Three tissues have the following relative proton densities and relaxation times: fat…

PHYSICS · Subjective · Fermi University Physics · Biophysics & Medical Physics · Radiation physics and diagnostic imaging · Radiation physics and diagnostic imaging

Life at Thermal Energy, Ch Echoes, precession and the therapeutic beam

Problem

Three tissues have the following relative proton densities and relaxation times: fat (ρH=1.00\rho_{\rm H} = 1.00, T1=250 msT_1 = 250\,\mathrm{ms}, T2=60 msT_2 = 60\,\mathrm{ms}), skeletal muscle (ρH=0.90\rho_{\rm H} = 0.90, T1=900 msT_1 = 900\,\mathrm{ms}, T2=50 msT_2 = 50\,\mathrm{ms}), and cerebrospinal fluid (ρH=1.00\rho_{\rm H} = 1.00, T1=4000 msT_1 = 4000\,\mathrm{ms}, T2=2000 msT_2 = 2000\,\mathrm{ms}). A scan is run with TR=600 ms\mathrm{TR} = 600\,\mathrm{ms} and TE=20 ms\mathrm{TE} = 20\,\mathrm{ms}. Using the signal rule signal=ρH(1−e−TR/T1)e−TE/T2,\text{signal} = \rho_{\rm H}\left(1 - e^{-\mathrm{TR}/T_1}\right)e^{-\mathrm{TE}/T_2}, calculate the signal from each tissue and rank them from brightest to darkest.

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