Homework-7: Imaging Hardware


  1. What is the resonance frequency of an imaging coil which has a 1x10-7 Henry inductor and a 100 picofarad capacitor across the inductor? How can this coil be made to resonate at 63.85 MHz?


  2. The two anit-Helmholtz coils of a Z gradient coil are separated by 120 cm. If this coil configuration can produce a magnetic field gradient of 2 G/cm, what is the magneitude of the magnetic field at the center of each coil?


  3. Will the following pulse sequence adhere to the USFDA SAR guidelines for the head?
    Sequence = multi-slice, spin echo
    TR = 600 ms
    TE = 25 ms
    Thk = 3 mm
    Number of slices = 17
    Energy per 90o pulse = 10 J
    Width of 90o pulse = 50 ms
    Signal acquisition time = 10 ms
    Patient weight = 80 kg


  4. The quadrature detector on your imager has a reference signal of 63.85 MHz coming into one of the channels. The signal channel has a signal of 63.84 MHz coming into it. What frequency or frequencies will be coming out of the detector?


  5. Safety Questions:
    Is it safe for someone with a tattoo to have an MRI?
    Is it safe for a pregnant woman to have an MRI?
    How many MRI scans can a person have?

    (Hint: check the Links of Interest on the ISMRM web site.)