Salivary gland complaint	Cause
Acute intermittent generalized swelling	Obstructive disorders including: Sialolithiasis – salivary stones Stricture or stenosis of the duct, usually secondary to surgery, stones or infection Recurrent parotitis of childhood

Acute generalized swelling

Infection, either:

Viral, e.g. mumps

Bacterial-ascending sialadenitis

Chronic generalized swelling

Sjögren’s syndrome, either primary or secondary

Discrete swelling

Intrinsic tumour, benign or malignant

Extrinsic tumour

Cysts

Overlying lymph nodes

Dry mouth

Sjögren’s syndrome

Post-radiation damage

Mouth breathing

Dehydration

Functional disorders, including:

Drugs, such as tricyclic antidepressants

Neuroses, particularly chronic anxiety states

Excess salivation

Psychological (false ptyalism)

Reflex, e.g. due to local stimulation

Heavy metal poisoning

Investigations

Several investigations can be used on the salivary glands, the most appropriate often being decided by the patient’s presenting symptoms. The main investigations include:

• Plain radiography

• Sialography

• Ultrasound

• Magnetic resonance (MR)

• Radioisotope imaging

• Computed tomography (CT)

• Flow rate studies

• Biopsy.

Plain radiography

The most common disorder of the major salivary glands is obstruction caused either by salivary stones (calculi) or stricture of the ducts. A large proportion of salivary calculi are radiopaque (approximately 40–60% in the parotid and 80% in the submandibular glands) so patients presenting with obstructive symptoms of acute intermittent swelling require routine radiographs to determine the presence and position of the stone(s), as shown in Fig. 32.1.

Fig. 32.1 A Lower 90° occlusal showing a large radiopaque calculus (arrowed) in the right submandibular duct. B Part of a panoramic radiograph showing another calculus (arrowed) in the left submandibular gland. C Rotated AP with the left cheek blown out to ensure the calculus (arrowed) is not superimposed on the underlying bones.

The radiographic projections used commonly for the parotid and submandibular glands are summarized in Table 32.2.

Table 32.2

A summary of the commonly used radiographic projections for the parotid and submandibular glands

Salivary gland	Radiographic projections used
Parotid	Panoramic radiograph Oblique lateral Rotated PA or AP with cheek blown out Intraoral view of the cheek

Submandibular

Panoramic radiograph

Oblique lateral

Lower 90° occlusal (to show the duct)

Lower oblique occlusal (to show the gland)

True lateral skull with the tongue depressed

Rotated AP (below mandible)

Sialography

Sialography can be defined as the radiographic demonstration of the major salivary glands by introducing a radiopaque contrast medium into their ductal system. It is also very effective for the diagnosis of obstruction whether caused by stones or strictures. It is widely used and is probably still the most common specialized salivary gland investigation.

The procedure is divided into three phases.

• The preoperative phase

• The filling phase

• The emptying phase.

Preoperative phase

This involves taking preoperative (scout) radiographs, if not already taken, before the introduction of the contrast medium, for the following reasons:

• To note the position and/or presence of any radiopaque obstruction

• To assess the position of shadows cast by normal anatomical structures that may overlie the gland, such as the hyoid bone

• To assess the exposure factors.

Filling phase

The relevant duct orifice needs to be found clinically, probed and dilated, and then cannulated. This is shown in Fig. 32.2. together with a diagram of the normal anatomy of the major salivary glands and ducts. The contrast medium can then be introduced.

Fig. 32.2 A Diagram showing the normal anatomy of the parotid and submandibular salivary glands, ducts and duct orifices. B Clinical photographs showing these duct orifices (arrowed), being dilated and cannulated.

Three main techniques are available for introducing the contrast medium, as described later. When this is complete, the filling phase radiographs are taken, ideally at least two different views at right angles to one another.

Emptying phase

The cannula is removed and the patient allowed to rinse out. The use of lemon juice at this stage to aid excretion of the contrast medium is often advocated but is seldom necessary. After 1 and 5 minutes, the emptying phase radiographs are taken, usually oblique laterals. These films can be used as a crude assessment of function.

Contrast media used

The types of contrast media (see Ch. 18) suitable for sialography are all iodine-based, and include:

• Ionic aqueous solutions, including:

– Diatrizoate (Urografin^®)

– Metrizoate (Triosil^®)

• Non-ionic aqueous solutions, including:

– Iohexol (Omnipaque^®)

• Oil-based solutions, including:

– Iodized oil, e.g. Lipiodol^® (iodized poppy seed oil)

– Water-insoluble organic iodine compounds, e.g. Pantopaque^®.

Most radiology departments use aqueous solutions. Their relative advantages and disadvantages are summarized in Table 32.3.

Table 32.3

A summary of the advantages and disadvantages of oil-based and aqueous contrast media

Contrast	Advantages	Disadvantages
Oil-based	Densely radiopaque, thus shows good contrast High viscosity, thus slows excretion from the gland

Extravasated contrast may remain in the soft tissues for many months, and may produce a foreign body reaction

High viscosity means considerable pressure needed to introduce the contrast, calculi may be forced down the main duct

Aqueous

Low viscosity, thus easily introduced

Easily and rapidly removed from the gland

Easily absorbed and excreted if extravasated

Less radiopaque, less easy to see in fine ducts

Excretion from the gland is very rapid unless used in a closed system

Note: Since the contrast medium is not being introduced into the bloodstream, there is no need to use the safer, but more expensive, non-ionic contrast media discussed in Chapter 18.

Main indications

The main clinical indications for sialography include:

• To determine the presence and/or position of calculi or other blockages, whatever their radiodensity

• To assess the extent of ductal and glandular destruction secondary to an obstruction

• To determine the extent of glandular breakdown and as a crude assessment of function in cases of dry mouth.

Contraindications

The main contraindications include:

• Allergy to compounds containing iodine although gadolinium may be used as an alternative

• Periods of acute infection/inflammation, when there is discharge of pus from the duct opening

• When clinical examination or routine radiographs have shown a calculus close to the duct opening, as injection of the contrast medium may push the calculus back down the main duct where it may be inaccessible.

The control of infection measures detailed in Chapter 7 are of particular importance, and should be adhered to during sialography. In addition, the wearing of eye protection glasses and a mask by operators is recommended.

The three main techniques available for introducing the contrast medium into the ductal system, having cannulated the relevant duct orifice, include:

• Simple injection

• Hydrostatic

• Continuous infusion pressure-monitored.

These techniques can be summarized as follows:

Sialographic appearances in Sjögren’s syndrome include:

• Widespread dots or blobs of contrast medium within the gland, an appearance known as punctate sialectasis or snowstorm (see Fig. 32.10). This is caused by a weakening of the epithelium lining the intercalated ducts, allowing the escape of the contrast medium out of the ducts

Fig. 32.10 Sialograph of a right parotid gland of a patient with Sjögren’s syndrome. The main duct is normal and there are widespread dots or blobs of contrast medium throughout the gland, the *snowstorm* appearance of *punctate sialectasis*.

• Considerable retention of the contrast medium during the emptying phase

• The main duct is usually normal.

An understanding of the underlying disease processes explains why the sialographic appearances of sialadenitis and Sjögren’s syndrome (two totally different conditions) are so similar. This is shown diagrammatically in Fig. 32.11.

Fig. 32.11 Diagrams showing an intercalated ductule and acinus. A In a normal gland. B In Sjögren’s syndrome, the epithelium lining the intercalated ductule becomes weakened allowing escape of the contrast medium out of the duct so producing the dots or blobs. C In sialadenitis, the acinus becomes dilated allowing the collection of contrast into a dot or blob.

Sialographic appearances of intrinsic tumours include:

• An area of underfilling within the gland, owing to ductal compression by the tumour

• Ductal displacement – the ducts adjacent to the tumour are usually stretched around it, an appearance known as ball in hand (see Figs 32.12 and 32.13)

Fig. 32.12 **A(i)** Sialograph of a right parotid showing a large area of underfilling in the lower lobe (arrowed) caused by an intrinsic tumour (biopsy confirmed a pleomorphic adenoma). **A(ii)** Rotated AP view showing the lateral bowing and displacement of the ducts (arrowed) around the tumour. B Rotated AP view of a normal parotid gland for comparison (arrowed).

Fig. 32.13 A Sialograph of a right parotid gland showing a large area of underfilling in the lower lobe (arrowed) caused by an intrinsic tumour (pleomorphic adenoma). B Rotated AP view showing extensive ductal displacement, the appearance described as *ball in hand* (arrowed).

• Retention of contrast medium in the displaced ducts during the emptying phase.

Note: If modern imaging, e.g., ultrasound or CT, is available, sialography for intrinsic tumours is no longer performed.

Interventional sialography

Conventional sialographic techniques can be supplemented and expanded into minimally invasive interventional procedures by using balloon catheters and small Dormia baskets under fluoroscopic guidance. The balloon catheter, as the name implies, can be inflated once positioned within a duct to produce dilatation of ductal strictures. The Dormia basket may be used to retrieve mobile ductal salivary stones (see Fig. 32.14). Both these procedures are now being used successfully to relieve salivary gland obstruction without the need for surgery.

Fig. 32.14 **(i)** Fluoroscopic sialograph showing an open Dormia basket in the left submandibular duct. The stone has been captured and is inside the basket (white arrows). Contrast media is evident in the dilated main duct within the gland. (Kindly provided by Mrs J.E. Brown.) **(ii)** The Meditech (Boston Scientific) Dormia basket: A closed for insertion beyond the stone; B open ready to draw back; C open with the stone inside; and D closed around the stone ready for withdrawal.

Ultrasound

Ultrasound imaging of the salivary glands as shown in Fig. 32.15 is becoming increasingly common. Modern high resolution scanners produce excellent images and that coupled with the numerous advantages shown below has elevated ultrasound to the imaging modality of choice for many patients with salivary gland disorders, as shown in Figs 32.16–32.18.