Tc-99m sestamibi Stress/Rest Myocardial Perfusion SPECT Radiotracer
Sestamibi (Mibi) labeled with 99mTc has been used for myocardial scan for 2-3 decades. Initially with planar and later on with tomographic SPECT imaging. After intravenous injection it concentrates quickly in the normal and viable cardiac cells, by means of passive diffusion into the mitochondria, in proportion to blood flow. It has no significant redistribution, remaining without changes for a long time, so images can be taken 4 h to 6 h after injection. It is primarily a perfusion agent but may also be employed for viability assessment with acceptable efficiency.
Adult dose may vary if a one day or two day protocol is employed. In the first case, the initial phase is carried out with 10 mCi (370 MBq) which may correspond to rest or stress. The last phase is done with a greater dose of 30 mCi (1110 MBq), to prevent superimposition of residual activity form first phase. In the second case of a two day protocol, similar doses are used for both stress and rest, ie 25 mCi (925 MBq).
References:
1 Clark AN, Beller GA. The present role of nuclear cardiology in clinical practice. Q J Nucl Med Mol Imaging. 2005 Mar;49(1):43-58.
2 Mut F. Diagnostico de la Enfermedad Coronaria and Gonzalez P et al. Viabilidad Miocardica, in Medicina Nuclear Aplicaciones Clínicas. Ignasi Carrio y Patricio González . Editorial Masson, Barcelona España, 2003, p 39-56 and 105-119, respectively.
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