(MPI) The myocardial perfusion scan is the most common nuclear medicine procedure in cardiac imaging and allows assessing the blood-flow patterns to the heart muscles. The comparison of the radiopharmaceutical distribution after stress and at rest provides information on myocardial viability and cardiac perfusion abnormalities. ECG-gated myocardial perfusion imaging allows the assessment of global and regional myocardial function such as wall motion abnormalities.
The diagnostic accuracy of myocardial perfusion scintigraphy (also abbreviated MPS) allows reliable risk stratification and guides the selection of patients for further interventions, such as revascularization. MPI also has particular advantages over alternative techniques in the management of a number of patient subgroups, including women, the elderly, and those with diabetes. The use of this type of cardiac scintigraphy is associated with greater cost effectiveness of treatment, in terms of life-years saved, particularly in these special patient groups.
Myocardial perfusion scintigrams are acquired with a gamma camera. Single photon emission computed tomography (SPECT) is preferred over planar imaging because of the three dimensional nature of the images and their superior contrast resolution.
Common MPI radiopharmaceuticals, approved by the U.S. Food and Drug Administration (FDA) include: Tl-201 and the Tc-99m-labeled radiopharmaceuticals, such as sestamibi, tetrofosmin, and teboroxime for single-photon imaging. Rb-82 is used for positron emission tomography (PET) imaging.

See also Gated Blood Pool Scintigraphy, Myocardial Late Enhancement, Cardiac MRI and Echocardiography.

An Osteo CT or quantitative computed tomography (QCT) is used to measure bone mineral density (BMD). The high contrast discrimination of computed tomography can be used to examine the central skeleton for osteoporosis. Common CT scanners require a standard of reference to properly perform quantitative tissue analysis.
Osteo CT is the most accurate bone densitometry study, but is not widely available and delivers more radiation to the patient than dual energy x-ray absorptiometry.

Virtual colonoscopy provides a less invasive option to conventional polyp detection in the large intestine (colon and rectum). A virtual colonoscopy is a synthesis of a computed tomography (CT) scan, digital processing and virtual reality computer software.
A virtual colonoscopy is less invasive and more comfortable for patients than either conventional colonoscopy or a barium enema. No sedation is required and the examination takes less than 30 minutes.
A CT colonography offers a new option for a total colon evaluation and cancer detection and has the potential to be used for screening. A problem is the amount of information captured in a CT exam. Reviewing these images can be time-consuming and challenging.

See also Computed Tomography Enterography.

Barium sulfate (BaSO4) is an inert and insoluble white powder with high density. Barium belongs chemically to the group of heavy metals. Mixed with water and additional ingredients (e.g., sweetening agents), barium sulfate is the preferred positive contrast agent for abdominal x-ray and computed tomography examinations. The extremely low solubility of barium sulfate protects patients from absorbing harmful amounts of the metal (water soluble metal compounds are often highly toxic). The high density in x-ray examinations is related to the high atomic number, since large nuclei absorb x-rays much better than smaller nuclei.
Barium sulfate agents for opacification of the gastrointestinal tract are not absorbed or metabolized and are resistant to dilution. These contrast agents are opaque white suspensions and usually swallowed or administered as an enema. They provide better delineation of mucosal details and are less expensive than water-soluble iodinated contrast media. The elimination rate is a function of gastrointestinal transit time. After GI application, it leaves the body with the feces.

Contraindications of barium sulfate products in case of known or suspected:

There are two kinds of beta decay: beta minus and beta plus decay. The differentiation depends on the charge of the emitted particle.
At the beta plus decay in the nucleus a proton changes to a neutron and emits a positron and a neutrino. The atom is after the decay a different element, but with the same number of particles in the nucleus.
At the beta minus decay in the nucleus a neutron changes to a proton and emits an electron and an antineutrino. As with the beta plus decay the atom changes to a different element but with the same number of particles in the nucleus.
Sometimes the electron capture is mentioned as a third kind of beta decay.
Beta decay is used for example in positron-electron tomography or in iodine-131 therapy.

See also Electron Capture.