Ch 3

Question 1

What disease is not easily diagnosed in a CT Brain scan? What may it appear as?

Answer 1

Alzheimer’s disease is not easily diagnosed w/CT brain. May show enlargement of temporal horns.

Question 2

What is the injection rate and delay in a CTA Brain for the Circle of Willis?

Answer 2

3-4mL/s, 12-20s delay after injection

Question 3

What does CT Perfusion evaluate? What is the primary indication?

Answer 3

Evaluates cerebral perfusion w/iodine through vascular structures in brain; acute stroke = primary indication

Question 4

Mean transit time

Answer 4

Average time (in seconds) for blood to pass through area of brain tissue (distance travelled between arterial inflow and venous outflow)

Question 5

Where is cerebrospinal fluid secreted from?

Answer 5

Choroid plexuses in each of the four ventricles

Question 6

Central volume principle formula

Answer 6

Cerebral blood flow (CBF) = cerebral blood volume (CBV) / mean transit time (MTT)

Question 7

What does reduced CBF indicate?

Answer 7

Ischemia due to stroke or other brain abnormalities

Question 8

What’s the best way to reduce contrast-induced nephrotoxicity?

Answer 8

Adequate hydration

Question 9

Best scout plane for neck

Answer 9

Lateral

Question 10

What breathing instructions are used for an HRCT chest?

Answer 10

Full expiration

Question 11

What does an HRCT chest demonstrate?

Answer 11

Air trapping from suspected small airway diseases (COPD and emphysema)

Question 12

What is required in CTA PE acquisition?

Answer 12

Peak enhancement of pulmonary arteries, thin sections (0.5-1.25), cauducephalad acquisition w/saline flush after contrast, 80-150mL low- or iso-osmolar contrast

Question 13

Why do CTVs of lower extremities follow CTAs for PE?

Answer 13

For deep vein thrombosis (blood clots within distal blood vessels), common in popliteal and femoral veins

Question 14

MDCT cardiac exams for coronary artery calcification (CAC) quantification:

Answer 14

Areas of calcium are identified as greater thab 1mm2 in area with 130+ HU

Question 15

Branches of RT coronary artery

Answer 15

RT posterior descending artery

Question 16

Branches of LT coronary artery

Answer 16

LT anterior descending and LT circumflex artery

Question 17

Blooming definition

Answer 17

Potential overestimation of vessel calcification due to partial volume effect (exaggeration of calcification due to partial volume effect)

Question 18

In cardiac MDCT studies, blooming can be mitigated with:

Answer 18

Increase in spatial resolution and appropriate window setting (1500HU) to reduce appearance of artifact

Question 19

Glomerulus definition and entrance/exit of blood and waste

Answer 19

Nephron responsible for filtering unwanted substances from blood plasma; Blood enters through afferent arteriole, exits efferent arteriole; Waste fluid exits through proximal tubule

Question 20

Azotemia (uremia) definition and symptom of:

Answer 20

Excessive nitrogen in blood; symptom of renal insufficiency and may occur during renal failure

Question 21

Should dx for renal cysts be done with or without contrast? What should be the attenuation valur of the cyst?

Answer 21

Renal cyst diagnosis done w/contrast. Attenuation values of cyst should be 0

Question 22

Define glioma

Answer 22

Group of glial tumors in brain (astocytomas, glioblasomas); glial cells are connective nerve cells

Question 23

What is another name for the pituitary gland? What is it responsible for?

Answer 23

Hypophysis cerebri; responsible for production of hormones (somatotrophin and prolactin)

Question 24

What are stereotactic unites used for?

Answer 24

Specifically for CT-guided biopsies; commonly for intracranial lesions

Question 25

What is another name for acoustic neroma and where does it arise from?

Answer 25

Schwannoma; from Schwann cells in 8th cranial nerve (vestibular nerve) seen in IAC exams

Question 26

What is hydrocephalus?

Answer 26

Abnormal accumulation of cerebrospinal fluid (CSF) in cerebral ventricular system; congenital disorder but can be caused by cranial lesions, hemorrhage, etc

Question 27

How are coronal paranasal sinuses scanned?

Answer 27

Perpendicular to hard palate

Question 28

Where is the thymus found? What happens before and after puberty?

Answer 28

Anterosuperior mediastinum; most visible before puberty, after puberty it becomes infiltrated with fat and difficult to image

Question 29

What are the branches (from RT to LT) of the superior portion of the aortic arch?

Answer 29

Brachiocephalic artery, common carotid artery and the subclavian artery

Question 30

What factors can be found in the periphery of an image?

Answer 30

Matrix size, algorithm type and section thickness

Question 31

How much contrast and at what rate would opacify the mediastinum and vascular structures of the chest?

Answer 31

50 - 150mL @ 2.5 - 4.0mL/s