Gradient Echo and Spin Echo Methods for Functional MRI

2000 ◽  
pp. 127-136 ◽  
Author(s):  
R. P. Kennan
Keyword(s):  
Functional Mri ◽  
Spin Echo ◽  
Gradient Echo

Functional MRI in human subjects with gradient-echo and spin-echo EPI at 9.4 T

2013 ◽  
Vol 71 (1) ◽  
pp. 209-218 ◽  
Author(s):  
Juliane Budde ◽  
G. Shajan ◽  
Maxim Zaitsev ◽  
Klaus Scheffler ◽  
Rolf Pohmann
Keyword(s):  
Functional Mri ◽  
Human Subjects ◽  
Spin Echo ◽  
Gradient Echo

scholarly journals A more accurate account of the effect of k-space sampling and signal decay on the effective spatial resolution in functional MRI

2016 ◽  
Author(s):  
Denis Chaimow ◽  
Amir Shmuel
Keyword(s):  
High Resolution ◽  
Functional Mri ◽  
Spatial Resolution ◽  
Spin Echo ◽  
7 Tesla ◽  
Gradient Echo ◽  
Magnitude Image ◽  
Signal Decay ◽  
The Absolute ◽  
High Pass

AbstractThe effects of k-space sampling and signal decay on the effective spatial resolution of MRI and functional MRI (fMRI) are commonly assessed by means of the magnitude point-spread function (PSF), defined as the absolute values (magnitudes) of the complex MR imaging PSF. It is commonly assumed that this magnitude PSF signifies blurring, which can be quantified by its full-width at half-maximum (FWHM). Here we show that the magnitude PSF fails to accurately represent the true effects of k-space sampling and signal decay.Firstly, a substantial part of the width of the magnitude PSF is due to MRI sampling per se. This part is independent of any signal decay and its effect depends on the spatial frequency composition of the imaged object. Therefore, it cannot always be expected to introduce blurring. Secondly, MRI reconstruction is typically followed by taking the absolute values (magnitude image) of the reconstructed complex image. This introduces a non-linear stage into the process of image formation. The complex imaging PSF does not fully describe this process, since it does not reflect the stage of taking the magnitude image. Its corresponding magnitude PSF fails to correctly describe this process, since convolving the original pattern with the magnitude PSF is different from the true process of taking the absolute following a convolution with the complex imaging PSF. Lastly, signal decay can have not only a blurring, but also a high-pass filtering effect. This cannot be reflected by the strictly positive width of the magnitude PSF.As an alternative, we propose to first approximate the MRI process linearly. We then model the linear approximation by decomposing it into a signal decay-independent MR sampling part and an approximation of the signal decay effect. We approximate the latter as a convolution with a Gaussian PSF or, if the effect is that of high-pass filtering, as reversing the effect of a convolution with a Gaussian PSF. We show that for typical high-resolution fMRI at 7 Tesla, signal decay in Spin-Echo has a moderate blurring effect (FWHM = 0.89 voxels, corresponds to 0.44 mm for 0.5 mm wide voxels). In contrast, Gradient-Echo acts as a moderate high-pass filter that can be interpreted as reversing a Gaussian blurring with FWHM = 0.59 voxels (0.30 mm for 0.5 mm wide voxels). Our improved approximations and findings hold not only for Gradient-Echo and Spin-Echo fMRI but also for GRASE and VASO fMRI. Our findings support the correct planning, interpretation, and modeling of high-resolution fMRI.

scholarly journals Gradient‐echo and spin‐echo blood oxygenation level–dependent functional MRI at ultrahigh fields of 9.4 and 15.2 Tesla

2018 ◽  
Vol 81 (2) ◽  
pp. 1237-1246 ◽  
Author(s):  
SoHyun Han ◽  
Jeong Pyo Son ◽  
HyungJoon Cho ◽  
Jang‐Yeon Park ◽  
Seong‐Gi Kim
Keyword(s):  
Functional Mri ◽  
Spin Echo ◽  
Blood Oxygenation Level Dependent ◽  
Blood Oxygenation ◽  
Gradient Echo ◽  
Blood Oxygenation Level ◽  
Oxygenation Level ◽  
Ultrahigh Fields

Spinal cord functional MRI at 3 T: Gradient echo echo-planar imaging versus turbo spin echo

NeuroImage ◽  
2008 ◽  
Vol 43 (2) ◽  
pp. 288-296 ◽  
Author(s):  
C.J.C. Bouwman ◽  
J.T. Wilmink ◽  
W.H. Mess ◽  
W.H. Backes
Keyword(s):  
Spinal Cord ◽  
Functional Mri ◽  
Spin Echo ◽  
Echo Planar Imaging ◽  
Turbo Spin Echo ◽  
Gradient Echo ◽  
Planar Imaging ◽  
Turbo Spin ◽  
Echo Planar

Variations in BOLD response latency estimated from event-related fMRI at 3T: Comparisons between gradient-echo and Spin-echo

2013 ◽  
Vol 23 (3) ◽  
pp. 215-221 ◽  
Author(s):  
Mei-Yu Yeh ◽  
Changwei W. Wu ◽  
Wan-Chun Kuan ◽  
Pei-Shan Wei ◽  
Yung-Liang Wan ◽  
...  
Keyword(s):  
Response Latency ◽  
Spin Echo ◽  
Bold Response ◽  
Gradient Echo

Experimental intracerebral and subarachnoid/intraventricular haemorrhages: MR detectability at 0.5 T and 1.5 T

2002 ◽  
Vol 43 (5) ◽  
pp. 464-473
Author(s):  
M. Alemany Ripoll ◽  
R. Raininko
Keyword(s):  
Cerebrospinal Fluid ◽  
Mr Imaging ◽  
Spin Echo ◽  
Autologous Blood ◽  
Pulse Sequences ◽  
Proton Density ◽  
Gradient Echo ◽  
The Brain ◽  
Formalin Fixed

Purpose: To compare the detectability of small experimental intracranial haemorrhages on MR imaging at 0.5 T and 1.5 T, from hyperacute to subacute stages. Material and Methods: 1 ml of autologous blood was injected into the brain of 15 rabbits to create intraparenchymal haematomas. Since the blood partially escaped into the cerebrospinal fluid (CSF) spaces, detectability of subarachnoid and intraventricular blood was also evaluated. MR imaging at 0.5 T and at 1.5 T was repeated up to 14 days, including T1-, proton density- and T2-weighted (w) spin-echo (SE), FLAIR and T2*-w gradient echo (GE) pulse sequences. The last MR investigation was compared to the formalin-fixed brain sections in 7 animals. Results: The intraparenchymal haematomas were best revealed with T2*-w GE sequences, with 100% of sensitivity at 1.5 T and 90–95% at 0.5 T. Blood in the CSF spaces was significantly ( p < 0.05) better detected at 1.5 T with T2*-w GE sequences and detected best during the first 2 days. The next most sensitive sequence for intracranial blood was FLAIR. SE sequences were rather insensitive. Conclusion: 1.5 T equipment is superior to 0.5 T in the detection of intracranial haemorrhages from acute to subacute stages. T2*-w GE sequences account for this result but other sequences are also needed for a complete examination.

scholarly journals MR contrast of ferritin and hemosiderin in the brain: comparison among gradient-echo, conventional spin-echo and fast spin-echo sequences

2003 ◽  
Vol 48 (3) ◽  
pp. 230-236 ◽  
Author(s):  
Tabassum Laz Haque ◽  
Yukio Miki ◽  
Mitsunori Kanagaki ◽  
Takahiro Takahashi ◽  
Akira Yamamoto ◽  
...  
Keyword(s):  
Spin Echo ◽  
Fast Spin Echo ◽  
Gradient Echo ◽  
The Brain ◽  
Conventional Spin Echo ◽  
Fast Spin ◽  
Spin Echo Sequences

scholarly journals Improvement of the Diagnostic Performance of Facial Neuritis Using Contrast-Enhanced 3D T1 Black-Blood Imaging: Comparison with Contrast-Enhanced 3D T1-Spoiled Gradient-Echo Imaging

2021 ◽  
Vol 10 (9) ◽  
pp. 1850
Author(s):  
Seun-Ah Lee ◽  
Sang-Won Jo ◽  
Suk-Ki Chang ◽  
Ki-Han Kwon
Keyword(s):  
Quantitative Analysis ◽  
Diagnostic Performance ◽  
Spin Echo ◽  
Fast Spin Echo ◽  
Black Blood ◽  
Gradient Echo ◽  
Diagnostic Confidence ◽  
Contrast Enhanced ◽  
Black Blood Imaging ◽  
Spoiled Gradient Echo

This study aims to investigate the diagnostic ability of the contrast-enhanced 3D T1 black-blood fast spin-echo (T1 BB-FSE) sequence compared with the contrast-enhanced 3D T1-spoiled gradient-echo (CE-GRE) sequence in patients with facial neuritis. Forty-five patients with facial neuritis who underwent temporal bone MR imaging, including T1 BB-FSE and CE-GRE imaging, were examined. Two reviewers independently assessed the T1 BB-FSE and CE-GRE images in terms of diagnostic performance, and qualitative (diagnostic confidence and visual asymmetric enhancement) and quantitative analysis (contrast-enhancing lesion extent of the canalicular segment of the affected facial nerve (LEC) and the affected side-to-normal signal intensity ratio (rSI)). The AUCs of each reviewer, and the sensitivity and accuracy of T1 BB-FSE were significantly superior to those of CE-GRE (p < 0.05). Regarding diagnostic confidence and visual asymmetric enhancement, T1 BB-FSE tended to be rated greater than CE-GRE (p < 0.05). Additionally, in quantitative analysis, LEC and rSI of the canalicular segment on T1 BB-FSE were larger than those on CE-GRE (p < 0.05). The T1 BB-FSE sequence was significantly superior to the CE-GRE sequence, with more conspicuous lesion visualization in terms of both qualitative and quantitative aspects in patients with facial neuritis.

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