16. Introduction to Anatomical Imaging

Question 1

What color would the contrast agent be in a normal X-Ray with contrast?

What color would it be in a negative image / subtraction technology?

Answer 1

White

Black

Question 2

What is the correct orientation for a cardiac (thorax) Xray?

Why?

Answer 2

PA (Posterior to Anterior)

Because AP makes the heart look enlarged, since it is closer to the tungsten target

Question 3

How many frames per second would you use for fluoroscopy of the peripheral vasculature?

What about for coronary artery studies?

Answer 3

Two to Three FPS

15 to 30 FPS

Question 4

What is digital subtraction angiography?

Answer 4

A fluoroscopy method by which an image is taken, contrast is introduced, and then another image is taken and compared with the first. Everything that doesn’t show the contrast is removed from the display for better imaging.

Question 5

What is the downside of digital subtraction angiography?

Answer 5

You have to inject the contrast directly into an artery, which can cause a pulsatory bleed

Question 6

What is computed tomography?

Answer 6

Helical Xrays are reconstructed into an axial (transverse) view of a body section

Question 7

Which direction are you looking when reading a CT?

Answer 7

From the feet up

Question 8

What is the correct Hounsfield Scale window level and width for

Lung Tissue

Answer 8

Level: -550

Width: 1600

Remember that air is -1000, so it makes sense that lung is really low, and since we’re starting so low, we need a wide window.

Question 9

What is the correct Hounsfield Scale window level and width for

Soft Tissue

Answer 9

Level: 70

Width: 450

Question 10

What is the correct Hounsfield Scale window level and width for

Bone

Answer 10

Level: 500 ish

Width: 1000-3000 ish

Really high and really wide, since bone varies greatly in density, and is obviously very dense.

Question 11

What is cheaper, CT or MRI?

Answer 11

MRI costs roughly double

Question 12

What must you do before you order a CT with contrast?

Answer 12

Check renal function!

Question 13

Would you have to have your patient hold still more for an MRI or a CT?

Answer 13

MRI

CT’s are more resistant to motion

Question 14

Which image can be manipulated post hoc; MRI or CT?

Answer 14

CT

MRI has to be set beforehand, CT has adjustable grey scale using the Hounsfield scale

Question 15

Is fluid light or dark in T1 MRI?

Answer 15

Dark

Question 16

Is fluid light or dark in T2 MRI?

Answer 16

Light

Question 17

Which has better soft tissue contrast, MRI or CT?

Answer 17

MRI

Question 18

Which is worse for claustrophobic patients, MRI or CT?

Answer 18

MRI

Question 19

Why shouldn’t metal workers get an MRI?

Answer 19

They can have metal shards in their tissues (eg the eye) and not know it. The MRI magnet can pull it out.

Question 20

What can Nuclear Medicine imaging be used for?

Answer 20

Finding areas of metabolic “hotspots,” especially metastases of cancers.

Question 21

For Ultrasound, when would you use a 7-15 MHz transducer?

Answer 21

When you are trying to visualize structures near the surface

(thyroid gland, neck vessels, breasts, testes)

Question 22

For Ultrasound, when would you use low frequency (1 to 3.5 MHz) transducers?

Answer 22

To visualize deep structures