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Refocusing flip angle

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August undefined, 2024

WebMay 28, 2016 · First, consider a small flip angle α (e.g., 5° to 30°). As can be seen in Figure 20-11, a small flip angle results in a large amount of (persistent) longitudinal magnetization after application of the RF Only gold members can continue reading. Log In or Register to continue You may also need Load more posts WebJun 20, 2012 · Influence of refocusing flip angles and flow velocity on the signal behavior of the echo train. Left to right refocusing flip angle = 180°, 90°, 60°, 30°. When we used the low refocusing flip angle, the signal of flow spins decreased at an early point of the echo trains, and the results were similar at both slow and fast flow velocities

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WebAug 26, 2016 · A single-shot fast spin-echo pulse sequence with variable refocusing flip angles and full-Fourier acquisition leads to a doubling of 3-T acquisition speed via reduced radiofrequency energy deposition and demonstrates significant improvements in perceived image quality and perceived diagnostic capability when evaluating structures in the pelvis. grieving husband of teacher dies

Multiecho imaging sequences with low refocusing flip …

WebPurpose: To develop and validate clinically a single-shot fast spin echo (SSFSE) sequence utilizing variable flip angle refocusing pulses to shorten acquisition times via reductions in specific absorption rate (SAR) and improve image quality. Materials and methods: A variable refocusing flip angle SSFSE sequence (vrfSSFSE) was designed and implemented, with … WebJul 1, 1988 · Patient images using refocusing flip angles a = 60(Figs. 6 and 7) demonstrate the high signal intensity and the lack of artifacts in images produced with this method. … WebJul 1, 2024 · Recently, a variation of SSFSE with variable refocusing flip angles (variable refocusing single-shot FSE [vrfSSFSE]) has been described. 16 This flip angle modulation … fiestaware daffodil collection

Simultaneous Dual Contrast Weighting Using Double Echo …

Variable Refocusing Flip Angle Single-Shot Imaging for …

WebApr 12, 2024 · The 3D TSE magnetic resonance sequence with a variable flip angle 16–21 is an emerging MRI technology. The 3D T1W BrainVIEW sequence, an advanced 3D TSE black-blood technology produced by Philips MRI, has been … WebMar 18, 2003 · Based on this interpretation, one may speculate that changing the refocusing flip angle to α 2 for such magnetization will lead to a new PSS, the trajectory of which will … grieving husband after wife\u0027s deathWebApr 26, 2004 · The raw signal may be corrected for refocusing flip angle modulation by inverting the expected signal modulation due to flip angle variation: (3) Because the correction amplifies noise as well as signal for the higher spatial frequencies, an overall increase in image noise is expected. grieving heart pillow

"WebMaterials and methods: A variable refocusing flip angle echo-train was optimized for the spine to improve the point spread function and minimize the specific absorption rate, yielding images with improved spatial resolution and SNR compared with the constant flip angle sequence. " - Refocusing flip angle

Refocusing flip angle

Sensitivity of Low Flip Angle SSFSE of the Abdomen to …

WebJul 8, 2024 · Properly designed variable refocusing flip angle echo trains can stabilize signal amplitude over the course of the echo train by initially storing magnetization in the longitudinal direction, with slow conversion back to … WebOct 1, 2009 · The most important advantage of 3.0-T magnetic resonance (MR) imaging systems is their increased signal-to-noise ratio (SNR) compared with 1.5-T systems. The higher SNR can be used to shorten acquisition time, achieve higher spatial resolution, or a combination of the two, thereby improving image quality and clinical diagnosis.

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WebFeb 1, 2024 · Although a lower refocusing flip angle brings about a greater signal loss caused by the spin phase dispersion of moving protons, too low a refocusing flip angle … Webamplitudes by using variable refocusing flip angles converging to a over the first refocusing periods. More recently it was demonstrated that even setting only the first refocusing flip …

Webmm, slice thickness¼5 mm, t¼15 ms. The nominal flip angle was set to 130 for the first two refocusing pulses in the echo train to ensure balanced intensities for the primary SE and primary STE. A nominal flip angle of 180 was set for the remaining refocusing pulses. Phase encoding direction was head to feet (H–F) for all phan-tom experiments. WebBy adjusting the phase of transmission, the 180° pulse may be applied along the x-axis, y-axis, or any other direction. On the left side of the diagram is a 180 y ° pulse, that is, one that rotates the spins around the y-axis. The echo forms in the +y-direction. On the right is a 180 x ° pulse that causes the echo to form along the −y ...

WebAbstract. Purpose: To develop and validate clinically a single-shot fast spin echo (SSFSE) sequence utilizing variable flip angle refocusing pulses to shorten acquisition times via … WebAbstract. Radiofrequency (RF) transmit field (B 1) mapping is a promising method in mitigating the B 1 inhomogeneity in various magnetic resonance imaging (MRI) applications. Although several phase- or magnitude-based B 1 mapping methods have been proposed, these methods often require complex modeling, long acquisition time, or specialized MRI …

WebJun 20, 2012 · We have examined the following three conditions; (1) constant refocusing flip angles, (2) two refocusing flip angle sweep methods, and (3) flow compensation …

WebMay 22, 2024 · A refocusing pulse of less than 180° can be considered an insufficient flipping of the transverse magnetization. The induced MR signal is diminished, because it … fiestaware dancing lady figurineWebrefocusing flip angle. The use of a reduced flip angle dramatically decreases the power deposited by the se- quence and also reduces the slice interaction. A method for optimizing the flip angles of the first few refocusing pulses to achieve a constant amplitude echo train was later presented by LeRoux and Hinks (10). They grieving heart quotes with imagesWebAug 1, 2024 · The pulse sequence required for a certain flip angle depending on the RF pulse type, coil load and imaging location. In fact, the RF pulse of MRI scan is characterized by several basic physical quantities of B1+ field, including (1) the RF pulse envelope B1+ ( t ), (2) the pulse width ( T ), and (3) the pulse bandwidth ( Δ f). grieving husband of teacherWebReducing and continuously varying the flip angle of the refocusing RF pulses in a rapid acquisition with relaxation enhancement (RARE; fast/turbo spin echo) sequence is a … grieving holy spiritNational Center for Biotechnology Information grieving how to copeWebrefocusing ﬂip angle sweeps at a sagittal plane (in-plane ﬂow situation) and an axial-plane (through-plane ﬂow sit- uation) in the carotid arteries of a volunteer. fiestaware dancing lady pitcherWebJul 1, 2024 · Recently, a variation of SSFSE with variable refocusing flip angles (variable refocusing single-shot FSE [vrfSSFSE]) has been described. 16 This flip angle modulation was originally introduced to reduce T2-decay–associated blurring, mostly in the context of volumetric imaging. 17 ⇓- 19 Coincidentally, the flip angle modulation also reduces … fiestaware deck the halls