Improving contrast to noise ratio of resonance frequency contrast images (phase images) using balanced steady-state free precession

Lee, Jong-Ho; Fukunaga, Masaki; Duyn, Jeff H.

doi:10.1016/j.neuroimage.2010.10.071

Cited by 12 publications

(18 citation statements)

References 57 publications

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“…This suggests that the local B 0 field reflects underlying architecture and complements the anatomic information from water peak height images, which is consistent with previously published studies performed using T 2 * -weighted images, phase sensitive images, and susceptibility weighted imaging (SWI). [14][15][16][17][18][19][20][21] Interestingly, Figs. 4(e) and 4(f) show a relative frequency inversion and frequency convergence between the labeled layers, respectively (the unlabeled single and double headed line arrows), that corresponds to a change in orientation of the axons in the granular cell layer; specifically, the axons become oriented perpendicular to B 0 .…”

Section: Discussionmentioning

confidence: 97%

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3D high spectral and spatial resolution imaging of ex vivo mouse brain

et al. 2015

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Purpose: Widely used MRI methods show brain morphology both in vivo and ex vivo at very high resolution. Many of these methods (e.g., T 2 * -weighted imaging, phase-sensitive imaging, or susceptibility-weighted imaging) are sensitive to local magnetic susceptibility gradients produced by subtle variations in tissue composition. However, the spectral resolution of commonly used methods is limited to maintain reasonable run-time combined with very high spatial resolution. Here, the authors report on data acquisition at increased spectral resolution, with 3-dimensional high spectral and spatial resolution MRI, in order to analyze subtle variations in water proton resonance frequency and lineshape that reflect local anatomy. The resulting information compliments previous studies based on T 2 * and resonance frequency. Methods: The proton free induction decay was sampled at high resolution and Fourier transformed to produce a high-resolution water spectrum for each image voxel in a 3D volume. Data were acquired using a multigradient echo pulse sequence (i.e., echo-planar spectroscopic imaging) with a spatial resolution of 50 × 50 × 70 µm 3 and spectral resolution of 3.5 Hz. Data were analyzed in the spectral domain, and images were produced from the various Fourier components of the water resonance. This allowed precise measurement of local variations in water resonance frequency and lineshape, at the expense of significantly increased run time (16-24 h). Results: High contrast T 2 * -weighted images were produced from the peak of the water resonance (peak height image), revealing a high degree of anatomical detail, specifically in the hippocampus and cerebellum. In images produced from Fourier components of the water resonance at −7.0 Hz from the peak, the contrast between deep white matter tracts and the surrounding tissue is the reverse of the contrast in water peak height images. This indicates the presence of a shoulder in the water resonance that is not present at +7.0 Hz and may be specific to white matter anatomy. Moreover, a frequency shift of 6.76 ± 0.55 Hz was measured between the molecular and granular layers of the cerebellum. This shift is demonstrated in corresponding spectra; water peaks from voxels in the molecular and granular layers are consistently 2 bins apart (7.0 Hz, as dictated by the spectral resolution) from one another. Conclusions: High spectral and spatial resolution MR imaging has the potential to accurately measure the changes in the water resonance in small voxels. This information can guide optimization and interpretation of more commonly used, more rapid imaging methods that depend on image contrast produced by local susceptibility gradients. In addition, with improved sampling methods, high spectral and spatial resolution data could be acquired in reasonable run times, and used for in vivo scans to increase sensitivity to variations in local susceptibility. C 2015 American Association of Physicists in Medicine. [http://dx

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Section: Discussionmentioning

confidence: 97%

“…Extensions of T 2 * -weighting, often referred to as "phase sensitive" imaging or "susceptibility-weighted imaging," have further increased sensitivity to local susceptibility gradients, thereby providing exceptional anatomic detail. [14][15][16][17][18][19][20][21] Such methods are often used for both in vivo and ex vivo imaging.…”

Section: Introductionmentioning

confidence: 99%

3D high spectral and spatial resolution imaging of ex vivo mouse brain

et al. 2015

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“…We have demonstrated that this sequence allows superior depiction of the medial temporal lobe and cortical microstructure such as the line of Gennari, and it rivals typical iron-sensitive multi-echo GRE for deep brain iron-containing nuclei. Extensive prior efforts at high-field imaging have shown the line of Gennari, but most of these were not isotropic whole-brain imaging protocols that yielded contrast useful for multiple brain regions [21, 37]. The benefit of bSSFP likely stems from the coupling of ultra-high resolution with iron sensitivity.…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, bSSFP demonstrates iron-sensitivity [19] and is an efficient sequence with a high intrinsic signal-to-noise ratio (SNR) [20]. At 7T, phase-imaging with bSSFP has demonstrated SNR benefits compared to GRE per unit imaging time [21]. While bSSFP suffers from bands of signal hypointensity due to B0 inhomogeneity, these can be remedied by phase cycling [22, 23].…”

Section: Introductionmentioning

confidence: 99%

Ultrahigh-Resolution Imaging of the Human Brain with Phase-Cycled Balanced Steady-State Free Precession at 7 T

Zeineh

Parekh²,

Zaharchuk³

et al. 2014

Investigative Radiology

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Objective To acquire ultra-high resolution images of the brain using balanced steady-state free precession (bSSFP) at 7.0T and to identify the potential utility of this sequence. Materials and Methods 8 subjects participated in this study after providing informed consent. Each subject was scanned with 8 phase-cycles of bSSFP at 0.4mm isotropic resolution using 0.5 NEX and two-dimensional parallel acceleration of 1.75 × 1.75. Each phase cycle required 5 minutes of scanning, with pauses between the phase cycles allowing short periods of rest. The individual phase cycles were aligned and then averaged. The same subjects underwent scanning using 3D multi-echo GRE at 0.8mm isotropic resolution, 3D CUBE T2 at 0.7mm isotropic resolution, and thin-section coronal oblique T2-weighted FSE at 0.22 × 0.22 × 2.0 mm resolution for comparison. Two neuroradiologists assessed image quality and potential research and clinical utility. Results Subjects generally tolerated the scan sessions well, and composite high-resolution bSSFP images were produced for each subject. Rater analysis demonstrated that bSSFP had superior 3D visualization of the microarchitecture of the hippocampus, very good contrast to delineate the borders of the subthalamic nucleus, and relatively good B1 homogeneity throughout. In addition to excellent visualization of the cerebellum, subtle details of brain and skull base anatomy were also easier to identify on the bSSFP images, including the line of Gennari, membrane of Lillequist, and cranial nerves. bSSFP had a strong iron contrast similar to or better than the comparison sequences. However, cortical gray-white contrast was significantly better with CUBE T2 and T2-weighted FSE. Conclusions bSSFP can facilitate ultra-high resolution imaging of the brain. While total imaging times are long, the individually short phase-cycles can be acquired separately, improving exam tolerability. These images may be beneficial for studies of the hippocampus, iron-containing structures such as the subthalamic nucleus and line of Gennari, and the basal cisterns and their contents.

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“…In most of these bSSFP studies magnitude imaging has been used, and phase imaging has not been investigated well. The feasibility of phase imaging with transition‐band bSSFP was investigated in a recent study . By using the steep phase changes in the transition bands of bSSFP, the study successfully visualized refined in vivo anatomy with a better contrast to noise ratio (CNR) per unit time than that of GRE.…”

Section: Introductionmentioning

confidence: 99%

Phase imaging with multiple phase‐cycled balanced steady‐state free precession at 9.4 T

Kim

Park

2017

NMR in Biomedicine

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While phase imaging with a gradient echo (GRE) sequence is popular, phase imaging with balanced steady-state free precession (bSSFP) has been underexplored. The purpose of this study was to investigate anatomical and functional phase imaging with multiple phase-cycled bSSFP, in expectation of increasing spatial coverage of steep phase-change regions of bSSFP. Eight different dynamic 2D pass-band bSSFP studies at four phase-cycling (PC) angles and two T /T values were performed on rat brains at 9.4 T with electrical forepaw stimulation, in comparison with dynamic 2D GRE. Anatomical and functional phase images were obtained by averaging the dynamic phase images and mapping correlation between the dynamic images and the stimulation paradigm, and were compared with their corresponding magnitude images. Phase imaging with 3D pass-band and 3D transition-band bSSFP was also performed for comparison with 3D GRE phase imaging. Two strategies of combining the multiple phase-cycled bSSFP phase images were also proposed. Contrast between white matter and gray matter in bSSFP phase images significantly varied with PC angle and became twice as high as that of GRE phase images at a specific PC angle. With the same total scan time, the combined bSSFP phase images provided stronger phase contrast and visualized neuronal fiber-like structures more clearly than the GRE phase images. The combined phase images of both 3D pass-band and 3D transition-band bSSFP showed phase contrasts stronger than those of the GRE phase images in overall brain regions, even at a longer T of 20 ms. In contrast, phase functional MRI (fMRI) signals were weak overall and mostly located in draining veins for both bSSFP and GRE. Multiple phase-cycled bSSFP phase imaging is a promising anatomical imaging technique, while its usage as fMRI does not seem desirable with the current approach.

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Improving contrast to noise ratio of resonance frequency contrast images (phase images) using balanced steady-state free precession

Cited by 12 publications

References 57 publications

3D high spectral and spatial resolution imaging of ex vivo mouse brain

3D high spectral and spatial resolution imaging of ex vivo mouse brain

Ultrahigh-Resolution Imaging of the Human Brain with Phase-Cycled Balanced Steady-State Free Precession at 7 T

Phase imaging with multiple phase‐cycled balanced steady‐state free precession at 9.4 T

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