Source: Alycia G. Berman, James A. Schaber, and Craig J. Goergen, Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana
Here we will demonstrate the fundamentals of single-photon emission computed tomography/computed tomography (SPECT/CT) imaging using mice. The technique involves injecting a radionuclide into a mouse, imaging the animal after it is distributed throughout the body, and then reconstructing the produced images to create a volumetric dataset. This can provide information about anatomy, physiology, and metabolism to improve disease diagnosis and monitor its progression.
In terms of collected data, SPECT/CT provides similar information as positron emission tomography (PET)/CT. However, the underlying principles of these two techniques are fundamentally different since PET requires the detection of two gamma photons, which are emitted in opposite directions. In contrast, SPECT imaging directly measures radiation via a gamma camera. As a result, SPECT imaging has lower spatial resolution than PET. However, it is also less expensive because the SPECT radioactive isotopes are more readily available. SPECT/CT imaging provides both noninvasive metabolic and anatomical information that can be useful for a wide variety of applications.…
Source: Rachel Liu, BAO, MBBCh, Emergency Medicine, Yale School of Medicine, New Haven, Connecticut, USA
The heart lies within the pericardium, a relatively inelastic fibrous sac. The pericardium has some compliance to stretch when fluid is slowly introduced into the pericardial space. However, rapid accumulation overwhelms pericardial ability to accommodate extra fluid. Once a critical volume is reached, intrapericardial pressure increases dramatically, compressing the right ventricle and eventually impeding the volume that enters the left ventricle. When these chambers cannot fill in diastole, stroke volume and cardiac output are diminished, leading to cardiac tamponade, a life-threatening compression of the cardiac chambers by a pericardial effusion. Unless the pressure is relieved by aspiration of pericardial fluid (pericardiocentesis), cardiac arrest is imminent.
Cardiac tamponadeis a critical emergency that can carry high morbidity and mortality. Patients may present in extremis, without much time to make the diagnosis and perform life-saving treatments. Causes of this condition are broken into traumatic and non-traumatic categories, with different treatment algorithms. Stab and gunshot wounds are the primary cause of traumatic tamponade, but it may occur from blunt trauma associated with…
Emergency Medicine and Critical Care
Source: Gurneet S. Sangha and Craig J. Goergen, Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana
Photoacoustic tomography (PAT) is an emerging biomedical imaging modality that utilizes light generated acoustic waves to obtain compositional information from tissue. PAT can be used to image blood and lipid components, which is useful for a wide variety of applications, including cardiovascular and tumor imaging. Currently used imaging techniques have inherent limitations that restrict their use with researchers and physicians. For example, long acquisition times, high costs, use of harmful contrast, and minimal to high invasiveness are all factors that limit the use of various modalities in the laboratory and clinic. Currently, the only comparable imaging techniques to PAT are emerging optical techniques. But these also have disadvantages, such as limited depth of penetration and the need for exogenous contrast agents. PAT provides meaningful information in a rapid, noninvasive, label-free manner. When coupled with ultrasound, PAT can be used to obtain structural, hemodynamic, and compositional information from tissue, thereby complementing currently used imaging techniques. The advantages of PAT illustrate its capabilities to make an impact in both the preclinical and clinical…
Source: Suneel Dhand, MD, Attending Physician, Internal Medicine, Beth Israel Deaconess Medical Center
The cardiac assessment is one of the core examinations performed by almost every physician whenever encountering a patient. Disorders of the cardiac system are among the most common reasons for hospital admission, with conditions ranging from myocardial infarction to congestive heart failure. Learning a complete and thorough cardiac examination is therefore crucial for any practicing physician.
If there is pathology in the heart or circulatory system, the consequences can also be manifested in other bodily areas, including the lungs, abdomen, and legs. Many physicians instinctively reach straight for their stethoscopes when performing cardiac exams. However, a large amount of information is gained before auscultation by going through the correct sequence of examination, starting with inspection and palpation.…
Physical Examinations I
Source: Arvin H. Soepriatna1, Kelsey A. Bullens2, and Craig J. Goergen1
1 Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana
2 Department of Biochemistry, Purdue University, West Lafayette, Indiana
Near-infrared fluorescence (NIRF) imaging is an exciting optical technique that utilizes fluorescent probes to visualize complex biomolecular assemblies in tissues. NIRF imaging has many advantages over conventional imaging methods for noninvasive imaging of diseases. Unlike single photon emission computed tomography (SPECT) and positron emission tomography (PET), NIRF imaging is rapid, high-throughput, and does not involve ionizing radiation. Furthermore, recent developments in engineering target-specific and activatable fluorescent probes provide NIRF with high specificity and sensitivity, making it an attractive modality in studying cancer and cardiovascular disease. The presented procedure is designed to demonstrate the principles behind NIRF imaging and how to conduct in vivo and ex vivo experiments in small animals to study a variety of diseases. The specific example shown here employs an activatab…
Source: Kay Stewart, RVT, RLATG, CMAR; Valerie A. Schroeder, RVT, RLATG. University of Notre Dame, IN
There are many commonly used routes for compound administration in laboratory mice and rats. Protocols may, however, require the use of the less commonly used routes: intracardiac, footpad, and retro-orbital injections. Specialized training is essential for these procedures to be performed successfully. Justification for these routes may need to be provided to gain Institutional Animal Care and Use Committee (IACUC) approval. …
Lab Animal Research