Publications by authors named "F Martinez-Santiesteban"
This study shows the use of hyperpolarized C magnetic resonance spectroscopic imaging (MRSI) to assess therapeutic efficacy in a preclinical tumor model. C-labeled pyruvate was used to monitor early changes in tumor metabolism based on the Warburg effect. High-grade malignant tumors exhibit increased glycolytic activity and lactate production to promote proliferation.
View Article and Find Full Text PDFThe fundamental limit to in vivo imaging applications of hyperpolarized C-enriched compounds is their finite spin-lattice relaxation times. Various factors affect the relaxation rates, such as buffer composition, solution pH, temperature, and magnetic field. In this last regard, the spin-lattice relaxation time can be measured at clinical field strengths, but at lower fields, where these compounds are dispensed from the polarizer and transported to the MRI, the relaxation is even faster and difficult to measure.
View Article and Find Full Text PDFThis 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 (pH - pH) compared with normal tissue that expresses a negative gradient.
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- This study measured how quickly murine tissues relax after being exposed to different magnetic field strengths, specifically between 0.24 mT and 3 T.
- Researchers used both ex vivo (outside of a living organism) and in vivo (inside a living organism) techniques, analyzing various tissues like brain, liver, kidney, muscle, and fat, to create dispersion profiles of relaxation rates at various temperatures.
- The findings indicate that relaxation rates depend significantly on magnetic field strength below 1 T but show less sensitivity above that, suggesting that FFC-MRI, combined with specific contrast agents, could enhance sensitivity for detecting early changes in tumors.
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.
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