benign,malignant.Extrinsic tumorCystLymph nodes

5)Dry mouthSjogren’s syndromePost radiationMouth breathingDehydrationDrugsSystemic diseases

6)Excess salivationReflexHeavy metal poisoningSystemic diseasesParkinsonismEpilepsy

Physical examination

Inspection Intra oral inspection – duct orificeExtra oral inspection –

Colour,symmetry,pulsation,sinus discharge.Palpation Extra oral - Intra oralBimanual palpation

Differential diagnosis of enlargement in salivary gland1)Parotid area:UnilateralBacterial sialadenitisSialodochitisCystBenign neoplasmMalignant neoplasmIntraglandular lymph nodeMasseter muscle hypertrophyLesions of adjacent osseous structures

Bilateral Bacterial sialadenitisViral sialadenitisSjogren syndromeAlcoholic hypertrophyMedication induced hypertrophy(I, heavymetal)HIVMasseter muscle hypertrophyAccessory salivary glandTMJ related

2)Submandibular areaUnilateralBacterial sialdenitisSialodochitisFibrosisCystBenign neoplasmMalignant neoplasm

BilateralBacterial sialadenitisSjogren’s syndrome lymphadenitisBranchial cleft cystSpace infection

Imaging modalities

1)Plain radiography. Parotid - Intra oral view of cheek. Lateral oblique. Panoramic. Submandibular - lower 90 degree occlusal. lower oblique occlusal. Lateral oblique. Panoramic.

2)Sialography. Conventional sialography. MR sialography. CBCT sialography.3)Ultrasound.4)Computed Tomography.5)Multidetector computed tomographic imaging5)Magnetic resonance.6)Radioisotope imaging.7)Sialendoscopy.

Intra oral radiography For Wharton’s duct sialolith

In anterior 2/3 rd of submandibular duct

Mandibular occlusal view

Extraoral radiographyPanoramic view – both parotid & submandibular duct

sialolith.Lateral oblique view of submandibular gland (modified)

Parotid calculi AP view with cheek blown out. – sialolith in

distal portion

Conventional Sialography

Defined as radiographic demonstration of major salivary glands by introducing a radiopaque contrast medium into their ductal system.

Stones & strictures.First - 1902The preoperative phaseThe filling phase.The emptying phase.

Preoperative phase: scout radiographs.

Position of radiopaque obstruction.Position of normal anatomical structures.Exposure factors.

Filling Phase :

Filling phase:

Techniques:1)Simple injection.2)Hydrostatic.3)Continuous infusion pressure monitored.

Filling phase radiographs at two different views at right angles to each other.

Simple injection technique: oil based /aqueous contrast media .Gentle hand pressure till tightness

/discomfort is felt.Parotid – 1 ml,submandibular – 0.8 ml.Simple & cheap.Arbitary pressure - under or over filling due

to patient response.

Hydrostatic techniqueAqueous contrast media – overhead reservoir under

force of gravity.

Simple ,inexpensive.

Pt lying position and position for filling phase radiographs.

Continuous infusion pressure monitored technique:

Aqueous contrast media and ductal pressure monitored.No damage/overfilling of gland.Independent of pt response.

Complex equipment.Time consuming.

Emptying phase:

Removal of cannula & pt asked to rinse.Lemon juice aids in excretion.Emptying phase radiographs.

Submandibular gland

Contrast agents in sialography Iodine basedIonic aqueous solutionDiatrizoate(urografin).Metrizoate(triosil).Non ionic aqueous solutionIohexol (omniopaque).

Oil based solutionIodized oil (lipiodol)Water insoluble organic iodine

compounds(pantopaque).

Indications:1)The presence of calculi2)To assess extent of ductal & glandular destruction.3)To determine the extend of glandular breakdown and

crude assessment of function.

Contraindication:1)Allergic to iodine compounds.2)Acute infections3)Calculus close to the ductal opening.

The main pathological changes are:

Ductal changes associated with –CalculiSialodochitis (ductal inflammation).Glandular changes associated with – Sialadenitis.(glandular inflammation).Sjogren syndrome.Intrinsic tumours.

Sialographic appearance of calculi

Sialographic appearance of sialodochitis

Sialographic appearance of sialadenitis

Sialectasis – blobs /dots

Sialographic appearance in sjogren syndrome

Intercalated ductule & acinus

Sialographic appearance of intrinsic tumors

CBCT imagingUseful for evaluating structures in &

adjacent to salivary gland Cannot resolve soft tissue densities.Minimal calcified sialolith well depicted.Three D visualization possible.

CBCT SIALOGRAPHY IMAGING 3D reconstruction can be performed and the

ductal architecture viewed in all possible dimensions.

Information about measurements and location of sialoliths.

Highly reliable technique for identifying both radiopaque as well as radiolucent sialoliths and ductal strictures.

Less exposure dose and cost effective.

Lateral and axial view

Computer tomographyUseful for evaluating salivary

gland pathology,adjacent structures and proximity to facial nerve.

Calcified structures are visualized.

Abscess – hypervascular wall is evident.

Definition of cystic walls and contents.

Osseous erosions and sclerosis are visualized.

Sialolith

CT (contrast) images of enlarged parotid

Multidetector computed tomographic imaging

MRI

Provides superior soft tissue contrast resolution than CT.

Fewer problems with streak artifacts from metallic dental restoration.

Image – multiplanar reconstruction software algorithm.

iv contrast(gadolinium) – Differentiate cystic & solid masses.

MRI revealing lymphoepithelial cyst involving right parotid

MR sialographyMRI with evoked

salivation.Lemon juice –

stimulate salivation.Reveal ductal

morphology accurately ,sialolith identification

Alternative to conventional sialography.

Advantages Ionizing radiation not used.Excellent soft tissue details.Differentiate benign & malignant.Identify facial n.Images in all planes.Co- localization with PET scans.MR sialography – no contrast.MR spectroscopy – differentiate tissues by chemical

constituents.In acute stage & cannulation not possible.

DisadvantagesSalivary gland function cannot be

determined.Limited adjacent hard tissue information.

Ultrasound

High resolution scanners produce excellent images.Indications:Discrete & generalised swelling both intrinsic and

extrinsic to gland.Salivary obstruction.Differentiate solid masses from cystic ones.Guided fine needle aspiration biopsy.

*

Benign tumour Sialolith

Advantages

Ionisation radiation not used.Good imaging of superficial masses.Differentiates solid & cystic masses.Different echo signals from different tumoursBlood flow assessment using colour doppler.Identify radiolucent stones.Lithotripsy of salivary stones.Ultra sound aided fine needle aspiration.Intraoral US possible with small probes.Differentiates intra and extra glandular masses.

Disadvantages Limited area for investigation.No information on fine architecture.

Scintigraphy (Nuclear medicine, PET)Functional study of salivary glands.Iv injection of technetium 99m pertechnetate –

concentrated in and excreated by glandular structures (salivary, thyroid,mammary ).

Appearance in ducts max. 30 to 45 min.Sialagogue administered to evaluate secretory

capacity. major salivary glands studied at once.High diagnostic sensitivity but lacks specificity.Pathosis – increased/decreased/absent radionuclide

uptake.

• PET – greater resolution .• Not used as such.

•Increased uptake of radioisotope in right parotid.

SialendoscopySialendoscopy is a relatively new procedure that allows endoscopic transluminal visualization of major salivary gland ductal system and offers a mechanism for diagnosing and treating both inflammatory and obstructive pathology related to ductal system

Image interpretation of salivary gland disorders SIALOLITHIASIS

radiopaque / radiolucent.(mucous plugs).occlusal view, IOPA, Sialography.Radiolucent sialolith – ductal filling defect.MDCT – minimally calcified sialoliths.Ultrasound - > 2mm as echo dense spots with

acoustic shadow.

Submandibular calculi

Sialolith from phleboliths

Sialolith from tonsillolith

Sialolith from calcified lymphnode

Bacterial sialadenitis

Sialography contraindicated in acute infections.

Chronic cases – Sialectasia(sac like acinar areas). Abscess - seen inMDCT,US,MRI.

SialodochitisDuctal sialadenitis.Sialography – sausage string appearance

(interstitial fibrosis).Seen in MRI.Scintigraphy & CT not indicated.

Autoimmune SialadenitisSialography is helpful.Early stage – punctate (<1 mm) & globular

(1-2 mm) collection of contrast media – sialectasia.

Cavitary sialectases - larger & irregular suggestive of advanced stage.

MRI – multiple punctate sialectases.US – multiple hypoechoic areas.

SialadenosisIt is a non neoplastic,noninflammatory

enlargment of parotid gland.Sialography - enlargement /normal

appearance. CT & MRI – straightforward depiction

but are nonspecific.

Cystic lesions

Ultrasound - cyst are sharply marginated and echo free areas.

Well circumscribed ,high signal areas on T 2 weighted MRI.

Benign tumorsWell defined radiolucency - in CT & MRI.Contrast agents in CT - >radiopaque due to

increased vascularity of tumor.MRI - for submandibular gland neoplasm due

to superior soft tissue resolution.USG – benign masses are less echogenic

than parenchyma.Sialography – ball in hand.

Pleomorphic adenomaMDCT – sharply circumscribed ,round

homogenous lesion with high density than adjacent tissue.

MRI - dark in T 1 weighted images, intermediate in proton density weighted images & homogenous high intensity in T 2 weighted images.

Signal voids – calcification present.

Pleomorphic adenoma

Warthin’s tumor

MDCT – soft tissue /cystic density.MRI – heterogenous with hemorhagic foci.USG – solid anechoic.

HemangiomaAssociated with phlebolithsPlain radiographs and MDCT images.MDCT – well defined soft tissue mass.MRI – T1 (muscle adjacent) T2 – high signal.US – hypoechoic hemangioma,phleboliths as

multiple hyperechoic areas .

Malignant tumorsIndicators – illdefined margins,invasion of

adjacent soft tissues,destruction of osseous structures and perivascular involvement.

Mucoepidermoid carcinomaLow grade similar to

benign.High grade – in CT

(irregular homogenous mass).

In MRI – homogenous & dark (T1)

Heterogenous & bright (T2).

Other malignant & metastatic tumors

Adenoid cystic carcinoma

Conclusion Imaging of the salivary glands uses many

different modalities . no established absolute algorithm as to

which study should be performed.Depends upon the radiologist preference.

References1)Oral Radiology Principles and

Interpretation.Stuart White,Micheal Pharoah.2)Salivary gland disorders.Eugene

Myers,Robert Ferris.3)Oral and Maxillo facial radiology. Freny

Karjodkar.4)Textbook of colour atlas of salivary gland

pathology.Eric Carlson,Robert Ford.5)Atlas of oral diagnostic imaging.Tomomitsu

Higashi.6) Taneja et al. Salivary gland imaging.IJMDS.7)Yousem et al.Major salivary gland

imaging.Radiology.