This research was supported in part by the JPI-HDHL-INTIMIC &#34;GUTMOM&#34; Project: Maternal obesity and cognitive dysfunction in the offspring: Cause-effect role of the GUT MicrobiOMe and early dietary prevention (project no. INTIMIC-085, Italian Ministry of Education, University and Research Decree no. 946/2019).

Daniele Panetta received grants for the R&amp;D of micro-CT instrumentation from Inviscan Sas.

The protocol presented in this paper focuses on a typical experimental procedure for translational cardiovascular research on small animal models of cardiac injury by using high-resolution PET/CT imaging. The presented results are indicative of the high quantitative and qualitative value of PET and Cine-CT images, providing both functional and structural information of the whole heart regarding its glucose metabolism, shape, and the dynamics of its contraction. Moreover, all the images obtained are 3D, time-resolved, and...

Small animal models are extremely important for the advancement of the understanding of cardiovascular diseases1,2. Non-invasive, diagnostic imaging tools have revolutionized the way we look at cardiac function in the last decades, both in clinical and preclinical settings. As far as small animal models of cardiac diseases are concerned, specific imaging tools have been developed with very high spatiotemporal resolution. Thus, such instruments can match the need for accurate quantification of the relevant metabolic and kinetic myocardial parameters on the very small and very fast-moving hearts of mice and rats in specific disease models, such as heart failure (HF)3 or myocardial infarction (MI)4. Several modalities are available for this purpose, each with their own strengths and weaknesses. Ultrasound (US) imaging is the most widely used modality due to its great flexibility, very high temporal resolution, and relatively low cost. The adoption of US cardiac imaging in small animals has increased considerably since the advent of systems using probes with ultra-high frequency5,6, featuring spatial resolutions below 50 &#181;m.
Among the main disadvantages of US for fully 3D cardiac imaging is the need for linear scans along the heart axis by mounting the probe on a motorized translation stage to create a full stack of dynamic B-mode images of the whole heart7. Eventually, this procedure gives rise (after accurate spatial and temporal registration of the images acquired in each probe position) to a 4D image with different spatial resolutions between the in-plane and out-of-plane directions. The same problem of non-uniform spatial resolution occurs in cardiac MR (CMR),8 which still represents the gold standard in the functional imaging of the heart. Real isotropic 3D imaging can be instead obtained using both computed tomography (CT) and positron emission tomography (PET)9. PET provides a very sensitive tool in terms of image signal per quantity of injected probe (in the nanomolar range), even though it suffers from a reduced spatial resolution compared to CT, MR, or US. The main advantage of PET is its ability to display the cellular and molecular mechanisms underlying the organ&#39;s pathophysiology. For instance, a PET scan following the injection of [18F]FDG allows the reconstruction of a 3D map of the glucose metabolism in the body. By combining this with dynamic (i.e., time-resolved) data acquisition, tracer kinetic modeling can be used to calculate parametric maps of the metabolic rates of glucose uptake (MRGlu), which will provide important information about myocardial viability10.
CT requires significant volumes of external contrast agents (CA) at high concentrations (up to 400 mg of iodine per mL) to provide a measurable enhancement of the relevant tissue components (e.g., blood vs. muscle), but it excels in spatial and temporal resolution, especially when using state-of-the-art micro-CT scanners designed for small animal imaging.11 A typical disease model in which the cardiac PET/CT can be applied is the experimental evaluation of myocardial infarction and heart failure and related response to therapy. A common way of inducing MI in small animals is by surgical ligation of the left anterior descending (LAD) coronary artery12,13 and then longitudinally evaluating the progression of the disease and the cardiac remodeling in the subsequent days4. Nevertheless, the quantitative morphofunctional evaluation of the heart in small animals is largely applicable also for other disease models, such as the evaluation of the effect of aging on cardiac function14 or altered receptor expression in models of obesity15. The presented imaging protocol is not restricted to any given disease model and, hence, could be of the widest interest in several contexts of preclinical research with small rodents.
In this paper, we present a start-to-end experimental protocol for cardiac imaging using small animal integrated PET/CT. Even though the presented protocol is designed for a specific bimodal integrated scanner, the PET and CT parts of the described procedure could be performed independently on separate scanners from different manufacturers. In the PET/CT scanner in use, the sequence of operations is organized in a preprogrammed workflow. The main branches of each workflow are one or more acquisition protocols; each acquisition protocol can have one or more branches for specific preprocessing protocols, and in turn, each preprocessing protocol can have one or more branches for specific reconstruction protocols. Both the preparation of the animal on the imaging bed and the preparation of the external agents to be injected during the imaging procedures are described. After the completion of the image acquisition procedure, example procedures for quantitative image analysis based on commonly available software tools are provided. The main protocol is specifically designed for mouse models; even though the mouse remains the most used species in this field, we also show an adaptation of the protocol for rat imaging at the end of the main protocol. Representative results are shown for both mice and rats, demonstrating the type of output that might be expected with the described procedures. A thorough discussion is made at the end of this paper to emphasize the pros and cons of the technique, critical points, as well as how different PET radiotracers could be used with almost no modification to the preparatory and acquisition/reconstruction steps.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>0.9% sterile saline</td>
			<td>Fresenius Kabi</td>
			<td></td>
			<td>0.9% sodium chloride for injection</td>
		</tr>
		<tr>
			<td>1025L Physiological Monitoring</td>
			<td>Small Animal Instruments</td>
			<td></td>
			<td>Physiological monitoring system for small animal imaging</td>
		</tr>
		<tr>
			<td>5 mL syringes</td>
			<td>Artsana</td>
			<td></td>
			<td>Syringes with needle for injection of PET tracer</td>
		</tr>
		<tr>
			<td>Atomlab 500</td>
			<td>Else Nuclear</td>
			<td></td>
			<td>PET Dose calibrator</td>
		</tr>
		<tr>
			<td>Atrium software</td>
			<td>Inviscan</td>
			<td>Version 1.5.5</td>
			<td>PET/CT operating software</td>
		</tr>
		<tr>
			<td>Butterfly catheters</td>
			<td>Delta Med</td>
			<td></td>
			<td>27.5 G needle</td>
		</tr>
		<tr>
			<td>Carimas software</td>
			<td>Turku PET Center</td>
			<td>Version 2.10</td>
			<td>Image analysis software</td>
		</tr>
		<tr>
			<td>Fenestra VC</td>
			<td>Medilumine</td>
			<td></td>
			<td>Lipid emulsion iodinated contrast agent for small animals</td>
		</tr>
		<tr>
			<td>Heat lamp</td>
			<td></td>
			<td></td>
			<td>Heat lamp with clamp and switch</td>
		</tr>
		<tr>
			<td>Insulin syringes</td>
			<td>Artsana</td>
			<td></td>
			<td>Syringes with needle for injection of CT CA</td>
		</tr>
		<tr>
			<td>Iomeron 400 mgI/mL</td>
			<td>Bracco</td>
			<td></td>
			<td>Iomeprol, vascular contrast agent</td>
		</tr>
		<tr>
			<td>IRIS PET/CT</td>
			<td>Inviscan</td>
			<td></td>
			<td>PET/CT scanner for small animals</td>
		</tr>
		<tr>
			<td>Isoflurane</td>
			<td>Zoetis</td>
			<td></td>
			<td>Inhalation anesthetic, 250 mL</td>
		</tr>
		<tr>
			<td>OneTouch Glucometer</td>
			<td>Johnson&#38;Johnson Medical</td>
			<td></td>
			<td>Glucose meter kit</td>
		</tr>
		<tr>
			<td>Osirix MD software</td>
			<td>Pixmeo</td>
			<td>Version 11</td>
			<td>Image analysis software</td>
		</tr>
		<tr>
			<td>Oxygen</td>
			<td>Air liquide</td>
			<td></td>
			<td>Compressed gas</td>
		</tr>
		<tr>
			<td>Rectal probe for 1025L</td>
			<td>Small Animal Instruments</td>
			<td></td>
			<td>Rectal probe with cable for SAII 1025L systems</td>
		</tr>
		<tr>
			<td>Respiratory sensor for 1025L</td>
			<td>Small Animal Instruments</td>
			<td></td>
			<td>Respiratory pillow with tubings for SAII 1025L systems</td>
		</tr>
		<tr>
			<td>TJ-3A syringe pump</td>
			<td>Longer</td>
			<td></td>
			<td>Motorized syringe pump for CT CA injection</td>
		</tr>
	</tbody>
</table>

high-resolution cardiac positron emission tomography/computed tomography for small animals

Positron emission tomography (PET) and computed tomography (CT) are among the most employed diagnostic imaging techniques, and both serve in understanding cardiac function and metabolism. In preclinical research, dedicated scanners with high sensitivity and high spatio-temporal resolution are employed, designed to cope with the demanding technological requirements posed by the small heart size and very high heart rates of mice and rats. In this paper, a bimodal cardiac PET/CT imaging protocol for experimental mouse and/or rat models of cardiac diseases is described, from animal preparation and image acquisition and reconstruction to image processing and visualization.
In particular, the 18F-labeled fluorodeoxyglucose ([18F]FDG)-PET scan allows for the measurement and visualization of glucose metabolism in the different segments of the left ventricle (LV). Polar maps are convenient tools to display this information. The CT part consists of a time-resolved 3D reconstruction of the entire heart (4D-CT) using retrospective gating without electrocardiography (ECG) leads, allowing the morphofunctional evaluation of the LV and the subsequent quantification of the most important cardiac function parameters, such as ejection fraction (EF) and stroke volume (SV). Using an integrated PET/CT scanner, this protocol can be executed within the same anesthesia induction without the need to reposition the animal between different scanners. Hence, PET/CT can be seen as a comprehensive tool for the morphofunctional and metabolic evaluation of the heart in several small animal models of cardiac diseases.

In this section, typical results are shown for both PET and CT analysis following the procedures described so far. Figure 6 shows the results of the automatic myocardial and LV cavity segmentation of the [18F]FDG PET scan of a control (healthy) CD-1 mouse. Even though the right ventricle is not always visible in the reconstructed images, the orientation axes based on the DICOM header can be used to correctly discriminate the interventricular septum from the other LV walls, as requ...

Watch this Scientific Journal Video about High-Resolution Cardiac Positron Emission Tomography/Computed Tomography for Small Animals at JoVE.com

High-Resolution Cardiac Positron Emission Tomography/Computed Tomography for Small Animals

Here, we present an experimental imaging protocol for the quantification of cardiac function and morphology using high-resolution positron emission tomography/computed tomography for small animals. Both mice and rats are considered, discussing the different requirements of computed tomography contrast agents for the two species.

Positron emission tomography (PET) and computed tomography (CT) are among the most employed diagnostic imaging techniques, and both serve in understanding ...

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2.7K Views.  CNR Institute of Clinical Physiology. Here, we present an experimental imaging protocol for the quantification of cardiac function and morphology using high-resolution positron emission tomography/computed tomography for small animals. Both mice and rats are considered, discussing the different requirements of computed tomography contrast agents for the two species.

Video: High-Resolution Cardiac Positron Emission Tomography/Computed Tomography for Small Animals

Basic Surgical Techniques in the G&ouml;ttingen Minipig: Intubation, Bladder Catheterization, Femoral Vessel Catheterization, and Transcardial Perfusion

The emergence of the G&ouml;ttingen minipig in research of topics such as neuroscience, toxicology, diabetes, obesity, and experimental surgery reflects the close resemblance of these animals to human anatomy and physiology 1-6.The size of the G&ouml;ttingen minipig permits the use of surgical equipment and advanced imaging modalities similar to those used in humans 6-8. The aim of this instructional video is to increase the awareness on the value of minipigs in biomedical research, by demonstrating how to perform tracheal intubation, transurethral bladder catheterization, femoral artery and vein catheterization, as well as transcardial perfusion. 
Endotracheal Intubation should be performed whenever a minipig undergoes general anesthesia, because it maintains a patent airway, permits assisted ventilation and protects the airways from aspirates. Transurethral bladder catheterization can provide useful information about about hydration state as well as renal and cardiovascular function during long surgical procedures. Furthermore, urinary catheterization can prevent contamination of delicate medico-technical equipment and painful bladder extension which may harm the animal and unnecessarily influence the experiment due to increased vagal tone and altered physiological parameters. Arterial and venous catheterization is useful for obtaining repeated blood samples and monitoring various physiological parameters. Catheterization of femoral vessels is preferable to catheterization of the neck vessels for ease of access, when performing experiments involving frame-based stereotaxic neurosurgery and brain imaging. When performing vessel catheterization in survival studies, strict aseptic technique must be employed to avoid infections6. Transcardial perfusion is the most effective fixation method, and yields preeminent results when preparing minipig organs for histology and histochemistry2,9. For more information about anesthesia, surgery and experimental techniques in swine in general we refer to Swindle 2007. Supplementary information about premedication and induction of anesthesia, assisted ventilation, analgesia, pre- and postoperative care of G&ouml;ttingen minipigs are available via the internet at <a href="http://www.minipigs.com">http://www.minipigs.com</a>10. For extensive information about porcine anatomy we refer to Nickel et al. Vol. 1-511.

Basic Surgical Techniques in the G&amp;#246;ttingen Minipig: Intubation, Bladder Catheterization, Femoral Vessel Catheterization, and Transcardial Perfusion

The use of domestic and miniature pigs in science has increased significantly in recent years. By demonstrating how to perform intubation, transurethral bladder catheterization, femoral artery and vein catheterization, as well as transcardial perfusion, we aim to further increase the value of G&ouml;ttingen minipigs in biomedical research.

The emergence of the G&ouml;ttingen minipig in research of topics such as neuroscience, toxicology, diabetes, obesity, and experimental surgery reflects ...

Quantification of Atherosclerotic Plaque Activity and Vascular Inflammation using [18-F] Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography (FDG-PET/CT)

Conventional non-invasive imaging modalities of atherosclerosis such as coronary artery calcium (CAC)1 and carotid intimal medial thickness (C-IMT)2 provide information about the burden of disease. However, despite multiple validation studies of CAC3-5, and C-IMT2,6, these modalities do not accurately assess plaque characteristics7,8, and the composition and inflammatory state of the plaque determine its stability and, therefore, the risk of clinical events9-13.
[18F]-2-fluoro-2-deoxy-D-glucose (FDG) imaging using positron-emission tomography (PET)/computed tomography (CT) has been extensively studied in oncologic metabolism14,15. Studies using animal models and immunohistochemistry in humans show that FDG-PET/CT is exquisitely sensitive for detecting macrophage activity16, an important source of cellular inflammation in vessel walls. More recently, we17,18 and others have shown that FDG-PET/CT enables highly precise, novel measurements of inflammatory activity of activity of atherosclerotic plaques in large and medium-sized arteries9,16,19,20. FDG-PET/CT studies have many advantages over other imaging modalities: 1) high contrast resolution; 2) quantification of plaque volume and metabolic activity allowing for multi-modal atherosclerotic plaque quantification; 3) dynamic, real-time, in vivo imaging; 4) minimal operator dependence. Finally, vascular inflammation detected by FDG-PET/CT has been shown to predict cardiovascular (CV) events independent of traditional risk factors21,22 and is also highly associated with overall burden of atherosclerosis23. Plaque activity by FDG-PET/CT is modulated by known beneficial CV interventions such as short term (12 week) statin therapy24 as well as longer term therapeutic lifestyle changes (16 months)25.
The current methodology for quantification of FDG uptake in atherosclerotic plaque involves measurement of the standardized uptake value (SUV) of an artery of interest and of the venous blood pool in order to calculate a target to background ratio (TBR), which is calculated by dividing the arterial SUV by the venous blood pool SUV. This method has shown to represent a stable, reproducible phenotype over time, has a high sensitivity for detection of vascular inflammation, and also has high inter-and intra-reader reliability26. Here we present our methodology for patient preparation, image acquisition, and quantification of atherosclerotic plaque activity and vascular inflammation using SUV, TBR, and a global parameter called the metabolic volumetric product (MVP). These approaches may be applied to assess vascular inflammation in various study samples of interest in a consistent fashion as we have shown in several prior publications.9,20,27,28

Quantification of Atherosclerotic Plaque Activity and Vascular Inflammation using [18-F] Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography FDG-PET/CT

There is great need to identify atherosclerosis non-invasively, and here we demonstrate how FDG-PET/CT can be used to detect and quantify atherosclerotic plaque activity and vascular inflammation.

Conventional non-invasive imaging modalities of atherosclerosis such as coronary artery calcium (CAC)1 and carotid intimal medial thickness (C-IMT)2 ...

Protocol for Long Duration Whole Body Hyperthermia in Mice

Hyperthermia is a general term used to define the increase in core body temperature above normal. It is often used to describe the increased core body temperature that is observed during fever. The use of hyperthermia as an adjuvant has emerged as a promising procedure for tumor regression in the field of cancer biology. For this purpose, the most important requirement is to have reliable and uniform heating protocols. We have developed a protocol for hyperthermia (whole body) in mice. In this protocol, animals are exposed to cycles of hyperthermia for 90 min followed by a rest period of 15 min. During this period mice have easy access to food and water. High body temperature spikes in the mice during first few hyperthermia exposure cycles are prevented by immobilizing the animal. Additionally, normal saline is administered in first few cycles to minimize the effects of dehydration. This protocol can simulate fever like conditions in mice up to 12-24 hr. We have used 8-12 weeks old BALB/Cj female mice to demonstrate the protocol.

This paper describes a protocol for whole body hyperthermia in mice that can stimulate fever like conditions up to 12-24 hr.

Hyperthermia is a general term used to define the increase in core body temperature above normal. It is often used to describe the increased core body ...

Computed Tomography-guided Time-domain Diffuse Fluorescence Tomography in Small Animals for Localization of Cancer Biomarkers

Small animal fluorescence molecular imaging (FMI) can be a powerful tool for preclinical drug discovery and development studies1. However, light absorption by tissue chromophores (e.g., hemoglobin, water, lipids, melanin) typically limits optical signal propagation through thicknesses larger than a few millimeters2. Compared to other visible wavelengths, tissue absorption for red and near-infrared (near-IR) light absorption dramatically decreases and non-elastic scattering becomes the dominant light-tissue interaction mechanism. The relatively recent development of fluorescent agents that absorb and emit light in the near-IR range (600-1000 nm), has driven the development of imaging systems and light propagation models that can achieve whole body three-dimensional imaging in small animals3.
Despite great strides in this area, the ill-posed nature of diffuse fluorescence tomography remains a significant problem for the stability, contrast recovery and spatial resolution of image reconstruction techniques and the optimal approach to FMI in small animals has yet to be agreed on. The majority of research groups have invested in charge-coupled device (CCD)-based systems that provide abundant tissue-sampling but suboptimal sensitivity4-9, while our group and a few others10-13 have pursued systems based on very high sensitivity detectors, that at this time allow dense tissue sampling to be achieved only at the cost of low imaging throughput. Here we demonstrate the methodology for applying single-photon detection technology in a fluorescence tomography system to localize a cancerous brain lesion in a mouse model.
The fluorescence tomography (FT) system employed single photon counting using photomultiplier tubes (PMT) and information-rich time-domain light detection in a non-contact conformation11. This provides a simultaneous collection of transmitted excitation and emission light, and includes automatic fluorescence excitation exposure control14, laser referencing, and co-registration with a small animal computed tomography (microCT) system15. A nude mouse model was used for imaging. The animal was inoculated orthotopically with a human glioma cell line (U251) in the left cerebral hemisphere and imaged 2 weeks later. The tumor was made to fluoresce by injecting a fluorescent tracer, IRDye 800CW-EGF (LI-COR Biosciences, Lincoln, NE) targeted to epidermal growth factor receptor, a cell membrane protein known to be overexpressed in the U251 tumor line and many other cancers18. A second, untargeted fluorescent tracer, Alexa Fluor 647 (Life Technologies, Grand Island, NY) was also injected to account for non-receptor mediated effects on the uptake of the targeted tracers to provide a means of quantifying tracer binding and receptor availability/density27. A CT-guided, time-domain algorithm was used to reconstruct the location of both fluorescent tracers (i.e., the location of the tumor) in the mouse brain and their ability to localize the tumor was verified by contrast-enhanced magnetic resonance imaging.
Though demonstrated for fluorescence imaging in a glioma mouse model, the methodology presented in this video can be extended to different tumor models in various small animal models potentially up to the size of a rat17.

Diffuse fluorescence tomography offers a relatively low-cost and potentially high-throughout approach to preclinical in vivo tumor imaging. The methodology of optical data collection, calibration, and image reconstruction is presented for a computed tomography-guided non-contact time-domain system using fluorescent targeting of the tumor biomarker epidermal growth factor receptor in a mouse glioma model.

Small animal fluorescence molecular imaging (FMI) can be a powerful tool for preclinical drug discovery and development studies1. However, light ...

Non-invasive Imaging and Analysis of Cerebral Ischemia in Living Rats Using Positron Emission Tomography with 18F-FDG

Stroke is the third leading cause of death among Americans 65 years of age or older1. The quality of life for patients who suffer from a stroke fails to return to normal in a large majority of patients2, which is mainly due to current lack of clinical treatment for acute stroke. This necessitates understanding the physiological effects of cerebral ischemia on brain tissue over time and is a major area of active research. Towards this end, experimental progress has been made using rats as a preclinical model for stroke, particularly, using non-invasive methods such as 18F-fluorodeoxyglucose (FDG) coupled with Positron Emission Tomography (PET) imaging3,10,17. Here we present a strategy for inducing cerebral ischemia in rats by middle cerebral artery occlusion (MCAO) that mimics focal cerebral ischemia in humans, and imaging its effects over 24 hr using FDG-PET coupled with X-ray computed tomography (CT) with an Albira PET-CT instrument. A VOI template atlas was subsequently fused to the cerebral rat data to enable a unbiased analysis of the brain and its sub-regions4. In addition, a method for 3D visualization of the FDG-PET-CT time course is presented. In summary, we present a detailed protocol for initiating, quantifying, and visualizing an induced ischemic stroke event in a living Sprague-Dawley rat in three dimensions using FDG-PET.

Non-invasive Imaging and Analysis of Cerebral Ischemia in Living Rats Using Positron Emission Tomography with 18F-FDG

Brain damage resulting from cerebral ischemia may be non-invasively imaged and studied in rats using pre-clinical positron emission tomography coupled with the injectable radioactive probe, 18F-fluorodeoxyglucose. Further, the use of modern software tools that include volume of interest (VOI) brain templates dramatically increase the quantitative information gleaned from these studies.

Stroke is the third leading cause of death among Americans 65 years of age or older1. The quality of life for patients who suffer from a stroke fails to ...

Human Brown Adipose Tissue Depots Automatically Segmented by Positron Emission Tomography/Computed Tomography and Registered Magnetic Resonance Images

Reliably differentiating brown adipose tissue (BAT) from other tissues using a non-invasive imaging method is an important step toward studying BAT in humans. Detecting BAT is typically confirmed by the uptake of the injected radioactive tracer 18F-Fluorodeoxyglucose (18F-FDG) into adipose tissue depots, as measured by positron emission tomography/computed tomography (PET-CT) scans after exposing the subject to cold stimulus. Fat-water separated magnetic resonance imaging (MRI) has the ability to distinguish BAT without the use of a radioactive tracer. To date, MRI of BAT in adult humans has not been co-registered with cold-activated PET-CT. Therefore, this protocol uses 18F-FDG PET-CT scans to automatically generate a BAT mask, which is then applied to co-registered MRI scans of the same subject. This approach enables measurement of quantitative MRI properties of BAT without manual segmentation. BAT masks are created from two PET-CT scans: after exposure for 2 hr to either thermoneutral (TN) (24 &#176;C) or cold-activated (CA) (17 &#176;C) conditions. The TN and CA PET-CT scans are registered, and the PET standardized uptake and CT Hounsfield values are used to create a mask containing only BAT. CA and TN MRI scans are also acquired on the same subject and registered to the PET-CT scans in order to establish quantitative MRI properties within the automatically defined BAT mask. An advantage of this approach is that the segmentation is completely automated and is based on widely accepted methods for identification of activated BAT (PET-CT). The quantitative MRI properties of BAT established using this protocol can serve as the basis for an MRI-only BAT examination that avoids the radiation associated with PET-CT.

The method presented here uses 18F-Fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET-CT) and fat-water separated magnetic resonance imaging (MRI), each scanned following 2 hr exposure to thermoneutral (24 &#176;C) and cold conditions (17 &#176;C) in order to map brown adipose tissue (BAT) in adult human subjects.

Reliably differentiating brown adipose tissue (BAT) from other tissues using a non-invasive imaging method is an important step toward studying BAT in ...

Assessing Cortical Cerebral Microinfarcts on High Resolution MR Images

Cerebral microinfarcts are frequent findings in the post-mortem human brain, and are related to cognitive decline and dementia. Due to their small sizes it is challenging to study them on clinical MRI scans. It was recently demonstrated that cortical microinfarcts can be depicted with MRI scanners using high magnetic field strengths (7T). Based on this experience, a proportion of these lesions is also visible on lower resolution 3T MRI. These findings were corroborated with ex vivo imaging of post-mortem human brain tissue, accompanied by histopathological verification of possible cortical microinfarcts.
Here an ex vivo imaging protocol is presented, for the purpose of validating MR observed cerebral microvascular pathology with histological evaluation. Furthermore, guidelines are provided for the assessment of cortical microinfarcts on both in vivo 7T and 3T MR images. These guidelines provide researchers with a tool to rate cortical microinfarcts on in vivo images of larger patient samples, to further unravel their clinical relevance in cognitive decline and dementia, and establish these lesions as a novel biomarker of cerebral small vessel disease.

A high resolution ex vivo 7T MR imaging protocol is presented, to perform MR-guided histopathological validation of microvascular pathology in post-mortem human brain tissue. Furthermore, guidelines are provided for the assessment of cortical microinfarcts on in vivo 7T as well as 3T MR images.

Cerebral microinfarcts are frequent findings in the post-mortem human brain, and are related to cognitive decline and dementia. Due to their small sizes ...

Disposable Dosators for Pulmonary Insufflation of Therapeutic Agents to Small Animals

Development of new therapeutic products requires efficacy testing in an animal model. The pulmonary route of administration can be utilized to deliver drugs locally and systemically. Evaluation of dry powder aerosols necessitates an efficient dispersion mechanism to maintain high concentrations in an exposure chamber or for direct endotracheal administration. While solutions exist to expose animals by passive inhalation to dry powder aerosols, most require masses of powder in large excess of the dose delivered. This precludes conducting early feasibility studies as insufficient drug is available at the research or early development stage to support the dose delivery requirements for conventional aerosol delivery systems. When designing an aerosol drug product, aerodynamic performance can relate directly to delivery efficiency and efficacy. Dispersion of powder into an aerosol requires energy input sufficient to overcome interparticulate forces, and particle engineering approaches can substantially improve aerosol performance. We have developed a dispersion system (dosator) which can aerosolize engineered dry powder aerosols efficiently for the purpose of direct pulmonary insufflation, dispersion into an exposure system or generation for analytical purposes.

During development of drugs for pulmonary delivery, it is necessary to evaluate pharmacokinetics and efficacy in an animal model. We present a method to build a disposable aerosol dispersion system from of-the-shelf components that can be used to administer intrapulmonary dry powder aerosol to rodents.

Development of new therapeutic products requires efficacy testing in an animal model. The pulmonary route of administration can be utilized to deliver ...

Continuous Blood Sampling in Small Animal Positron Emission Tomography/Computed Tomography Enables the Measurement of the Arterial Input Function

For quantitative analysis and bio-kinetic modeling of positron emission tomography/computed tomography (PET/CT) data, the determination of the temporal blood time-activity concentration also known as arterial input function (AIF) is a key point, especially for the characterization of animal disease models and the introduction of newly developed radiotracers. The knowledge of radiotracer availability in the blood helps to interpret PET/CT-derived data of tissue activity. For this purpose, online blood sampling during the PET/CT imaging is advisable to measure the AIF. In contrast to manual blood sampling and image-derived approaches, continuous online blood sampling has several advantages. Besides the minimized blood loss, there is an improved resolution and a superior accuracy for the blood activity measurement. However, the major drawback of online blood sampling is the costly and time-consuming preparation to catheterize the femoral vessels of the animal. Here, we describe an easy and complete workflow for catheterization and continuous blood sampling during small animal PET/CT imaging and compared it to manual blood sampling and an image-derived approach. Using this highly-standardized workflow, the determination of the fluorodeoxyglucose ([18F]FDG) AIF is demonstrated. Further, this procedure can be applied to any radiotracer in combination with different animal models to create fundamental knowledge of tracer kinetic and model characteristics. This allows a more precise evaluation of the behavior of pharmaceuticals, both for diagnostic and therapeutic approaches in the preclinical research of oncological, neurodegenerative and myocardial diseases.

Here a protocol for continuous blood sampling during PET/CT imaging of rats to measure the arterial input function (AIF) is described. The catheterization, the calibration and setup of the system and the data analysis of the blood radioactivity are demonstrated. The generated data provide input parameters for subsequent bio-kinetic modeling.

For quantitative analysis and bio-kinetic modeling of positron emission tomography/computed tomography (PET/CT) data, the determination of the temporal ...

Positron Emission Tomography Using 64-Copper as a Tracer for the Study of Copper-Related Disorders

Copper is an essential trace element, functioning in catalysis and signaling in biological systems. Radiolabeled copper has been used for decades in studying basic human and animal copper metabolism and copper-related disorders, such as Wilson disease (WD) and Menke&#39;s disease. A recent addition to this toolkit is 64-copper (64Cu) positron emission tomography (PET), combining the accurate anatomical imaging of modern computed tomography (CT) or magnetic resonance imaging (MRI) scanners with the biodistribution of the 64Cu PET tracer signal. This allows the in vivo tracking of copper fluxes and kinetics, thereby directly visualizing human and animal copper organ traffic and metabolism. Consequently, 64Cu PET is well-suited for evaluating clinical and preclinical treatment effects and has already demonstrated the ability to diagnose WD accurately. Furthermore, 64Cu PET/CT studies have proven valuable in other scientific areas like cancer and stroke research. The present article shows how to perform 64Cu PET/CT or PET/MR in humans. Procedures for 64Cu handling, patient preparation, and scanner setup are demonstrated here.

The present protocol describes how to perform 64Cu PET/CT and PET/MRI imaging in humans to study copper-related disorders, such as Wilson disease, and the treatment effect on copper metabolism.

Copper is an essential trace element, functioning in catalysis and signaling in biological systems. Radiolabeled copper has been used for decades in ...