Three-frequency RF coil designed for optimized imaging of hyperpolarized,13C-labeled compounds
GE Global Research Center, Niskayuna, New York, 12309, USA.Magnetic Resonance in Medicine (Impact Factor: 3.57). 10/2008; 60(4):928-33. DOI: 10.1002/mrm.21698
Imaging exams involving hyperpolarized, (13)C-labeled compounds require novel RF coils for efficient signal utilization. While (13)C coils are required for mapping the spatial distribution of the hyperpolarized compounds, imaging/pulsing at different frequencies is also needed for scan setup steps prior to the image acquisition. Imaging/pulsing at the (1)H frequency is typically used for anatomical localization and shimming. Flip angle (FA) calibration, which is difficult or impossible to achieve at the (13)C frequency, can be accurately performed at the (23)Na frequency using the natural abundance signal that exists in any living tissue. We demonstrate here a single RF resonant structure that is capable of operating linearly at the (1)H and (23)Na frequencies for scan setup steps, and in quadrature at the (13)C frequency for imaging. Images at the three resonant frequencies of this coil are presented from an exam involving hyperpolarized (13)C compounds in vivo.
- [Show abstract] [Hide abstract]
ABSTRACT: NMR Research Centre of INMAS has developed an in-house Helmholtz coil. It will be used as a component of the system for hyperpolarizing Xenon gas for MRI application. The system will be helpful in imaging low proton density area of the body such as lungs efficiently. This paper describes the mathematical approach for designing the Helmholtz coil. Structure geometry, number of turns in winding and power supply calculations were done. The practical coil was constructed & magnetic field was measured at different points. The results were validated with the simulated results and there was good agreement. The field was uniform.
- [Show abstract] [Hide abstract]
ABSTRACT: Hyperpolarization of (13) C labeled substrates via dynamic nuclear polarization has been used as a method to noninvasively study real-time metabolic processes occurring in vivo. In these studies, proper calibration of radiofrequency transmit power is required to efficiently observe rapidly decaying magnetization. Conventional transmit radiofrequency field (B₁⁺) mapping methods rely on placing magnetization in a fixed, known state prior to imaging, making them unsuitable for imaging of hyperpolarized magnetization. Recently, a phase-based B(1) mapping method based on the Bloch-Siegert shift has been reported. This method uses a B(1) -dependent shift in the resonance frequency of nuclei in the presence of an off-resonance radiofrequency pulse. In this article, we investigate the feasibility of Bloch-Siegert B(1) mapping and observation of metabolism of hyperpolarized [1-¹³C] pyruvate in vivo, in a single injection. The technique is demonstrated with phantom experiments, and in normal rat and pigs in vivo. This method is anticipated to improve quantitative measurements of hyperpolarized (13) C metabolism in vivo by enabling accurate flip-angle corrections. This work demonstrates the use of Bloch-Siegert B(1) mapping under challenging out-of-equilibrium imaging conditions.Magnetic Resonance in Medicine 01/2012; 67(1):62-71. DOI:10.1002/mrm.22977 · 3.57 Impact Factor
Conference Paper: A high stability magnetic field applied in atomic magnetometer system[Show abstract] [Hide abstract]
ABSTRACT: A pair of Helmholtz coils producing a magnetic field with super-high stability in atomic magnetometer experiment has been designed and realized. To drive this coils, we developed a DC constant current source, which can provide a near 1 mA DC current with short-term stability of 5.8 parts in 107 in experimentally. Analysis shows that the stability of center magnetic field is about 0.06 pT.2012 International Conference on Measurement, Information and Control (MIC); 05/2012
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.