Technetium Tc-99m sestamibi

aka Sestamibi, MIBI, Miraluma (breast imaging)

A radioactive tracer injected into a vein that lodges inside heart muscle cells in proportion to blood flow, so a gamma camera picture taken after exercise or a stress drug shows which parts of the heart are not getting enough blood.

Technetium Tc-99m sestamibi (Cardiolite) is a cationic isonitrile SPECT perfusion agent, FDA-approved in December 1990, supplied as a cold kit reconstituted with generator-eluted Tc-99m and injected intravenously for rest and stress myocardial perfusion imaging. Its first-pass myocardial extraction fraction is 55-68%, lower than thallium-201's 82-88% but adequate because the higher injectable activity and 140 keV photon (near-ideal for gamma cameras) compensate with better image counts and a 6-hour half-life that allows same-day or two-day rest/stress protocols.

The FDA label indications are detecting coronary artery disease by localising reversible (ischaemic) and non-reversible (infarcted) defects, and evaluating myocardial function to inform patient management. The suggested adult dose range is 370-1,110 MBq (10-30 mCi) per injection; a separate approved indication (as Miraluma) at 740-1,110 MBq is for breast imaging as an adjunct to mammography, outside this cardiac scope.

In practice sestamibi SPECT (usually gated, giving ejection fraction and wall motion alongside perfusion) is the workhorse test to decide whether a patient with chest pain or an abnormal stress test needs coronary angiography and revascularisation versus medical therapy, and it can also serve as the resting perfusion half of a cardiac sarcoidosis PET/SPECT work-up when PET perfusion tracers are unavailable.

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Technetium-99m sestamibi

See it in action

A lipophilic cationic isonitrile complex of Tc-99m that crosses cell membranes passively and accumulates in mitochondria, driven by the mitochondrial and plasma membrane potentials of viable myocytes. Myocardial uptake is proportional to coronary blood flow at the time of injection, with a first-pass extraction fraction of about 55-68% (roughly 65% at rest) that plateaus ("rolls off") at high flow rates, so it somewhat underestimates very high flow. Unlike thallium-201 it shows minimal redistribution, so a snapshot taken at stress genuinely reflects flow at the moment of injection, and separate rest and stress doses are needed.

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1. Where it connects

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2. Step by step

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1.Technetium Tc-99m sestamibi slips into a pocket on its target.

Modality

SPECT tracer

Mechanism

Brand / code

Cardiolite

Dosing & schedule

Route: Intravenous injection
Schedule: 370-1,110 MBq (10-30 mCi) per dose for myocardial imaging (rest and stress doses given separately); imaging typically begins 15-60 minutes after injection

Source: www.accessdata.fda.gov/drugsatfda_docs/label/2019/019785s022lbl.pdf. Doses are for orientation; the current label governs.

Regulatory

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Approvals

Region	Year	Indication
US	1990	Detecting coronary artery disease by localising myocardial ischaemia and infarction, and evaluating myocardial function

Trials

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ClinicalTrials.gov · phase 2/3

refreshed 2026-10-19

9 studies0 recruiting3 Phase 26 Phase 3

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