The hydrogen nuclei in the body are found mainly in fat and water. The T value of fat was measured to be 100 ms and that of water to be 500 ms. In a spin-echo experiment, calculate the delay between the 90 pulse and the 180 pulse that maximizes the difference in signal intensities between the fat and the water. 90% T 180 Intensity Thousands 300 250 200 150 100 50 0 2 +12 14 x/s 5 6