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Sipariş Takip

    Animation 8.4 (Gradient Moment Nulling)

    This animation supports Figure 8.43. It shows how the gradient configuration used in gradient moment nulling or flow compensation corrects for phase dispersal of flowing spins. The first lobe of the gradient causes the magnetic moment of the flowing spin to phase shift clockwise by 90°. The second lobe of the gradient is switched on to twice the amplitude of the first lobe, but with opposite polarity. As the second lobe has twice the amplitude of the first, it causes the magnetic moment of the spin to alter its phase by 180°. However, as the second lobe of the gradient has an opposite polarity to the first, the magnetic moment of the spin is phase shifted 180° anticlockwise rather than clockwise. The third lobe of the gradient is applied to the same polarity and amplitude as the first lobe. This, therefore, causes the magnetic moment of the spin to phase shift 90° in a clockwise direction, so that it ends up with the same phase position as before it started its travel through the gradients. In this way flowing spins, that would normally produce a signal void due to phase dispersal of their magnetic moments, maintain their phase coherency. This strategy, therefore, reduces flow artefact.

    Dersler

    Animation 1.1 Rotating and Fixed Frame of Reference Animation 1.1 Rotating and Fixed Frame of Reference 09/05/2023 Animation 1.2 (NMV and Coil) Animation 1.2 (NMV and Coil) 09/05/2023 Animation 1.3 (NMV Coil and Oscilloscope) Animation 1.3 (NMV Coil and Oscilloscope) 09/05/2023 Animation 2.1 (T1 vs T2) Animation 2.1 (T1 vs T2) 09/05/2023 Animation 2.2 (Diffusion) Animation 2.2 (Diffusion) 09/05/2023 Animation 3.1 (The 180° RF Pulse) Animation 3.1 (The 180° RF Pulse) 09/05/2023 Animation 3.2 (The Larmor Grand Prix) Animation 3.2 (The Larmor Grand Prix) 09/05/2023 Animation 3.3 Inversion Recovery Animation 3.3 Inversion Recovery 09/05/2023 Animation 6.1 (Slices Chest of Drawers) Animation 6.1 (Slices Chest of Drawers) 09/05/2023 Animation 6.2. (Sampling Frequencies) Animation 6.2. (Sampling Frequencies) 09/05/2023 Animation 6.3 (Filling Methods) Animation 6.3 (Filling Methods) 09/05/2023 Animation 8.1 (In and Out of Phase) Animation 8.1 (In and Out of Phase) 09/05/2023 Animation 8.2 (Entry-slice Phenomenon) Animation 8.2 (Entry-slice Phenomenon) 09/05/2023 Animation 8.3 Time of Flight Animation 8.3 Time of Flight 09/05/2023 Animation 8.4 (Gradient Moment Nulling) Animation 8.4 (Gradient Moment Nulling) 09/05/2023 Animation 9.1 (Closed and Open Systems) Animation 9.1 (Closed and Open Systems) 09/05/2023 Animation 9.2 (Active Shielding) Animation 9.2 (Active Shielding) 09/05/2023 Animation 9.3 (NMV Coil and Scanner Loop) Animation 9.3 (NMV Coil and Scanner Loop) 09/05/2023