Ligaments attach your breasts to the pectoral muscle on your chest. When you wear a bra, your supported breast does not allow the pectoral muscle to be exercised as much as it could be. When you do not wear a bra, as you move your arms, reach, and lift, your pectoral muscle is strengthened.
Positron emission tomography. Positron emission tomography (PET) is a nuclear medicine functional imaging technique that is used to observe metabolic processes in the body. The system detects pairs of gamma rays emitted indirectly by a positron-emitting radionuclide (tracer), which is introduced into the body on a biologically active molecule.
Overview. A positron emission tomography (PET) scan is a type of nuclear imaging test that shows the metabolic activities (energy usage) of your brain. While X-ray, CT, and MRI scans look at the anatomy of your brain, a PET scan can give your doctor information about how your brain is working.