Lecture 7: 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

In an x-ray, what colors will the bone and air filled organs be?

Answer 2

Bone: White

Organs with air: Dark

Question 3

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

Why?

Answer 3

PA (Posterior to Anterior)

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

Basically keep the structure of interest closer to the recording plate!

Question 4

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

What about for coronary artery studies?

Answer 4

Two to Three FPS

15 to 30 FPS

Question 5

What is digital subtraction angiography?

Answer 5

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 6

What is the downside of digital subtraction angiography?

Answer 6

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

Question 7

What is computed tomography?

Answer 7

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

Question 8

Which direction are you looking when reading a CT?

Answer 8

From the feet up

Question 9

What is the correct Hounsfield Scale window level and width for

Lung Tissue

Answer 9

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 10

What is the correct Hounsfield Scale window level and width for

Soft Tissue

Answer 10

Level: 70

Width: 450

Question 11

What is the correct Hounsfield Scale window level and width for

Bone

Answer 11

Level: 500 ish

Width: 1000-3000 ish

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

Question 12

What is cheaper, CT or MRI?

Answer 12

CT

Question 13

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

Answer 13

Check renal function!

Question 14

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

Answer 14

MRI

CT’s are more resistant to motion

Question 15

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

Answer 15

CT

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

Question 16

Is fluid light or dark in T1 MRI?

Answer 16

Dark

Question 17

Is fluid light or dark in T2 MRI?

Answer 17

Light

Question 18

Which has better soft tissue contrast, MRI or CT?

Answer 18

MRI

Question 19

Which is worse for claustrophobic patients, MRI or CT?

Answer 19

MRI

Question 20

Why shouldn’t metal workers get an MRI?

Answer 20

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

Question 21

What can Nuclear Medicine imaging be used for?

Answer 21

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

Question 22

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

Answer 22

When you are trying to visualize structures near the surface

(thyroid gland, neck vessels, breasts, testes)

Question 23

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

Answer 23

To visualize deep structures