Sequences

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145297/1/cpmib0500.pd

Preface

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145289/1/cpmipref.pd

Motion Compensation Along All Three Different Directions

This unit addresses how one can deal with phase perturbations that arise due to the presence of motion. Techniques to reduce or remove their associated artifacts are explained in detail. Artifacts due to phase changes that come from the read gradient, from the slice select gradient and from the phase encoding gradient are also discussed.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145397/1/cpmib0702.pd

Magnetic Moment of a Spin, Its Equation of Motion, and Precession

This unit discusses the basic spin properties of the proton. The motion of a spin in an magnetic field that give rise to magnetic moment, is also discussed. The key to grasping much of MRI lies in understanding the concept of precession. Famous Bloch equation that basically leads to the description of the precession of a spin in the presence of an external magnetic field is also explained.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145243/1/cpmib0101.pd

Radiofrequency Excitation

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145389/1/cpmib0202.pd

Magnetic Moment of a Spin, Its Equation of Motion, and Precession

This unit discusses the basic spin properties of the proton. The motion of a spin in an magnetic field that give rise to magnetic moment, is also discussed. The key to grasping much of MRI lies in understanding the concept of precession. Famous Bloch equation that basically leads to the description of the precession of a spin in the presence of an external magnetic field is also explained.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145300/1/cpmib0101.pd

Signal Detection

The bulk magnetization represents the equilibrium value of the magnetization when all spins have aligned themselves parallel to the main field. When this magnetization is tipped into the transverse plane, it precesses about the main field. This precession generates a changing flux through the face of an appropriately placed coil inducing an electromotive force (emf) in the coil. The measured signal is proportional to the induced emf. This unit discusses the basic physics behind detecting MR signal. The process of calculating induced emf based on Faradays law of induction is explained.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145226/1/cpmib0201.pd

Nulling Signal of a Slice, Slice Select Profile, and Radiofrequency Power

This unit discusses nulling of remaining signal from a RF pulse prior to the next RF pulse. This is to avoid mixing leftover signal with the signal generated from the next RF pulse. The slice select profile is also discussed in detail. The power of the RF pulse and its limit imposed by the Food and Drug Administration (FDA) is also discussed.Normal.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145235/1/cpmib0203.pd

Phase Dependence on Motion

This unit introduces the sources of variable phase in the presence of motion. The sources of these phase changes can come from the read gradient, from the slice select gradient and from the phase encoding gradient. Motion during the gradient moves the spin from one location to another and, therefore, changes the effective field it sees. This field change leads to a frequency change in time during either the dephasing or rephasing gradient or both. As a result, the spins do not refocus at the expected time.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145395/1/cpmib0701.pd

Phase Dependence on Motion

This unit introduces the sources of variable phase in the presence of motion. The sources of these phase changes can come from the read gradient, from the slice select gradient and from the phase encoding gradient. Motion during the gradient moves the spin from one location to another and, therefore, changes the effective field it sees. This field change leads to a frequency change in time during either the dephasing or rephasing gradient or both. As a result, the spins do not refocus at the expected time.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145363/1/cpmib0701.pd