DSF Imaging

Question 1

X-rays

Answer 1

Electromagnetic energy
No mass, no charge
Produces conventional 2D images
Primary/initial modality for: acute pulmonary disease, many abd complaints, skeletal abnormalities/injuries
X-rays can be: deflected/scattered, absorbed, , pass through
X-rays that pass through body to detector: BLACK (air, other low atomic #)
X-rays that are totally blocked do not reach detector: WHITE (substances w/ high atomic #)

Question 2

5 basic densities on x-rays

Answer 2

Metal: absorbs nearly all x-rays - BRIGHT WHITE
Calcium: bone, most dense tissue - WHITE
Soft tissue: equal fluid & soft tissue: GRAY
Fat: DARK GRAY
Air: absorbs least x-ray: BLACK

Question 3

Fluoroscopy

Answer 3

Dynamic x-ray imaging used in real time
Uses barium, iodinated liquids and/or air to create contrast
Most useful for certain GI and GU as well as joint (arthrogram) pathology

Question 4

CT

Answer 4

Uses ionizing radiation (x-rays)
Connected to computer that processes data to produce slice-like images
Images can be formatted in multiple imaging planes
Images can be windowed to display same info in different ways
HU (densities) quantity used to express CT numbers in standardized form

Question 5

MRI

Answer 5

Images produced using a high-field strength magnet and radio frequency signals - no ionizing radiation
Gadolinium for contrast

Question 6

Ultrasound

Answer 6

Images created using reflected sound waves
No ionizing radiation/harmful effects
Highly operator dependent
Grayscale and Doppler imaging
Can assess blood flow and vascular patency
Hyperechoic (white) vs. Hypoechoic (gray) vs. Anechoic (black)

Question 7

Nuclear Imaging

Answer 7

Provides functional assessment of the region of interest - anatomic detail usually poor
Radioisotope + Pharmaceutical
V/Q scan, GI bleeding scan, HIDA scan, bone scan, Gastric emptying study

Question 8

PET

Answer 8

Positron Emission Tomography
Assesses metabolic activity using a radioactive glucose analog
Most commonly used for cancer staging and follow-up