02 (10.14) Advanced Imaging Flashcards

(28 cards)

1
Q

____ is the retrograde injection of iodinated contrast media into the ductal system of a salivary gland

A

Sialography

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2
Q

alternating areas of fusiform dilation and stricturing of the primary duct (“string of sausages”) is referred to as…

A

Sialodochitis

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3
Q

in Sialography, fat-soluble contrast agents (___) ___ diluted by saliva or absorbed across the glandular mucosa, but in cases of ductal rupture and contrast extravasation, ___ develop

A
  • are not
  • Ethiodol
  • foreign body granulomata
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4
Q

In sialography, water-soluble contrast agents (____) ___ diluted by saliva and pass rapidly across glandular mucosa resulting in poor visualization of peripheral ducts, but do not incite an inflammatory reaction if extravasated

A
  • Sinografin

- are

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5
Q

when the parotid glands are destroyed (like in Sjorgren’s syndrome) the appearance of _____ and ____ _____ in a pattern described as “________” on sialography

A
  • punctate
  • globular pseudosialectasis
  • “a fruit-laden, branchless tree”
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6
Q

what does CT not visualize well?

A

-CT does not generally add to the soft tissue characterization of a lesion, although it may help in assessing the presence of soft tissue extension outside of bone or the degree of intramedullary extension within bone

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7
Q

what does CT stand for?

A

Computed Tomography

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8
Q

What does CT visualize?

A
  • primary lesions and asses the presence/absence of lymph node metastases with considerable certainty
  • Follow up scans enable an evaluation of the effects of treatment and allow comparison among treatments
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9
Q

What are the selection criteria for CT?

A
  • extensive lesions in the mandible or maxilla (esp if sinus is involved)
  • suspected malignancy
  • soft tissue mass of a salivary gland
  • osseous lesions affecting the TMJ
  • developmental disorders affecting the mandibulomaxillofacial complex
  • assessment of maxillofacial trauma
  • pre-surgical implant planning, altho the radiation dose is significant
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10
Q

what are the different types of contrast agents used in sialography?

A

-fat-soluble and water-soluble

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11
Q

what is the ductal phase in sialography?

A

just when the ducts are filled with the contrast agents, the acinar phase is when the acini are filled

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12
Q

how much more sensitive are CT scans than plain films?

A

100 times

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13
Q

what is the orientation of the standard CT image?

A

-axial cross-sectional view, oriented as if looking at the patient from the floor upward, then the computer can reconstruct it into other views

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14
Q

what are the units of measurement in CT?

A

Hounsfield units (HU), according to density

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15
Q

what is the Hounsfield unit based off of?

A

water, HU=0

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16
Q

if a tissue has a density greater than water, how will the HU number change?

A

it will have a + CT number

less dense than water results in a -CT number

17
Q

what is a scout Image?

A

displays the number and position of all slices to be obtained in the imaging study

  • this facilitates spatial localization of the final slices
  • also called a scannogram
18
Q

which systems do not use ionizing radiation?

A

Ultrasound and MRI

19
Q

What is MRI best for visualizing?

A

-soft tissues (esp compared to CT)

20
Q

what does the signal strength depend on in an MRI?

A

Hydrogen content of the tissue (cortical bone has a very low Hyrdrogen content and fat has a high content)

21
Q

on a T1-weighted image (MRI), what is bright and dark?

A

fat is bright (hyperintense) and cystic fluid is dark (hypointense)

22
Q

on T2-weighted images…

A

-fat is dark and fluid is bright

23
Q

when is an MRI contraindicated?

A

presence of implanted ferromagnetic devices (pacemakers, aneurysm clips, prosthetic joints or heart valves, hearing aids etc)

24
Q

how long does it take to get an MRI?

A

exam may take from 15 minutes to 1.5 hours

25
which system has the "head coil?"
MRI
26
what is the selection criteria for an MRI?
 Evaluation of suspected internal derangement of the TMJ  Salivary gland disease  Assessment of soft tissue invasion by malignant disease  Evaluation of intracranial extension of inflammatory or neoplastic processes  Assessment of perineural spread of malignancy  Assessment of suspected brain tumors  Neurologic involvement with HIV  Vastly superior for identifying MS plaques and other white matter disorders  Revealing the extent and mechanism of stroke
27
MRI is NOT useful in examining what?
bony lesions bc of the lack of signal generated by bone
28
nuclear medicine
is useless