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Technetium (99m Tc) sestamibi is a lipophilic cation which, when injected intravenously into a patient, distributes in the myocardium proportionally to the myocardial blood flow. Single photon emission computed tomography imaging of the heart is performed using a gamma camera to detect the gamma rays emitted by the technetium-99m as it decays.
By the late 1980s, two different compounds containing technetium-99m were introduced: teboroxime [10] and sestamibi. The utilization of Tc-99m would allow higher doses (up to 1,100 MBq or 30 mCi) due to the shorter physical (6 hours) half life of Tc-99m.
A cardiac specific radiopharmaceutical is administered, e.g., 99m Tc-tetrofosmin (Myoview, GE healthcare), 99m Tc-sestamibi (Cardiolite, Bristol-Myers Squibb) or Thallium-201 chloride. Following this, the heart rate is raised to induce myocardial stress, either by exercise on a treadmill or pharmacologically with adenosine , dobutamine , or ...
Effective doses can range from 6 μSv (0.006 mSv) for a 3 MBq chromium-51 EDTA measurement of glomerular filtration rate to 11.2 mSv (11,200 μSv) for an 80 MBq thallium-201 myocardial imaging procedure. The common bone scan with 600 MBq of technetium-99m MDP has an effective dose of approximately 2.9 mSv (2,900 μSv). [24]
Technetium-99m (Tc-99m) can be readily detected in the body by medical equipment because it emits 140.5 keV gamma rays (these are about the same wavelength as emitted by conventional X-ray diagnostic equipment), and its half-life for gamma emission is six hours (meaning 94% of it decays to 99 Tc in 24 hours). Besides, it emits virtually no beta ...
The most common isotope used in diagnostic scans is Technetium-99m, used in approximately 85% of all nuclear medicine diagnostic scans worldwide. It is used for diagnoses involving a large range of body parts and diseases such as cancers and neurological problems. [ 1 ]
Technetium-99m is a gamma emitter. It is obtained on-site at the imaging center as the soluble pertechnetate which is eluted from a technetium-99m generator , and then either used directly as this soluble salt, or else used to synthesize a number of technetium-99m-based radiopharmaceuticals.
Before the widespread application of technetium-99m in nuclear medicine, the radioactive isotope thallium-201, with a half-life of 73 hours, was the main substance for nuclear cardiography. The nuclide is still used for stress tests for risk stratification in patients with coronary artery disease (CAD). [56]