CT

Question 1

What does a CT scan measures?

Answer 1

Density

Question 2

On CT image, what is calculated for every slice?

Answer 2

Attenuation coefficient

Question 3

What are the two types of CT imaging?

Answer 3

Sequential scanning

Helical scanning

Question 4

In which type of CT scan do we usually use?

Sequential scanning
Helical scanning

Answer 4

Helical scanning

Question 5

For lungs HRCT, which CT scan will we choose?

Sequential scanning
Helical scanning

Answer 5

Sequential scanning

Question 6

2 new CT scan options

Answer 6

Multi Slice CT (256 and 320 detector row MSCT)

Dual source CT

Question 7

HU for bones

Answer 7

+400 -> +1000

Question 8

HU for Soft tissues

Answer 8

+40 -> +80

Question 9

HU for water

Answer 9

0

Question 10

HU for fat

Answer 10

-60 -> -100

Question 11

HU for lungs

Answer 11

-400 -> -600

Question 12

HU for air

Answer 12

-1,000

Question 13

In windowing, above the interval values is shown in which color?

Answer 13

White

Question 14

In windowing, below the interval values is shown in which color?

Answer 14

Black

Question 15

Parameters for windowing (2)

Answer 15

Level (HU center)

Width (HU values within the window)

Question 16

Non contrast CT is used for

Give examples

Answer 16

Foreign body
Kidney stone
Lung HRCT
Adrenal gland adenoma
Bone structure
Lipoma
Atherosclerosis
Exclude brain hemorrhage

Question 17

Contrast CT is used for

Give examples

Answer 17

Angiography
Study vascularization
Tumor differantiation
Inflammation process
Abscesses

Question 18

What are the phases of contrast enhancement? And time

Answer 18

(Non enhanced CT)
Early arterial - 20 sec (or 0 sec after bolus)
Late arterial- 40 sec (or 20 sec after bolus)
Hepatic- 80 sec (or 60 sec after bolus)
Nephrogenic- 100 sec (or 80 sec after bolus)
Delayed- 6 min

Question 19

Early arterial phase is useful for the diagnosis of

Answer 19

Aorta dissection

Arterial bleeding

Question 20

Late arterial phase is useful for the diagnosis of

Answer 20

Liver HCC
Pancreas AC
Insulinoma
Bowel ischemia

Question 21

Hepatic phase is useful for the diagnosis of

Answer 21

Hypovascular liver lesions

Question 22

Nephrogenic phase is useful for the diagnosis of

Answer 22

Renal cell carcinoma

Question 23

Delayed phase is useful for the diagnosis of

Answer 23

Cholangiocarcinoma
Fibrotic metastasis
Breast cancer
Transitional cell carcinoma
Liver Hemangioma

Question 24

In which parients will we have increased risk for Post Contrast Acute Kidney Injury?

Answer 24

GFR < 30 mL/min
Impaired kidney function
Multiple contrast admin.

Question 25

We should perform GFR test 7 days after the contrast CT for which patients?

Answer 25

GFR < 60 mL/min
Age > 70
Other diseases (kidney failure…)

Question 26

Which patient are at risk for lactate acidosis post contrast CT?

Answer 26

Patients who take Metformin for their DM-II

Question 27

Which patients can continue to take Metformin normally before contrast CT?

Answer 27

GFR > 45 mL/min

Question 28

Effective dose of CT is ___ mSV

Answer 28

5-20 mSV

Question 29

On HRCT, what is the thickness of the slice

Answer 29

< 1 mm

Question 30

Which Imaging modality is used in case of pelvic soft tissue imaging?

Answer 30

MRI