Development of 99mTc-ethyl cysteinate dimer (Neurolite) for imaging brain blood flow in stroke and other disorders

Compounds labeled with 99mTc are widely used for imaging in diagnostic medicine to provide information on physiological functions of the body not obtainable with other imaging techniques that give primarily anatomical information, such as X-ray and magnetic resonance imaging. These radiopharmaceuticals are typically injected intravenously and allowed to distribute in the body; the patient is then imaged using a scintillation gamma camera. For example, in patients suspected of coronary artery disease, 99mTc-Sestamibi (Cardiolite reg-sign) is injected into the blood stream during a stress test and is rapidly extracted by the heart muscle in proportion to its regional blood supply. The resulting images of the heart clearly distinguish areas of normal heart muscle form areas where the blood supply is compromised by coronary artery disease. In recent years, there has been considerable interest in the application of 99mTc compounds to the diagnosis of brain diseases and disorders. This paper describes the development of 99mTc-ethyl cysteinate dimer (99mTc-ECD, Neurolite reg-sign) as a radiopharmaceutical for imaging the blood supply to the brain in patients with stroke or head trauma. In research, this agent is also useful in studying the effect of sensory stimuli, therapeutic drugs, and drugs of abuse on brain blood flow