SESTAMIBI (Cardiolite) is a large synthetic molecule of the isonitrile family, which can be labeled with Tc99m.

This molecule passes cells membranes passively; the driving force is the negative membrane potential (see Thallium).
Once intracellular it further accumulates in the mitrocondrias where the membrane potential is even lower. As with Tl the distribution in the body after iv injection reflect cardiac output, about 5% goes to the heart. The extraction coefficient is lower than for Tl at about 65%. Sestamibi was introduced 1984 and in clinical trials in the late 80-ties. The diagnostic accuracy was demonstrated to be similar to Tl.


ADVANTAGE WITH SESTAMIBI

DISADVANTAGE WITH SESTAMIBI

  • Ideal energy for gamma cameras

    • higher dose can be used
    better image quality

  • Eliminated by the liver
    scatter and scaling problems

  • Produced from kit

    • always available

  • NO significant redistribution over 3 hours

    		•
     

    The originaly a 2-day protocol used two identical doses. Again, this protocol was inconvenient.

    A one-day protocol was introduced using 8 mCi for the first study and 24 mCi for the second study 2-4 hours later. Rest followed by stress was first practiced. Soon stress followed by rest imaging became popular because, if the stress study was normal, there was no reason for the rest study, leading to less radiation to the patient and savings.

     


    REST-STRESS PROTOCOL
    2-4 hours
    8 mCi at REST ------------------------------------24 mCi at peak STRESS
    imaging after 30-60----------------------------imaging after 30-60 min


    STRESS -REST PROTOCOL
    2-4 hours
    8 mCi at peak STRESS -------------------------24 mCi at REST
    imaging after 30-60----------------------------imaging after 30-60 min



    An important point is, that in all one-day protocols the second dose must be "strong" enough (2 ½ - 3 times) to overpower what is left of the first dose.
    TETROFOSMIN (Myoview)
    TETROPHOSMIN(Myoview) is an alternative Tc-based synthetic imaging agent with properties similar to SESTAMIBI. Doses, protocols, and diagnostic accuracy are the same as for SESTAMIBI.

    IN GENERAL

    The overall cost for Tl, Sestamibi and Tetrophosmin is similar - however local differences may exist.

    A highly significant advantage with the Tc-based tracers is the high count statistics (3 to 10 times higher than Tl), which makes it possible to perform gated SPECT, thus adding functional information to the conventional perfusion information.


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    Initiated: Nov 19, 1995. Last updated: April 26, 1999.