What is spin lock in NMR?
From NMR Wiki spin lock is pulse sequence that allows to keep magnetization in the transverse plane for certain amount of time. Examples of spin-lock pulse sequences are: Clean TOCSY.
What is spin lock MRI?
Abstract. Spin-lock and spin-tip excitations are the two magnetization components created by the preparatory RF pulse of an MRI contrast enhancement sequence. Only spin-lock is inherently adiabatic, preserving spin alignment so that tissue-specific relaxation can generate desired saturation contrasts.
What is a pulse sequence diagram?
A pulse sequence diagram (PSD) illustrates the sequence of events that occur during magnetic resonance imaging (MRI). It is a timing diagram showing the radio frequency (RF) pulses, gradients, and echoes.
What is t1rho MRI?
T1 rho, also known as T1ρ or “spin lock” (‘ρ’ is the symbol for the Greek letter rho), is an MRI sequence that is being developed for use in musculoskeletal imaging. At the moment it is mostly investigational and does not yet have widespread clinical use.
What is spin echo pulse sequence?
The spin echo sequence is made up of a series of events : 90° pulse – 180° rephasing pulse at TE/2 – signal reading at TE. This series is repeated at each time interval TR (Repetition time). With each repetition, a k-space line is filled, thanks to a different phase encoding.
What is pulse sequence in NMR?
In Fourier transform NMR spectroscopy and imaging, a pulse sequence describes a series of radio frequency pulses applied to the sample, such that the free induction decay is related to the characteristic frequencies of the desired signals.
What is T1ρ?
T1ρ (or T1ρ) relaxation time describes spin-lattice relaxation in the rotation frame at the presence of an external RF pulse in the transverse plane.
What is the purpose of spin echo?
The “spin-echo” pulse sequence [9,10,11] is used to obtain a signal by means of a 90º excitation pulse and a 180º inversion pulse, which were sent to the nuclei of hydrogen atoms of the tissues present in the region to be analyzed (Figure 2).
What is CPMG pulse sequence?
A sequence of pulses used for spin-echo experiments in nuclear magnetic resonance (NMR) in which the initial pulse is 90° followed by a series of 180° pulses. A CPMG sequence is designed so that the spin echoes die away exponentially with time.
What is spin echo sequence?
Why do we use RF pulses in NMR?
Most NMR spectroscopic measurements are concerned with measuring more than one signal and each of them has a different Larmor frequency. A sufficiently strong rf pulse is needed to overcome the induced field to move all the signals at different Larmor frequencies away from equilibrium. This is called a hard pulse.
What is the purpose of the 90 degree pulse in the spin echo pulse sequence?
(Such groups of like-behaving spins are called spin isochromats, literally “spins of the same color”.) The 90°-pulse first tips these spins into the transverse plane. Because the local microscopic fields may differ slightly, some spin groups may precess faster (and gain phase) relative to others.