Alternative radiographic modalities Flashcards
Why might imaging of the salivary glands be indicated?
Obstruction (mucous plugs, stones, neoplasia)
Xerostomia
Swellings
What makes ultrasound suitable for investigating salivary glands?
Glands are superficially located, other than the deep lobe of the parotid.
Can assess ductal dilation and vasculature.
Can give sialogue to aid salivary flow (citric acid)
What is ultrasound scanning?
An imaging modality utilising no ionising radiation, and using high frequency sound waves instead.
A coupling agent is required to help the sound waves get into the tissue.
Outline the imaging protocol for investigating major salivary stones?
Ultrasound
True mandibular occlusal radiograph
Sialography
What are the common symptoms of sialoliths (salivary gland stones)?
“Meal time symptoms”
Prandial swelling and pain
“rush of saliva into the mouth”
Bad taste
Thick saliva
Dry mouth
Describe the aetiology of sialoliths.
Aetiology
– Sialolith or mucous plug
– 80% sialoliths associated with the submandibular gland
– 80% of submandibular stones are radiopaque
What is sialography?
Injection of iodinated radiographic contrast into salivary duct to look for obstruction.
Done either with Panoramic (DPT), skull views or Fluoroscopic approach.
Very small volume of contrast injected (1.0- 1.5ml)
What are the indications for sialography?
Look and diagnose stricture location.
Planning for future surgical intervention such as basket retrieval or ballon catheter widening.
What are some of the risks of sialography?
Discomfort
Swelling
Infection
Allergy to contrast (very rare)
When should you consider ultrasound of minor salivary glands?
Only need to image if enlarged or pathological
Usually ultrasound if superficial.
MRI beneficial if deeper or possible bony involvement.
In general, minor salivary glands have higher chance of malignancy if pathological than a lesion in the major salivary glands.
Ranula? Lipoma? look that shit up
What imaging methods can be used for hard tissue/bony imaging?
CBCT or CT scanning
MRI to check for changes in bone marrow
What is CBCT?
Low dose multi-planar imaging
Images form isotropic voxels
Allows for axial, coronal, and sagittal plane views
What are the drawbacks of CBCT?
Poor contrast of soft tissues
Limited facilities/operators
Technique dependant
Expensive
Higher radiation dose than plain radiography
What are the main differences between CBCT and CT scanning?
CBCT:
- Cone shaped beam
- Lower dose
- Poor soft tissue contrast
- Patient sitting/standing
CT:
- Fan shaped beam
- Higher dose
- Good soft tissue contrast
- Patient lying horizontal
