Our staff has implemented, validated, and optimized discovery MRI applications since 2003. Today we offer a wide range of in vivo MRI applications using our 7T small animal MRI system.
Magnetic resonance imaging (MRI) is based on the phenomenon of nuclear magnetic resonance (NMR). Since the magnetic resonance properties of nuclei such as hydrogen nuclei (or protons) in water are affected by a variety of physiological parameters, MRI can be used to spatially encode a variety of tissue properties including water content, cellular density, iron content, oxygenation, metabolite concentration, and elasticity.
Additionally, MRI probes such as gadolinium-, iron oxide-, manganese-, nitrous oxide-, and 19-fluorine-containing molecules can be used to further interrogate disease states. Probe use can be leveraged to improve diagnostic sensitivity or to provide unique biomarkers for properties including blood flow, blood volume, and tissue perfusion.
While MRI is one of the most flexible imaging modalities, it has relatively low sensitivity, which limits throughput compared to other established imaging modalities. Years of experience have honed our staff’s ability to overcome the challenge of maintaining quality, while driving MRI throughput, to make powerful, industry-relevant MRI studies feasible.
We offer a large assortment of optimized, anatomical imaging protocols designed to delineate disease morphology and heterogeneity against normal tissue, including extensive applications in orthotopic and metastasis tumor models. Intracranial tumor models have been one of our most noteworthy focus applications for MRI.
Dynamic Contrast-Enhanced (DCE) MRI
A clinical standard in oncology, DCE MRI allows the quantification of spatially resolved parameters that are measures of tumor permeability, blood flow, and vascular surface area. The protocol is based on systemic administration of a bolus of a gadolinium-containing contrast molecule, then tracking its extravasation over time.
We collaborated with the technique’s industry pioneers to optimize our DCE MRI protocol. Our DCE MRI acquisition and analysis procedures provide maximal clinical relevance, data reproducibility, and efficiency and span a broad range of subcutaneous and orthotopic tumor models, using both small and large gadolinium-containing molecules. By varying the size and characteristics of the gadolinium-containing contrast agent, the DCE-based readout can be weighted toward permeability or blood flow, respectively.
Apparent Diffusion Coefficient (ADC) MRI
MRI-based resolution of tissue water, ADC is a clinical standard for measurement of disease progression and therapeutic response across a variety of indications, including cancer and neurodegenerative diseases. In cancer, a large body of preclinical and clinical published articles have proven that ADC can accurately predict patient survival very early into treatment, based on the cellular density changes and corresponding water mobility (ADC) changes that occur through anti-cancer activity, including cell kill. We have a proprietary, motion-compensated, motion-corrected ADC pulse sequence that provides high-throughput, high-quality in vivo tissue ADC maps. We use this protocol for tracking modifications to tumor extra-cellular matrix and acute anti-cancer efficacy.
MRI Cell Tracking and Imaging of Inflammatory Cells
19-Fluorine (19F) Based Cell Tracking
Fluorinated nanoparticles, such as those available from Celsense, can be used for tracking macrophages in vivo after systemic injection or for tracking cells (including cell-based therapies) after pre-labeling of cells in vitro. 19F MRI provides excellent sensitivity due to favorable MR properties and the lack of 19F background in normal tissue. 19F signals can be overlaid on 1H anatomical images to provide tissue signal localization.
Iron-Oxide-Based Cell Tracking
Super paramagnetic iron oxide (SPIO) nanoparticles can be used for labeling cells in vitro and tracking them after administration in vivo using T2 and T2-weighted MRI. SPIOs can also be used for labeling endogenous cell populations. Iron oxide provides excellent sensitivity for MRI based detection.
pH Chemical Exchange Saturation Transfer (CEST)
pH CEST MRI utilizes a clinically approved contrast agent to measure pH of tissues in a highly sensitive manner and with high spatial resolution. Applications include assessment of anticancer activity in tumor models and characterization of tissue bioenergetics.
MRI Contrast Agent Assessment
MRI contrast-agent assessment, including biodistribution, pharmacokinetics, and tissue pharmacodynamics, has been another of our focus areas. Protocols and models are optimized for gadolinium-, iron-oxide-, and fluorine-based contrast agents, including a variety of nanoparticle platforms.
MRI is well suited to non-invasive visualization and characterization of implanted biomaterials and medical devices, both from a safety and performance perspective. Our surgical expertise can accommodate medical device or material implant prior to in vivo imaging time courses.