Construction and evaluation of a switch‐tuned 13C ‐ 1H birdcage radiofrequency coil for imaging the metabolism of hyperpolarized 13C‐enriched compounds

Lim, Heeseung; Thind, Kundan; Martinez-Santiesteban, Francisco M.; Scholl, Timothy J.

doi:10.1002/jmri.24458

Cited by 26 publications

(23 citation statements)

References 15 publications

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“…Multiparametric protocols consisting of acquisitions that measure different nuclei can be made practically applicable by using multinuclear coil designs. Coil setups that allow for combined 1 H and 23 Na or 13 C acquisitions within the same experiment without the need for moving the RF coil or subject have been described previously.…”

Section: Discussionmentioning

confidence: 99%

MRI methods for the evaluation of high intensity focused ultrasound tumor treatment: Current status and future needs

Hectors

Jacobs

Moonen

et al. 2015

Magnetic Resonance in Med

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Thermal ablation with high intensity focused ultrasound (HIFU) is an emerging noninvasive technique for the treatment of solid tumors. HIFU treatment of malignant tumors requires accurate treatment planning, monitoring and evaluation, which can be facilitated by performing the procedure in an MR-guided HIFU system. The MR-based evaluation of HIFU treatment is most often restricted to contrast-enhanced T 1 -weighted imaging, while it has been shown that the non-perfused volume may not reflect the extent of nonviable tumor tissue after HIFU treatment. There are multiple studies in which more advanced MRI methods were assessed for their suitability for the evaluation of HIFU treatment. While several of these methods seem promising regarding their sensitivity to HIFU-induced tissue changes, there is still ample room for improvement of MRI protocols for HIFU treatment evaluation. In this review article, we describe the major acute and delayed effects of HIFU treatment. For each effect, the MRI methods that have beenor could be-used to detect the associated tissue changes are described. In addition, the potential value of multiparametric MRI for the evaluation of HIFU treatment is discussed. The review ends with a discussion on future directions for the MRIbased evaluation of HIFU treatment. Magn Reson Med 75:302-317, 2016. V C 2015 Wiley Periodicals, Inc.

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Section: Discussionmentioning

confidence: 99%

MRI methods for the evaluation of high intensity focused ultrasound tumor treatment: Current status and future needs

Hectors

Jacobs

Moonen

et al. 2015

Magnetic Resonance in Med

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“…A switch-tuned 1 H– 13 C RF coil was used to acquire inherently coregistered proton images and 13 C MRSI data of the rat models at 3 T ( 26 ). Tumors were identified using a T2-weighted anatomical 1 H scan of the rat brain using an FSE sequence with the following parameters: FOV = 80.0 × 80.0 mm 2 , isotropic in-plane resolution = 0.3 mm, section thickness = 3 mm, TR = 4000 milliseconds, TE = 85 milliseconds, bandwidth = 10.42 kHz, ETL = 16, and number of averages = 4.…”

Section: Methodsmentioning

confidence: 99%

Longitudinal Measurements of Intra- and Extracellular pH Gradient in a Rat Model of Glioma

Lim

Albatany

Martinez-Santiesteban

et al. 2018

Tomography

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This study presents the first longitudinal measurement of the intracellular/extracellular pH gradient in a rat glioma model using noninvasive magnetic resonance imaging. The acid–base balance in the brain is tightly controlled by endogenous buffers. Tumors often express a positive pH gradient (pHi – pHe) compared with normal tissue that expresses a negative gradient. Alkaline pHi in tumor cells increases activity of several enzymes that drive cellular proliferation. In contrast, acidic pHe is established because of increased lactic acid production and subsequent active transport of protons out of the cell. pHi was mapped using chemical exchange saturation transfer, whereas regional pHe was determined using hyperpolarized 13C bicarbonate magnetic resonance spectroscopic imaging. pHi and pHe were measured at days 8, 12, and 15 postimplantation of C6 glioma cells into rat brains. Measurements were made in tumors and compared to brain tissue without tumor. Overall, average pH gradient in the tumor changed from −0.02 ± 0.12 to 0.10 ± 0.21 and then 0.19 ± 0.16. Conversely, the pH gradient of contralateral brain tissue changed from −0.45 ± 0.16 to −0.25 ± 0.21 and then −0.34 ± 0.25 (average pH ± 1 SD) Spatial heterogeneity of tumor pH gradient was apparent at later time points and may be useful to predict local areas of treatment resistance. Overall, the intracellular/extracellular pH gradients in this rat glioma model were noninvasively measured to a precision of ∼0.1 pH units at 3 time points. Because most therapeutic agents are weak acids or bases, a priori knowledge of the pH gradient may help guide choice of therapeutic agent for precision medicine.

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“…Relaxation measurements at 3.0 T were obtained using a clinical MRI system (Discovery MR750 3.0 T, GE Healthcare, Waukesha, WI, USA). The hyperpolarized solution was placed inside a custom‐made RF coil tuned for the 13 C Larmor frequency at 3.0 T . Immediately after placement and using a rectangular excitation pulse, 128 non‐spatially located free induction decay signals (FIDs) were acquired from the entire volume of solution using a standard FID pulse sequence ( T R = 3000 s, number of points = 2048, spectral width = 5000 Hz, α = 10°).…”

Section: Methodsmentioning

confidence: 99%

T₁ nuclear magnetic relaxation dispersion of hyperpolarized sodium and cesium hydrogencarbonate‐¹³C

Martinez-Santiesteban

Dang

Lim

et al. 2017

NMR in Biomedicine

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In vivo pH mapping in tissue using hyperpolarized hydrogencarbonate- C has been proposed as a method to study tumor growth and treatment and other pathological conditions related to pH changes. The finite spin-lattice relaxation times (T ) of hyperpolarized media are a significant limiting factor for in vivo imaging. Relaxation times can be measured at standard magnetic fields (1.5 T, 3.0 T etc.), but no such data are available at low fields, where T values can be significantly shorter. This information is required to determine the potential loss of polarization as the agent is dispensed and transported from the polarizer to the MRI scanner. The purpose of this study is to measure T dispersion from low to clinical magnetic fields (0.4 mT to 3.0 T) of different hyperpolarized hydrogencarbonate formulations previously proposed in the literature for in vivo pH measurements. C-enriched cesium and sodium hydrogencarbonate preparations were hyperpolarized using dynamic nuclear polarization, and the T values of different samples were measured at different magnetic field strengths using a fast field-cycling relaxometer and a 3.0 T clinical MRI system. The effects of deuterium oxide as a dissolution medium for sodium hydrogencarbonate were also analyzed. This study finds that the cesium formulation has slightly shorter T values compared with the sodium preparation. However, the higher solubility of cesium hydrogencarbonate- C means it can be polarized at greater concentration, using less trityl radical than sodium hydrogencarbonate- C. This study also establishes that the preparation and handling of sodium hydrogencarbonate formulations in relation to cesium hydrogencarbonate is more difficult, due to the higher viscosity and lower achievable concentrations, and that deuterium oxide significantly increases the T of sodium hydrogencarbonate solutions. Finally, this work also investigates the influence of pH on the spin-lattice relaxation of cesium hydrogencarbonate- C measured over a pH range of 7 to 9 at 0.47 T.

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Construction and evaluation of a switch‐tuned ¹³C ‐ ¹H birdcage radiofrequency coil for imaging the metabolism of hyperpolarized ¹³C‐enriched compounds

Abstract: A surface coil can be integrated with a switch-tuned (13) C - (1) H coil for (13) C TORO operation producing improved SNR. In vivo metabolic imaging of [1-(13) C]pyruvate in a rat model of glioma is demonstrated using TORO operation, which is co-registered with (1) H-imaged anatomy.

Cited by 26 publications

References 15 publications

MRI methods for the evaluation of high intensity focused ultrasound tumor treatment: Current status and future needs

MRI methods for the evaluation of high intensity focused ultrasound tumor treatment: Current status and future needs

Longitudinal Measurements of Intra- and Extracellular pH Gradient in a Rat Model of Glioma

T₁ nuclear magnetic relaxation dispersion of hyperpolarized sodium and cesium hydrogencarbonate‐¹³C

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Construction and evaluation of a switch‐tuned 13C ‐ 1H birdcage radiofrequency coil for imaging the metabolism of hyperpolarized 13C‐enriched compounds

Abstract: A surface coil can be integrated with a switch-tuned (13) C - (1) H coil for (13) C TORO operation producing improved SNR. In vivo metabolic imaging of [1-(13) C]pyruvate in a rat model of glioma is demonstrated using TORO operation, which is co-registered with (1) H-imaged anatomy.

Cited by 26 publications

References 15 publications

MRI methods for the evaluation of high intensity focused ultrasound tumor treatment: Current status and future needs

MRI methods for the evaluation of high intensity focused ultrasound tumor treatment: Current status and future needs

Longitudinal Measurements of Intra- and Extracellular pH Gradient in a Rat Model of Glioma

T1 nuclear magnetic relaxation dispersion of hyperpolarized sodium and cesium hydrogencarbonate‐13C

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Construction and evaluation of a switch‐tuned ¹³C ‐ ¹H birdcage radiofrequency coil for imaging the metabolism of hyperpolarized ¹³C‐enriched compounds

T₁ nuclear magnetic relaxation dispersion of hyperpolarized sodium and cesium hydrogencarbonate‐¹³C