MRI In Practice Chapter 2 Best Exam Solutions Guaranteed Success.

Parameters that cannot be changed because they are inherent to the body's tissue - correct answer intrinsic contrast parameters Name the MRI intrinsic contrast parameters - correct answer T1 recovery time, T2 decay time, proton density, flow, apparent diffusion coefficient or ADC Parameters that can be changed, all selected at the operator console, selection depends on the pulse sequence used - correct answer extrinsic contrast parameters Name the MRI extrinsic contrast parameters - correct answer TR, TE, flip angle, TI, turbo factor/echo train length, b value An MRI image has contrast if there are areas of ______ signal or white on the image and areas of _______ signal or dark on the image - correct answer high, low Some areas have an intermediate signal and will display what? - correct answer shades of gray in between black and white The ________ can be separated into the individual vectors or quantities of the tissue present in the patient such as fat, CSF and muscle - correct answer NMV A tissue has a high signal if it has a large ____________ component of coherent magnetization at the time of TE - correct answer transverse If a tissue has a small transverse component of coherent magnetization at time _______ it will return a small signal, resulting in a _______ area on the image - correct answer TE, dark Images obtain contrast mainly through the mechanisms of what? - correct answer T1 recovery, T2 decay and proton or spin density The number of mobile hydrogen protons per unit volume of that tissue - correct answer proton density Water - correct answer Molecules are spaced apart in there and molecular tumbling rate is relatively fast Fat - correct answer Large molecules closely packed together and who is molecular tumbling rate is relatively slow Fat - correct answer Has a low inherent energy and can easily absorb energy into its lattice from hydrogen nuclei Fat - correct answer The NMV of _______ realigns rapidly with B0 so the T1 time of this is short Water - correct answer Has a high inherent energy and cannot easily absorb energy into its lattice from hydrogen nuclei Water - correct answer The NMV of _______ takes longer to realign with B0 so the T1 time of this is long Short - correct answer The T2 decay process in the hydrogen in fat is efficient because the molecules are closely packed together and therefore spin spin interactions are more likely to occur. As a result spins dephase rapidly and the loss of transverse magnetization is rapid. The T2 time of fat is therefore ________ Long - correct answer T2 decay in water is less efficient than in fat, as the molecules are spaced apart and spin spin interactions are less likely to occur. As a result, spins dephase slowly and the loss of transverse magnetization is gradual. The T2 time of water is therefore __________ Fat - correct answer What has a high signal and appears bright on a T1 contrast image? Water - correct answer What has a low signal and appears dark on a T1 contrast image? T1 weighted images - correct answer On what type of image does fat appear bright and water appear dark? Water - correct answer What has a high signal and appears bright on a T2 contrast image? Fat - correct answer What has a low signal and appears dark on a T2 contrast image? T2 weighted images - correct answer On what type of image does water appear bright and fat appear dark? High - correct answer Tissues with a _________ proton density have a large transverse component of magnetization Low - correct answer Tissues with a _________ proton density have a small transverse component of magnetization proton density weighting - correct answer What is always present and depends on the patient and the area being examined. It is the basic MRI contrast Fat - correct answer