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Diagnostic Imaging 1 > Final Material > Flashcards

Final Material Flashcards

1
Q

List 10 indicators for when to order diagnostic imaging

A
  • Trauma - recent or old
  • unexplained weight loss
  • night pain
  • neuromotor deficit
  • inflammatory arthritis
  • history of malignancy
  • fever of unknown origin
  • abnormal blood finding
  • deformity (scoliosis)
  • failure to respond to therapy
  • medicolegal implications (legally bound to take an x-ray)
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2
Q

What is conventional tomography? Is it used too much?

A

Requires specific area to be visualized, b/c difficult to see on plain films and is clinically necessary to see. Creates small focal point to be clear & other portions in picture to be blurry. Not used very often.

- Adv: cost effective, minimal radiation, & bony anatomy visualized
- Disadv: visualize only small areas
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3
Q

What is the difference in appearance between a plain x-ray and conventional tomography?

A

Plain x-ray does not allow you to see slight bone destruction (need about 30-50%), or axial images, and usually a broad area of focus.

Conventional tomography has radiographic “slices” taken with moving camera and film, where thin “slices” of bony anatomy are visualized but can only visualize a small area (soft tissues are also seen)

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4
Q

Which imaging plane is commonly used in computed tomography (CT)?

Can more than one imaging plane be demonstrated with CT?

A

Axial (same as transverse/horizontal)

Yes, but the resolution is decreased (reconstructed images in sagittal or coronal or direct (sp?)-small body parts

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5
Q

What is the difference between CT soft tissue and bone window?

A
  • Soft tissue window= better visualization of soft tissues, and can be differentiated between different planes of tissues.
  • Bone window= better visualization of the fine details of the osseous structures. Cortical bone can be differentiated from cancellous (medullary) bone.
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6
Q

What is the appearance of bone in a soft tissue window?

What is the appearance of bone in a bone window?

A

Bone appears as uniformly white without distinction between cortical & medullary bone.

Cortex and medullary bone are distinctly different in contrast. The cortex is whiter, and the medullary bone is more lucent (different contrast).

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7
Q

Does CT utilize the theory of attenuation (absorption of x-rays)?

A

Yes (plain is controlled by kVp, CT is a result of electric manipulation of the digital image, namely window width and leveling setting)

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8
Q

Which is more sensitive in the differentiation of tissue densities, CT or plain x-ray?

A

CT= more sensitive to structural density. CT is superior for soft tissue contrast.
X-ray is manipulated by how much radiation is emitted whereas CT uses electronic manipulation of the digital image

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9
Q

What is the appearance of fat on CT vs. MRI?

A

MRI= TI→white (T2→ dark)

CT= black (second to air)

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10
Q

By what routes can CT contrast material be administered?

A

Oral (barium to see tumors) or IV (liver and kidney will take up contrast-w/o contrast liver and kidney will look like muscle) or myleographic or intra-articular

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11
Q

How does MRI acquire images?

A

No radiation. Nuclei of atoms have spin randomly (usually the dipole moment). That dipole moment of the spin aligns with the magnetic field. Then the field stops and the amount of energy released from going back to equilibrium gives us the picture of densities

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12
Q

What does a T1 weighted MRI image look like compared to a T2 weighted image?

A

T1 (short TE & short TR)=fat image fat is bright precise anatomy
Low signal cortical bone spinal cord CSF intermediate medullary bone
-lightest to darkest: fat, marrow, brain & spinal cord, muscle & CSF, fluid filled cavities, & compact bone. *Cord is brighter than CSF

T2 (long TE & long TR)= water image less precise detail normal discs bright
CSF is bright
-lightest to darkest: CSF (water base), edema & normal disc, marrow & spinal cord, muscle, ligaments, & compact bone. *CSF is brighter than cord
(T tests are based on H atoms. If you have a high concentration of H atoms-like water or fat-they appear white)

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13
Q

What structures are high signal (white) vs. low signal (dark) on each weighting?

A

T1= fat will appear bright/white
T2= water will appear bright (i.e. CSF)
T1 & T2= ligaments and tendons produce little or no signal, and cortical bone will appear as a signal void

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14
Q

Which modality would best demonstrate dehydration (dessication) of the nucleus pulposis, CT or MRI?

A

MRI

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15
Q

Which modality would best demonstrate an intervertebral disc herniation, CT or MRI?

A

MRI (mb discography)

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16
Q

What is the contrast called that is sometimes used with MRI and why is it used?

A

Gadolinum. Used to help physicians get a clear and detailed picture of the patients internal organs, tissues, bones & vessels. Highlights tumors & infections.

17
Q

Where is the contrast material placed in myelography?

A

Subarachnoid space (by injection)

18
Q

What modality besides plain film radiography is myelography often used with?

A

Usually followed by a CT to better define the anatomy and any abnormalities. Often performed pre-surgically.

19
Q

When is myelography utilized?

A

When CT & MRI are not available, or when MRI can’t find source of pain. Used to visualize indirectly a lesion within the spinal canal (i.e. disc herniation, tumor, hematoma, osteophyte, inflammation, developmental anomaly)

20
Q

What is a “hot spot” in bone scan?

A
  • Small areas of destruction or accumulation of bone (increased cell activity due to fracture or tumor)
  • Areas of rapid bone growth or repair absorb increased amounts of tracer, & show up as bright or “hot spots” (i.e. arthritis, presence of tumor, fracture, or infection). Only 3-5% bone destruction needed to see “hot areas” on scan, but don’t specify process.
  • (“cold”/dark spots absorb little to no amount of tracer and indicate a lack of blood supply or certain types of cancer)
21
Q

When might SPECT scan be useful?

A
  • Better localization of a lesion

- Confirming a fatigue fracture in the pars interarticularis

22
Q

When might PET scan be useful?

A
  • Tumor localization
  • Ascertaining treatment success
  • Has better resolution than SPECT or scintigraphy
  • Dx a health condition/ find out how it’s developing
  • Used alongside X-rays or MRI to get more data
23
Q

When might discography be useful?

A
  • Provocative test for low back pain (may demonstrate dessicated discs & herniated discs).
  • Document specific disc as source of pain & examine disc integrity
24
Q

When might diagnostic ultrasound be useful?

A
  • evaluate a fetus
  • diagnose gallbladder dz
  • guide a needle biopsy -evaluate flow in blood vessels
  • check thyroid gland
  • guide biopsy & treatment of a tumor
  • study the heart
  • diagnose some forms of infection/cancer
  • reveal abnormalities in the scrotum & prostate
25
Q

Which modality would be most appropriate to evaluate an intervertebral disc protrusion?

A

MRI or bone scan

26
Q

Which modality would be most appropriate to evaluate a stress fracture?

A

MRI or bone scan

27
Q

Which modality would be most appropriate to confirm or rule out an occult fracture or questionable fracture initially discovered on plain x-ray?

A

MRI

28
Q

Which modality would be most appropriate to evaluate avascular necrosis?

A

MRI

29
Q

Which modality would be most appropriate to evaluate most chest and abdomen pathologies?

A

CT-since it is fast

30
Q

What are the relative radiation doses for each imaging modality discussed?

A

(- CT (many x-rays)>MRI (no ionization))

  • x-ray
  • CT
  • MRI (no radiation)
  • PET
  • ultrasound
  • discography
  • SPECT
31
Q

Know your imaging planes (i.e. axial, coronal, sagittal).

A
  • Coronal= A/P view or P/A view
  • Sagittal= Left to Right, or Right to Left
  • Axial= Top to bottom, or Bottom to top

Diagnostic Imaging 1 (3 decks)

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