QUESTION 1 5 points Save Answer A spin-echo image of the abdomen was acquired at 3 T using a frequency-encoding gradient strength of \( 2 \mathrm{mT} / \mathrm{m} \). The extent of the chemical shift offset artifact observed for fat in this image would be approximately: a. 2 mm b. 3 mm c. 5 mm d. 8 mm QUESTION 2 2 points Save Answer In the image acquisition described in Q1 the receiver bandwidth was set to \( 54,000 \mathrm{~Hz} \) and an image matrix of \( 256 \times 128 \) data points was acquired. The chemical shift offset between fat and water was therefore: a. 1 pixel b. 2 pixels c. 3 pixels d. 4 pixels
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- The chemical shift between fat and water is approximately 3.5 ppm. - At 3 T, the Larmor frequency is about 128 MHz. - Chemical shift in Hz = \( 3.5 \, \text{ppm} \times 128 \times 10^6 \, \text{Hz} = 448 \, \text{Hz} \). Show more…
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