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Preclinical Molecular Imaging Systems
Published in Michael Ljungberg, Handbook of Nuclear Medicine and Molecular Imaging for Physicists, 2022
Proper animal preparation and handling is a very important aspect of preclinical imaging [12, 93]. Imaging animals usually means that the animal is put under general anaesthesia during the imaging session to reduce motion artefacts. Inhalant anaesthesia such as vaporized isoflurane is the most-used method in preclinical imaging, primarily due to the advantages of both short induction and recovery time [93]. Many preclinical imaging procedures can be lengthy, especially multi-modality imaging procedures and dynamic imaging. For these procedures, it is necessary that the anaesthesia can be delivered continuously and at a constant level. Physiological monitoring is required to maintain safe anaesthetic levels and to ensure that good homeostasis is maintained, since this may affect tracer uptake [12]. Physiological monitoring usually includes monitoring of heart rate and respiratory rate. Since an anesthetized animal cannot maintain its core body temperature, it is necessary to provide external heating, such as the use of heating pads or integral heating elements in the imaging fixture.
Quantification in Nuclear Preclinical Imaging
Published in George C. Kagadis, Nancy L. Ford, Dimitrios N. Karnabatidis, George K. Loudos, Handbook of Small Animal Imaging, 2018
Preclinical imaging is a powerful tool to enhance the ways in which biological processes are studied. Different imaging technologies (modalities) provide different and usually complementary information about the tissues. All modalities convert the acquired information to images, regardless of how abstract (i.e., relaxation of the spins in MRI) or substantially different (i.e., sound waves in ultrasound [US]) the underlying physical phenomena providing the information are. In order to draw valid conclusions from the images regarding the underlying biochemical processes, understanding each modality and their limitations is necessary.
Multimodality Imaging Instrumentation and Techniques
Published in Martin G. Pomper, Juri G. Gelovani, Benjamin Tsui, Kathleen Gabrielson, Richard Wahl, S. Sam Gambhir, Jeff Bulte, Raymond Gibson, William C. Eckelman, Molecular Imaging in Oncology, 2008
Douglas J. Wagenaar, Bradley E. Patt
Working our way up from cell samples to tissue samples, the next biological research entity to consider is the intact living specimen. The field of “preclinical imaging” has emerged from the use of separate imaging components developed at various research institutions from the 1980s until the early 2000s. Preclinical imaging is generally described as imaging of small animals such as zebra fish, mice, rats, guinea pigs, and rabbits. Specialpurpose imaging instruments, usually obsolete clinical, novel prototype, or niche-market products, are still being used for research on larger animals such as pigs, dogs, and nonhuman primates. In the following section, we concentrate on the preclinical research imaging of small animals in which a viable market for multimodality instruments has developed in the new millennium.
Targeting efficiency of nanoliposomes on atherosclerotic foam cells: polyethylene glycol-to-ligand ratio effects
Published in Expert Opinion on Drug Delivery, 2020
Anastasia Darwitan, Yang Fei Tan, Yee Shan Wong, Anu Maashaa Nedumaran, Bertrand Czarny, Subbu Venkatraman
Approval for animal model was obtained from the Institute Animal Care and Use Committee (IACUC) at Nanyang Technological University (NTU) and all procedures were performed in accordance with the protocols and guidelines for the use of animals. Apoe−/- mice (B6.129P2-Apoetm1Unc) of 10 weeks old were fed a high-cholesterol diet (Teklad TD 88,137) for 13–16 weeks before trials. The mice were administered a single bolus dose of ATTO-labeled liposomes through lateral tail vein injection (18 mM lipid concentration). ATTO-labeled liposomes were prepared by incorporating commercially available ATTO-conjugated lipids (ATTO-TEC GmbH, Germany) into the lipid-solvent mixture during liposome preparation. Subsequently, thin film was prepared by rotary evaporation and the multilamellar vesicles yielded were downsized with extruder as explained above in the liposome preparation section. At 1-h post-injection, the mice were euthanized and perfused with 20 mL of PBS/mouse through cardiac puncture. Organs of interest (aorta, liver, spleen, kidneys, lungs, and heart) were excised and imaged using ex vivo near-infrared fluorescence (NIRF) imaging system and their fluorescent content per organ was measured using IVIS Spectrum Preclinical Imaging System (Perkin Elmer).
In vivo near-infrared fluorescent optical imaging for CNS drug discovery
Published in Expert Opinion on Drug Discovery, 2020
Maria J. Moreno, Binbing Ling, Danica B. Stanimirovic
This short review will focus on the latest progress in near infrared (NIR)-fluorescent optical imaging modalities with special emphasis on its recent expansion to the shortwave infrared (SWIR) window. We will review advantages and challenges in developing and deploying instrumentation and novel organic and inorganic SWIR emitters, with special emphasis on their toxicology and pharmacology. Future prospects in preclinical imaging and potential for clinical translation in the field of neuroimaging will also be discussed.
Advanced clinical imaging for the evaluation of stem cell based therapies
Published in Expert Opinion on Biological Therapy, 2021
Michail E. Klontzas, George A. Kakkos, Georgios Z. Papadakis, Kostas Marias, Apostolos H. Karantanas
The vast majority of preclinical stem cell MRI studies has been performed on high field scanners and do not employ conventional MRI protocols. This poses an important limitation for the clinical translation of such studies. Most preclinical scanners employ magnetic fields ranging between 4.7 and 11.7 T [13,15,23,25,42,51–55] which afford high signal-to-noise ratio but do not directly translate to clinically used 1.5–3 T scanners. As the magnetic field increases, MRI can exert physiological effects on patients including dizziness, nausea, excessive heating as a result of radiofrequency stimulation, metallic taste, cardiac conduction abnormalities, susceptibility, and motion artifacts not present at lower field strengths [56,57]. In addition, the evaluation of each body part is performed in routine clinical practice using standardized protocols with little inter-departmental variability. Unfortunately, there is no homogeneity in stem cell literature utilizing MRI sequences, with most studies using custom and highly variable sequences with limited information about sequence parameters in their text. All the aforementioned limitations currently hinder the translation of preclinical imaging findings to the clinical reality [39]. However, a limited number of studies mainly published in clinical journals utilize clinical-grade magnets and relevant protocols, the findings of which can be directly applied to patients. Such an example is the study by Elmi et al., who used muscle stem cells for the treatment of anal sphincter injuries in rabbits. In their study, they utilized 1.5 T scanners with a protocol including T1, T2, T2* gradient echo (GRE) sequences in three planes, demonstrating that MRI can offer anatomical information about stem cell location, and that T2* GRE sequences are ideal for the evaluation of iron oxide nanoparticle labeled stem cells [58]. Similarly, clinical grade 1.5 T scanners with conventional sequences (T1-w and fat saturated T2-w) were used by Lebouvier et al., who injected BMMSCs in porcine femoral heads with avascular necrosis, showing that healing and normalization of imaging findings occurred within 9 weeks from injection [59].