|The parotid will be seen wrapping around the angle of mandible up to the tragus of the ear. An extension of the gland or accessory parotid lies medially on the cheek and is the landmark for the parotid duct.
||An accessory parotid gland can sometimes be seen just medial to the main parotid gland. This is the scan plane to visualise it.
Normal Parotid Gland
A normal lymph-node embedded within the Parotid gland.
The parotid gland is far more attenuative than the submandibular gland and may contain embedded lymphnodes. The submandibular gland forms earlier embryologically and should never contain other tissue.
U/S OF THE PAROTID GLAND - PROTOCOL
ROLE OF ULTRASOUND
Intraglandular and extraglandular lesions to be localised and differentiated.
To identify the cause of:
- A lump in the gland/neck. The patient can sometimes palpate a stone under the mandible.The stone can block the duct causing infection and swelling.
- Illness, including mouth or dental infections
- Mouth dryness
- Abnormality on previous xrays,CT or sialogram
- Guidance of injection, aspiration or biopsy
- Low collared shirt
- May have to remove jewellery
- Towel across the chest/shoulders
- Lie the patient so their head is at the top of pillow and neck extended.
- A pillow or towel can be placed under the shoulders.
EQUIPMENT SELECTION AND TECHNIQUE
- Use of a high resolution 7-14mHz linear transducer. You may need to use a lower frequency or curved linear probe (5-7MHz)to visualise the deep portion of the submandibular or parotid glands.
- Good colour / power / Doppler capabilities when assessing vessels or vascularity of a structure.
- Be prepared to change frequency output of probe (or change probes) to adequately assess both superficial and deeper structures.
- Tip the patient's head back for better access.
- Assess the gland's echogenicity. It should be hypoechoic with a homogeneous echotexture compared to the surrounding tissue, similar to a muscle's echogenicity.
- Due to it's fat content, the parotid will be more attenuative than the submandibular gland.
- Compare both sides if necessary.
- Scan the entirety of the gland from midline to lateral several times to assess :
- The size
- For increased vascularity
- Any abnormality in the surrounding anatomy including the lymph nodes.
- Duct dilatation (use Colour Doppler so you do not mistake a vessel to be a dilated duct)
- The Parotid duct runs from the deep gland to the ampulla adjacent to the upper 2nd molar tooth.
- The Duct starts from the level of the ear-lobe and courses across the cheek via the accessory parotid gland. Tthe duct generally will not be visible unless dilated.
- The Kuttner lymph node is a normal, prominant lymph node between the parotid and submandibular gland.
BASIC HARD COPY IMAGING
A salivary gland series should include the following minimum images:
- Submandibular gland, Long & trans
- Submandibular duct
- Parotid gland, long & trans
- Accessory parotid gland
- Right side of the neck and lymph nodes
- Left side of the neck and lymph nodes
- Document the normal anatomy. Any pathology found in 2 planes, including measurements and any vascularity