SIALOGRAPHY-CONVENTIONAL, CT, MRI

Shivaprakash.B.H

PG-BIR

SIALOGRAPHY• Sialography is an invasive

procedure in which radiopaque contrast material is injected retrograde into ductal system via the intraoral opening of either Wharton’s or Stensen’s duct.

• Sublingual glands unlikely to be imaged due to difficulty in the cannulation

Ductal anatomy

• Parotid duct’s normal luminal caliber is only 1 to 2 mm, and on a direct conventional posteroanterior film, the duct should lie within 15 to 18 mm of the lateral mandibular cortex

• Normally, the ducts do not lie parallel to one another in any plane

• Wharton’s duct is seen to run downward and laterally at about a 45° angle to both the sagittal and horizontal planes.

Indications

• Sialolithiasis• Infectious diseases• Neoplastic or tumour like

conditions• Auto immune disorders• Trauma and its complications• As a dilatation procedure rarely

in mild ductal stenosis

Contraindications

• Acute suppurative or inflammatory conditions of salivary gland

• Previous reaction to contrast in sialography

• Anticipated thyroid investigations

Pre-procedure

• Procedure is to be explained • Consent to be taken for the

procedure• No pre-procedure stipulations

Equipments • Fluoroscopic unit w/spot film

capabilities• Cannula for introducing contrast• Connecting tubing• Lemons• Dilators for duct• 5 mL syringe• Overhead light• Gauze• Contrast

Catheters usually used.

Contrast agents

• Fat soluble-Pantopaque,Ethoidol (39% bound iodine,ethiodised poppy seed oil)

• Water soluble contrast with high iodine is preferred when available.Sinograffin(38% bound iodine,diatrizoate meglumine)

• Water soluble contrast materials donot produce adequate visualisation of the ductal system due to rapid diffusion and dilution by saliva,absorption of contrast into the blood stream.

Conventional sialography (technique)• Identify the orifice of ductal

system to be studied.• Dilatation can be done by

lacrimal probes.• Curved blunt needle with olive

1cm from the tip is preferred prevents over penetration & backflow of contrast media

Catheter introduced co-axially introduced into the salivary duct

• Connecting tubing is attached to the needle & is anchored to the corner of the mouth.

• 1 to 1.5 ml of contrast is injected (parotid) n 0.2 to 0.5 ml (submandibular).

• Examination is performed under flouroscopic guidance, multiple well coned spot sialograms in multiple projections at various stages of filling of ductal system.

• Upon opacification of the gland parenchyma with fluffy,cloudy contrast stain conventional overhead roentgenograms in anteroposterior,lateral and oblique projections are taken.

• Films are checked for technical adequacy and the tube is removed.

• Sialogogue(lemon juice) to stimulate salivary secretion is used.

• Overhead roentgenograms are taken in conventional position after 10 to 15 minutes,to evaluate the degree of evacuation of injected contrast.

Lateral Submandibular Set-Up

Parotid Radiographs Set-Up

Phases of sialography• Filling phase absence of normal ductal filling

can be due to, a. complete obstruction of the

main duct by an impacted stone or cicatricial obstruction;

b.invasion of the main duct by neoplasm;

c.catheter positioning with the catheter tip beyond the wall of the main duct or an acutely kinked segment of the main duct.

• Parenchymal opacification phase Injection of contrast material

under fluoroscopic control is carried to the stage where filling of the acini can be recognized.

• This phase of examination is mainly useful for two conditions

a.Subacute autoimmune sialosis• there is diffuse parenchymal

edema with consequent elevation of the pressure in the acini.Acinar filling may be impossible by the retrograde sialographic technique.

b.peripheral intraglandular space occupying lesion

• Lesions of this type can be easily missed by duct system opacification only

• Post evacuation phase complete evacuation on

sialogogue stimulation is noted in normal salivary glands with active salivary secretion.

• If contrast remains in the portion of the gland even after 24 hrs its distinctly abnormal.

• If contrast material is noted out of the confines of the ductal system or the acini it may be due traumatisation secondary to faulty technique,or disease such as invasive neoplasm or inflammatory process.

• Complete evacuation may be delayed in the presence of stricture in the ductal system

• Contrast may also remain in duct & acini due to absence of secretion by the salivary gland.

Normal sialograms

Parotid sialogram

Both parotid & submandibular sialograms

Calculus

Stenosis

Sialodochitis

Sialosis

Sjogren’s syndrome

Neoplasms

Trauma

CT sialography

• CT is better than conventional for delineation of calculi and various calcifications.

• Cannulation of the duct is same as in conventional sialography

• Axial sections are obtained in chin elevated position

• In case of dental fillings,semi-axial projections with gantry tilted to 15-20 degree

• CT parameterso 3 mm spiral acquisitions

reconstructed at continuous 3 mm intervals

o Pitch of 1o 170 to 280 mA & 120 kV

o Axial sections are obtained from skull base at the level of external auditory canal to the level of mid-thyroid cartilage.

o Imaging prior to contrast injection is necessary for the baseline image.

MR sialography• ionizing radiation,dependence

on the operator’s technical skills for successful ductal cannulation, and the need for retrograde injection of contrast material are relative drawbacks of conventional sialography. Potential complications include rupture of the ductal system,

• activation of a clinically quiescent infection, and adverse reactions to contrast material. Catheter manipulation or the pressure of injection of contrast material may also result in the displacement of an anteriorly placed ductal stone into a position in which its retrieval by means of endoscopy or intraoral surgery becomes more difficult or even impossible.

• MR sialography is based on the principle that stationary fluids are hyperintense on heavily T2-weighted images.

• No specific preparation• Need to breathe quietly and

refrain from coughing or vigorous swallowing during image acquisition.

• Rapid sagittal, coronal, and axial localizers were obtained to facilitate section positioning.

• MR sialographic images were obtained in a axial plane parallel to the hard palate and in a sagittal-oblique plane parallel to either the Wharton or Stensen duct.

Available MR sequences

• RARE (Rapid acquisition with relaxation enhancement)

• GRASE (Gradient and spin echo sequence)

• HASTE (Single shot turbo spin echo)

• 2D-FSE (2D fast spin echo)• 3D-FSE (3D fast spin echo)

sialolithiasis and shows the distal displacement of the calculus (longstraight arrow) caused by active filling of the ductal system

SIALOLITHIASIS

SJOGREN’S

Sagittal oblique-WARTHIN’S

To summarise

• Sialography is a valuable diagnostic procedure in the work-up of disease conditions of the major salivary glands

• A complete sialographic examination should include 3 stages:

a. Filling stage performed under fluoroscopic control and spot filmed during the initial visualization of the duct system

b. Parenchymal opacification stage for the study of the gland parenchyma beyond the duct system

c. Postevacuation stage for the study of secretory activity of the gland and to detect any destruction of the walls of the duct system or the acini.

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