MRI Review

46 Questions  I  By Athelco
Complete review of MRI

  
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1.  These substances exhibit a very slight negative or repelling effect when placed  in externally applied magnetic field.  They have low and negative suseptibility
A.
B.
C.
D.
2.  Substances that exhibit a slight increase in the magnetic field when placed in an externally applied magnetic field.  They have low and positive suseptibility.
A.
B.
C.
D.
3.  Gadilinium is an example of a _ substance
A.
B.
C.
D.
4.  These substances exhibit positive suseptibility, but when placed in an external magnetic field they will remain magnetized when external magnetic field is removed
A.
B.
C.
D.
5.  These substances exhibit positive suseptibility , are stronger than paramagnetic substances, but are weaker than ferromagnetic substances, and are used as T2 contrast agents
A.
B.
C.
D.
6.  10000 gauss = _ Tesla
A.
B.
C.
D.
2 comments
7.  Magnets made of blocks or slabs or naturally occurring ferrous material.
A.
B.
C.
D.
8.  Permanent magnets have field strengths of
A.
B.
C.
D.
9.  Wires are aligned side by side to create magnet field
A.
B.
C.
D.
10.  This magnet can be used in horizontal or vertical field system, and have strengths up to 0.3 T, and can be turned off.
11.  Magnets that utilize direct current applied to a coil of wire, and are submerged in liquid helium or cryogen to cool the wires.
12.  The majority of superconducting magnets are __ in design and exhibit a (horizontal or vertical) magnetiic field.
13.  Superconductive magnets are limited to _ T in clinical MRI by the FDA.
14.  This type magnetic shielding uses metal, usually steel, in the scan room walls to contain the fringe field
A.
B.
15.  This type of magnetic shielding uses other magnets and their associated magnetic field to confine the field of the main magnet
A.
B.
16.  These coils utilize additional loops and circiutry to improve the efficiency with which the MR signal is induced in the coil, and increase SNR approximately 40% over the coil of the same size.
A.
B.
C.
D.
17.  Require the use of solenoid coils due to the orientation of the B0, more effiecient than linear coil, and can be combine with other coils electronically to improve signal uniformity through a region of interest.
A.
B.
C.
D.
18.  Two coils are combined in such a manner that they utilize the same receiver electronics, and has been utilized in coils designed to image the cervical spine and neck.  It can improve the signal homogenity across a region but SNR is not necessarily increased.
A.
B.
C.
D.
19.  Allow for increased area of coverage without the reduction in SNR, have multiple coils and receivers.
A.
B.
C.
D.
20.  A narrow bandwidth allows for _slices
A.
B.
21.  The slice location is determined by the
A.
B.
C.
D.
22.  The receiver gandwidth represents the range of frequencies sampled during the
A.
B.
C.
D.
23.  The receiver bandwidth is determined by the number of
A.
B.
24.  If 256 frequency samples are collected and the readout or sampling period is 8 ms, the receiver bandwidth would be
25.  The main purpose of the gradient subsystem is to
A.
B.
C.
D.
26.  This gradient coil varies the intensity of the magnetic field in the head to foot direction 
A.
B.
C.
27.  This gradient coil varies the intensity of the magnetic field in the right to left direction
A.
B.
C.
28.  This gradient coil varies the intensity of the magnetic field in the anterior to posterior direction
A.
B.
C.
29.  A way to express the gradient performance referring to the acceleration of the gradient magnetic field to its maximum amplitude, expressed in units of T/m/s.
A.
B.
C.
30.  The gyromagnetic ratio of h+ in 1 T is
31.  THE SIGNAL INDUCED IN A RECEIVER COIL IMMEDIATELY FOLLOWING AN RF EXCITATION PULSE IS KNOWN AS THE
32.  THE FID CAN BE ALTERED BY
33.  THE DIFFERENCE IN PRECESSIONAL FREQUENCY  OF THE HYDROGEN IN FAT AND WATER IS KNOWN AS
A.
B.
C.
D.
34.  THE CHEMICAL SHIFT BETWEEN FAT AND WATER AT 1.5 T IS __, OR  H + WATER WILL PRECESS THIS MUCH FASTER THAN THE H+ IN FAT
35.  THE DIFFERENCE IN PRECESSIONAL FREQUENCY, DUE TO THE CHEMICAL/MOLECULAR ENVIRONMENT, IS KNOWN AS
36.  TO EVALUATE IMAGES WITH T2* CONTRAST _ IMAGES ARE REQUIRED
37.  WHEN IS THE SLICE SELECTION GRADIENT APPLIED
A.
B.
C.
D.
38.  SLICE THICKNESS IS DETERMINED BY THESE 2 THINGS
39.  WHEN DOES THE FREQUENCY ENCODING OCCUR
A.
B.
C.
D.
40.  THE PHASE ENCODING GRADIENT REPRESENTS
A.
B.
C.
41.  WHEN DOES PHASE ENCODING TAKE PLACE
42.  THE MIDDLE LINES OF K SPACE CONTAIN OVER 90% OF THE  
43.  THE OUTER LINES OF K SPACE HOLD
44.  IF A THICKER SLICE IS DESIRED
A.
B.
C.
D.
45.  THE ONLY WAY THE SPATIAL RESOLUTION CAN INCREASED IS TO
A.
B.
C.
D.
46.  RF SHIELDING IS KNOWN AS A
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