Download ARMRIT REGISTRY| FINAL EXAM| Q&A and more Exams Nursing in PDF only on Docsity!
ARMRIT REGISTRY| FINAL EXAM| Q&A
10,000 Gauss is equivalent to: - ANSWER-1.0 Tesla In the absence of a magnetic field the orientation of the spins are all: - ANSWER- Random As magnetic field strength increases the number of protons that align in the parallel direction of the magnet: - ANSWER-Increases The summation of all the magnetic moments of individual spins along the surface plane of the magnetic field is referred to as the: - ANSWER-Longitudinal Magnetization Vector (LMV) Of the 3 magnet types used in MRI, the one used most is: - ANSWER-Superconductive Of the 3 magnet types used in MRI which can be routinely turned on and off: - ANSWER-Resistive True/False: The magnetic field strength of an MRI system can be determined by looking at its size: - ANSWER-False Of the 3 magnet types in MRI which is mostly used in "open" designs: - ANSWER- Permanent Of the 3 magnet types used in MRI which can yield the highest magnetic field strength: - ANSWER-Superconductive Of the 3 magnet types in MRI which is the heaviest: - ANSWER-Resistive Of the 3 magnet types in MRI which accommodates the highest performance levels in image quality and speed: - ANSWER-Superconductive Of the 3 magnet types in MRI which requires special cooling to maintain its magnetic field: - ANSWER-Superconductive
In a superconductive magnet, electrical current flowing through the magnet experiences: - ANSWER-virtually no resistance The medium used to make a conductor superconductive is called a: - ANSWER- Cryogen The strong magnetic field produced by heavy electric current passing through a conductor is an example of: - ANSWER-Faraday's Law Helium liquifies a -453 degrees Fahrenheit which is equivalent to: - ANSWER- Degrees Kelvin 0 Degree Kelvin, the theoretical point where all molecular motion stops, is also referred to as: - ANSWER-Absolute zero The process of liquid helium explosively turning gaseous is referred to as: - ANSWER-A Quench All MR systems have a transmitting antenna surrounding the patient referred to as: - ANSWER-The body coil The computer component that performs the mathematical reconstruction of MRI images is: - ANSWER-Array Processor The mathematical reconstruction of an MRI images uses the ____________ process to create the image: - ANSWER-Fourier Transform When used properly, MRI has: - ANSWER-No adverse biological effects The amount of force a magnet exerts on an object depends on the: - ANSWER-Amount of ferrous material on the object and the distance to the center of the magnet As the distance of an object to the magnet decreases, the force exerted on the object: - ANSWER-Increases MRI related injuries are: - ANSWER-Rare MRI related accidents are: - ANSWER-Rarely reported
Safety procedures are meant to protect ____________: - ANSWER-Everyone Who has the ultimate responsibility and authority for the safety of everyone entering the magnet room: - ANSWER-The technologist True/False: Neurostimulators are an absolute contraindication for MRI: - ANSWER- False The most common MRI-related injury is: - ANSWER-Radio frequency burns Which of the following is not a type of radio frequency burn: - ANSWER-Burns due to electrical conductor arcing Burns caused by looped cables may show ______________ symptoms: - ANSWER- Delayed A best practice for any cables in the magnet bore is to _______________: - ANSWER- keep the amount of cable in the bore to a minimum Skin contact with the inside of the bore is unsafe because it: - ANSWER-Comes into contact with a transmitting antenna which can lead to a burn This type of patient is at a higher risk of radio frequency burns: - ANSWER-Sedated patients Non-ferrous implants may be unsafe if they are: - ANSWER-Mechanically or electrically activated Ferrous implants may be dangerous because they may: - ANSWER-Torque in the magnetic field All metal implants _________________ though pose little or no risk to the patient: - ANSWER-Distort the magnetic field causing artifact The radio frequency energy transmitted to the patient overtime is referred to as: - ANSWER-Specific Absorption Rate (SAR) SAR is measured in: - ANSWER-Watts/Kilogram
In the United States, SAR is regulated by: - ANSWER-The FDA Magnetism arises from: - ANSWER-Electrons What is an example of a ferromagnetic: - ANSWER-iron, cobalt, nickel What is an example of a paramagnetic: - ANSWER-aluminum What is an example of a diamagnetic: - ANSWER-Copper The ability of a material to become magnetized is: - ANSWER-Susceptibility Faraday's Law states: - ANSWER-A magnetic field moving across a conductor produces an electrical current The transmitted frequency that is perfectly matched to the frequencies of a set of protons is the: - ANSWER-Resonant Frequency In MRI a rotating proton will have a type of inertia referred to as: - ANSWER-Angular Momentum what is the lamour e - ANSWER-Precessional frequency = gyromagnetic ratio x field strength ω = γB A vector is a graphic illustration showing: - ANSWER-Direction & Magnitude Vector that are equal but opposite: - ANSWER-Cancel each other out Vector that cancel each other are known as: - ANSWER-Out of Phase Looking at the front of an MR system, the Z direction is: - ANSWER-Down the bore of the magnet When all spins are pointing in the Z direction it results in: - ANSWER-The Longitudinal Magnetization Vector (Mz) In MRI we refer to radio frequency transmission as a: - ANSWER-Radio Frequency Pulse
Fat is bright on a T1 weighted image because it has a ________ T1 time: - ANSWER- Short CSF is dark of a T1 weighted image because it has a ________ T1 time: - ANSWER- Long CSF is bright on a T2 weighted image because it has a __________ T2 time: - ANSWER-Long The person credited with the concept and development of MRI gradient fields is: - ANSWER-Paul Lauterbur The 3 main functions of MRI gradients are: - ANSWER-Slice excitation, phase encoding, frequency encoding The measurement of a gradients minimum to maximum field difference is known as: - ANSWER-Amplitude The time interval from a gradients minimum to maximum field difference is known as: - ANSWER-Rise Time The slope of the gradient that derives from a combination of the rise time and amplitude:
- ANSWER-Slew Rate The measurement for slew rate: - ANSWER-Tesla/meter/sec, (T/m/sec) How many gradient coils are there in an MRI system: - ANSWER- If electrical current is run in the same direction of the main magnetic field, the gradients induced magnetic field ______ to/from the main magnetic field: - ANSWER-Adds The effect of the gradient magnetic field is to: - ANSWER-Change the processional frequency of the spins The type of gradients that are used to denote specific functions on a pulse sequence are referred to as: - ANSWER-Logical Gradients
In a pulse sequence diagram , Gz refers to the gradient performing: - ANSWER-Slice excitation In a pulse sequence diagram, Gy refers to as the gradient performing: - ANSWER- Phase encoding The physical gradient that encodes in the inferior - superior direction is: - ANSWER-Gz The physical gradient that encodes in the anterior-posterior direction is: - ANSWER-Gy The 4 main parts of any pulse sequence are: - ANSWER-Slice excitation, Phase encoding, Echo generation, Frequency encoding In a pulse sequence diagram Gx indicates: - ANSWER-Frequency encoding In a pulse sequence diagram Gz indicates: - ANSWER-Slice encoding In a spin echo sequence the first RF pulse is the: - ANSWER-90 degree RF pulse In a spin echo sequence the 90 degree RF pulse: - ANSWER-Places the LMv into the transverse plane In a spin echo pulse sequence, FID means: - ANSWER-Free Induction Decay In a spin echo pulse sequence, FID is immediately: - ANSWER-Dephased and phase encoded In a spin echo pulse sequence, immediately after the 90 degree RF pulse the spins are:
- ANSWER-In the transverse plane and phase coherent In a spin echo pulse sequence the first gradient that is used is the: - ANSWER-Slice encoding gradient In a spin echo pulse sequence the phase encoding gradient is turned on: - ANSWER- Immediately following the 90 degree RF pulse In a spin echo pulse sequence, the refocusing pulse is accomplished by using: - ANSWER-A 180 degree RF pulse
In IR the first slice excitation pulse places LMz into the: - ANSWER--Z axis A parameter used in IR that is not used in Spin Echo: - ANSWER-TI (Inversion time) In IR the time between the 180 and the first 90 degree RF pulse is called TI as well as: - ANSWER-Tau STIR is an IR sequence used to produce: - ANSWER-Robust Fat Suppression In the IR pulse sequence known as FLAIR, __________ is suppressed: - ANSWER- Fluid The point at which the LMv crosses from the -Z axis to the +Z axis is known as: - ANSWER-The null point What is a signal characteristic of a tissue at null point: - ANSWER-Low SNR In a T2 weighted FLAIR sequence of the brain_________ is suppressed in order to make long T2 pathologies more conspicuous: - ANSWER-CSF What are the main differences between gradient echo imaging vs spin echo imaging: - ANSWER-Short TRs, Gradient induced echos, <90 degree excitation pulses A tissue that is "saturated" will yield: - ANSWER-Low SNR Tissues become saturated due to: - ANSWER-High flip angles and very short TR's When the TR is shorter than a tissues T2 decay time, the left over transverse magnetization of that tissue is referred to as: - ANSWER-Residual Transverse Magnetization The gradient used to generate an echo in a GRE is: - ANSWER-Gx Signal dephasing due to local inhomogeneities is referred to as: - ANSWER-T2' (prime) Gradient Echoes are __________ at correcting for dephasing caused by inhomogeneities while 180 degree radio frequency echoes are____________ - ANSWER-Ineffective, effective
The ability of a tissue to become magnetized is: - ANSWER-Magnetic susceptibility Magnetic Susceptibility effects can both degrade and improve diagnostic image quality:
- ANSWER-True In GRE __________ are used to eliminate residual transverse magnetization: - ANSWER-Spoiler pulses In a SE sequence if 120 phase encoding steps are selected the TR is repeated _________: - ANSWER-120 times In a fast/turbo spin echo, the echo train length is made up of: - ANSWER-A series of 180 degree RF pulses In a fast/turbo spin echo if the echo train is 8 and the number of phase encoding steps selected is 256 the number of TRs repeated is: - ANSWER-32. (256/8) The calculation for scan time in a F/TSE is the same as SE except for: - ANSWER- Dividing the result by the echo train length A single shot or snapshot F/TSE sequence is when the _________ equals the _________. - ANSWER-ETL, phase encoding steps F/TSE blurring occurs when: - ANSWER-There is a great variance of T2 decay in the ETL Echo spacing is: - ANSWER-The time between each echo in the echo train Which is an effective method for reducing echo spacing: - ANSWER-Decrease frequency encoding steps, increase receive bandwidth As TR increases, SNR: - ANSWER-increases As TR increases, Spatial Resolution: - ANSWER-Does not change As TR increases, Scan Time: - ANSWER-Increases As TE increases - ANSWER-decreases
As Receive bandwidth increases, scan time - ANSWER-Does not change A MR image artifact is: - ANSWER-Information in the image that is incorrect or misrepresents true anatomy as a result of the imaging process itself. MR image artifacts may occur: - ANSWER-When hardware fails, if software bugs exist, when incorrect parameters are selected, when the appropriate parameters are not selected, directly from the patient, or the system needs maintenance. What is the most common artifact in MR imaging: - ANSWER-MOTION What is an example of an action that may cause a physiological image artifact: - ANSWER-Cardiac motion that has been ungated, noncorrected patient breathing during abdominal imaging Motion artifacts occur in which direction: - ANSWER-Phase Motion artifacts are caused by: - ANSWER-Spins that change location from one phase encoding step to the next. Pre-saturation RF pulses are: - ANSWER-RF pulses placed spatially over specific areas of anatomy to prevent artifact originating from the anatomy The parameter used by a technologist that uses a frequency or slice encoding mulit- lobed gradient to rewind moving spins such as blood or CSF to prevent or reduce flow artifacts is: - ANSWER-Gradient moment nulling Susceptibility artifacts can be caused by: - ANSWER-Metal in the AOI, tissue-air interfaces, or tissue-compact bone interfaces. One effective method of reducing metal artifacts is to: - ANSWER-Increase the receive bandwidth Good methods for reducing respiratory ghosting artifacts is to: - ANSWER-Breath hold the patient, use respiratory navigators Aliasing is caused by: - ANSWER-The FOV being smaller that the area of excitation
The default frequency encoding direction for an axial of the brain is: - ANSWER-Anterior to posterior Chemical shift artifacts occur in the ______________ direction: - ANSWER-Frequency The precessional frequency difference between water and fat at 1.5 tesla is: - ANSWER-220Hz The most effective way to decrease chemical shift is to: - ANSWER-Increase the receive bandwidth Chemical shift artifacts _______________ as field strength increases: - ANSWER- Increase Truncation/Gibbs artifacts appear as a "_______________" appearance: - ANSWER- Ringing Truncation/Gibbs can be reduced by: - ANSWER-Increasing phase or frequency matrix Fat suppression is a valuable tool in MRI what are examples of fat suppression techniques: - ANSWER-STIR, 2-3 Point Dixon, Chemical saturation Radiofrequency leaks into the magnet room can result in an artifact often referred to as:
- ANSWER-Zipper Corduroy artifacts most likely require: - ANSWER-A call to the field service engineer Most injected MRI contrast agents are: - ANSWER-Gadolinium based and non specific extracellular Gadolinium based contrast agents work by: - ANSWER-Increasing the local magnetic field by the Gd ion GBCA's are __________________: - ANSWER-Paramagnetic Gadolinium is a very effective agent due to its: - ANSWER-Large number of unpaired electrons
