Tehran University of Medical Sciences
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Davood Beiki

Single Tc-99m Sestamibi injection, double acquisition gated SPECT after stress and during low-dose dobutamine infusion: a new suggested protocol for evaluation of myocardial perfusion


Authors: Fallahi B, Beiki D, Gholamrezanezhad A, Mahmoudian B, Ansari Gilani K, Eftekhari M, Fard-Esfahani A, Mohseni Z, Saghari M,
Keywords: Dobutamine, Functional reserve, Gated SPECT,  Myocardial perfusion,  Reversibility
Int J Cardiovasc Imaging , Vol.24, No.8, 2008,Page:825-835

BACKGROUND:

The ability of low dose dobutamine (LDD) has been established in exploiting the reserved contractility of ischemic myocardium. This study was designed to assess the value of a new protocol, with an additional stress imaging during LDD infusion instead of the rest images, for evaluation of coronary artery disease (CAD) and perfusion reversibility.

METHODS:

A total of 51 patients (42 men, 9 women; 57.2 +/- 11.3 years) were included in the study and underwent three sequential steps of imaging; the first step-stress gated SPECT with Tc-99m sestamibi, immediately followed by the second step-gated SPECT during constant infusion of 7.5 microg/kg/min dobutamine and finally the third step-rest phase scan following trinitroglycerine administration in the next day. The findings were interpreted using the images in three sets of display; first vs. second step-single injection-double acquisition gated SPECT before and during LDD (SIDAGS-LDD), first vs. third step-standard stress/rest protocol, and only first step-gated stress-only SPECT. In all cases, the Visual perfusion index of each protocols were calculated by summating the premeditated 5-point scale (5: normal, 4: completely reversible, 3: partially reversible, 2: nontransmural fixed and 1: transmural fixed defects) of 17 standard myocardial segments. The accuracy as well as the correlation and agreement of protocols for detecting perfusion abnormality and corresponding reversibility were statistically analyzed.

RESULTS:

Calculated sensitivity, specificity, positive predictive value, negative predictive value and accuracy regarding the presence of CAD in both SIDAGS-LDD and standard protocols were 90.9% (40/44), 71.4% (5/7), 95.2% (40/42), 55.6% (5/9) and 88.2% (45/51), respectively. The extent and local