FINAL

Question 1

What are some indications that you should order imaging?

Answer 1

Trauma (recent or old)
Unexplained weight loss
Night pain
Neuromotor deficit
Inflammatory arthritis
History of malignancy
Fever of unknown origin (>100 F)
Abnormal blood finding
Deformity (Scoliosis, etc.)
Failure to respond to therapy
Medicolegal implications

Question 2

What is conventional tomography? Is it used much?

Answer 2

Conventional tomography is an x-ray slice that focuses on a small area of the body. Because of the movement of the x-ray source, everything around the area of interest is blurred. Tomography has been rendered obsolete by computed tomography (CT)

Question 3

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

Answer 3

Plain x-ray is 2-D with everything superimposed. Conventional tomography blurs everything not in the plane of focus, thus removing some of the difficulties in reading images.

Question 4

Which imaging plane is commonly used in computed tomography (CT)? Can more than one imaging plane be demonstrated with CT?

Answer 4

CT commonly takes axial slices of the body. From these axial slices, other image planes can be constructed, but at lower resolution.

Question 5

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

Answer 5

CT Soft tissue window has the contrast adjusted to make soft tissue more visible. Bone window makes the details of bony structures more visible so that cortex and medullary bone can be easily distinguished.

Question 6

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

Answer 6

It all looks very white.

Question 7

What is the appearance of bone in a bone window?

Answer 7

Much less opaque with details easily differentiated.

Question 8

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

Answer 8

Yes. Each pixel of the final image gets its density based on how much radiation hit it, and consequently represents the amount of attenuation.

Question 9

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

Answer 9

CT provides much better soft tissue contrast

Question 10

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

Answer 10

On a CT, fat will be rather dark, whereas on a T1 weighted MRI, it will be white

Question 11

By what routes can CT contrast material be administered?

Answer 11

Oral & Intravenous

Question 12

How does MRI acquire images?

Answer 12

MRI uses a super-conductive electro-magnet which aligns the spin of hydrogen nuclei (protons). When the magnet is shut off, the hydrogens go back to a relaxed (chaotic) state. The energy is released as radio waves and measured by a computer to be turned into a meaningful image.

Question 13

What does a T1 weighted MRI image look like compared to a T2 weighted image? What structures are high signal (white) vs. low signal (dark) on each weighting?

Answer 13

T1 = Fat is most opaque, compact bone and water are dark
T2 = Water is most opaque, compact bone is dark (fat may still be visible)

Question 14

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

Answer 14

MRI because the nucleus pulposis will show up as a darker color due to the lesser water content

Question 15

Which modality would best demonstrate an intervertebral disc herniation, CT or MRI?
What is the contrast called that is sometimes used with MRI and why is it used?

Answer 15

MRI would show it better since it shows all soft tissue better.
Gadolinium is an intravenous contrast agent that is sometimes used with MRI. It goes to areas of increased vascularity. Performed with T1 weighted images only

Question 16

Where is the contrast material placed in myelography?

Answer 16

Into the subarachnoid space

Question 17

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

Answer 17

CT

Question 18

When is myelography utilized?

Answer 18

When MRI or CT would be contraindicated, or with a CT pre-surgery

Question 19

What is a “hot spot” in bone scan?

Answer 19

A hot spot is an area where a large amount of radionuclide migrates to because of increased cellular activity. (hot spots take up more dye because they are more metabolically active, and on a bone scan the dye appears as density)

Question 20

When might SPECT scan be useful?

Answer 20

To localize a lesion better, particularly good for a fatigue fracture of the pars interarticularis

Question 21

When might PET scan be useful?

Answer 21

Excellent for tumor localization, grading and ascertaining treatment success, looking for lymph node metsastasis, looking at brain activity or lesions

Question 22

When might discography be useful?

Answer 22

May demonstrate dessicated discs and herniated discs. Document specific disc as source of pain, Examine disc integrity

Question 23

When might diagnostic ultrasound be useful?

Answer 23

Evaluate a fetus, Diagnose gallbladder disease, stones, Evaluate flow in blood vessels, Guide a needle biopsy, Guide the biopsy and treatment of a tumor, Check thyroid gland, Study the heart, Diagnose some forms of infection, Diagnose some forms of cancer, Reveal abnormalities in the scrotum and prostate, could help you find an occult fracture

Question 24

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

Answer 24

MRI

Question 25

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

Answer 25

Bone scan or MRI (if not visible on Xray)

Question 26

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

Answer 26

ultrasound

Question 27

Which modality would be most appropriate to evaluate avascular necrosis?

Answer 27

MRI

Question 28

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

Answer 28

CT because you don’t have to worry about movement and you get a good image of soft tissue

Question 29

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

Answer 29

MRI = No radiation < X-ray < CT < Bone scan = most radiation

Question 30

What else do you need to know about imaging?

Answer 30

• Know your imaging planes (i.e. axial, coronal, sagittal).
• Be able to identify each of the imaging studies discussed in this course, whether contrast is used, which window (CT) or weighting (MRI – T1 or T2) is demonstrated, and identify basic anatomy.

Question 31

What is a SPECT scan?

Answer 31

Single-photon Emission Computed Tomography is an imaging technique using positron emission from contrast to combine with electrons in the body to emit gamma rays. The image is captured using a gamma camera. It is able to provide true 3D imaging. This information is typically presented as cross-sectional slices through the patient, but can be freely reformatted or manipulated as required.

Question 32

What is a PET scan?

Answer 32

Positron Emission Tomography is an imaging technique that produces a 3-dimensional image of functional processes in the body. The system detects pairs of gamma rays emitted indirectly by a positron-emitting radionuclide (tracer), which is introduced into the body on a biologically active molecule. Three-dimensional images of tracer concentration within the body are then constructed by computer analysis.

Question 33

What is a discography?

Answer 33

Radiography of the vertebral column after injection of radiopaque material into an intervertebral disk.