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University of Iowa - BME 2210Homework4_solutions.

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Homework #4: BME 2210 Due as a single PDF file ICON submission by Monday, October 08, 2018 by 9:30 AM 1. Calculate the precession frequency (the Larmor frequency) for 31? nuclei in both 1.5 and 3.0 ... T scanners. Report your answer in rads/sec and in MHz. 2. A rectangular RF excitation pulse is used to flip the net magnetic moment vector into the transverse plane. A 60 ?? ?1 field is used. a) Find the equation to describe ?(?), the angle of the net magnetic moment vector relative to the z axis, as a function of time. ?(?) = ?1 ∙ ? = ? ∙ ?1(?) ∙ ? b) Plot ?(?) vs. time for 0 ≤ t ≥ 250 ????. https://www.coursehero.com/file/36872817/Homework4-solutionspdf/ This study resource was shared via CourseHero.com c) A 90° flip angle is desired. Find the minimum value of the pulse length, ??, to obtain the 90° flip. ?(?) = d) Now assume that a 180° flip angle is desired. Find the minimum value of the pulse length, ??, to obtain 180° flip. ?e) Assume we are interested in using a triangular pulse at the same peak amplitude as the rectangular pulse above (generating the same field strength ?1), what is the duration of this pulse? To get the same area under the curve, for the same peak amplitude, the duration ?? must be twice that of a rectangular pulse. ? 3. You are running an MR experiment and have used RF excitation to produce and record the free precession MR signal, ?(?). ?(?) is given in the table below. a) In Matlab, plot ?(?) ??. ? and the natural logarithm of ?(?); ???(?(?)) ??. ?. b) Develop a method to estimate ?2 from this data. Explain your method and give your best estimate of ?2 [Show More]

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