Any piece of program code in a high-level language which, when (if) its execution terminates, returns a value. In most programming languages, expressions consist of constants, variables, operators, functions, and parentheses. The operators and functions may be built-in or user defined.
If oral contrast is required, about 45 to 60 minutes is needed for the contrast to move through your digestive tract. Actual scan times vary from a few seconds to several minutes. If no oral contrast is required, the examination will take about 15 to 30 minutes, including the time for intravenous preparation and interview. In some cases additional scanning is required as scans are tailored to suit individual diagnostic needs.
1 The tracer is not a dye or contrast and will not affect your kidney function. After the tracer is injected, you will wait about 15-60 minutes for the tracer to be taken up in the heart muscle.  Then you will be asked to lie very still under a camera for about 15 minutes. The camera will rotate around your chest and the images will be recorded on the computer. The gamma camera does not produce radiation; it detects and makes pictures of your heart from tiny amounts of radiation in you.