Capturing alterations of intracellular-extracellular lactate distribution in the brain using diffusion-weighted MR spectroscopy in vivo.

While the intracellular-extracellular distribution of lactate has been suggested to play a critical role in the healthy and diseased brain, tools are lacking to noninvasively probe lactate in intracellular and extracellular spaces. Here, we show that, by measuring the diffusion of lactate with diffusion-weighted magnetic resonance (MR) spectroscopy in vivo and comparing it to the diffusion of purely intracellular metabolites, noninvasive quantification of extracellular and intracellular lactate fractions becomes possible. More specifically, we detect alterations of lactate diffusion in the APP/PS1 mouse model of Alzheimer's disease.

Assessing potential correlation between T relaxation and diffusion of lactate in the mouse brain.

Purpose: While diffusion and T relaxation are intertwined, little or no correlation exists between diffusion and T relaxation of intracellular metabolites in the rodent brain, as measured by diffusion-weighted MRS at different TEs. However, situation might be different for lactate, since it is present in both extracellular and intracellular spaces, which exhibit different diffusion properties and may also exhibit different T . Such a TE dependence would be crucial to account for when interpreting or modeling lactate diffusion.

Using spectrally-selective radiofrequency pulses to enhance lactate signal for diffusion-weighted MRS measurements in vivo.

Measurement of lactate diffusion properties using diffusion-weighted magnetic resonance spectroscopy in vivo may allow elucidating brain lactate cellular compartmentation, which would be of great importance for neuroscience. However, measuring lactate signal is complicated by low signal-to-noise ratio due to low lactate concentration and J-modulation of its 1.3 ppm peak.

Correlative Imaging of Motoneuronal Cell Elasticity by Pump and Probe Spectroscopy.

Because of their role of information transmitter between the spinal cord and the muscle fibers, motor neurons are subject to physical stimulation and mechanical property modifications. We report on motoneuron elasticity investigated by time-resolved pump and probe spectroscopy. A dual picosecond geometry simultaneously probing the acoustic impedance mismatch at the cell-titanium transducer interface and acoustic wave propagation inside the motoneuron is presented.