AART MRI FINAL EXAM, PRACTICE EXAM TEST BANK, Exams of Nursing

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AART MRI FINAL EXAM, PRACTICE EXAM TEST BANK AND STUDY GUIDE | CONTAINS 700 QUESTIONS TOTAL WITH ACCURATE DETAILED AND EXPERT VERIFIED ANSWERS | EXPERT VERIFIED | GUARANTEED PASS | GRADED A | 2024 LATEST UPDATE The maximum exposure to radio frequency averaged over the head is: - CORRECT ANSWER B)No more than 3.2 w/kg The recieve signal amplitude for a pixel usually depends on thr substance's... - CORRECT ANSWER A) T1, T2 , proton density Small magnetic field intoduced to the hydrogen protons in order to cause them yo move from the low energy state to the high energy state is... - CORRECT ANSWER C) RF pulse at any one time, human body tissue, in general, is made up of 50%-90% of what substance? - CORRECT ANSWER Hydrogen. once the patient's area of interest is placed in the main magnetic field of the MRI system, the hydrogen protons will... - CORRECT ANSWER precess parallel to B sub zero In most tissues hydrogen concentration varies - CORRECT ANSWER 10%- to 15% T1 is the measurement of time for the longitudinal component of the net magnetization vector to recover what percentage of its original value after the application of a 90 degree radio frequency pulse? - CORRECT ANSWER 63% because of the spinning motion of the hydrogen proton, it has the same properties as a bar magnet. the hydrogen proton spinning motion gives it a... - CORRECT ANSWER magnetic moment Magnetic resonance imaging is derived from the process known as... - CORRECT ANSWER Nuclear magnetic resonance normally enhancing structures post gadolinium - CORRECT ANSWER choroid plexus because of only a 10% to 15% variation in most tissues, the tissue character that does not provide much contrast resolution... - CORRECT ANSWER hydrogen concentration An inversion recovery pulse sequence can be which of the following? - CORRECT ANSWER ACC RF. average over the whole body is answer 1. averaged over the head is answer 2. in one gram (1gr) of tissue is answer 3. - CORRECT ANSWER 1.C) no more than 0.4 w/kg 2.A) no more than 3.2w/kg 3.B) maximum spatial peak if 8 w/kg on T1 weighted images sub-acute hemorrhage will appear bright? - CORRECT ANSWER TRUE which characteristic of tissue, in MRI, is the result of fast transition phenomenon &/or entry phenomenon? - CORRECT ANSWER flow/velocity effects radio frequency RF coils that are placed close to the patient's body specifically for structures that are superficial & are receive coils only are... - CORRECT ANSWER surface coils chemical shift artifacts will show up on the image in what gradient direction? - CORRECT ANSWER B) frequency encoding coils that superimpose small magnetic fields within the patient during the MRI process & allow for special encoding are... - CORRECT ANSWER gradient coils In an Inversion Recovery pulse sequence what TI will produce STIR fat-suppressed pulse sequence? - CORRECT ANSWER 80-120 The Larmor precessional or resonance frequency of hydrogen protons in a static magnetic field of 0.5 is approximately... - CORRECT ANSWER 21.288 MHz The NMV is rotated to the physical negative Z axis by applying a...? - CORRECT ANSWER C)180 pulse Increasing which parameter is considered the "best" technique for improving image quality? - CORRECT ANSWER C)NEX Studies have concluded that static magnetic fields up to what tesla produce no substantial harmful biological effects. - CORRECT ANSWER C)2.0 Tissues that have low (short) relaxation times have: - CORRECT ANSWER Higher relaxation rates Nuclei in their natural enviroment ( in the absence of a significant magnetic field) are aligned... - CORRECT ANSWER Randomly Using the followong protocol, determine the scan time for this pulse sequence (rounding to nearest minute) FOV 320mm/ TR 2000ms/ TE 20-80ms/ NEX 1/ Matrix 250×120 - CORRECT ANSWER 4minutes. TR× NEX ×Matrix ÷1000 (sec) and agian ÷60 (min)... 2000× 1 × 128= 256,000 ÷1000=256 ÷60=4.2min The main magnetic field of the MRI System is described as constant and always oriented in one set direction, either horizontal or vertical (depending on magnet type). The transmitted radio frequency in comparison is described as - CORRECT ANSWER Oscillating and always perpendicular to B sub zero The gradient magnetic fields are - CORRECT ANSWER A)Always on Of the following statements, which describes part of the basic MR imaging process? - CORRECT ANSWER Radio frequency signals interact with hydrogen protons The basic process of MR signal generation contains two basic steps, they are... - CORRECT ANSWER Simulation & relaxation In MR imaging, for a chemical substance to be affected by the main magnetic field and the radio wave, it must contain an... - CORRECT ANSWER Odd number of total protons and neurons A pulse w sequence where only 90 degree RF pulses are used is called... - CORRECT ANSWER D)Saturation recovery __blank__ is the property of most substances having paired orbital electrons resulting in these substances being weakly repelled by the magnetic field. - CORRECT ANSWER D) diamagnetic Which type of electro magnetic coils are designed to stimulate and detect an MR signal? - CORRECT ANSWER Radio frequency coils The slice selection gradient exposes the body to a series of increasing or decreasing magnetic fields to select a slice. In what relation to the slice is this gradient introduced? - CORRECT ANSWER D) perpendicular A pulse sequence that replaces the second RF pulse with a gradient magnetic field to rephase the transverse vector and produce an echo is called - CORRECT ANSWER Gradient echo In a pulse sequence, transmitting an initial 90 degree radio- frequency pulse will cause the net magnetization vector to - CORRECT ANSWER Shift in both size and direction The property of substances with large positive magnetic susceptibility that become magnetized within a magnetic field and remain magnetized after being removed - CORRECT ANSWER D) ferromagnetic There are__blank__ of__blank__ serving the purpose of providing spatial information within the MR signal - CORRECT ANSWER A) three pairs/gradient coils The electromagnetic coil responsible for producing the strong magnetic field of a superconducting magnet is embedded in a __blank__ which serves as an insulator grin heat in three event of a quench. - CORRECT ANSWER C) copper matrix The transmit radio frequency coil generates a second electromagnetic field to the hydrogen protons. This field is designated - CORRECT ANSWER B1 In a horizontal field magnet, what is the primary gradient for an axial slice? - CORRECT ANSWER G z At rest, the approximate basal metabolic rate for humans is - CORRECT ANSWER B) 1 w/kg Specific absorption rate is the taste at which RF power is coupled to tissue, typically measured in watts per kilogram (w/kg). True or false - CORRECT ANSWER True The time decay between the original 90 degree RF pulse and the echo signal - CORRECT ANSWER A) TE The H protons that are left over and parallel to B sub zero after equilibrium has been established - CORRECT ANSWER Net magnetization What year was the first MRI enhancement agent approved for clinical use? - CORRECT ANSWER A) 1988 Types of gadolinium used are - CORRECT ANSWER D) all of the above. The difference in signal intensity between two adjacent structures is - CORRECT ANSWER CNR Cryogen levels should never fall below - CORRECT ANSWER 50% The maximum exposure of the head and trunk to the main magnetic field is - CORRECT ANSWER 3T Of the following size molecules, which one will precess closer to the Larmor (resonance) frequency when placed within a large static magnetic field? - CORRECT ANSWER B) medium ( fat) Different tissues that have signals that appear similar on an MR image are described as: - CORRECT ANSWER Isointense In a large main magnetic field such as those employed in MRI, the motion of a hydrogen proton has been described as wobbling like a spinning top. This motion is called: - CORRECT ANSWER Precession Magnetic Resonance Imaging is derived from the process known as: - CORRECT ANSWER Nuclear magnetic resonance Once the net magnetization vector (NMV) has moved away from equilibrium, the following will occur: - CORRECT ANSWER The transverse component will increase In MRI, substances respond to a specific radio frequency which is known as: - CORRECT ANSWER Resonance frequency The introduction of gadolinium based contrast enhancement agents by intravenous injection can involve passing through an abnormal brain barrier. The tissue compartments involved are the: - CORRECT ANSWER Intravascular to interstitial T2 is the measurement of time for the transverse component of net magnetization vector to decrease what percentage of its maximum value after the application of a 90 degree radio- frequency pulse - CORRECT ANSWER 37% In the USA, the MRI system's main magnetic field and the vector that represents it is symbolized: - CORRECT ANSWER B0 The resonance frequency of any substance in a magnetic field can be calculated by employing the - CORRECT ANSWER Larmor equation Which type of electromagnetic coils are designed to stimulate and detect an MR signal? - CORRECT ANSWER Radio-frequency coils Magnetic susceptibility is defined as: (RESEARCH THIS) - CORRECT ANSWER Tendency of a substance to attract or repel magnetic lines of force which is decided by the magnetic properties of its electrons (RESEARCH THIS) In comparison to computed axial tomography, an advantage of MR is: - CORRECT ANSWER Superior soft-tissue contrast resolution Fast transition phenomenon and entry phenomenon are theories that explain which of the following tissue characteristics? - CORRECT ANSWER Velocity effects In a loop of conductor in which an electric current is introduced and maintained, a magnetic field will be produced in the center perpendicular to the flow of electric current. This is called: - CORRECT ANSWER Faraday's Law Which type of MRI magnet has attainable field strengths of 0.35 Tesla to 3 Tesla for clinical use in the U.S.A, and higher strengths elsewhere and in research? - CORRECT ANSWER Superconcuctive The purpose of the first use of metal ions in MRI enhancement, like gadolinium, is to - CORRECT ANSWER Decrease relaxation time for H(ydrogen) in tissues A permanent magnet requires liquids helium and liquid nitrogen on a dedicated cooling system - CORRECT ANSWER False Which type of MRI magnet is made up of naturally ferromagnetic material - CORRECT ANSWER Permanent MRI magnets that must have a dedicated, special cooling system due to heat produced by large currents ( approx. 100-150 amps) are - CORRECT ANSWER Resistive Substances which have magnetic properties of their own, such as methemoglobin or gadolinium, cause shortened T1 and T2 values for tissues in their vicinity are - CORRECT ANSWER Paramagnetic Information acquired when you increase or decrease the frequency of the RF pulse of the Gs, ..... - CORRECT ANSWER To be continued....... In MRI substances respond to a specific radio frequency which is known as - CORRECT ANSWER Resonance frequency Effects associated with gradient magnetic fields in MR systems are - CORRECT ANSWER A)Tissue hearing and cataract formation Possible effects of exposure to the transient radio frequency signals are - CORRECT ANSWER B) tissue hearing and cataract composition Possible effects of exposure to the main magnetic field are - CORRECT ANSWER D) magnetophosphenes, bones healing faster, cardiac fibrillation Relaxation from Resonance Begins set the time - CORRECT ANSWER C) B sub 1 isturned off In 1990 Lauffer described two types of contrast media, the mechanism of the T1 agent is to - CORRECT ANSWER D) decrease T1 relaxation time, this emitting high signal. For the following spin echo protocol: fov 320/TR 500/ TE 25/ slice thickness 5mm/ slice gap 1 mm/ NEX 4/ matrix 192. Increasing the Field of View will - CORRECT ANSWER Increase SNR What factor, in spatial localization, does the slope of the slice select gradient? - CORRECT ANSWER Slice thickness What is the gyro-magnetic ratio of hydrogen - CORRECT ANSWER 42.58MHz For the followong spin echo protocol. FOV 320/ TR 500/ TE 25/ slice thickness 5mm/ slice gap 1mm/ NEX 4/ matrix 192. Decreasing slice thickness will - CORRECT ANSWER Decrease SNR The Process of relaxation begins when - CORRECT ANSWER B1 is turned off A sinewave is a symbol used to measure electromagnetic energy. A sinewave's two components of measure are: - CORRECT ANSWER Wavelength and frequency Magnetic fields have direction which are usually designated as north and south, therefore magnetic fields are described as: - CORRECT ANSWER Dipoles At any one time, human body tissue, in general, is made up of 50-90%: - CORRECT ANSWER H(Hydrogen) Once the net magnetization vector (NMV) has moved away from equilibrium the following will occur: - CORRECT ANSWER The transverse component will increase The T1 process is also known as: - CORRECT ANSWER Spin-Lattice Which of the following is the Larmor equation? - CORRECT ANSWER W0=Y+B0 The mechanism of T2 contrast enhancement agents is to: - CORRECT ANSWER Decrease T2 relaxation time, therefore producing low signal Which type of MRI magnet requires cryogen to cool magnetic coils to 4 degrees Kelvin? - CORRECT ANSWER Superconductive A time constant that characterizes the fast rate of transverse magnetization because of the inhomogeneities of the main magnetic field is: - CORRECT ANSWER T2* As the net magnetization vector precesses within the transverse plane, it induces an electrical current in a: - CORRECT ANSWER Radio-frequency coil To symbolize the flow and area of a magnetic field, lines are used which are called: - CORRECT ANSWER Field or flux All chemical substances have an assigned constant known as the: - CORRECT ANSWER Gyro-magnetic ratio. MRI systems require rooms that provide specific shielding requirements. These rooms are lined with what types of materials? - CORRECT ANSWER Copper or galvanized steel Which type of MRI magnet requires no electricity to maintain its magnetic field and can weigh from 18,000 lb to 200,000 lb? - CORRECT ANSWER Permanent An equation derived to predict the MR signal intensity of a particular tissue as the result of a Spin-echo pulse sequence is the: - CORRECT ANSWER Larmor equation At any one time, human body tissue, in general, is made up of 50-90% of what substance? - CORRECT ANSWER H(Hydrogen) Tissues that are very efficient at spin-lattice interactions near the Larmor frequency, such as fatty tissues, should have: - CORRECT ANSWER Low T1 values and produces hyperintense signals. A sinewave is a symbol used to measure electromagnetic energy. A sinewave's two components of measurement are: - CORRECT ANSWER Wavelength and frequency Tissues that are efficient at both T1 and T2 interactions have low (short) relaxation times, and therefore have: - CORRECT ANSWER High relaxation rates Because of only a 10-15% variation in most tissues, the tissue characteristic that does not provide much contrast resolution is: - CORRECT ANSWER Hydrogen concentration A sudden loss of superconductivity with explosive boiling off of liquid helium is called - CORRECT ANSWER C) quench Following the excitation pulse, the FID decays - CORRECT ANSWER Exponentially Nuclei that lose phase coherence ? - CORRECT ANSWER Decrease MR signal In a large main magnetic field such as those employed in MRI, the motion of a hydrogen proton had been described as a wobbling-like spinning top. This motion is called - CORRECT ANSWER Precession Increasing the number of phase encoding steps will produce an image with... - CORRECT ANSWER Higher resolution Fatty tissues have a molecular structure that is very efficient at spin-lattice interactions at the larmor frequency, so fatty tissues should - CORRECT ANSWER A) have short TI values and appear hyperintense Spatial resolution is an image quality factor determined by - CORRECT ANSWER Slice thickness & pixel size A ___blank___ is defined as two magnetic poles of. Equal strength or magnitude, opposite in direction, and separated by an infinitesimal distance - CORRECT ANSWER C) dipole SAR limitation problems are more likely to be experienced using which transmitter coil? - CORRECT ANSWER A) body coil....SAR limits are less of a problem with the smaller FOV coils because the transmit lower RF power than larger FOV coils Once the net magnetization vector (NMV) has moved equilibrium, the following will occur - CORRECT ANSWER The transverse component will increase The following spin echo protocol FOV 320/ TR 500/ TE 25/ Slice thickness 5mm/ slice gap 1mm/ NEX 4/ matrix 192/ Decreasing NEX will - CORRECT ANSWER B) decrease SNR and resolution The maximum exposure to radio frequency (RF), averaged over the whole body is - CORRECT ANSWER No more than 0.4 w/kg The introduction out gadolinium based contrast enhancement agents by intravenous injection. Can involve passing through an abnormal blood brain barrier (BBB). The tissue compartments involved are the - CORRECT ANSWER Intravascular to interstitial The field strength of an MR imaging magnet as measured within the bore is most typically expressed in terms of - CORRECT ANSWER Tesla The larmor equation is - CORRECT ANSWER C)Wo =Y× Bo Which type of MRI magnet requires a steady current of electricity in the coils of conductor wrapped around an air iron core - CORRECT ANSWER Resistive Immediately after an initial 90 degree radio frequency pulse its turned off, the hydrogen protons will begin to - CORRECT ANSWER Dephase RF should cause no more than a ___blank___ increase in body core temperature - CORRECT ANSWER C)1 degree C (Celsius) As spin lattice occurs - CORRECT ANSWER D) the spinning nuclei begin to move out of the XY plane and realign toward the Z axis RF pulses are identified according to the - CORRECT ANSWER Flip angle All FDA approved gadolinium agents for MRI are administered at the same dose - CORRECT ANSWER A) 0.1 mmols/kg All chemical substances have an assigned constant known as the - CORRECT ANSWER Gyro-magnetic ratio The longitudinal component of the NMV is designated - CORRECT ANSWER Mz In the USA, the MRI systems main magnetic field and the vector that represents it is symbolized - CORRECT ANSWER B sub zero Which of the following parameters controls the amount of contrast seen in an image due to T2 relaxation: - CORRECT ANSWER TE A magnetic field strength of 0.5T is equivalent to: - CORRECT ANSWER 5000G An example of a dipole is: - CORRECT ANSWER A hydrogen nucleus, a bar magnet, and the earth Hydrogen nuclei have a magnetic moment because they posses a property called: - CORRECT ANSWER Spin Protons that aligned in the anti-parallel direction are in: - CORRECT ANSWER A high energy state The formula that describes the relationship between the static magnetic field and the processional frequency of the hydrogen proton is the: - CORRECT ANSWER Larmor equation To calculate the processional frequency, the strength of the static magnetic field is multiplied by a constant known as: - CORRECT ANSWER The gyromagnetic ratio The field strength of an MR imaging magnet as measured within the bore is most typically expressed in terms of: - CORRECT ANSWER Tesla The Larmor, processional or resonance frequency of hydrogen protons in a static magnetic field of 0.5T is approximately: - CORRECT ANSWER 21.288 MHz Following RF excitation, as transverse magnetization (Mxy) decays to zero, The MR signal: - CORRECT ANSWER Decays to zero RF pulses are identified according to the: - CORRECT ANSWER Flip angle Following the excitation pulse, the FID decays: - CORRECT ANSWER Exponentially Of the following tissues, which has the longest T2 value - CORRECT ANSWER Cerebrospinal fluid (1600) Of the following tissues, which has the shortest T1 value? - CORRECT ANSWER Fat Nuclei in their natural environment (in absence of a significant magnetic field) are aligned: - CORRECT ANSWER Randomly The characteristic time constant for loss of phase coherence or transverse magnetization due to static magnetic field inhomogeneities is known as: - CORRECT ANSWER T2* Which characteristic of tissue, in MRI is the result of fast transition phenomenon and/or entry phenomenon: - CORRECT ANSWER Flow/velocity effects MRI magnets that require a steady current of electricity passed through coils wrapped around an iron or air core are: - CORRECT ANSWER Resistive MRI magnets that require cryogen's to cool a substance to approximately 4 degrees Kelvin are: - CORRECT ANSWER Superconducting Coils that superimpose small magnetic fields within the patient during the MRI process and allow for spatial encoding are: - CORRECT ANSWER Gradient coils The primary factor of an Inversion Recovery pulse sequence is which of the following parameters? - CORRECT ANSWER TI Of the Different types of coils used in MRI, which type(s) are found only in the housing of the main magnet? - CORRECT ANSWER Shim/Gradient Which of the following causes artifacts on MR images is most commonly mistaken for pathological signal: - CORRECT ANSWER Chemical shift Of the following anatomical structures which is considered to be normally enhancing post gadolinium injection? - CORRECT ANSWER Choroid Plexus Cryogen levels should never fall below: - CORRECT ANSWER 50% The electromagnetic coil responsible for producing the strong magnetic field of a superconducting magnet is embedded in a __ which serves as an insulator from heat in the event of a quench - CORRECT ANSWER Copper matrix There are __ of __ serving the purpose of providing spatial information within the MR signal - CORRECT ANSWER Three pairs/ Gradient coils The temperature of the liquid helium in which the electromagnetic coil is immersed is approximately: - CORRECT ANSWER -436 F (-269 C) Cooling the electromagnetic coil windings to the point of superconductivity and then inducing an electric current from an external power supply until the magnet is at full power is called: - CORRECT ANSWER Ramping- up Mri Magnets that can range from 26,000 to 2000,000 lb are: - CORRECT ANSWER Permanent Following the injection of a gadolinium enhancement agent, the pulse sequence most commonly employed is a: - CORRECT ANSWER T1 weighted All FDA approved gadolinium enhancement agents for MRI are administered at the same dose, it is: - CORRECT ANSWER 0.1mmols/kg On MRI images, an acute hemorrhage will have a bright signal intensity in a T2 weighted pulse sequence: - CORRECT ANSWER False Employing an Inversion Recovery pulse sequence with a water suppression technique, a normal intervertebral disc will appear dark: - CORRECT ANSWER True A T2 weighted pulse sequence of the brain results in the white matter appearing brighter than the gray matter: - CORRECT ANSWER False When describing overall image quality, which best describes the difference in signal intensity between two adjacent structures (A & B) divided by noise (N): - CORRECT ANSWER Contrast-to-noise ratio In spatial localization, an efficient digital implementation of the mathematical method for converting a time-varying signal into its frequency and/or phase components that is actually performed by the MRI computer is known as: - CORRECT ANSWER Fast Fourier transform A paramagnetic, rare, earth substance, attached to a chelating liquid for MRI enhancement purposes is: - CORRECT ANSWER Gadolinium In understanding MRI enhancement agents it is important to know that tissues that have low (short) relaxation times, have: - CORRECT ANSWER Higher relaxation rates In 1990, Lauffer described two types of enhancement media, the mechanism of the T1 agent is to: - CORRECT ANSWER Increase T1 relaxation time, therefore emitting high signal In 1990, Lauffer described two types of enhancement media, the mechanism of the T2 agent is to: - CORRECT ANSWER Increase T2 relaxation time, therefore emitting low signal Of the following enhancement agents, which is still investigational? - CORRECT ANSWER Hepatobiliary, liver/spleen, blood pool, tumor specific The normal pituitary gland should appear bright following injection of a gadolinium enhancement agent: - CORRECT ANSWER True Gadolinium enhancement agents will readily pass their tendency to bind to proteins, enzymes or membranes. The degree to which they dissociate is a measure of their: - CORRECT ANSWER Toxicity Passing from one compartment to another is the process of passing through an abnormal blood- brain-barrier. The compartments involved are the: - CORRECT ANSWER Intravascular to interstitial Of the following MRI enhancement agents, which are FDA approved for clinical use? - CORRECT ANSWER Gd-DTPA, Gd-HP-DO3A, Gd-DTPA-BMA Enhancement can be demonstrated on which of the following pulse sequences post gadolinium injection: - CORRECT ANSWER T1 weighted, gradient echo, inversion recovery SAR (Specific Absorption Rate), set by the FDA, is the rate that the RF energy is introduced to the body tissue, measured in watts per kilogram: - CORRECT ANSWER True The maximum exposure of the head and trunk to the main magnetic field (B0), is: - CORRECT ANSWER 3T The maximum exposure of extremities to the main magnetic field (B0) is: - CORRECT ANSWER 5T Exposure to gradient magnetic fields are based on the premise that the fields should be too weak to cause neuromuscular stimulation by at least a factor of three (3): - CORRECT ANSWER True Maximum exposure to gradient magnetic fields are set at a rate of - CORRECT ANSWER 6T/second The maximum exposure to Radiofrequency (RF), averaged over the head is: - CORRECT ANSWER No more than 3.2 w/kg The maximum exposure to Radiofrequency (RF), in one gram of tissue is: - CORRECT ANSWER A maximum spatial peak of 8 w/kg In regards to Radiofrequency (RF), the concern is that there should not be an increase in the body core temperature of: - CORRECT ANSWER 1 degree C Currently, patients and personnel are excluded from exposure to MRI for the 1st trimester of pregnancy: - CORRECT ANSWER True Guidelines excluding pregnant individuals from MRI is mainly to protect the individual from: - CORRECT ANSWER Radiofrequency (RF) Of the following categories of patients, the one that would not present any special safety considerations is: - CORRECT ANSWER Patients with previous arthroscopic knee surgery Some older implanted ferromagnetic neuro-aneurysm clips, suture materials, and surgical clips will experience a force of __, as the material is passed through a strong magnetic field. - CORRECT ANSWER Torque The __ is a level of dose below which no response will be elicited: - CORRECT ANSWER Threshold dose Local exposures to the Radiofrequency (RF) are: less than 38 degrees C in the head, Less than 39 degrees C in the trunk, less than 40 degrees C in the extremities: - CORRECT ANSWER True TE is defined - CORRECT ANSWER B) the interval between the 90 degree pulse and the echo signal The term used to describe magnetic uniformity in the large static magnetic field is - CORRECT ANSWER C) inhomogeniety The temperature of the liquid helium in which the electromagnetic coil is immersed is approximately? - CORRECT ANSWER D) -436 degree Fahrenheit Measurement of the magnetic field strength outside the bore of the MR imager is most typically expressed in units of: - CORRECT ANSWER Gauss Nuclei in their natural environment (in the absence of a significant magnetic field) are aligned: - CORRECT ANSWER Randomly __ occurs when frequency of the RF pulse matches the frequency of the precessing nuclei: - CORRECT ANSWER Resonance T2 is the characteristic time constant for: - CORRECT ANSWER 63% loss of magnetization in the XY plane The net magnetization vector will generate a stronger MR signal if the alignment is at: - CORRECT ANSWER 90 degrees The __ and __ are terms which indicate the amount of macroscopic magnetization vector is rotated by an RF pulse with respect to the static magnetic field: - CORRECT ANSWER Flip angle/ nutation angle Nuclei having an __ of nucleons (neutrons or protons) will tend to possess magnetic properties: - CORRECT ANSWER Odd numbers Spin-lattice relaxation time is another term representing: - CORRECT ANSWER T1 relaxation The tendency of a substance to become magnetized or to distort an applied magnetic field is: - CORRECT ANSWER Magnetic susceptibility __ is the uniformity of the static magnetic field, expressed in terms of PPM (parts per million) over a defined volume - CORRECT ANSWER Homogeneity Spin-spin relaxation is another term for: - CORRECT ANSWER T2 relaxation __ is the property of most substances having paired orbital electrons resulting in these substances being weakly repelled by the applied magnetic field: - CORRECT ANSWER Diamagnetic A spin-lattice occurs: - CORRECT ANSWER The spinning nuclei begin to move out of the XY plane and realign toward the Z axis __ occurs when the frequency of the intermittent magnetic field, the RF pulse, matches the frequency of the precessing nuclei- the nuclei absorbing the energy of the RF pulse and flipping the nuclei at some alpha angle from the Z axis and into the XY plane: - CORRECT ANSWER Resonance Because of a variation of only 10-15%, in most tissue, which tissue characteristic does not allow for much contrast resolution on MR images: - CORRECT ANSWER Hydrogen concentration Raw data (digitized echoes) is loaded into the array processor in a 2D data acquisition matrix, commonly referred to as: - CORRECT ANSWER K-space In MR, spatial resolution is determined by __ and __: - CORRECT ANSWER Slice thickness/ pixel size TR is defined as: - CORRECT ANSWER The time interval between 90 degree pulses TE is defined as: - CORRECT ANSWER The time interval between the 90 degree pulse and the echo signal During 2DFT, spin echo pulse sequences, fast flowing blood usually appears: - CORRECT ANSWER Hypointense During 2DFT, spin-echo pulse sequences, slow flowing blood usually appears: - CORRECT ANSWER Hyperintense The measure of spin-spin interactions is: - CORRECT ANSWER T2 relaxations TI is defined as: - CORRECT ANSWER The time interval between the 180 degree and the 90 degree pulses Which pulse sequences do not use Fourier Transform? - CORRECT ANSWER None of the above In a 2DFT conventional spin-echo multislice pulse sequence, scan time is given by the following equation: - CORRECT ANSWER TR x NEX x # of phase encoding steps Using the following scan parameters, determine the scan time for this pulse sequence: round off your answer to the nearest minute. TR: 2000 ms, TE 20/80 ms, FOV 320 mm, NEX 1, Matrix 256x128: - CORRECT ANSWER 4 minutes The mathematical operation that converts a time varying RF signal to a graph that shows amplitude as a function of frequency and contains information about signal strength as a function of position, is: - CORRECT ANSWER Dimensional Fourier Transform The receive signal amplitude for a pixel usually depends on the substance's: - CORRECT ANSWER T1, T2 Proton Density, System noise, Motion artifact T2 relaxation is defined as when __ of the __ magnetization has decayed: - CORRECT ANSWER 63%/ transverse A magnetic field strength of 0.5 Tesla is equivalent to __ Gauss - CORRECT ANSWER 5000 Gradient magnetic fields are used to: - CORRECT ANSWER Spatially encode the data Following a 90 degree RF pulse, the signal that is created is called: - CORRECT ANSWER Free induction decay Hydrogen nuclei have magnetic moment because they possess a property called: - CORRECT ANSWER Spin Spins aligned in the anti-parallel direction are in: - CORRECT ANSWER High energy state The individual hydrogen protons aligned in the parallel direction, in excess of the number aligned in the anti-parallel direction, produce a __ vector parallel to the main magnetic field: - CORRECT ANSWER Net magnetization The formula that describes the relationship between the static magnetic field and the precessional frequency of the hydrogen protons is the: - CORRECT ANSWER Larmor equation Electromagnetic energy is symbolized by a sinewave that has two components of measurement, they are: - CORRECT ANSWER Wavelength and frequency In contrast to B0 the B1 RF field is: - CORRECT ANSWER rapidly rotating and always perpendicular to B0 Relaxation from resonance begins at the time: - CORRECT ANSWER B1 is turned off The artifact known as aliasing, wrap around or fold over will always show up in what gradient direction? - CORRECT ANSWER Phase encoding Chemical shift artifact will show up on the image in what gradient direction? - CORRECT ANSWER Frequency encoding On T1 weighted images sub-acute hemorrhage will appear bright: - CORRECT ANSWER True On T2 or T1 weighted images cortical bone will appear: - CORRECT ANSWER Signal void Acquiring half of the phase views (+8) of K-space and then extrapolating the data for the rest of the K-space is a technique known as: - CORRECT ANSWER half-Fourier Using a conventional spin-echo multi-slice pulse sequence, increasing the TE from 20 msec. to 40 msec will __ the number of slices allowed: - CORRECT ANSWER Reduce Motion artifact on the acquired images is seen as a smearing in what gradient direction: - CORRECT ANSWER Phase encoding Aliasing occurs due to tissue outside of the selected Field of View being - CORRECT ANSWER Undersampled The gradient that is on longest is the __________ encoding gradient - CORRECT ANSWER frequency The four phases of a spin echo pulse sequence, in correct order, are - CORRECT ANSWER Excitation, encoding, refocusing, readout. Using an NSA of 3, if a phase resolution of 192 is desired, then the TR must be repeated - CORRECT ANSWER 576 times In a fast spin echo sequence, the effective TE is the echo that is performed with the - CORRECT ANSWER Low amplitude phase encoding gradient. In a 2D multiecho pulse sequence, ETL = 8, scan time is given by the equation TR x - CORRECT ANSWER Number of signals averaged x number of phase encodings / the number of echoes. When using MRA to evaluate extracranial vascular flow, such as that within common carotid arteries, a recommended technique is - CORRECT ANSWER 2D time of flight MRA When using bright blood MRA to evaluate peripheral vascular flow, such as that within the arteries of the legs, saturation pulses are - CORRECT ANSWER placed inferior to the acquired slices In a 3D acquisition, the slices are produced by - CORRECT ANSWER A phase encoding gradient applied in the slice direction. Acquired by volume imaging. To create a projection image in MRA, the technique MOST commonly employed is - CORRECT ANSWER 19. maximum intensity pixel If a given conventional spin echo pulse sequence takes 12 minutes to acquire, a multiecho sequence, using a 6 echo train, with all factors that affect scan time remaining the same, will take ________________ to acquire the same images - CORRECT ANSWER 2 minutes Gadolinium chelates are - CORRECT ANSWER Paramagnetic. Acquiring half the phase views of k space and then calculating the data for the other half is a technique known as - CORRECT ANSWER partial Fourier The MRA sequence that is more sensitive to slow flow is - CORRECT ANSWER 2D time of flight 3D gradient echo axial views can be used in cervical spine imaging to provide - CORRECT ANSWER Thin, contiguous sections of the spine, the ability to reformat into any other imaging plane, retrospectively, the ability to get either T1, spin density or T2* information by changing parameters. In complete spine imaging, to rule out metastatic lesions of the spinal cord, contrast enhancement can be used with T1 weighted images because - CORRECT ANSWER metastatic lesions enhance and normal cord does not Due to the differences in frequencies across the magnetic field we - CORRECT ANSWER use gradients, use sat bands, . use different coils To avoid the "magic angle" (an artifactual brightness seen in the medial segment of the posterior horn of the lateral meniscus when short TEs are used) artifact when imaging the knee, - CORRECT ANSWER use a longer TE, reposition the knee, orient the affected anatomy to another angle To best visualize the anterior cruciate ligament on knee MR - CORRECT ANSWER externally rotate the leg about 15 When using MRA to evaluate intracranial vascularity, flow within smaller vessels can best be demonstrated by - CORRECT ANSWER 3D time of flight MRA or 3D phase contrast MRA To produce the echo, a gradient echo pulse sequence uses - CORRECT ANSWER a gradient magnetic field only The rate of dephasing due to inhomogeneities is called - CORRECT ANSWER T2 inhomogeneity If the TR of a gradient echo pulse sequence is considerably less than the T2 (and T2*), the condition that will exist is known as - CORRECT ANSWER steady state The gradient that is on during the production of the echo is the __________ encoding gradient - CORRECT ANSWER frequency A major advantage of MRA over conventional angiography is that - CORRECT ANSWER 2D time of flight The removal of signal from vessels in an MRA sequence is achieved by - CORRECT ANSWER spatial presaturation In a spin echo sequence, flowing blood is normally seen as a signal void because - CORRECT ANSWER the 90o pulse and the 180o pulse are both slice selective In a time of flight sequence, the tissue is hypointense relative to flowing blood because of - CORRECT ANSWER saturation effects Phase contrast techniques produce image in which the signal intensity within the vessel is dependent on (among other parameters) the - CORRECT ANSWER velocity of the flowing blood A major advantage of 3D time of flight techniques over 2D time of flight is the ability to - CORRECT ANSWER visualize smaller vessels A major advantage of a 2D time of flight sequence over a 3D time of flight is the ability to - CORRECT ANSWER image a larger area without saturation of the flowing blood. The presaturation pulses usually occur - CORRECT ANSWER prior to the excitation pulse The time during which the frequency encoding gradient is on __________________ a reduction in receiver bandwidth - CORRECT ANSWER increases with adjacent to high-contrast interfaces. These artifacts are particularly problematic in spinal imaging, in which they may artifactually widen or narrow the cord or mimic a syrinx. How can we correct for a Gibb's artifact? - CORRECT ANSWER Increase number of phase encodings or decrease FOV Fat and water precess at different frequencies, causing a _________ artifact. - CORRECT ANSWER chemical shift What can be done to the receiver bandwidth to compensate for chemical shift? - CORRECT ANSWER Increase receiver bandwidth Artifacts from motion will appear in which direction? - CORRECT ANSWER Phase encoding direction Energy given to nuclei in adjacent slices due to spin lattice relaxation can cause adjacent slices in an acquisition to have different image contrast. What type of artifact is this? - CORRECT ANSWER Cross Talk An artifact seen in a GRADIENT ECHO image that appears as black and white banding on the edges of the FOV - CORRECT ANSWER Moire Diseases, such as Malaria, in which microorganisms are transferred via an insect are classified as - CORRECT ANSWER vector borne A complication or illness caused by the treatment from a healthcare professional is termed - CORRECT ANSWER latrogenic In a medical malpractice lawsuit, the ____ must be able to prove medical malpractice - CORRECT ANSWER plaintiff / patient During transport of the patient, the urinary collection bag should be placed - CORRECT ANSWER below the bladder The stray magnetic field outside the bore of the magnet is termed - CORRECT ANSWER fringe field FDA revision in 2003 on RF absorption limits the absorption to ______ for the head - CORRECT ANSWER 3 w/kg - 10 min Which of the following has been documented to cause muscle contractions, alterations in vision and biochemistry of cells? - CORRECT ANSWER time varying magnetic fields What is the RF absorption limit for the whole body based off the 2003 FDA revision? - CORRECT ANSWER 4 w/kg - 15 min When a sudden loss in temperature occurs which causes the coils to no longer be superconducting, resulting in helium escaping from the cryogenic bath is termed: - CORRECT ANSWER a quench Force of an object in a magnetic environment depends on the following: - CORRECT ANSWER mass of the object, strength of the magnet, ferromagnetic properties of the object The medial and lateral rectus muscles are located where? - CORRECT ANSWER The eye The first major branch of the abdominal aorta is the: - CORRECT ANSWER celiac trunk The largest ventricle in the heart - CORRECT ANSWER left ventricle In what plane would a tear of the collateral ligaments of the knee be best evaluated? - CORRECT ANSWER coronal The ______ valve lies between the left atrium and left ventricle - CORRECT ANSWER bicuspid / mitral Which fissure divides the frontal lobe from the temporal lobes? - CORRECT ANSWER Sylvian The common carotid bifurcates into the internal and external carotid artery at the level of ______ - CORRECT ANSWER C3 / C4 What three branches come off the aorta? - CORRECT ANSWER brachiocephalic, left subclavian, left carotid Which veins transport oxygenated blood? - CORRECT ANSWER pulmonary Which valve lies between the right atrium and right ventricle? - CORRECT ANSWER tricuspid Water has a ______ T1 relaxation time and a _______ T2 relaxation time - CORRECT ANSWER long / long The transmit bandwidth of the RF pulse effects: - CORRECT ANSWER spatial resolution, SNR, slice thickness The process the digitizes the MR signal is known as: - CORRECT ANSWER Fourier / Fast Fourier Reducing the TE results in images with what change in contrast? - CORRECT ANSWER decreased T2 information The phase encoding step is performed prior to the ________ step - CORRECT ANSWER frequency encoding What element in the body is the principle nucleus used in MR? - CORRECT ANSWER hydrogen In a super conducting magnet, the magnetic field strength is increased by increasing the - CORRECT ANSWER # of turns in the wires Which parameter adjustments would shorten scan time? - CORRECT ANSWER Decrease TR Increase echo train length Decrease NEX Reducing the FOV will result in - CORRECT ANSWER decreased SNR How can thin slices be selected? - CORRECT ANSWER Steep slice gradient narrow bandwidth All the following result in increased SNR - CORRECT ANSWER Parameter adjustments that increase SNR are: Increase TR Reduce phase matrix Increase FOV Reduce receiver bandwidth Increase NEX The readout gradient is turned on during the sampling or readout of the peak echo and also during which other process? - CORRECT ANSWER frequency encoding Reducing the number of lines filled in K space will produce an image with: - CORRECT ANSWER decreased spatial resolution increased SNR Decreased scan time Reducing scan time can be achieved by: - CORRECT ANSWER reducing TR reducing NEX using half fourier Which is the best sequence to use to evaluate a patient with MS? - CORRECT ANSWER T2 FLAIR Which gradient echo sequence will give us TRUE T2? - CORRECT ANSWER SSFP (steady state free precession) As the number of phase encodings increase from 250 to 500, the SNR will _______ - CORRECT ANSWER decrease (less protons per voxel) Choose the correct slice thickness to create an isotropic voxel for the following: TR2000 TE 90 matrix 272 x 272 FOV 24cm - CORRECT ANSWER Formula: FOV / matrix *remember to convert FOV from cm to mm by multiplying it by 10 240 / 272 = .88235 .88 slice thickness What would the scan time be in a 3D volume acquisiton as this: TR 24ms TE 7ms Flip angle 15 degrees FOV 20cm 2mm slice thickness 76 slices 176 x 256 matrix 1 NEX - CORRECT ANSWER Formula: TR x Phase matrix x NEX x # slices 24 x 176 x 1 x 76 = 321024 * next step, divide by 60,000 321024 / 60000 = 5.35 5 min / 35 sec In a FSE, what would scan time be for: 25cm FOV 224 x 320 matrix TR 2500 100 TE 3mm slice thickness 12 ETL 4 NEX - CORRECT ANSWER Formula: TR x Phase Matrix x NEX / ETL 2500 x 224 x 4 = 2240000 2240000 / 12 = 186666 *next, divide answer by 1000 to convert ms into sec 186.66 *next, divide by 60 to get mins and secs 3 min, 11 sec. If a brain exam is being performed and the request is made to rule out acoustic neuroma, a protocol with thin cuts through the _________ should be performed. Inner auditory canals The _____________ imaging plane would be the most optimal slice orientation for evaluation of Arnold Chiari Malformation and its inferior cerebellar tonsillar herniation. sagittal A FLAIR sequence with a long TI is utilized to: null the signal from CSF If a brain exam is being perfomed and the request is made to rule out microadenoma due to elevated prolactin levels, a protocol with thin cuts through the ____________ should be performed. pituitary gland If a brain exam is being perfomed and the request is made to rule out globe tumor due to symptoms of diplopia, a protocol with thin cuts through the ____________ should be performed orbits/ optic nerves MR findings of a low volume corpus callosum and increased white matter lesions can be indicative of a diagnosis of: multiple sclerosis If a brain exam is being performed and the request is made to evaluate cranial nerves VII and VIII due to the patient's symptoms of tinnitus, a protocol with thin cuts through the ____________ should be performed. Inner Auditory Canal How many cranial nerves are there? 12 pairs To best visualize the pituitary gland in MRI, high resolution T1 weighted images in the __________ planes pre and post contrast are optimal. sagittal and coronal ____________ is a condition in which part of the cerebellar tonsil is displaced through the foramen magnum. chiari malformation When imaging a hemorrhagic infarct in the brain, which pulse sequence would demonstrate the magnetic susceptibility effects better? gradient echo _______ sequences are performed to suppress CSF (cerebro-spinal fluid)and aid in the detection of demyelination. FLAIR The brainstem includes what? midbrain, pons, medulla oblongata On a T2 weighted image, CSF appears bright because it has a __________ relaxation time. long T2 Which area(s) of the brain is/are typically affected in patients with a history of epilepsy? frontal lobe and/or temporal lobe The right and left optic nerve join at the: Optic chiasm The medial and lateral rectus muscles are located in the: Eyes What scan plane would be optimal for visualization of the hippocampus? Coronal oblique Which dural venous sinuses drain from the confluence of sinuses (by the internal occipital protuberance) to the mastoid portion of the temporal? Transverse sinuses The stalk of the pituitary gland is also known as the Infundibulum Which structure lies adjacent to the head of the caudate nucleus? Anterior horn of the lateral ventricle In the TMJ's, the articular disc lies between what two anatomical structures? Mandibular fossa and mandibular condyle The insular cortex is primarily responsible for: Motor control; cognitive function Which cranial nerve is responsible for Bell's Palsy? Cranial nerve VII (the facial nerve) To accurately depict the VII and VIII cranial nerves, the patient would centered at the level of the: External auditory meatus The dural venous sinuses that drain into the internal jugular vein are the: Sigmoid sinus When positioning a patient for a brain MRI, the centering should be placed at what anatomical landmark? Nasion If the third ventricle is dilated, but the fourth ventricle is not, there would then be pathology associated with: Aqueduct of Sylvius A depression in the base of the skull where the pituitary gland is located is called the ___________. Sella turcica Which fissure divides the frontal and parietal lobes from the temporal lobes? Identify Abducens nerve (CN VI)- Left side Identify Trigeminal nerve (CN V)- Left side identify the trochlear nerve (cranial nerve IV)- right. side Identify Trochlear nerve (CN IV)- left side Identify the cochlea Identify Facial nerve (CN VII)- left side identify the semicircular canal identify the Vestibulocochlear nerve (CN VIII)- Left side identify the Vestibulocochlear nerve (CN VIII)- right. side identify the facial nerve- right side identify the Spinal accessory nerve (CN XI) Identify the hypoglossal nerve (CN XII)- Left side Identify the hypoglossal nerve (CN XII)- Right side identify chiari malformation identify syrinx identify vestibular schwannoma identify pituitary tumor identify vagus nerve (CN X) identify the glossopharyngeal nerve (CN IX)- left side identify the glossopharyngeal nerve (CN IX)- right side If a sequence with a matrix of 256 x 512 is adjusted to 512 x 512, The SNR will decrease and the scan time will increase The scan time of a fast spin echo sequence utilizing a TR of 3500ms, a TE of 90ms, a 256x256 matrix, 1NSA, a 220mm FOV and an echo train length of 5 is ______ minutes, approximately. 3 ___________ does not aid in reducing scan time 2D acquisitions usually require an ________________. interslice gap In a gradient echo sequence, reducing the flip angle while maintaining the TR reduces: Saturation Reducing the TE: Decreases the contrast based on T2 tissue relaxation times Reducing the TR: decreases the SNR of the image and increases saturation effects Increasing the TE: increases the contrast based on the T2 relaxation of the tissues Complete saturation is a condition where Longitudinal magnetization is not allowed to recover between excitations Gradient echo sequences use flip angles: To control saturation effects The presaturation pulses typically are found: Prior to the excitation pulse Presaturation pulses are often used to: Reduce flow artifacts Decreasing rBW (receiver bandwidth)by a factor of two: Increases SNR by √2 Decreasing the receiver bandwidth (utilizing a narrow BW) increases ______ and readout time -- increases the sampling time and lengthens the sequence timing, creating ___________ minimum TR and TE values. SNR, longer Decreasing the receiver bandwidth (utilizing a narrow BW): Decreases the number of slices available The time during which the frequency encoding gradient is on: Increases with a reduction in receiver bandwidth Increasing the receiver bandwidth (rBW): Decreases chemical shift artifacts If a brain exam is being performed and the request is made to rule out acoustic neuroma, a protocol with thin cuts through the _________ should be performed. - CORRECT ANSWER Inner auditory canals The _____________ imaging plane would be the most optimal slice orientation for evaluation of Arnold Chiari Malformation and its inferior cerebellar tonsillar herniation. - CORRECT ANSWER sagittal A FLAIR sequence with a long TI is utilized to: - CORRECT ANSWER null the signal from CSF If a brain exam is being perfomed and the request is made to rule out microadenoma due to elevated prolactin levels, a protocol with thin cuts through the ____________ should be performed. - CORRECT ANSWER pituitary gland If a brain exam is being perfomed and the request is made to rule out globe tumor due to symptoms of diplopia, a protocol with thin cuts through the ____________ should be performed - CORRECT ANSWER orbits/ optic nerves MR findings of a low volume corpus callosum and increased white matter lesions can be indicative of a diagnosis of: - CORRECT ANSWER multiple sclerosis If a brain exam is being performed and the request is made to evaluate cranial nerves VII and VIII due to the patient's symptoms of tinnitus, a protocol with thin cuts through the ____________ should be performed. - CORRECT ANSWER Inner Auditory Canal How many cranial nerves are there? - CORRECT ANSWER 12 pairs To best visualize the pituitary gland in MRI, high resolution T1 weighted images in the __________ planes pre and post contrast are optimal. - CORRECT ANSWER sagittal and coronal ____________ is a condition in which part of the cerebellar tonsil is displaced through the foramen magnum. - CORRECT ANSWER chiari malformation When imaging a hemorrhagic infarct in the brain, which pulse sequence would demonstrate the magnetic susceptibility effects better? - CORRECT ANSWER gradient echo _______ sequences are performed to suppress CSF (cerebro-spinal fluid)and aid in the detection of demyelination. - CORRECT ANSWER FLAIR The brainstem includes what? - CORRECT ANSWER midbrain, pons, medulla oblongata On a T2 weighted image, CSF appears bright because it has a __________ relaxation time. - CORRECT ANSWER long T2 Which area(s) of the brain is/are typically affected in patients with a history of epilepsy? - CORRECT ANSWER frontal lobe and/or temporal lobe The right and left optic nerve join at the: - CORRECT ANSWER Optic chiasm The medial and lateral rectus muscles are located in the: - CORRECT ANSWER Eyes What scan plane would be optimal for visualization of the hippocampus? - CORRECT ANSWER Coronal oblique Which dural venous sinuses drain from the confluence of sinuses (by the internal occipital protuberance) to the mastoid portion of the temporal? - CORRECT ANSWER Transverse sinuses The stalk of the pituitary gland is also known as the - CORRECT ANSWER Infundibulum Which structure lies adjacent to the head of the caudate nucleus? - CORRECT ANSWER Anterior horn of the lateral ventricle In the TMJ's, the articular disc lies between what two anatomical structures? - CORRECT ANSWER Mandibular fossa and mandibular condyle The insular cortex is primarily responsible for: - CORRECT ANSWER Motor control; cognitive function Which cranial nerve is responsible for Bell's Palsy? - CORRECT ANSWER Cranial nerve VII (the facial nerve) To accurately depict the VII and VIII cranial nerves, the patient would centered at the level of the: - CORRECT ANSWER External auditory meatus The dural venous sinuses that drain into the internal jugular vein are the: - CORRECT ANSWER Sigmoid sinus When positioning a patient for a brain MRI, the centering should be placed at what anatomical landmark? - CORRECT ANSWER Nasion If the third ventricle is dilated, but the fourth ventricle is not, there would then be pathology associated with: - CORRECT ANSWER Aqueduct of Sylvius A depression in the base of the skull where the pituitary gland is located is called the ___________. - CORRECT ANSWER Sella turcica Which fissure divides the frontal and parietal lobes from the temporal lobes? - CORRECT ANSWER sylvan fissure The __________________ runs the length of the falx cerebri. - CORRECT ANSWER Superior sagittal sinus How do the vertebral arteries enter the cranium? - CORRECT ANSWER foramen magnum The central lines of k-space are associated with _____________ in a fast spin echo sequence. - CORRECT ANSWER contrast information Reducing the number of lines filled in k-space will produce an image: - CORRECT ANSWER With a decrease in spatial resolution K-space is typically filled: - CORRECT ANSWER one line at a time Lower bandwidth = ________ signal-to-noise = _______ chemical shift - CORRECT ANSWER higher; more A ______________ is defined as a picture element and has _________ characteristics. - CORRECT ANSWER Pixel, two-dimensional The maximum intensity projection algorithm: - CORRECT ANSWER Projects the high intensity pixels which represent blood vessels/ducts into one image Two gradients applied at the same time during slice selection are utilized for: - CORRECT ANSWER Encoding oblique slice planes The readout gradient is usually turned on during the sampling or readout of the peak echo and also during which other process? - CORRECT ANSWER Frequency encoding If the maximum slices in a set TR is 10, and the necessary number of slices for a given sequence's anatomical coverage is 36, how many acquisitions (packages) will be required? - CORRECT ANSWER 4 What effect would decreasing the FOV have on the spatial resolution of an image? - CORRECT ANSWER Increase What effect would using a steep slice select slope and/or narrow bandwidth have on slice thickness? - CORRECT ANSWER Slices will be thin An isotropic voxel refers to a __________ shaped voxel. - CORRECT ANSWER cubic If the radiologist requires 3mm slices axially acquired through the IAC, with a slice gap of 0.5mm, and requires 4.2cm total coverage, how many slices must be selected? - CORRECT ANSWER 12 If 30 4mm slices are planned with a gap of 1mm, the total anatomic coverage is _______ cm. - CORRECT ANSWER 15 True or False: Anatomical structures are displayed smaller in the image when the FOV is reduced. - CORRECT ANSWER False Creating additional images in various planes from a 3D data set is accomplished by a technique known as: - CORRECT ANSWER Multi-Planar reconstruction (MPR) What is an advantage of selecting a 3D acquisition as opposed to a 2D acquisition? - CORRECT ANSWER greater SNR and elimination of crosstalk artifacts. The process that digitizes the MR signals is known as: - CORRECT ANSWER Fourier transform The signal produced immediately following an RF pulse is: - CORRECT ANSWER FID __________ is defined as a small change in the magnetic field along a particular axis. - CORRECT ANSWER a gradient _________ is a file on the computer where the collected echoes are stored prior to being processed into an image by the Fourier Transform. - CORRECT ANSWER Raw data In order to generate an MR image, the slice select gradient must be turned on during: - CORRECT ANSWER RF energy application Decreasing the slice selection gradient strength will ________ of the resulting slice - CORRECT ANSWER Change the slice thickness The range of transmitted frequencies at each slice position must _____ to maintain slice thickness. - CORRECT ANSWER Remain constant Applying two gradients simultaneously during slice selection would: - CORRECT ANSWER produce an oblique slice