Multiecho reconstruction for simultaneous water‐fat decomposition and T2* estimation

Yu, Hong; McKenzie, Charles A.; Shimakawa, Ann; Vu, Anthony T.; Brau, Anja C. S.; Beatty, Philip J.; Pineda, Angel R.; Brittain, Jean H.; Reeder, Scott B.

doi:10.1002/jmri.21090

Cited by 391 publications

(526 citation statements)

References 22 publications

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“…Some Dixon techniques may also be helpful in the assessment of the tissue iron concentration through the determination of transverse relaxation times (8,59,70). Furthermore, many phase-correction algorithms used for a Dixon technique can be extended directly to imaging of silicone implants (71)(72)(73) or other phase-sensitive MRI techniques such as phase-sensitive inversion recovery imaging (74,75).…”

Section: Discussionmentioning

confidence: 99%

Dixon techniques for water and fat imaging

2008

Magnetic Resonance Imaging

513

442

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In 1984, Dixon published a first paper on a simple spectroscopic imaging technique for water and fat separation. The technique acquires two separate images with a modified spin echo pulse sequence. One is a conventional spin echo image with water and fat signals in-phase and the other is acquired with the readout gradient slightly shifted so that the water and fat signals are 180°out-of-phase. Dixon showed that from these two images, a water-only image and a fat-only image can be generated. The wateronly image by the Dixon's technique can serve the purpose of fat suppression, an important and widely used imaging option for clinical MRI. Additionally, the availability of both the water-only and fat-only images allows direct imagebased water and fat quantitation. These applications, as well as the potential that the technique can be made highly insensitive to magnetic field inhomogeneity, have generated substantial research interests and efforts from many investigators. As a result, significant improvement to the original technique has been made in the last 2 decades. The following article reviews the underlying physical principles and describes some major technical aspects in the development of these Dixon techniques. MR IMAGES ACQUIRED IN VIVO usually contain signals from both water and fat. In many pulse sequences, fat appears hyperintense. However, the contribution from water is often of the primary interest for many practical applications. Without suppression, the bright fat signal may result in aggravated motion-related artifacts and, more importantly, reduce the underlying lesion conspicuity. Because of its chemical shift, fat is also responsible for the well-known spatial misregistration artifacts, which can appear both along the frequency encode direction and along the slice select direction. For a few other applications such as diagnosis of bone marrow diseases or hepatic steatosis, detection rather than suppression of the fat signal can also be valuable.Several approaches have been proposed and developed for achieving fat suppression. Perhaps the most popular is the chemical shift selective saturation (1) or its variants. In this approach, a frequency selective radiofrequency (RF) pulse and a spoiler gradient pulse are used in conjunction to first excite and then saturate the fat magnetization before water is excited for imaging. Alternatively, a frequency selective RF pulse can be used to directly excite only the water magnetization and leave the fat magnetization alone along the longitudinal axis. These techniques, particularly the selective saturation technique, are easy to implement and have been widely used with great success. However, both selective saturation pulses and selective excitation pulses increase the scan time. Another limitation for fat suppression by the selective saturation pulses is that it typically requires an accurate 90°flip angle, and as a result, its performance can be dependent on B1 homogeneity. Perhaps most importantly, fat suppression using the frequency selective approach...

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Section: Discussionmentioning

confidence: 99%

Dixon techniques for water and fat imaging

2008

Magnetic Resonance Imaging

513

442

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“…Next, the length of the axis of the cloud in the direction defined by axisvector is calculated by axislength 1 …”

Section: Appendix: Calculation Of Long and Short Axis Lengths For Ratmentioning

confidence: 99%

“…Magnetic resonance (MR) is an accurate, noninvasive tool for the assessment of diffuse hepatic deposition disease, namely hepatic steatosis and iron overload (1)(2)(3). A variety of MR-based techniques are available for detection and characterization of hepatic deposition disease, including dual-echo technique, multiecho acquisition, and breath-hold single voxel or volumetric spectroscopy (1,(4)(5)(6)(7)(8)(9).…”

Section: Introductionmentioning

confidence: 99%

“…A variety of MR-based techniques are available for detection and characterization of hepatic deposition disease, including dual-echo technique, multiecho acquisition, and breath-hold single voxel or volumetric spectroscopy (1,(4)(5)(6)(7)(8)(9). Non-invasive techniques have several advantages over percutaneous liver biopsy (the reference standard for diagnosis of deposition disease), including a much larger sample volume, lower cost, and avoidance of the periprocedural complications associated with biopsy (3,(10)(11)(12)(13)(14).…”

Section: Introductionmentioning

confidence: 99%

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Automated liver sampling using a gradient dual‐echo Dixon‐based technique

Bashir

Dale

Merkle

et al. 2011

Magnetic Resonance in Med

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Magnetic resonance spectroscopy of the liver requires input from a physicist or physician at the time of acquisition to insure proper voxel selection, while in multiecho chemical shift imaging, numerous regions of interest must be manually selected in order to ensure analysis of a representative portion of the liver parenchyma. A fully automated technique could improve workflow by selecting representative portions of the liver prior to human analysis. Complete volumes from three-dimensional gradient dual-echo acquisitions with twopoint Dixon reconstruction acquired at 1.5 and 3 T were analyzed in 100 subjects, using an automated liver sampling algorithm, based on ratio pairs calculated from signal intensity image data as fat-only/water-only and log(in-phase/opposedphase) on a voxel-by-voxel basis. Using different gridding variations of the algorithm, the average correct liver volume samples ranged from 527 to 733 mL. The average percentage of sample located within the liver ranged from 95.4 to 97.1%, whereas the average incorrect volume selected was 16.5-35.4 mL (2.9-4.6%). Average run time was 19.7-79.0 s. The algorithm consistently selected large samples of the hepatic parenchyma with small amounts of erroneous extrahepatic sampling, and run times were feasible for execution on an MRI system console during exam acquisition.

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“…Multi--echo chemical shift imaging also enables detection of T2* relaxation time of the water and lipid signals (Yu et al 2007, O'Regan et al 2008. T2* quantification enables correction of signal loss due to T2* relaxation and also provides an additional parameter for characterization of BAT tissue (Hu et al 2013).…”

Section: Mri Introductionmentioning

confidence: 99%

Brown Adipose Tissue in Humans

Borga

Virtanen

Romu

et al. 2014

Methods in Enzymology

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Research with the aim to translate findings of the beneficial effects induced by brown adipose tissue (BAT) on metabolism, as seen in various non--human experimental systems to also include human metabolism requires tools that accurately measure how BAT influences human metabolism. This review sets out to discuss such techniques, how they can be used, what they can measure and also some of their limitations. The focus is on detection and functional analysis of human BAT and how this can be facilitated by applying advanced imaging technology such as: PET (Positron Emission Tomography), MRI (Magnetic Resonance Imaging), and DECT (Dual Energy Computed Tomography).

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Multiecho reconstruction for simultaneous water‐fat decomposition and T2* estimation

Cited by 391 publications

References 22 publications

Dixon techniques for water and fat imaging

Dixon techniques for water and fat imaging

Automated liver sampling using a gradient dual‐echo Dixon‐based technique

Brown Adipose Tissue in Humans

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