MRI in Practice Review Ch.6 Advanced Preset Questions And Answers Pass Guaranteed.

NSA is? - correct answer the number of times a line in k-space is filled with data Frequency of the echo are digitized and data is acquired and located in k-space. - correct answer True K-space is rectangular and has two axis perpendicular to each other. - correct answer True The lowest number is near the central lines and the highest number is near the outer edges. - correct answer True The number of data points horizontally in each line equals the phase matrix. - correct answer False (it's the frequency matrix) Receive bandwidth is the range of frequency that are sampled during the readout. - correct answer True (frequency is readout) Data is going to be determine by the _____ of the _____ encoding gradient. - correct answer polarity, phase Nyquist Theorem - correct answer The most optimum digital sampling frequency and calculates the minimal digital sample frequency needed. Sampling windows is how long the system has to acquire data and it's the time the the _____ encoding gradient is on. - correct answer Frequency Conventional spin echo lines in k-space is filled every _____ period. - correct answer TR The two directions in k-space are? - correct answer Phase, frequency The simplest way of filling k-space is? - correct answer Cartesian filling What are the parameters to calculate scan time in a conventional spin echo? - correct answer ST=TRxPha(m)xNSA The polarity of frequency encoding gradient determines wether k-space is transverse from _____ to _____. - correct answer Left, right The grid of data point in k-space corresponds to the grid of pixels in the image. - correct answer False (k-space is not the image) What would frequency matrix be if sampling window is 16 and receiver bandwidth is 16? - correct answer 256 (16 (SW) x 16 (RB)) K-space stores digital information for the image that is _____ shape and it has _____axis which is phase and frequency. - correct answer Rectangular, two Frequency is stored in _____ axis and its centered in the middle of several horizontal lines. - correct answer Horizontal Phase is stored in _____ axis and its centered in the middle of several lines. - correct answer Vertical The number of lines equals the number of phase matrix and it's the? - correct answer Frequency matrix The number of data points that equals the number of frequency matrix is called? - correct answer Phase matrix How is analog going to be illustrated? - correct answer Wave form How is digital going to be illustrated? - correct answer Binary numbers () The aliasing artifact is caused by? - correct answer Under sampling (increase FOV=bigger pixels =decrease resolution and its corrected by more slices) (misregistration of anatomical location, in the phase direction, but on the opposite side of the anatomical location, also known as wrap-around artifact) The size of each pixel is going to be determined by? - correct answer Spatial resolution Image matrix is determined by the number of _____ in k-space. - correct answer Data points F.F.T. stands for? - correct answer Fast Fourier Transform (number of info points in k-space) Number of data points in each column corresponds to? - correct answer Phase matrix Rate at which sampling occurs is called? - correct answer Digital sampling rate or digital frequency rate Transmit bandwidth is the range of frequency transmitted in the? - correct answer RF excitation pulse (transmit bandwidth means its being transmitted) The Outer lines equals low amplitude and high resolution and that equals _____. - correct answer Steep gradient The Central lines equals high amplitude and low resolution and that equals _____. - correct answer Shallow gradient Number of data points horizontally in each line represent? - correct answer Frequency matrix Number of lines vertically in each column represent? - correct answer Phase matrix The slope of the phase gradient is changed every? - correct answer TR Define spatial resolution - correct answer Resolution of image and availability to distinguish two points in the image as separate Define frequency resolution - correct answer Resolution of spatial frequencies in k-space. (K-space is frequency domain) The grid of data points in k-space corresponds to the grid of pixels. - correct answer False (k-space is not the image) Phase encoding gradient negative fills the top half of k-space - correct answer False (bottom half) FOV divided by matrix equals pixel size - correct answer True (320/320=1mm slice) A phase matrix of 256 selected 129 lines are filled and 256 TR are completed to finish the scan. - correct answer False (it's 256 lines) Four lines of k-space are required per TR, the scan time decreases by a factor of four. - correct answer True Frequency matrix is 256 and receive bandwidth is 32 kHz and sampling window is 8. What would be the frequency matrix be if sampling window is 16ms and receive bandwidth is 16 kHz? - correct answer 16 (SW) x 16 (RB) = 256 frequency matrix