CT Instrumentation part 3 Flashcards
What year did the first CT scanner appear?
1970
When did the first CT Injector appear?
1984
The Pressure in _____ must exceed the resistance from the pipe and fluid. (tubing, reservoir/syringe, bath tube, pressure gage)
Reservoir/Syringe
A smaller diameter catheter requires ____ pressure to make fluid move. (lower, same, higher, no)
higher
If the pressure in the reservoir or syringe reaches 100psi what would the pressure at the end of the catheter be if the fluid is flowing freely? (100psi, 50psi, 1000psi, 0psi)
0 psi
What are some of the benefits of power injectors over hand injectors?
tight bolus, precise timing, consistency & reproducibility, time & cost savings
What is the formula to calculate flowrate through a pipe?
flowrate = reservoir pressure / pipe and fluid resistance
With Laminar flow do all of the “layers” of the fluid flow at an equal rate in a pipe?
No, friction causes the layers next to the walls at a slower rate than the unhindered center layers
Are you more likely to get turbulent flow with a large or small diameter pipe?
A smaller diameter pipe is more likely to result in turbulent flow because of increased friction.
How would you achieve an equivalent flow rate when using a smaller diameter pipe?
Increase reservoir pressure
The pressure in _____ must exceed the resistance from the pipe and fluid. (tubing, reservoir/syringe, bath tube, pressure gauge)
Reservoir/Syringe
A smaller diameter catheter requires _____ pressure to make fluid move. (lower, same, higher, no)
higher
If the pressure in the reservoir/syringe reaches 100psi what would the pressure in the end of the catheter be if the fluid is flowing freely?
0psi
What is the advantage or a “tight bolus”?
there will be less dilution with blood and therefore the enhancement will be better
Does IV contrast cross into cell membranes?
No, it mixes in with the blood plasma
What is the difference between ionic and nonionic Iodinated contrast?
It is related to viscosity and the chemical bond used. Essentially it is related to the number of iodine atoms or particles per the volume.
Which type of iodinated IV contrast is better tolerated by patients? (ionic vs non-ionic?
Non-ionic
Name three things that affect the viscosity of IV contrast.
molecular structure, molecular weight, and temperature
Why do we use warmers on our CT injector syringes?
To make the fluid flow more easily.
How many HU (housnsfield units) does it take to appriciate a difference in density?
10 HU
The liver receives its blood supply from two sources: the hepatic artery and the portal vein. What percentages are attributed to each?
Hepatic artery is 25% and the Portal Vein in 75%
Do tumors within the liver receive their blood supply from the hepatic artery, the portal vein, or a mixture of the two?
Almost exclusively from the hepatic artery.
What are the three phases of liver enhancement?
Aterial Phase (aka Blous phase), the Portal Venous Phase (aka the non-equilibrium phase), and finaly the Equilibrium Phase (aka the Delayed Phase).
What is the risk of getting the timing wrong on a tri-phasic liver exam?
Abnormalities could be potentially masked
Superior Image Quality, Increase patient safety, Decrease per patient cost, and increase throughput are all characteristics of what kind of injector?
A dual head injection that can do Saline as well as Contrast
Will you get a better peak enhancement by using contrast alone or with a saline flush?
with a saline flush
True/False - Using a pretest saline flush can improve patient safety
True - a test saline injection done at the same rate as the intended contrast injection can test the integrity of the vessel
When all is said and done, how much potential contrast is wasted by being left in the tubing and veins when not using a saline flush?
As much as 25 cc
What situation would you want to use a simultaneous injection where the saline and contrast are actually mixed and injected simultaneously?
Cardiac Imaging
Dual flow (simultaneous) injection makes it possible to (visualize both the right and left sides of the heart, visualize the right coronary ateries, have uniform enhancement that contribultes to more efficient 3D rendering or D: All of the above)
All of the above
Has it been proven that contrast can cross cell membranes?
No it has not.
What happens to PSI when you change the temperature of the fluid?
When the fluid temperature is raised (such as with contrast warmers) you reduce the amount of PSI required to push the fluid.
What can happen if you increase the temperature of the solution from room temperature (20 - 25C) to body temperature (37C).
Decrease Viscosity
Using a test injection of saline at the same flow rate used for the contrast in the beginning, can help reduce serious extravisations. (T,F)
True
All intravascular contrast media are based on what kind of benzene ring?
A tri-iodinated benzene ring
The 1st 40 slice CT scanner was introduced at RSNA in what year?
2003
The 1st 64 slice CT scanner was introduced at RSNA in what year?
2004
To overcome resistance for Hypaque 60%, the pressure should be set to:
170 PSI
Ionic concentration of the dissolved substances per unit of solvent is the definition for what?
Osmolality
The concentration of osmotically active particles in solution is known as what?
Osmolarity
The longest duration of the 3 phases, below 10 HU difference, and persists until contrast is completely excreted are all characteristics of what phase of a dynamic liver?
Equilibrium Phase
As osmolality increases, side effects ______.
Increase
