Scan Principles Image Contrast/Weighting* Flashcards
A sequence with a _________ TR and a _________ TE will exhibit T1 weighting.
short; short
Which of the following statements is TRUE regarding spin echo sequences?
T1 contrast is maximized with short TR’s
What is wrong with a T2 weighted, fast spin echo image that has a 1.1 second TR and an 90 millisecond TE?
The TR does not sufficiently minimize the T1 weighted contrast
The TR of 1100 ms is not long enough for T2 weighting
Tissues with _______ are bright on T1 weighted spin echo scans and tissues with _________ are bright on T2 weighted spin echo scans.
short T1 times; long T2 times
Enabling Driven Equilibrium will enable the operator to:
TE
The longer the TE, the more T2 weighting an image will exhibit.
What determines the amount of T1 weighting in an image?
TR
To produce an image based on differences in T1, the time interval between 90° excitation pulses should be:
Short
A sequence with a _________ TR and a _________ TE will exhibit PD weighting.
Long; short
A sequence with a _________ TR and a _________ TE will exhibit T2 weighting.
Long; long
A T2 weighted image will have a repetition time (TR) in the range of:
2000 - 6000 ms
A T2 weighted image will have an echo time (TE) in the range of:
80 - 120 ms
A T1 weighted image will have a repetition time (TR) in the range of:
350 - 700 ms
A T1 weighted image will have an echo time (TE) in the range of
10 - 30 ms
A proton density weighted image will have a repetition time (TR) in the range of:
1600 - 4000 ms
A proton density weighted image will have an echo time (TE) in the range of:
10 - 35 ms
Water is dark and fat is bright in:
T1 weighted images
Which of the following parameter combinations would yield the most T2 weighted image?
3500 TR, 120 TE
Which of the following parameter combinations would yield the most T1 weighting?
350 TR, 15 TE
Which of the following statements is FALSE?
T1 weighting is adjusted with short TE’s
Water is hyperintense and fat is typically dark in:
T2 weighted images
T2 weighted images provide bright signal from fluids and fat is typically dark
Short TR, short TE are the parameter requirements
Transverse magnetization
T1 relaxation time is the recovery of 63% longitudinal magnetization of a specific tissue.
All of the following are properties of T2 weighting EXCEPT:
Flip angle controls contrast
Contrast is controlled by TE in a T2 weighted sequence.
All of the following are true EXCEPT:
Gradient echo — 90° RF followed by 180° RF
Gradient echo lacks 180° RF pulses
T1 is useful for __________, whereas T2 is utilized for depicting __________.
Anatomy; pathology
T1 is useful for anatomy, whereas T2 is utilized for depicting pathology(edema).
All of the following are examples of INTRINSIC contrast parameters in tissues EXCEPT:
TR
Intrinsic parameters in tissues are those that are specific to each tissue, inherent, and cannot be changed, such as ADC, T1/T2 time, specific proton density, and flow.
All of the following are examples of EXTRINSIC contrast parameters EXCEPT:
T1 time
Extrinsic contrast parameters are those that the MR technologist can adjust to alter the image
Structures that will always appear black on an MR image include all of the following EXCEPT:
CSF
Presaturation pulses typically occur:
Prior to the excitation pulse
Presaturation pulses typically occur prior to the excitation pulse.
Increasing the TE in a spin echo pulse sequence:
Enables more T2 information in the image
Increasing the TE in a spin echo pulse sequence enables more T2 information in the image.
In an inversion recovery sequence, image contrast is controlled by:
All of the above
In an inversion recovery sequence, image contrast is controlled by TR (repetition time), TE (echo time) and TI (inversion time)
Chemical or spectral fat suppression techniques suppress fat signal based on the:
Precessional frequency of fat
Chemical or spectral fat suppression techniques suppress fat signal based on the precessional frequency of fat.
Which of the following sets of parameters would show edema as hyperintense?
4000 TR, 90 TE
T2 weighted sequences (long TR – >2000 and long TE >80) will yield hyperintense(bright) signal from fluid (edema
As the TR increases the amount of T1 weighted contrast ___________.
Decreases
As the TR increases the amount of T1 weighted contrast decreases
A Proton Density weighted image has a TR that is long to _____________, and a TE that is short to _____________.
Minimize T1 contrast; minimize T2 contrast
A Proton Density weighted image has a TR that is long to minimize T1 contrast, and a TE that is short to minimize T2 contrast, yielding an image that is neither T1 nor T2.
