Imaging in Cancer Flashcards

1
Q

Describe CT scans

A
  • Cross section plane
  • Different tissue absorb different amount of photons –HU - attenuation values relates to that of water (0) - +3000 bone to -1000 air
  • Higher HU = higher density
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2
Q

CT contrast agents

A
  • Gastrogafin outlines GI tract (oral)

- Oanipaque shows blood vessel or vascularity of different tissues (IV)

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3
Q

Mechanism of MRI scanning?

A

Radiofrequency excites photons causing them to tilt.

The image is generated by measuring the time taken for the photon to return back to its original state (relax)

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4
Q

What does MRI show?

A
  • Bone soft tissue
  • Vessels
  • Brain, spine and musculoskeletal
  • Abdomen and pelvis
  • Cardiac scanning
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5
Q

Disadvantages of MRI?

A
  • Claustrophobic and noisy
  • Patient movement results in blur
  • No imaging in patients with pacemaker and aneurysm clips
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6
Q

MRI contrast agents

A

Gadolinium DTPA changes in local magnetic field so alter tissue signal (IV

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7
Q

What cancers does the NHS screen for?

A

Breast, bowel and cervix

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8
Q

Principles of screening

A
  • Condition fatal
  • Screening at latent stage of disease
  • Disease treatable
  • Facilities for diagnosis available
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9
Q

Why is lung cancer unsuitable for screening?

A

Develops to rapidly

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10
Q

Screening test principles

A
  • Detect disease at early stage
  • Cause no harm
  • High sensitivity and specificity
  • Benefit to population outweigh cost
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11
Q

What three factors influence diagnosis and treatment of cancer?

A

T - relationship to adjacent structure (local spread)
N - invasion of lymph nodes
M - presence of distant metastases

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12
Q

Mechanism of SPECT

A
  • Radiotracer injected in the patient (glucose and radioisotope)
  • As tumour grows, requires glucose so uptake of radiotracer
  • It emits gamma rays which is absorbed by rotating gamma cameras
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13
Q

Mechanism of PET

A
  • Radionuclide taken up and decays by positron emission
  • Proton - neutron + positron
  • Emits two gamma rays which is found detected by detector
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14
Q

What diseases can SPECT indicate?

A
  • Alzheimer’s disease
  • Parkinson’s disease
  • Myocardial perfusion
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