Molecular imaging is revolutionizing the way we study the inner workings of the human body, diagnose diseases, approach drug design, and assess therapies. The field as a whole is making possible the visualization of complex biochemical processes involved in normal physiology and disease states, in real time, in living cells, tissues, and intact subjects. In this review, we focus specifically on molecular imaging of intact living subjects. We provide a basic primer for those who are new to molecular imaging, and a resource for those involved in the field. We begin by describing classical molecular imaging techniques together with their key strengths and limitations, after which we introduce some of the latest emerging imaging modalities. We provide an overview of the main classes of molecular imaging agents (i.e., small molecules, peptides, aptamers, engineered proteins, and nanoparticles) and cite examples of how molecular imaging is being applied in oncology, neuroscience, cardiology, gene therapy, cell tracking, and theranostics (therapy combined with diagnostics). A step-by-step guide to answering biological and/or clinical questions using the tools of molecular imaging is also provided. We conclude by discussing the grand challenges of the field, its future directions, and enormous potential for further impacting how we approach research and medicine.

A Molecular Imaging Primer: Modalities, Imaging Agents, and Applications

National Cell Bank, Pasteur Institute of Iran, Tehran 1316943551, Iran, Cardiovascular Research Center, Mount Sinai School of Medicine, New York, New York 10029, United States, Department of General, Organic, and Biomedical Chemistry, NMR and Molecular Imaging Laboratory, University of Mons, Avenue Maistriau, 19, B-7000 Mons, Belgium, Institute for Nanoscience and Nanotechnology, Sharif University of Technology, Tehran 14588, Iran, Department of Biomedical Engineering, National Yang Ming University, No 155, Sec. 2, LiNong Street, Taipei 112, Taiwan, Nanotechnology Toxicology Consulting & Training, Inc., Nova Scotia, Canada, Faculty of Medicine, Dalhousie Medical School, Dalhousie University, Halifax, Nova Scotia, Canada, and Institute for Nanoscale Science and Technology (INSAT), University of Newcastle upon Tyne, Newcastle upon Tyne, NE1 7ER, U.K., Nanotechnology Research Centre, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran

Magnetic resonance imaging tracking of stem cells in vivo using iron oxide nanoparticles as a tool for the advancement of clinical regenerative medicine.

Purpose: To study the performance of different dual energy computed tomography (DECT) techniques, which are available today, and future multi energy CT (MECT) employing novel photon counting detectors in an image-based material decomposition task. Methods: The material decomposition performance of different energy-resolved CT acquisition techniques is assessed and compared in a simulation study of virtual non-contrast imaging and iodine quantification. The material-specific images are obtained via a statistically optimal image-based material decomposition. A projection-based maximum likelihood approach was used for comparison with the authors’ image-based method. The different dedicated dual energy CT techniques are simulated employing realistic noise models and x-ray spectra. The authors compare dual source DECT with fast kV switching DECT and the dual layer sandwich detector DECT approach. Subsequent scanning and a subtraction method are studied as well. Further, the authors benchmark future MECT with novel photon counting detectors in a dedicated DECT application against the performance of today’s DECT using a realistic model. Additionally, possible dual source concepts employing photon counting detectors are studied. Results: The DECT comparison study shows that dual source DECT has the best performance, followed by the fast kV switching technique and the sandwich detector approach. Comparing DECT with future MECT, the authors found noticeable material image quality improvements for an ideal photon counting detector; however, a realistic detector model with multiple energy bins predicts a performance on the level of dual source DECT at 100 kV/Sn 140 kV. Employing photon counting detectors in dual source concepts can improve the performance again above the level of a single realistic photon counting detector and also above the level of dual source DECT. Conclusions: Substantial differences in the performance of today’s DECT approaches were found for the application of virtual non-contrast and iodine imaging. Future MECT with realistic photon counting detectors currently can only perform comparably to dual source DECT at 100 kV/Sn 140 kV. Dual source concepts with photon counting detectors could be a solution to this problem, promising a better performance.

Performance of today’s dual energy CT and future multi energy CT in virtual non-contrast imaging and in iodine quantification: A simulation study

Epicardial adipose tissue and coronary artery plaque characteristics

Recent trends in antibody-based oncologic imaging.

Comparison of the accuracy of subtraction CT angiography performed on 320-detector row volume CT with conventional CT angiography for diagnosis of intracranial aneurysms

Background: Epidermal growth factor receptor (EGFR) overexpression is associated with several key features of cancer development and growth. Therefore, EGFR is a very promising biological target for tumor diagnosis and anticancer therapy. Characterization of EGFR expression is important for clinicians to select patients for EGFR-targeted therapy and evaluate therapeutic effects.Purpose: To investigate whether near-infrared (NIR) fluorescent dye Cy5.5-labeled anti-EGFR monoclonal antibody Erbitux can characterize EGFR expression level in MDA-MB-231 and MCF-7 breast cancer xenografts using an in vivo NIR imaging method.Material and Methods: A fluorochrome probe was designed by coupling Cy5.5 to Erbitux through acidylation, and the fluorescence property of the Erbitux-Cy5.5 conjugate was characterized by fluorospectroscopy. Flow cytometry and laser confocal microscopy were used to test the EGFR specificity of the antibody probe in vitro. Erbitux-Cy5.5 was also injected intravenously into immune-deficient mic...

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Characterizing breast cancer xenograft epidermal growth factor receptor expression by using near-infrared optical imaging.

Purpose
The aim of this study is to monitor endostatin gene expression and therapy using transferrin receptor (TfR) as reporter gene and transferrin conjugate of ultrasmall supramagnetic iron oxide nanoparticle (Tf–USPIO) as magnetic resonance (MR) reporter probe.

MR Reporter Gene Imaging of Endostatin Expression and Therapy

AimTo investigate the relationship between epicardial adipose tissue (EAT) volume and coronary plaque composition.MethodsEAT volume (measured using coronary computed tomography angiography) and coronary plaque characteristics were assessed on a per-segment basis (modified 15-segment American College of Cardiology/American Heart Association classification) in patients with severe coronary artery stenosis. Coronary plaques were classified into four types: 1, calcified plaques; 2, mixed plaques (calcification dominant); 3, mixed plaques (non-calcification dominant); and 4, non-calcified plaques. The gold standard for luminal stenosis was conventional coronary angiography.ResultsIn 365 patients (mean age 58.7 ± 8.0 years), EAT volume was 169.85 ± 29.94 ml. There were no significant between-group differences in patient characteristics. Statistically significant differences in EAT volume between non-calcified and calcified plaque groups were observed. EAT volume showed a positive correlation with total choleste...

https://journals.sagepub.com/doi/pdf/10.1177/0300060513496169

Relationship between epicardial adipose tissue volume measured using coronary computed tomography angiography and atherosclerotic plaque characteristics in patients with severe coronary artery stenosis.

Dan Wang

Papers

Comparison of the accuracy of subtraction CT angiography performed on 320-detector row volume CT with conventional CT angiography for diagnosis of intracranial aneurysms

Characterizing breast cancer xenograft epidermal growth factor receptor expression by using near-infrared optical imaging.

MR Reporter Gene Imaging of Endostatin Expression and Therapy

Relationship between epicardial adipose tissue volume measured using coronary computed tomography angiography and atherosclerotic plaque characteristics in patients with severe coronary artery stenosis.