MEDRADSC 3DE3 Lecture Notes - Lecture 8: Field Of View, Chemical Shift, Voxel

• School: McMaster University
• Department: Medical Radiation Sciences
• Course: MEDRADSC 3DE3
• Professor: Alana Trainor

Document Summary

Turned on as soon as possible after the rf excitation pulse. Spatial resolution is the ability to distinguish between 2 points as separate & distinct. Small voxels result in high sr as small structures are easily differentiated. In large voxels, individual signal intensities are average together & not represented as distinct within the voxel - this process is called parietal voluming. Thin slices increase sr in the slice select plane. Catch 22: thinner slices result in smaller voxels, fewer spins - snr decreases. Parameters for trade offs - increase sr but end up decreasing snr. Image matrix determines the # of pixels in the fov. High or fine matrix divides the fov by more pixels than a low or coarse matrix. Smaller pixels increase sr - increase the ability to distinguish between 2 structures that are close together in the patient. Increase sr bc of smaller voxels = decrease snr.