Power Injector

Question 1

Automatic Pressure Injector

Answer 1

used during angiography and IR procedures to deliver contrast medium to an area of interest at a controlled rate.

Question 2

Power Injector Controls

Answer 2

-Volume
-Flow rate
-Rate(linear rise)
-lb.s/inch^2 of pressure
-Injection Delay
-X-ray Delay

Question 3

Volume (Bolus)

Answer 3

total volume of contrast per injection
(ex. 20mLs / 2sec.)

Question 4

Flow Rate

Answer 4

Speed at which the injector is set to push a bolus of contrast through an angiographic catheter. (Volume that passes through a catheter per unit of time.)

Question 5

Catheters and Contrast Flow

Answer 5

Longer Cath. = Greater Resistance (require low flow rate)
Shorter Cath. = Lower Resistance (higher flow rate)
Lrg. Inner Diameter = Lower Resistance (Higher flow)
Sml. Inner Diameter = High Resistance (low flow)
Many Side Holes = less catheter recoil = higher flow
Few or One Hole = high resistance = lower flow rate

Question 6

Catheter Materials

Answer 6

Catheter material affects resistance
- Polyethylene or polyvinyl = low flow rate due to HIGH friction between the catheter and the contrast media
- Teflon = high flow rate due to LOW friction between catheter and the contrast media

Question 7

Contrast Factors

Answer 7

Viscosity of the contrast material affects the flow rate
-High Viscosity = High Resistance = Low Flow
-Low Viscosity = Low Resistance = High Flow

Question 8

Rate Rise (Linear Rise)

Answer 8

Rate at which the contrast volume reaches its peak delivery rate. Useful to decrease catheter recoil or whiplash. Steady rise in flow is desirable to maintain access to high complex superselected vessels

Question 9

Pressure Setting

Answer 9

Amount of pressure used to deliver a contrast bolus. Most Power Injectors can apply 100 to 1200 PSI.

Question 10

Injection Delay

Answer 10

Used during DSA to give the imaging equipment time to make a pre-contrast “mask” image. Injection delay helps reduce x-ray exposure to patients and decreases the contrast volume required to create a diagnostic quality image. (2sec. is a typical injection delay)

Question 11

X-ray Delay

Answer 11

Used to give contrast time to completely opacify the vasculature of interest before images are taken. Decreases the time that patient and team are exposed to radiation

Question 12

Heating Mechanism

Answer 12

Raises the temperature of the loaded contrast in order to decrease viscosity as well as bring the temperature closer to the temperature of the patients blood.