Development of a symmetric echo planar imaging framework for clinical translation of rapid dynamic hyperpolarized <sup>13</sup>C imaging

Gordon, Jeremy W.; Vigneron, Daniel B.; Larson, Peder E. Z.

doi:10.1002/mrm.26123

Cited by 60 publications

(138 citation statements)

References 30 publications

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“…The center frequency was calibrated using an 8 M 13 C‐urea standard embedded in the receive coil. Sixteen 8 mm slices were acquired per time frame, alternating between pyruvate and lactate (Δf = 390 Hz) for each multi‐slice volume, with an effective 2 s temporal resolution and a total acquisition time of 42 s. To correct for Nyquist ghosting, a reference scan was acquired on the 1 H channel before 13 C imaging . After 13 C imaging, non‐localized spectra (TR = 3 s, θ = 20°, 10 time points) were acquired with a 500 μs hard pulse to measure the error in center frequency calibration.…”

Section: Methodsmentioning

confidence: 99%

Translation of Carbon‐13 EPI for hyperpolarized MR molecular imaging of prostate and brain cancer patients

Gordon

Chen

Autry

et al. 2018

Magnetic Resonance in Med

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Purpose To develop and translate a metabolite‐specific imaging sequence using a symmetric echo planar readout for clinical hyperpolarized (HP) Carbon‐13 (13C) applications. Methods Initial data were acquired from patients with prostate cancer (N = 3) and high‐grade brain tumors (N = 3) on a 3T scanner. Samples of [1‐13C]pyruvate were polarized for at least 2 h using a 5T SPINlab system operating at 0.8 K. Following injection of the HP substrate, pyruvate, lactate, and bicarbonate (for brain studies) were sequentially excited with a singleband spectral‐spatial RF pulse and signal was rapidly encoded with a single‐shot echo planar readout on a slice‐by‐slice basis. Data were acquired dynamically with a temporal resolution of 2 s for prostate studies and 3 s for brain studies. Results High pyruvate signal was seen throughout the prostate and brain, with conversion to lactate being shown across studies, whereas bicarbonate production was also detected in the brain. No Nyquist ghost artifacts or obvious geometric distortion from the echo planar readout were observed. The average error in center frequency was 1.2 ± 17.0 and 4.5 ± 1.4 Hz for prostate and brain studies, respectively, below the threshold for spatial shift because of bulk off‐resonance. Conclusion This study demonstrated the feasibility of symmetric EPI to acquire HP 13C metabolite maps in a clinical setting. As an advance over prior single‐slice dynamic or single time point volumetric spectroscopic imaging approaches, this metabolite‐specific EPI acquisition provided robust whole‐organ coverage for brain and prostate studies while retaining high SNR, spatial resolution, and dynamic temporal resolution.

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Section: Methodsmentioning

confidence: 99%

Translation of Carbon‐13 EPI for hyperpolarized MR molecular imaging of prostate and brain cancer patients

Gordon

Chen

Autry

et al. 2018

Magnetic Resonance in Med

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“…Therefore, specialized developments in MRI sequence design are required for hyperpolarized carbon-13 imaging. The implementation of different MRI data sampling strategies, including fast MRSI approaches such as echo-planar spectroscopic imaging with compressed sensing [7,8] and spiral MRSI [9], echo planar or spiral imaging with spectral-spatial excitation [10–14] and concentric rings trajectories [15], have all been applied in preclinical HP studies. While these sequences provided coverage and either sufficient spectral resolution (MRSI) or imaging of individual resonances (MRI), they were limited by relatively low spatial resolution, which can potentially limit their application.…”

Section: Introductionmentioning

confidence: 99%

Development of high resolution 3D hyperpolarized carbon-13 MR molecular imaging techniques

Milshteyn

Morze

Reed

et al. 2017

Magnetic Resonance Imaging

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The goal of this project was to develop and apply techniques for T2 mapping and 3D high resolution (1.5 mm isotropic; 0.003 cm3) 13C imaging of hyperpolarized (HP) probes [1-13C]lactate, [1-13C]pyruvate, [2-13C]pyruvate, and [13C,15N2]urea in vivo. A specialized 2D bSSFP sequence was implemented on a clinical 3T scanner and used to obtain the first high resolution T2 maps of these different hyperpolarized compounds in both rats and tumor-bearing mice. These maps were first used to optimize timings for highest SNR for single time-point 3D bSSFP acquisitions with a 1.5 mm isotropic spatial resolution of normal rats. This 3D acquisition approach was extended to serial dynamic imaging with 2-fold compressed sensing acceleration without changing spatial resolution. The T2 mapping experiments yielded measurements of T2 values of greater than 1 s for all compounds within rat kidneys/vasculature and TRAMP tumors, except for [2-13C]pyruvate which was ~730 ms and ~320 ms, respectively. The high resolution 3D imaging enabled visualization the biodistribution of [1-13C]lactate, [1-13C]pyruvate, and [2-13C]pyruvate within different kidney compartments as well as in the vasculature. While the mouse anatomy is smaller, the resolution was also sufficient to image the distribution of all compounds within kidney, vasculature, and tumor. The development of the specialized 3D sequence with compressed sensing provided improved structural and functional assessments at a high (0.003 cm3) spatial and 2 s temporal resolution in vivo utilizing HP 13C substrates by exploiting their long T2 values. This 1.5 mm isotropic resolution is comparable to 1H imaging and application of this approach could be extended to future studies of uptake, metabolism, and perfusion in cancer and other disease models and may ultimately be of value for clinical imaging.

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“…The 1D search renders a reference proton scan27 unnecessary, which can be compromised by differences in the spatial location of the 1 H and 13 C signals. Eddy currents, a major source of Nyquist ghosting, are spatially dependent, and a mismatch in location may render the proton reference scan less than optimal for phase correction (see Figure 4).…”

Section: Discussionmentioning

confidence: 99%

A referenceless Nyquist ghost correction workflow for echo planar imaging of hyperpolarized [1‐¹³C]pyruvate and [1‐¹³C]lactate

et al. 2017

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Single‐shot echo planar imaging (EPI), which allows an image to be acquired using a single excitation pulse, is used widely for imaging the metabolism of hyperpolarized 13C‐labelled metabolites in vivo as the technique is rapid and minimizes the depletion of the hyperpolarized signal. However, EPI suffers from Nyquist ghosting, which normally is corrected for by acquiring a reference scan. In a dynamic acquisition of a series of images, this results in the sacrifice of a time point if the reference scan involves a full readout train with no phase encoding. This time penalty is negligible if an integrated navigator echo is used, but at the cost of a lower signal‐to‐noise ratio (SNR) as a result of prolonged T 2* decay. We describe here a workflow for hyperpolarized 13C EPI that requires no reference scan. This involves the selection of a ghost‐containing background from a 13C image of a single metabolite at a single time point, the identification of phase correction coefficients that minimize signal in the selected area, and the application of these coefficients to images acquired at all time points and from all metabolites. The workflow was compared in phantom experiments with phase correction using a 13C reference scan, and yielded similar results in situations with a regular field of view (FOV), a restricted FOV and where there were multiple signal sources. When compared with alternative phase correction methods, the workflow showed an SNR benefit relative to integrated 13C reference echoes (>15%) or better ghost removal relative to a 1H reference scan. The residual ghosting in a slightly de‐shimmed B 0 field was 1.6% using the proposed workflow and 3.8% using a 1H reference scan. The workflow was implemented with a series of dynamically acquired hyperpolarized [1‐13C]pyruvate and [1‐13C]lactate images in vivo, resulting in images with no observable ghosting and which were quantitatively similar to images corrected using a 13C reference scan.

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Development of a symmetric echo planar imaging framework for clinical translation of rapid dynamic hyperpolarized ¹³C imaging

Cited by 60 publications

References 30 publications

Translation of Carbon‐13 EPI for hyperpolarized MR molecular imaging of prostate and brain cancer patients

Translation of Carbon‐13 EPI for hyperpolarized MR molecular imaging of prostate and brain cancer patients

Development of high resolution 3D hyperpolarized carbon-13 MR molecular imaging techniques

A referenceless Nyquist ghost correction workflow for echo planar imaging of hyperpolarized [1‐¹³C]pyruvate and [1‐¹³C]lactate

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Development of a symmetric echo planar imaging framework for clinical translation of rapid dynamic hyperpolarized 13C imaging

Cited by 60 publications

References 30 publications

Translation of Carbon‐13 EPI for hyperpolarized MR molecular imaging of prostate and brain cancer patients

Translation of Carbon‐13 EPI for hyperpolarized MR molecular imaging of prostate and brain cancer patients

Development of high resolution 3D hyperpolarized carbon-13 MR molecular imaging techniques

A referenceless Nyquist ghost correction workflow for echo planar imaging of hyperpolarized [1‐13C]pyruvate and [1‐13C]lactate

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Development of a symmetric echo planar imaging framework for clinical translation of rapid dynamic hyperpolarized ¹³C imaging

A referenceless Nyquist ghost correction workflow for echo planar imaging of hyperpolarized [1‐¹³C]pyruvate and [1‐¹³C]lactate