myocardial perfusion imaging (mpi)

99mTc-MIBI cardiac perfusion scanning is recognized as a clinically useful method in evaluating coronary artery disease. By the implementation of new imaging techniques and systems, it seems possible to obtain high-quality images with a lower dose of radiopharmaceuticals. The purpose of this study was to evaluate the effect of injection dose of 99mTc-MIBI on quantitative parameters of cardiac perfusion scan.

Eighty-three patients with the known probability of coronary artery disease were imaged three times (15, 120, and 180 min) after one injection during the stress phase. Assuming that 99mTc-MIBI has not any significant redistribution at this time, the only parameter which has been changed is the amount of accumulated radioactivity within the myocardium. In this way, we have three different images with different deposited doses in the myocardium from each patient. Then quantitative data of End Systolic Volume (ESV), End Diastolic Volume (EDV), and Ejection Fraction (EF) were calculated and compared.

Examination of quantitative scanning data indicates that the changes in EF data were non-significant and that the changes in ESV and EDV were significant over time.

In this study, assuming a dose reduction of radioactivity up to 50% of the initial dose based on cumulative dose in myocardial and imaging time, no clinically significant changes in quantitative cardiac perfusion scan variables such as ESV, EDV and EF occurred.

Early diagnosis of coronary arterial disease (CAD) plays an important part in reducing the complications, non-invasive tests, exercise test and myocardial perfusion imaging in particular. This study is intended to compare the results of these two procedures as well as to evaluate the distribution of coronary risk factors in various patients groups. Methods and Material: MPI and exercise test were conducted for 167 patients who referred to the nuclear medicine clinic at Imam Hossein Hospital in Shahroud, Iran. Information on coronary risk factors were collected. The mean age for men and women were 49.8 and 49.1 years respectively MPI in 52.7% were noted. Hypertension was more frequent in female, while smoking was more frequent in males, with no otherwise remarkable difference for other coronary risk factors. Hypertension and familial history of IHD were higher in the abnormal MPI group. Than the normal group. Abnormal exercise test results were associated with abnormal MPI in 74.5%. However, normal exercise test results were accompanied with abnormal MPI in 43.1 %. The overall sensitivity and specificity of exercise test were 43% and 82.7% respectively. Sensitivity was higher in men while specificity was slightly higher in females.