MRI take home point (7)

• The data in the center of k-space determine SNR.
• The spin-echo pulse sequence consists of a 90-TE/2-180-TE/2-ADC.
• Total scan time for 2D spin-echo imaging is determined by the product of TR, the number of phase-encoding steps, and the number of excitations per phase-encoding step.
• In multislice SE, many slices are collected in the same scan time as a single slice. The maximum number of slices is determined by TR and TE, the longer TR and the shorter TE, the more slices that can be acquired.
• Gradient-echo pulse sequences speed image acquisitions by using partial flip angles (less than 90 degree) and gradient-reversal to form a signal echo.