# Shared Flashcard Set

## Details

MRI physics module 2
Image Weighting and Contrast
35
Physics
Professional
09/03/2012

Term
 At equilibrium, what signal is produced?
Definition
 None
Term
 Which axis is always vertical?
Definition
 Z axis
Term
 If M = ____, the patient is NOT in the Bo
Definition
 zero
Term
 The Z axis is always in the same direction as ____
Definition
 Bo
Term
 An ECHO is produced following a ____ RF pulse
Definition
 180
Term
 tissues with high signal (white or bright) have a _____ transverse vector in X/Y plane
Definition
 Large
Term
 tissue with a large transverse vector have ____ contrast
Definition
 high
Term
 tissues that show as shades gray have ____ contrast, or a smaller NMV than higher contrast tissuess
Definition
 intermediate
Term
 areas of low signal (dark/black) have _____ contrast, and a _____ transverse vector
Definition
 low, small
Term
 another term for high signal/bright on image tissue is ______
Definition
 hyperintense
Term
 another term for low signal/dark on image tissue is ______
Definition
 hypointense
Term
 why do we focus on fat and water in image weighting?
Definition
 because they are the extreme opposites in different weightings - if one is bright, the other will be dark.
Term
 fat is chemically linked to _____ in the body
Definition
 carbon
Term
 which precesses slower at 1 T, fat or water?
Definition
 fat
Term
 fat precesses slower than water - another way to say this is that fat has a lower ______ ______
Definition
 Larmor frequency
Term
 which type of tissue has an electron cloud that protects it from effects of Bo?
Definition
 fat
Term
 Water is chemically linked to _____ in the body
Definition
 oxygen
Term
 another term for proton density is ______ ______
Definition
 spin density
Term
 emphasizing one tissue characteristic over another is called
Definition
 image weighting
Term
 the term for values like TR, TE, slice thickness - things we select
Definition
 parameter
Term
 A group of parameters used for a particular scan is called a _______
Definition
 protocol.
Term
 An ______ is a set of protocols for a particular body part.
Definition
 exam
Term
 TR (repetition time) is ____
Definition
 time from first 90-degree RF pulse to the next 90-degree RF pulse
Term
 TE (echo time)
Definition
 time from 90 degree RF pulse until we collect the MR signal data that becomes our image.
Term
 another term for T1 relaxation is T1_______
Definition
 recovery
Term
 another term for T2 relaxation is T2_________
Definition
 decay
Term
 T1 relaxation refers to
Definition
 recovery of longitudinal magnetization
Term
 T2 relaxation refers to
Definition
 decay of transverse magnetization
Term
 The 180 RF pulse is also known as the __________ pulse or _________ pulse
Definition
 rephasing, refocusing
Term
 the RF receiver coils are located in the _______ plane
Definition
 horizontal
Term
 T1 recovery is also known as ______ ______ or _________ recovery
Definition
 spin lattice, longitudinal
Term
 T1 recovery is 63% regrowth of _________ ___________
Definition
 longitudinal magnetization
Term
 T1 is primarily controlled by which parameter?
Definition
 TR (repetition time)
Term
 When we send in the RF pulse, what frequency do we use?
Definition
 the precessional frequency of the tissue we are weighting
Term
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Definition
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