Keywords: Probes & Targets, Atherosclerosis, ADAMTS4

Motivation: A precise diagnosis of atherosclerosis is of clinical importance, since cardiovascular disease remain one of the leading causes of death worldwide.

Goal(s): The goal of this study was to evaluate the feasibility of characterizing a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS4) using molecular magnetic resonance imaging in a preclnical model of atherosclerosis. 

Approach: Molecular magnetic resonance imaging using a novel probe targeted against ADAMTS4 was used in a high-fat murine model. 

Results: It was possible to image atherosclerotic lesions in a mouse model using an ADAMTS4- specific probe for magnetic resonance imaging. 

Impact: Using molecular MRI targeting ADAMTS4 is a promising method for characterization of plaque composition and could possibly impact plaque vulnerability assessment in the diagnosis and treatment of atherosclerosis in patients. 

Keywords: Preclinical Image Analysis, Quantitative Imaging, Multi-tracer, Multiparameteric, Registration

Motivation: Robust preclinical multimodal image registration must be developed to provide rich multiparametric data to noninvasively reveal biological treatment-induced tumor alterations.

Goal(s): Establish a pipeline to enable multimodal registration of semi-rigid, subcutaneous tumors in preclinical models to evaluate multi-tracer multiparametric PET/CT-MR metric alterations.

Approach: Utilizing a breast cancer murine model, a custom-designed mouse couch, augmented with an injectable liquid fiducial marker, was assessed for MR-CT co-registration, facilitating the development of a registration pipeline.

Results: Post-registration tumor segmentation performed independently across modalities yielded high Dice Similarity Coefficient scores (0.92-0.95), indicating accurate tumor alignment, and enabling preliminary multiparametric voxel-wise comparisons of multimodal imaging metrics.

Impact: Preclinical imaging with our registration pipeline enables for biological treatment-induced characterization of subcutaneous tumors through sequential multi-tracer multiparametric PET/CT-MR.

Keywords: Preclinical Image Analysis, Quantitative Susceptibility mapping, QSM , SPION, Iron concentration

Motivation: Progressing the clinical translation of QSM is important for imaging of biometal dysregulation in neurodegenerative disease but available methods for calibrating QSM sequences between systems are limited.   

Goal(s): To develop and validate a superparamagnetic iron oxide nanoparticle (SPION) phantom replicating human brain iron concentration.  

Approach: Dilutions of Ferrotrace SPION (0.1-25 $$$\mu$$$g/mL) were scanned with research application QSM gradient echo sequence using two different 3T systems and multiple analysis methods. 

Results:  A good linear fit was demonstrated between QSM values and SPION concentration across a clinically relevant interval and different QSM analysis methods. Values differed between two scanners but there was high within-scanner concordance.  

Impact: A SPION based phantom replicating in vivo iron of healthy and diseased brain could be an invaluable calibration and QA tool for QSM clinical translation, normative datasets and emerging SPION-based theranostics for brain cancer.  

Keywords: Biology, Models, Methods, Data Acquisition, EPSI, flyback readout, ghost artifacts, micro-imaging, water-fat imaging

Motivation: To assess echo-planar spectroscopic imaging (EPSI) with flyback readout gradients in preclinical MR system.

Goal(s): To demonstrate spectral ghost artifacts produced by two, three,  and four interleaved gradient echo trains and to measure water, fat, and water-fat shift artifacts free images.      

Approach: Flyback EPSI with two, three, and four interleaved gradient echo trains.  

Results: The proposed approach with four interleaved gradient echo trains and with four echoes in each train enables high spectral bandwidth in combination with narrow receiver bandwidth and a very good water/fat signals separation. It improves SNR without the undesired consequence of water-fat shift artifacts.

Impact: Echo-planar spectroscopic imaging with flyback readout enables measurement of water, fat, and water-fat shift artifact-free images. Four interleaved echo trains with four echoes in each train provide high spectral, and narrow receiver bandwidth, and a very good water-fat separation.

Keywords: Probes & Targets, Preclinical, Resonators, Transmit-Receive Coil

Motivation: High permittivity dielectric resonators for high resolution MRI are fabricated ferroelectric materials and have a large temperature coefficient, which produces a significant frequency variation in a small temperature range.

Goal(s): Reduce the temperature coefficient in dielectric resonators through a composite design.

Approach: Depending on the Curie temperature of BST, single layered dielectric resonators have positive or negative temperature dependance of resonant frequency. Bi-layered resonators combine positive and negative coefficients to create a temperature stable resonant frequency.

Results: Bi-layered resonators show on average a 75% reduction in frequency variation compared to single layers.

Impact: Bi-layered resonators are a first step in overcoming high temperature coefficients present in high permittivity dielectric resonators. With further improvements, this method can be used to significantly increase SNR in preclinical studies.

Keywords: Probes & Targets, Tumor

Motivation: Currently used Neutron capture therapy agents in clinic have low tumor targeting ability and have different structures from imaging agents that can view bio-distribution, making it difficult to determine the exact distribution of the drug in the human body.

Goal(s): Development of a new MR-image guided drugs for neutron capture therapy

Approach: Two of gadolinium complexes of porphyrin derivative were designed and synthesized. Cell uptake study was performed using normal cell and glioblastoma cells. In vivo MR images and ex vivo fluorescence images were obtained. 

Results: We found that Gd-complexes could enter into the nucleus and be further uptaken by tumor tissues.

Impact: Using the two gadolinium complexes, it is possible to compare the therapeutic efficacy of GdNCT and BNCT and expect a synergistic effect. The development of NCT treatments using small molecule substances may have the potential for clinical application.

Keywords: Other Preclinical, Reproductive, Early Embryos

Motivation: Traditional methods for early embryos assessment are often invasive or lack detail, underscoring the necessity for non-invasive, high-resolution techniques.

Goal(s): The primary goal was to test MRS as a predictive tool for embryo viability. By leveraging microchip-based probes, we analyzed the metabolic profile of early-stage bovine embryos and oocytes. This aimed at predicting developmental outcomes with high precision and accuracy.

Approach: In total, we conducted multi-channel high-throughput spectroscopy to perform a minimally invasive analysis of 1 hour on 61 single 8-cell embryos and 84 single oocytes.

Results: We found strong correlation between spectra at the 8-cell stage and subsequent development to blastocyst.

Impact: This work offers new data for MRS and embryology, laying a foundation to improve fertility treatments  by selecting viable embryos. By revealing previously inaccessible data it opens to new embryonic research, potentially revolutionizing our understanding of early developmental biology.

Keywords: Biology, Models, Methods, High-Field MRI

Motivation: The zebrafish is an important model organism for the study of vertebrate biology with its genomes showing significant parallels to human genomes.

Goal(s): To show the feasibility of in-vivo imaging at a pre-clinical 11.7T MRI without the need for dedicated hardware components.

Approach: A budget-friendly zebrafish holder was created using a syringe barrel and needle adapters, with a rotating cylinder to maintain water flow. It was positioned on a Bruker Mouse Brain Surface Coil.

Results: The use of standard imaging equipment in combination with a low-cost and easy to built animal holder is sufficient to facility high-resolution imaging of the adult zebrafish.

Impact: This research enables cost-effective, high-resolution MRI for zebrafish, enhancing its potential as a pre-clinical model for vital research in vertebrate biology, ultimately advancing our understanding of human genomics.

Keywords: Preclinical Image Analysis, Drug Development, Protein structure

Motivation: The in-cell NMR method allows direct observations of proteins in cultured human cells, to evaluate protein conformations and interactions in an intracellular environment. Currently, target proteins must be highly soluble and thermally stable.

Goal(s): A technical in-cell NMR strategy is required for proteins with poor solubility and low thermal stability.

Approach: Protein concentration-dependent NMR analyses revealed the self-association sites of proteins. Site-directed mutants gained higher solubility. Cell treatment conditions at lower temperature were established.

Results: We successfully constructed an in-cell NMR protocol that improves protein solubility and cell treatment conditions at 25°C, the lowest temperature established so far.

Impact: By performing experiments according to our strategy, in-cell NMR can be applicable to more types of proteins with poor solubility and low thermal stability. Furthermore, we developed an in-cell system for evaluating therapeutic candidate compounds against target proteins.

Keywords: Biology, Models, Methods, Spectroscopy, MALDI imaging, heterospectroscopy

Motivation: Combining high-resolution (HR) magnetic resonance spectroscopy (MRS) and matrix-assisted laser desorption/ionization (MALDI) imaging of tissues and cells using new workflows and data analysis approaches will further advance metabolomic and lipidomic studies.

Goal(s): The goal is to develop Statistical Heterospectroscopy (SHY) of ¹H-HR-MRS and MALDI imaging data of tissues and cells.

Approach: Phantoms, cell lines, and tumors were measured by ¹H-HR-MRS and MALDI imaging, followed by analysis with newly developed MATLAB-based software for statistical correlation of both datasets.

Results: The new MALDI-MRS-SHY software correctly generated two-dimensional spectra with cross-peaks from phantoms of pure compounds and mixtures, as well as cell lines and tumor tissues.

Impact: The newly developed MALDI-MRS-SHY software will allow for a deeper analysis of complex metabolomic and lipidomic data obtained by combined HR-MRS and MALDI imaging of cells and tissues.

Keywords: Probes & Targets, Contrast Agent

Motivation: We aim to advance biocompatible ¹⁹F-MR contrast agent to enhance imaging diagnostic in cancer.

Goal(s): Nanoparticles (NPs) internal structure impacting Gd-enhanced effect on ¹⁹F-MR signal strength, relaxation times and pH-sensitivity.

Approach: Systematic investigation using ¹H/¹⁹F-MR to understand how NPs structure affects the interaction between co-encapsulated Gd and ¹⁹F and focusing on multi-core NPs and their acidic pH-sensitivity on ¹⁹F-MR relaxation times.

Results: Our study revealed that ¹⁹F-MR signal strength is pH-dependant. After cellular uptake, multi-core NPs co-encapsulating Gd and PFCE exhibited higher T2 values and stronger signal, influenced by lysosomal acidity, highlighting pH role in MR signal modulation.

Impact: The pH-sensitive ¹⁹F-MR probe enhance NPs tracking after cell internalization and by that it holds great promise for tissue pathology imaging, as cancer diagnostics.

Keywords: Preclinical Image Analysis, Preclinical

Motivation: Radiation therapy (RT) for primary tumors triggers regression in non-irradiated metastatic lesions via the abscopal effect, can potentiate the effects of immune-checkpoint blockade on the non-treated tumors in the same animal. 

Goal(s):  To examine physiological alterations of the treated tumor linked to the abscopal effect.

Approach: We used MRI-based imaging techniques, such as EPR oximetry, DCE MRI, and ¹³C DNP MRI.

Results: After RT and PD-1 blockade, we observed improved oxygenation, permeability, perfusion, and CD8+ T cell infiltration in metastatic (untreated) tumors. Interestingly, primary tumor with increased permeability and perfusion and reduced hypoxic fraction (HF10) before treatment correlated with augmented abscopal effect post-treatment.

Impact: Metastatic tumor conditions improved with RT and ICB, enhancing oxygenation, permeability, perfusion, and CD8+ T cell infiltration. Primary tumor's elevated permeability and lower HF10 correlated with higher AE in metastatic tumors, confirmed through carbogen-enhanced perfusion.

Keywords: Biomarkers, Cancer, Multiparametric, IVIM

Motivation: IVIM MRI potentially offers non-invasive, non-contrast-based quantification of tumor perfusion parameters, which would facilitate tumor tissue characterization and longitudinal assessment of radionuclide therapy.

Goal(s): The goal was to study the feasibility of using IVIM metrics for spatiotemporal tissue characterization in the context of radionuclide therapy in a neuroendocrine tumor model. 

Approach: Mice with human neuroendocrine tumors were imaged before and repeatedly after radionuclide treatment and parametric maps of perfusion-related parameters from IVIM and DCE were compared and studied longitudinally.

Results: Interesting spatiotemporal variations that revealed similarities between techniques show promise for further in-depth analysis using spatial image registration techniques and histopathological validation.

Impact: Non-invasive, spatiotemporally resolved tumor perfusion characterization using intravoxel incoherent motion MRI would benefit preclinical optimization and understanding of radionuclide treatment with possible rapid translation into the clinics due to the widespread use of MRI in both research and clinical practice. 

Keywords: Other Preclinical, Toxicity, In vitro Pharmacometabolomics, NMR spectroscopy, Nanocomposite, Nanotoxicology

Motivation: Conventional toxicity assays generally convey the efficiency of nanomaterial, but they lack a mechanistic molecular approach to toxicity. 

Goal(s): We aimed to employ NMR-based Pharmacometabolomics to detect early metabolic alterations associated with nanomaterial developed for healthcare. 

Approach: The NMR spectroscopy technique was used on Silver nanoparticles reinforced biocomposite exposed murine fibroblast (L929) cells. 

Results: Results demonstrated that cellular metabolic profiles reset towards control upon more exposure.

Impact: Our nanomaterial-based study accentuates the role of pharmacometabolomics, which will complement the findings of conventional assays, eventually leading to efficacious clinical translation. 

Keywords: Biomarkers, Vessels, Liver, tumor, biomechanics, Elastography

Motivation: Colorectal cancer is a major global cause of cancer-related deaths, often metastasizing to the liver. Standard treatment includes chemotherapy and anti-angiogenic therapy. Quantifying therapy efficacy remains a clinical challenge.

Goal(s): We explore multifrequency MR-Elastography (MRE) for assessing vascular organization, using a murine liver metastasis model correlated with histopathology.

Approach: The study used MRE imaging of murin liver metastasis model and the corresponding histopathology to analyze vascular organization (fractal dimension), by measuring Hurst index (H-index).

Results: The H-index differs significantly between tumor and healthy liver tissue, with normal vasculature displaying a lower H-index compared to the tumoral tissue.

Impact: Our in vivo elastography study demonstrates the organization of the vascular network by matching with histological findings. This innovative approach paves the way for non-invasive evaluation of treatments targeting tumor vessels, such as bevacizumab or FOLFOX.

Keywords: Biomarkers, Molecular Imaging, Melanoma, BRAF

Motivation: We use ¹H/³¹P MRS to monitor the metabolic effects of dabrafenib therapy in four human melanoma models, an FDA-approved treatment for late-stage melanoma. 

Goal(s): Differences in relative levels of metabolites and bioenergetics between four melanoma models may produce differential therapeutic responses to BRAF inhibitors.

Approach: Intratumor variations of lactate, alanine, and bioenergetics (β-NTP/Pi) measured by in-vivo and in-vitro ¹H/³¹P MRS have the potential to become early and sensitive biomarkers of dabrafenib inhibition therapy in melanoma.

Results: Changes in lactate, alanine, and bioenergetics response to targeted dabrafenib inhibitor therapy occur rapidly and are connected to the following tumor response.

Impact: Dabrafenib blocks cell division by inhibiting the hyperactive BRAF protein. Differences in the predominance of metabolites (Lactate and Alanine) and bioenergetics may explain dabrafenib therapeutic responses in DB-1/WM983B (Sensitive mutant type), WM983BR (Resistant mutant type), and WM3918 (Wild type).