Imaging

Question 1

for each and every test:

Answer 1

always

• verify name on study is your patient (patient identity)
• verify date/time of study (study type)
• verify you have correct study/x-ray/CT/MRI (study type)
• try to get an older study or record to compare with

Question 2

relative radiodensities from least dense to most dense

Answer 2

air (dark)
fat (less dark)
soft-tissue (medium)
bone (bright)
metal (very bright)

Question 3

what does posterior-anterior film mean?

Answer 3

x-ray beam travels from the back to front of the patient and hits the film in the front

Question 4

why use CXR?

Answer 4

chest c-rays are excellent to look at lungs

Question 5

abdomen x-ray

Answer 5

more difficult to evaluate solid organs; dense structures like calcifications and metal are visible (swallowed a pin); kidney stones

Question 6

patterns of plain film misdiagnosis

Answer 6

normal anatomy and variants
pattern recognition failure
associated pathology
suboptimal positioning and number of projections

Question 7

what is a CT “window”

Answer 7

different windowing in CT allows evaluation of each organ within a single image

Question 8

CT protocol

Answer 8

almost all are axial plane
reformatted into coronal and sagittal plane
if looking at abdomen, include appendix
if looking at pelvis, include kidneys

Question 9

what are reformatted images

Answer 9

CT can stack axial acquired images and make coronal, sagittal, oblique, or 3D images for interpretation

Question 10

CT angiography

Answer 10

scanning when IV contrast bolus reaches peak (arterial or venous); same info as conventional angiography, but less invasive
faster scanner, faster IV contrast injection (but larger needle)
head and neck: aneurysm, AVM, carotid atherosclerosis, venous sinus thrombosis
body: aortic dissection, pulmonary embolism, coronary artery, renal artery stenosis, DVT
extremity: brachial, femoral angiogram
no prep

Question 11

MRI basics (water appearance)

Answer 11

water is black on T1 but white on T2

Question 12

Advantages/Disadvantages of MRI

Answer 12

ad: greater differentiation between soft-tissue structures, acquired in any place, vascular study without IV contrast
disad: longer time (20-30 minutes), motion artifact is VERY sensitive (respiratory , chest, abdomen imaging)

Question 13

ultrasound mechanism

Answer 13

high-frequency sound waves and its reflection to create images in body

Question 14

advantages of ultrasound

Answer 14

no ionizing radiation
can be acquired anywhere
less expensive
can be performed at bedside (v sick pts)
real time imaging of heart, fetus, etc

Question 15

disadvantages of ultrasound

Answer 15

less sharp and clear images
takes more time than CT
quality and accuracy variable on operator skills
structures such as bone and lung not well examined

Question 16

Imaging and Pregnancy

Answer 16

iodinated contrast (crosses placenta), oral contrast 
weeks 3-4 and 5-10, possible spontaneous abortion and possible congenital malformation respectively
11-17 - possible IQ deficits
*gadolinium not recommended in pregnant women