Background: In the last decade, sodium mag-netic resonance imaging was investigated for its potential as a functional cardiac imaging tool for ischemia. Later interest was developed in contrast enhancement for intrace...Background: In the last decade, sodium mag-netic resonance imaging was investigated for its potential as a functional cardiac imaging tool for ischemia. Later interest was developed in contrast enhancement for intracellular sodium. Little success was reported to suppress extracellular sodium resulting in the intracellular sodium MRI image acquisition using quantum filters or sodium transition states as contrast properties. Now its clinical application is ex-panding as a new challenge in brain and other cancer tumors. Contrast enhancement: We highlight the physical principles of sodium MRI in three different pulse sequences using filters (single quantum, multiple quantum, and triple quantum) meant for sodium contrast enhancement. The optimization of scan parameters, i.e. times of echo delay (TE), inversion recovery (TI) periods, and utility of Dysprosium (DyPPP) shift contrast agents, enhances contrast in sodium MRI images. Inversion recovery pulse sequence without any shift reagent measures the intracellular sodium concentration to evaluate ischemia, apoptosis and membrane integrity. Membrane integrity loss, apoptosis and malignancy are results of growth factor loss and poor epithelial capability related with MRI visible intracellular sodium concentration. Applications and limitations: The sodium MR imaging technical advances reduced scan time to distinguish intracellular and extracellular sodium signals in malignant tumors by use of quantum filter techniques to generate 3D sodium images without shift regents. We observed the association of malignancy with increased TSC, and reduced apoptosis and epithelial growth factor in breast cancer cells. The validity is still in question. Conclusion: Different modified sodium MRI pulse sequences are research tools of sodium contrast enhancement in brain, cardiac and tumor imaging. The optimized MRI scan pa-rameters in quantum filter techniques generate contrast in intracellular sodium MR images without using invasive contrast shift agents. Still, validity and clinical utility are in展开更多
The design and development of a new dual-frequency RF probe-head are presented. This probe was initially dedicated for the MRI of both proton (1H) and hyperpolarized Xenon-129 (HP 129Xe) in the rat brain at 2.35 Tesla...The design and development of a new dual-frequency RF probe-head are presented. This probe was initially dedicated for the MRI of both proton (1H) and hyperpolarized Xenon-129 (HP 129Xe) in the rat brain at 2.35 Tesla. It consists of a double-tuned (100 MHz- 27.7 MHz) volume coil, which could be used for both transmitting and receiving, and of a receive-only single-tuned (27.7 MHz) coil. The double-tuned coil consists of two concentric birdcage resonators. The inner one is a low-pass design and it is tuned to 27.7 MHz, while the outer one, tuned to 100 MHz, is high-pass. The receive-only coil is a surface coil which is decoupled from the double-tuned volume coil by an active decoupling circuitry based on the use of PIN diodes. A home-built Transmit/Receive (T/R) driver ensures biasing of the PIN diodes in both volume and surface coils. The original concepts of the design are addressed, and practical details of realization are presented. One of the underlying ideas behind this work is to proceed well beyond the application to the MRI of HP 129Xe. Actually, this design could be easily adapted for a large palette of other MRI applications. Indeed, we tried to make the design versatile, simple and easy to replicate by other research groups, with a low-cost, minimum development time and accepted performances. The prototype was validated at 100 MHz and at 26.4 MHz (sodium-23 resonance frequency at 2.35 T). MRI experiments were performed using phantoms. In vivo 1H images and 23Na spectra of the rat brain are also presented.展开更多
Gliomas are the most common form of central nervous system tumor. The most prevalent form, glioblastoma multiforme, is also the most deadly with mean survival times that are less than 15 months. Therapies are severely...Gliomas are the most common form of central nervous system tumor. The most prevalent form, glioblastoma multiforme, is also the most deadly with mean survival times that are less than 15 months. Therapies are severely limited by the ability of these tumors to develop resistance to both radiation and chemotherapy. Thus, new tools are needed to identify and monitor chemoresistance before and after the initiation of therapy and to maximize the initial treatment plan by identifying patterns of chemoresistance prior to the start of therapy. Here we show how magnetic resonance imaging, particularly sodium imaging, metabolomics, and genomics have all emerged as potential approaches toward the identification of biomarkers of chemoresistance. This work also illustrates how use of these tools together represents a particularly promising approach to understanding mechanisms of chemoresistance and the development individualized treatment strategies for patients.展开更多
Water soluble upconversion （UC） luminescence hexagonal-phase NaGdF4： yb3＋/Tm3＋ nanoparticles have been successfully synthesized by the hydrothermal method. XRD, SEM, UC photoluminescence spectra and electron para...Water soluble upconversion （UC） luminescence hexagonal-phase NaGdF4： yb3＋/Tm3＋ nanoparticles have been successfully synthesized by the hydrothermal method. XRD, SEM, UC photoluminescence spectra and electron paramagnetic resonance （EPR） spectrum were used to characterize the nanoparticles. The intensity of UC emission region could be controlled through different sodium source and the fluorine source, 6PJ→8S7/2 emission of Gd3＋ is also observed at 310 nm. A broad spectrum with a dominant resonance at g of about 2 was observed by the EPR spectrum of the NaGdF4：Yb3＋/Tm3＋ nanoparticles. The transparent NaGdF4：yb3＋/Tm3＋ solution presented naked eye-visible violet-blue light under the 980 nm LD excitation. The current work paves the way for their potential application in infrared tomography and magnetic resonance imaging （MRI）.展开更多
文摘Background: In the last decade, sodium mag-netic resonance imaging was investigated for its potential as a functional cardiac imaging tool for ischemia. Later interest was developed in contrast enhancement for intracellular sodium. Little success was reported to suppress extracellular sodium resulting in the intracellular sodium MRI image acquisition using quantum filters or sodium transition states as contrast properties. Now its clinical application is ex-panding as a new challenge in brain and other cancer tumors. Contrast enhancement: We highlight the physical principles of sodium MRI in three different pulse sequences using filters (single quantum, multiple quantum, and triple quantum) meant for sodium contrast enhancement. The optimization of scan parameters, i.e. times of echo delay (TE), inversion recovery (TI) periods, and utility of Dysprosium (DyPPP) shift contrast agents, enhances contrast in sodium MRI images. Inversion recovery pulse sequence without any shift reagent measures the intracellular sodium concentration to evaluate ischemia, apoptosis and membrane integrity. Membrane integrity loss, apoptosis and malignancy are results of growth factor loss and poor epithelial capability related with MRI visible intracellular sodium concentration. Applications and limitations: The sodium MR imaging technical advances reduced scan time to distinguish intracellular and extracellular sodium signals in malignant tumors by use of quantum filter techniques to generate 3D sodium images without shift regents. We observed the association of malignancy with increased TSC, and reduced apoptosis and epithelial growth factor in breast cancer cells. The validity is still in question. Conclusion: Different modified sodium MRI pulse sequences are research tools of sodium contrast enhancement in brain, cardiac and tumor imaging. The optimized MRI scan pa-rameters in quantum filter techniques generate contrast in intracellular sodium MR images without using invasive contrast shift agents. Still, validity and clinical utility are in
文摘The design and development of a new dual-frequency RF probe-head are presented. This probe was initially dedicated for the MRI of both proton (1H) and hyperpolarized Xenon-129 (HP 129Xe) in the rat brain at 2.35 Tesla. It consists of a double-tuned (100 MHz- 27.7 MHz) volume coil, which could be used for both transmitting and receiving, and of a receive-only single-tuned (27.7 MHz) coil. The double-tuned coil consists of two concentric birdcage resonators. The inner one is a low-pass design and it is tuned to 27.7 MHz, while the outer one, tuned to 100 MHz, is high-pass. The receive-only coil is a surface coil which is decoupled from the double-tuned volume coil by an active decoupling circuitry based on the use of PIN diodes. A home-built Transmit/Receive (T/R) driver ensures biasing of the PIN diodes in both volume and surface coils. The original concepts of the design are addressed, and practical details of realization are presented. One of the underlying ideas behind this work is to proceed well beyond the application to the MRI of HP 129Xe. Actually, this design could be easily adapted for a large palette of other MRI applications. Indeed, we tried to make the design versatile, simple and easy to replicate by other research groups, with a low-cost, minimum development time and accepted performances. The prototype was validated at 100 MHz and at 26.4 MHz (sodium-23 resonance frequency at 2.35 T). MRI experiments were performed using phantoms. In vivo 1H images and 23Na spectra of the rat brain are also presented.
文摘Gliomas are the most common form of central nervous system tumor. The most prevalent form, glioblastoma multiforme, is also the most deadly with mean survival times that are less than 15 months. Therapies are severely limited by the ability of these tumors to develop resistance to both radiation and chemotherapy. Thus, new tools are needed to identify and monitor chemoresistance before and after the initiation of therapy and to maximize the initial treatment plan by identifying patterns of chemoresistance prior to the start of therapy. Here we show how magnetic resonance imaging, particularly sodium imaging, metabolomics, and genomics have all emerged as potential approaches toward the identification of biomarkers of chemoresistance. This work also illustrates how use of these tools together represents a particularly promising approach to understanding mechanisms of chemoresistance and the development individualized treatment strategies for patients.
基金Acknowledgements This work was supported by the National Natural Science Foundation of China （Grant No. 51361009）, Key Program for International S＆T Cooperation Projects of Hainan Province, China （GJXM201103）, Science and Technology Department of Hainan Province, China （Grant No. 090401）, and the Natural Science Foundation of Hainan Province, China （Grant No. 513136）.
文摘Water soluble upconversion （UC） luminescence hexagonal-phase NaGdF4： yb3＋/Tm3＋ nanoparticles have been successfully synthesized by the hydrothermal method. XRD, SEM, UC photoluminescence spectra and electron paramagnetic resonance （EPR） spectrum were used to characterize the nanoparticles. The intensity of UC emission region could be controlled through different sodium source and the fluorine source, 6PJ→8S7/2 emission of Gd3＋ is also observed at 310 nm. A broad spectrum with a dominant resonance at g of about 2 was observed by the EPR spectrum of the NaGdF4：Yb3＋/Tm3＋ nanoparticles. The transparent NaGdF4：yb3＋/Tm3＋ solution presented naked eye-visible violet-blue light under the 980 nm LD excitation. The current work paves the way for their potential application in infrared tomography and magnetic resonance imaging （MRI）.
