2-Methoxyisobutyl isonitrile (MIBI) is a key starting material in the preparation of the complex technetium (99mTc) hexakis(2-methoxyisobutylisonitrile) (technetium (99mTc) Sestamibi). This radiopharmaceutical, which is commercially available in the form of a kit under the tradenames CARDIOLITE® and MIRALUMA®, is useful for detecting coronary artery disease as well as evaluating breast lesions by planar imaging. Discovered in 1981 by Alan Davison, it received FDA approval in 1990 and it has been sold commercially since February 1991.Technetium 99m sestamibi is a relatively new radiopharmaceutical with improved imaging characteristics for exercise myocardial perfusion studies compared with thallium 201. The drug is a coordination complex consisting of the radioisotope technetium-99m bound to six (sesta=6) methoxyisobutylisonitrile (MIBI) ligands. Following intravenous injection of the drug, Technetium Tc-99m sestamibi is taken up by the myocardium, parathyroid, and/or breast tissue. The mechanism by which sestamibi localizes to these tissues has not been established. Single photon emission computed tomography (SPECT) is then performed to detect the gamma ray emmitted by the decay of Technetium-99m to Technetium-99. Currently available within a preparation kit for injection, Technetium Tc 99m Sestamibi is indicated for: 1) detecting coronary artery disease by localizing myocardial ischemia (reversible defects) and infarction (non-reversible defects); and 2) evaluating myocardial function and developing information for use in patient management decisions.