Sestamibis

Sestamibi refers to technetium-99m sestamibi, a radiopharmaceutical used in nuclear medicine. The compound is a lipophilic, cationic complex formed with the radiotracer technetium-99m and the chelating ligand methoxyisobutylisonitrile (MIBI). After intravenous administration, the tracer distributes in proportion to regional blood flow and accumulates in mitochondria, allowing visualization of tissue perfusion and viability.

In cardiology, technetium-99m sestamibi is used for myocardial perfusion imaging. It is administered at rest and/or during pharmacologic or exercise-induced stress, with single-photon emission computed tomography (SPECT) or planar imaging to identify regions of reduced blood flow due to coronary artery disease. The tracer's myocardial uptake reflects perfusion, while postischemic or scarred tissue shows diminished signal. It is also used to assess myocardial viability in patients with known infarction.

Sestamibi is also employed in parathyroid imaging to localize parathyroid adenomas, typically with dual-phase imaging that uses early and delayed pictures to distinguish adenomas from thyroid tissue. In some centers, sestamibi scintimammography has been used as an adjunct for breast lesion detection in patients with dense breasts or inconclusive mammography.

Safety and scheduling: technetium-99m has a short half-life and the procedure generally involves a low radiation dose. Potential adverse effects are rare. Contraindications include pregnancy and, in some cases, breastfeeding; appropriate precautions are advised for nursing mothers. The technique is subject to artifacts from body habitus, breast tissue, or liver activity, which can affect image interpretation.