Multimodality Imaging

Exploring innovative strides in radiolabeled nanoparticle progress for multimodality cancer imaging and theranostic applications

Multimodal imaging unfolds as an innovative approach that synergistically employs a spectrum of imaging techniques either simultaneously or sequentially. The integration of computed tomography (CT), magnetic resonance imaging (MRI), single-photon emission computed tomography (SPECT), positron emission tomography (PET), and optical imaging (OI) results in a comprehensive and complementary understanding of complex biological processes. This innovative approach combines the strengths of each method and overcoming their individual limitations. By harmoniously blending data from these modalities, it significantly improves the accuracy of cancer diagnosis and aids in treatment decision-making processes. Nanoparticles possess a high potential for facile functionalization with radioactive isotopes and a wide array of contrast agents. This strategic modification serves to augment signal amplification, significantly enhance image sensitivity, and elevate contrast indices. Such tailored nanoparticles constructs exhibit a promising avenue for advancing imaging modalities in both preclinical and clinical setting. Furthermore, nanoparticles function as a unified nanoplatform for the co-localization of imaging agents and therapeutic payloads, thereby optimizing the efficiency of cancer management strategies. Consequently, radiolabeled nanoparticles exhibit substantial potential in driving forward the realms of multimodal imaging and theranostic applications. This review discusses the potential applications of molecular imaging in cancer diagnosis, the utilization of nanotechnology-based radiolabeled materials in multimodal imaging and theranostic applications, as well as recent advancements in this field. It also highlights challenges including cytotoxicity and regulatory compliance, essential considerations for effective clinical translation of nanoradiopharmaceuticals in multimodal imaging and theranostic applications.

Unlocking the Hidden Depths: Multi-Modal Integration of Imaging Mass Spectrometry-Based and Molecular Imaging Techniques

Multimodal imaging (MMI) has emerged as a powerful tool in clinical research, combining different imaging modes to acquire comprehensive information and enabling scientists and surgeons to study tissue identification, localization, metabolic activity, and molecular discovery, thus aiding in disease progression analysis. While multimodal instruments are gaining popularity, challenges such as non-standardized characteristics, custom software, inadequate commercial support, and integration issues with other instruments need to be addressed. The field of multimodal imaging or multiplexed imaging allows for simultaneous signal reproduction from multiple imaging strategies. Intraoperatively, MMI can be integrated into frameless stereotactic surgery. Recent developments in medical imaging modalities such as magnetic resonance imaging (MRI), and Positron Emission Topography (PET) have brought new perspectives to multimodal imaging, enabling early cancer detection, molecular tracking, and real-time progression monitoring. Despite the evidence supporting the role of MMI in surgical decision-making, there is a need for comprehensive studies to validate and perform integration at the intersection of multiple imaging technologies. They were integrating mass spectrometry-based technologies (e.g., imaging mass spectrometry (IMS), imaging mass cytometry (IMC), and Ion mobility mass spectrometry ((IM-IM) with medical imaging modalities, offering promising avenues for molecular discovery and clinical applications. This review emphasizes the potential of multi-omics approaches in tissue mapping using MMI integrated into desorption electrospray ionization (DESI) and matrix-assisted laser desorption ionization (MALDI), allowing for sequential analyses of the same section. By addressing existing knowledge gaps, this review encourages future research endeavors toward multi-omics approaches, providing a roadmap for future research and enhancing the value of MMI in molecular pathology for diagnosis.

Evolution from Medical Imaging to Visualized Medicine

The discovery of X-ray in 1895 and the first X-ray image of Mrs. Röntgen's hand opened up a new era of radiology and the research of medical imaging. The evolution of traditional medical imaging has been lasting for over 100 years, serving the detection, diagnosis, and treatments of human diseases with a clear view of the anatomy information. In late 1990s, the concept of molecular imaging was proposed as the science and technology of molecular biology and bio-engineering rapidly developed, and it directly gave birth to the emergence of precision medicine for clinical lesion-targeted treatments against various cancers and cardiocerebrovascular diseases. Physiological and pathological changes in live bodies from zebrafish to human beings can be imaged to ensure an efficient image-guided therapy. Nowadays, the philosophy of medical and molecular imaging has been a powerful tool and indispensable modality for doctors to make their decisions and give patients reliable advices. With the ever-emerging developments of advanced intelligent technologies such as flexible sensors, medical meta-data analysis, brain sciences, surgical robots, VR/AR, etc., modern medicine has been evolving from traditional medical and molecular imaging to visualized medicine, which has created novel accessible approaches along with cutting-edge techniques for the revolutionized diagnostic and therapeutic paradigms. In this context, the history and milestones from medical imaging to visualized medicine will be elucidated. And in particular, representative visualized medicine advances including its application to COVID-19 epidemics will be discussed in order to look for its important contributions and a future perspective to modern medicine.

Targeting Tumor-Associated Macrophages for Imaging

As an important component of the tumor immune microenvironment (TIME), tumor-associated macrophages (TAMs) occupy a significant niche in tumor margin aggregation and respond to changes in the TIME. Thus, targeting TAMs is important for tumor monitoring, surgical guidance and efficacy evaluation. Continuously developing nanoprobes and imaging agents paves the way toward targeting TAMs for precise imaging and diagnosis. This review summarizes the commonly used nanomaterials for TAM targeting imaging probes, including metal-based nanoprobes (iron, manganese, gold, silver), fluorine-19-based nanoprobes, radiolabeled agents, near-infrared fluorescence dyes and ultrasonic nanobubbles. Additionally, the prospects and challenges of designing nanomaterials for imaging and diagnosis (targeting efficiency, pharmacokinetics, and surgery guidance) are described in this review. Notwithstanding, TAM-targeting nanoplatforms provide great potential for imaging, diagnosis and therapy with a greater possibility of clinical transformation.

Bioimaging: Evolution, Significance, and Deficit

Bioimaging is a digital technology-based medical advancement which is still relatively new. It has to do with real-time visualization of biological processes. This innovative imaging technology combines anatomical structure with functional data such as electric and magnetic fields, motion which is mechanical, and metabolism to provide information on anatomical structure. It's a non-invasive procedure that gives you a bird's-eye view of the human body, with more depth and detail as you go. As a result, bioimaging is a strong tool for seeing the interior functioning of the organism and its disorders. Examples of bioimaging in the medical industry include X-ray and ultrasound pictures, MRI, 3D and 4D body images utilizing Computed Tomography (CT) scans, DEXA scans which is useful for assessing bone density in osteoporosis, and so on. Maximum-resolution, two-positive charge fluorescent excitation microscopy, fluorescence redistribution after photobleaching, and fluorescence resonance energy transfer are some of the recent advancements in biological imaging. It provides us a cellular-level means of obtaining photographs of the entire body, anatomical locations, organs, tissues, and biological indicators. It may be used to aid illness management and therapy, as well as to detect, diagnose, and characterize the problems in clinical settings.

Mn(ii) chelate-coated superparamagnetic iron oxide nanocrystals as high-efficiency magnetic resonance imaging contrast agents

In this communication, a paramagnetic bifunctional manganese(ii) chelate ([Mn(Dopa-EDTA)]2-) containing a catechol group is designed and synthesized. The catechol can bind iron ions on the surface of superparamagnetic iron oxide (SPIO) nanocrystals to form core-shell nanoparticles. Both 4 and 7 nm SPIO@[Mn(Dopa-EDTA)]2- show good water solubility, single-crystal dispersion, and low cytotoxicity. The study of the interplay between the longitudinal and transverse relaxation revealed that 4 nm SPIO@[Mn(Dopa-EDTA)]2- with lower r 2/r 1 = 1.75 at 0.5 T tends to be a perfect T 1 contrast agent while 7 nm SPIO@[Mn(Dopa-EDTA)]2- with a higher r 2/r 1 = 15.0 at 3.0 T tends to be a T 2 contrast agent. Interestingly, 4 nm SPIO@[Mn(Dopa-EDTA)]2- with an intermediate value of r 2/r 1 = 5.26 at 3.0 T could act as T 1-T 2 dual-modal contrast agent. In vivo imaging with the 4 nm SPIO@[Mn(Dopa-EDTA)]2- nanoparticle shows unique imaging features: (1) long-acting vascular imaging and different signal intensity changes between the liver parenchyma and blood vessels with the CEMRA sequence; (2) the synergistic contrast enhancement of hepatic imaging with the T 1WI and T 2WI sequence. In summary, these Fe/Mn hybrid core-shell nanoparticles, with their ease of synthesis, good biocompatibility, and synergistic contrast enhancement ability, may provide a useful method for tissue and vascular MR imaging.

An Albumin-Binding T1- T2 Dual-Modal MRI Contrast Agents for Improved Sensitivity and Accuracy in Tumor Imaging

Magnetic resonance imaging (MRI) diagnosis is better assisted by contrast agents that can augment the signal contrast in the imaging appearance. However, this technique is still limited by the inherently low sensitivity on the recorded signal changes in conventional T₁ or T₂ MRI in a qualitative manner. Here, we provide a new paradigm of MRI diagnosis using T₁- T₂ dual-modal MRI contrast agents for contrast-enhanced postimaging computations on T₁ and T₂ relaxation changes. An albumin-binding molecule (i.e., truncated Evans blue) chelated with paramagnetic manganese ion was developed as a novel T₁- T₂ dual-modal MRI contrast agent at high magnetic field (7 T). Furthermore, the postimaging computations on T₁- T₂ dual-modal MRI led to greatly enhanced signal-to-noise ratios (SNR) and contrast-to-noise ratios (CNR) in both subcutaneous and orthotopic brain tumor models compared with traditional MRI methods. The T₁- T₂ dual-modal MRI computations have great potential to eliminate suspicious artifacts and false-positive signals in mouse brain imaging. This study may open new avenues for contrast-enhanced MRI diagnosis and holds great promise for precision medicine.

T1-T2 Dual-Modal Magnetic Resonance Imaging: From Molecular Basis to Contrast Agents

Multimodal imaging strategies integrating manifold images have improved our ability to diagnose, to guide therapy, and to predict outcomes. Magnetic resonance imaging (MRI) is among the most widely used imaging technique in the clinic and can enable multiparameter anatomical demonstration of diagnosis. Due to the inherent black-and-white production of MR images, however, MRI detection is largely hampered by the occurrence of false-positive diagnoses. In this Perspective, we introduce the paradigm of manipulating the multiparameter MRI, T₁-T₂ dual-modal MRI, along with enhancement by specific contrast agents. We hope this discussion will promote emerging research interest in T₁-T₂ dual-modal MRI and provoke the rational design of contrast agents for sophisticated MRI applications.

The Advents of Hybrid Imaging Modalities: A New Era in Neuroimaging Applications

Hybrid Imaging modalities have shown great potential in medical imaging and diagnosis. A more comprehensive and targeted view of neurological disorders can be achieved by blending the anatomical and functional perspectives through hybridization. With consistently improving technologies, there have been many developments in fused imaging techniques over the past few decades. This article provides an overview of various bimodal and trimodal hybrid imaging techniques being developed and explored for neuroimaging applications. Recent advancements and potentials are discussed for single photon emission computed tomography-computed tomography (SPECT-CT), positron emission tomography-CT (PET-CT), PET-magnetic resonance imaging (PET-MRI), electroencephalography-functional magnetic resonance imaging (EEG-fMRI), magnetoencephalography-fMRI (MEG-fMRI), EEG-near-infrared spectroscopy (EEG-NIRS), magnetic resonance-PET-EEG (MR-PET-EEG) and MR-PET-CT in the perspective of neuroimaging. A comparison of these hybrid approaches is provided on a single platform to analyze their performance on the basis of several common factors essential for imaging and analyzing neurological disorders and in vivo molecular processes. This article also provides an overview of recently developed advanced imaging technologies that are being hybridized with other imaging modalities and being explored as potential techniques for neuroscience. Novel approaches and clinical applications of hybrid neuroimaging are anticipated with inclusion of new technologies, better sensing capabilities, multimodal probes, and improved hybridization.

Multispectral Emissions of Lanthanide-Doped Gadolinium Oxide Nanophosphors for Cathodoluminescence and Near-Infrared Upconversion/Downconversion Imaging

Comprehensive imaging of a biological individual can be achieved by utilizing the variation in spatial resolution, the scale of cathodoluminescence (CL), and near-infrared (NIR), as favored by imaging probe Gd₂O₃ co-doped lanthanide nanophosphors (NPPs). A series of Gd₂O₃:Ln3+/Yb3+ (Ln3+: Tm3+, Ho3+, Er3+) NPPs with multispectral emission are prepared by the sol-gel method. The NPPs show a wide range of emissions spanning from the visible to the NIR region under 980 nm excitation. The dependence of the upconverting (UC)/downconverting (DC) emission intensity on the dopant ratio is investigated. The optimum ratios of dopants obtained for emissions in the NIR regions at 810 nm, 1200 nm, and 1530 nm are applied to produce nanoparticles by the homogeneous precipitation (HP) method. The nanoparticles produced from the HP method are used to investigate the dual NIR and CL imaging modalities. The results indicate the possibility of using Gd₂O₃ co-doped Ln3+/Yb3+ (Ln3+: Tm3+, Ho3+, Er3+) in correlation with NIR and CL imaging. The use of Gd₂O₃ promises an extension of the object dimension to the whole-body level by employing magnetic resonance imaging (MRI).

Harnessing medically relevant metals onto water-soluble subphthalocyanines: towards bimodal imaging and theranostics

Water-soluble subphthalocyanine (SubPc) - chelating ligands (DOTA, DTPA) conjugates were complexed with six metals relevant to medical imaging/therapies (MRI, PET, SPECT, RIT, NCT). Magneto-optical properties of the ditopic Gd complex and cellular microscopy studies were reported.

Calibrating the BOLD signal during a motor task using an extended fusion model incorporating DOT, BOLD and ASL data

Multimodal imaging improves the accuracy of the localization and the quantification of brain activation when measuring different manifestations of the hemodynamic response associated with cerebral activity. In this study, we incorporated cerebral blood flow (CBF) changes measured with arterial spin labeling (ASL), Diffuse Optical Tomography (DOT) and blood oxygen level-dependent (BOLD) recordings to reconstruct changes in oxy- (ΔHbO(2)) and deoxyhemoglobin (ΔHbR). Using the Grubb relation between relative changes in CBF and cerebral blood volume (CBV), we incorporated the ASL measurement as a prior to the total hemoglobin concentration change (ΔHbT). We applied this ASL fusion model to both synthetic data and experimental multimodal recordings during a 2-s finger-tapping task. Our results show that the new approach is very powerful in estimating ΔHbO(2) and ΔHbR with high spatial and quantitative accuracy. Moreover, our approach allows the computation of baseline total hemoglobin concentration (HbT(0)) as well as of the BOLD calibration factor M on a single subject basis. We obtained an average HbT(0) of 71 μM, an average M value of 0.18 and an average increase of 13% in cerebral metabolic rate of oxygen (CMRO(2)), all of which are in agreement with values previously reported in the literature. Our method yields an independent measurement of M, which provides an alternative measurement to validate the hypercapnic calibration of the BOLD signal.

Introduction: feature issue on phantoms for the performance evaluation and validation of optical medical imaging devices

The editors introduce the Biomedical Optics Express feature issue on "Phantoms for the Performance Evaluation and Validation of Optical Medical Imaging Devices." This topic was the focus of a technical workshop that was held on November 7-8, 2011, in Washington, D.C. The feature issue includes 13 contributions from workshop attendees.

Toward preparation of antibody-based imaging probe libraries for dual-modality positron emission tomography and fluorescence imaging

Two novel imaging agents trastuzumab-Cy5.5-CHX-A''1 and cetuximab-Cy7-CHX-A''2, bearing both a chelating moiety (CHX-A'') for sequestering metallic radionuclides ((86)Y or (111)In) and the near infrared dye Cy5.5/Cy7, were prepared by a novel modular synthetic strategy as examples of dual-labeled, antibody-based imaging probe library. Fluorescent microscopy illustrated that 1 and 2 strongly bind to HER2-expressing cancer cells (e.g., NIH3T3-HER2(+), SKOV-3) and to EGFR-expressing cancer cells (e.g., A431), respectively, thereby demonstrating that the functionality of the targeting moiety is conserved. Hence, the described novel synthesis strategy can be applied to engineer other tumor-targeted monoclonal antibody based probes for multimodality imaging.

Development of a simplified simulation model for performance characterization of a pixellated CdZnTe multimodality imaging system

Current requirements of molecular imaging lead to the complete integration of complementary modalities in a single hybrid imaging system to correlate function and structure. Among the various existing detector technologies, which can be implemented to integrate nuclear modalities (PET and/or single-photon emission computed tomography with x-rays (CT) and most probably with MR, pixellated wide bandgap room temperature semiconductor detectors, such as CdZnTe and/or CdTe, are promising candidates. This paper deals with the development of a simplified simulation model for pixellated semiconductor radiation detectors, as a first step towards the performance characterization of a multimodality imaging system based on CdZnTe. In particular, this work presents a simple computational model, based on a 1D approximate solution of the Schockley-Ramo theorem, and its integration into the Geant4 application for tomographic emission (GATE) platform in order to perform accurately and, therefore, improve the simulations of pixellated detectors in different configurations with a simultaneous cathode and anode pixel readout. The model presented here is successfully validated against an existing detailed finite element simulator, the multi-geometry simulation code, with respect to the charge induced at the anode, taking into consideration interpixel charge sharing and crosstalk, and to the detector charge induction efficiency. As a final point, the model provides estimated energy spectra and time resolution for (57)Co and (18)F sources obtained with the GATE code after the incorporation of the proposed model.

Magnetic and fluorescent nanoparticles for multimodality imaging

The development of nanoparticulate contrast agents is providing an increasing contribution to the field of diagnostic and molecular imaging. Such agents provide several advantages over traditional compounds. First, they may contain a high payload of the contrast-generating material, which greatly improves their detectability. Second, multiple properties may be easily integrated within one nanoparticle to allow its detection with several imaging techniques or to include therapeutic qualities. Finally, the surface of such nanoparticles may be modified to improve circulation half-lives or to attach targeting groups. Magnetic resonance imaging and optical techniques are highly complementary imaging methods. Combining these techniques would therefore have significant advantages and may be realized through the use of nanoparticulate contrast agents. This review gives a survey of the different types of fluorescent and magnetic nanoparticles that have been employed for both magnetic resonance and optical imaging studies.

Design, synthesis, and characterization of a dual modality positron emission tomography and fluorescence imaging agent for monoclonal antibody tumor-targeted imaging

A novel lysine-based trifunctional chelate 3 was designed, synthesized, and characterized and bears both a chelating moiety (CHX-A' ') for sequestering radiometals (86Y or 111In) and the near-infrared dye Cy5.5 for dual modality PET (or SPECT) and fluorescence imaging, respectively. Successful conjugation of 3 to the monoclonal antibody trastuzumab (Herceptin) was achieved by efficient thiol-maleimide chemistry, thereby yielding immunoconjugate 2. Analysis of 2 by flow cytometry and competitive binding assay demonstrates that immunoconjugate 2 binds to SKOV3 tumor cells comparably to native trastuzumab and, thus, may be used as a tumor-targeted monoclonal antibody probe for multimodality imaging.

MR molecular imaging and fluorescence microscopy for identification of activated tumor endothelium using a bimodal lipidic nanoparticle

In oncological research, there is a great need for imaging techniques that specifically identify angiogenic blood vessels in tumors on the basis of differences in the expression level of biomolecular markers. In the angiogenic cascade, different cell surface receptors, including the alphavbeta3-integrin, are strongly expressed on activated endothelial cells. In the present study, we aimed to image angiogenesis by detecting the expression of alphavbeta3 in tumor bearing mice with a combination of magnetic resonance imaging (MRI) and fluorescence microscopy. To that end, we prepared MR-detectable and fluorescent liposomes, which carry approximately 700 alphavbeta3-specific RGD peptides per liposome. RGD competition experiments and RAD-conjugated liposomes were used as controls for specificity. In vivo, both RAD liposomes and RGD liposomes gave rise to signal increase on T1-weighted MR images. It was established by the use of ex vivo fluorescence microscopy that RGD liposomes and RAD liposomes accumulated in the tumor by different mechanisms. RGD liposomes were specifically associated with activated tumor endothelium, while RAD liposomes were located in the extravascular compartment. This study demonstrates that MR molecular imaging of angiogenesis is feasible by using a targeted contrast agent specific for the alphavbeta3-integrin, and that the multimodality imaging approach gave insight into the exact mechanism of accumulation in the tumor.