Systemic Metabolic and Volumetric Assessment via Whole-Body [F]FDG-PET/CT: Pancreas Size Predicts Cachexia in Head and Neck Squamous Cell Carcinoma.

Cancer-associated cachexia in head and neck squamous cell carcinoma (HNSCC) is challenging to diagnose due to its complex pathophysiology. This study aimed to identify metabolic biomarkers linked to cachexia and survival in HNSCC patients using [F]FDG-PET/CT imaging and machine learning (ML) techniques. We retrospectively analyzed 253 HNSCC patients from Vienna General Hospital and the MD Anderson Cancer Center.

A CMOS NMR needle for probing brain physiology with high spatial and temporal resolution.

Magnetic resonance imaging and spectroscopy are versatile methods for probing brain physiology, but their intrinsically low sensitivity limits the achievable spatial and temporal resolution. Here, we introduce a monolithically integrated NMR-on-a-chip needle that combines an ultra-sensitive 300 µm NMR coil with a complete NMR transceiver, enabling in vivo measurements of blood oxygenation and flow in nanoliter volumes at a sampling rate of 200 Hz.

Diffusion properties of conventional and calcium-sensitive MRI contrast agents in the rat cerebral cortex.

Calcium-sensitive MRI contrast agents can only yield quantitative results if the agent concentration in the tissue is known. The agent concentration could be determined by diffusion modeling, if relevant parameters were available. We have established an MRI-based method capable of determining diffusion properties of conventional and calcium-sensitive agents.

New calcium-selective smart contrast agents for magnetic resonance imaging.

Calcium plays a vital role in the human body and especially in the central nervous system. Precise maintenance of Ca(2+) levels is very crucial for normal cell physiology and health. The deregulation of calcium homeostasis can lead to neuronal cell death and brain damage.

Biocytin-derived MRI contrast agent for longitudinal brain connectivity studies.

To investigate the connectivity of brain networks noninvasively and dynamically, we have developed a new strategy to functionalize neuronal tracers and designed a biocompatible probe that can be visualized in vivo using magnetic resonance imaging (MRI). Furthermore, the multimodal design used allows combined ex vivo studies with microscopic spatial resolution by conventional histochemical techniques. We present data on the functionalization of biocytin, a well-known neuronal tract tracer, and demonstrate the validity of the approach by showing brain networks of cortical connectivity in live rats under MRI, together with the corresponding microscopic details, such as fibers and neuronal morphology under light microscopy.

Dual-functional probes towards in vivo studies of brain connectivity and plasticity.

A Gd(3+) based paramagnetic dextran conjugate has been developed, which enables the tracking of neuroanatomical connectivity in the brain by both MR and optical imaging. Cell studies and subsequent in vivo experiments in rodents demonstrate efficient internalisation and transport properties of the new tracer molecule.

Tracing of noradrenergic projections using manganese-enhanced MRI.

We examined the applicability of manganese-enhanced MRI (MEMRI) to the in vivo tracing of diffuse neuromodulatory projections by means of simultaneous iontophoretic injections of an extremely low, non-toxic concentration of MnCl(2) (10mM) and fluorescent dextran in the locus coeruleus (LC) in the rat. We validated the use of the iontophoretic injection by reproducing previously reported results from pressure injections of MnCl(2) in primary somatosensory cortex. Twenty fourhours after injection in LC, Mn(2+) labeling was detected in major cortical and subcortical targets of LC projections including predominantly ipsilateral primary motor and somatosensory cortices, hippocampus and amygdala.

In vivo characterization of a smart MRI agent that displays an inverse response to calcium concentration.

Contrast agents for magnetic resonance imaging (MRI) that exhibit sensitivity toward specific ions or molecules represent a challenging but attractive direction of research. Here a Gd(3+) complex linked to an aminobis(methylenephosphonate) group for chelating Ca(2+) was synthesized and investigated. The longitudinal relaxivity (r(1)) of this complex decreases during the relaxometric titration with Ca(2+) from 5.

Functional MRI evidence for LTP-induced neural network reorganization.

The hippocampal formation is a region of the forebrain that is important for memory and spatial navigation. On the basis of a vast amount of literature, the hippocampus is linked with long-term potentiation (LTP), the increased synaptic strength following repeated stimulation of the hippocampal neurons. LTP is considered to be the experimental demonstration of Hebb's postulate on synaptic strength and learning, and it is the dominant model of an experience-dependent modification of brain circuits.

Synthesis and characterization of a smart contrast agent sensitive to calcium.

A novel first-generation Ca2+ sensitive contrast agent, Gd-DOPTRA has been synthesized and characterized. The agent shows approximately 100% relaxivity enhancement upon addition of Ca2+. The agent is selective and sensitive to Ca2+ also in the presence of Mg2+ and Zn2+.

Electric stimulation fMRI of the perforant pathway to the rat hippocampus.

The hippocampal formation is a brain system that is implicated in learning and memory. The major input to the hippocampus arrives from the entorhinal cortex (EC) to the dentate gyrus (DG) through the perforant path. In the present work, we have investigated the functional properties of this connection by concomitantly applying electrophysiological techniques, deep-brain electric microstimulation and functional magnetic resonance imaging in anesthetized rats.

Anatomical and functional MR imaging in the macaque monkey using a vertical large-bore 7 Tesla setup.

Functional magnetic resonance imaging (MRI) in the nonhuman primate promises to provide a much desired link between brain research in humans and the large body of systems neuroscience work in animals. We present here a novel high field, large-bore, vertical MR system (7 T/60 cm, 300 MHz), which was optimized for neuroscientific research in macaque monkeys. A strong magnetic field was applied to increase sensitivity and spatial resolution for both MRI and spectroscopy.