Introduction: A dipyridamole induced stress myocardial perfusion scintigraphy with Tc-99m Sestamibi is utilized for diagnosing coronary artery diseases. The use of dipyridamole as form of pharmacologic stressor has expected hemodynamic changes. Objective: The objective of this study was to determine the association of these changes with the scan parameters in patients with suspected coronary artery disease (CAD). Methodology: A total of 101 patients, with suspected CAD, who underwent a dipyridamole-induced stress myocardial perfusion scintigraphy using Tc-99m Sestamibi from January 2019 to March 2020 were included in this study. The patient databases, monitoring sheets, and scan results were reviewed . Results: The blood pressure responses had no significant association with the scan parameters and results. The normal (> 1.2) and abnormal (<1.2) heart rate ratios (HRR), which is the peak HR/baseline HR, likewise had no significant association with the scan results. However, in terms of the median HRR, the higher ratio of 1.29 (normal scan results) against the ratio of 1.25 (abnormal scan results) was determined to be significant (p-value of 0.032). The HRR also had a direct and indirect weak correlation with stress and rest Left Ventricular Ejection Fraction (LVEF) values (p-values of 0.09 and 0.011) and Summed Rest Score (p-value of 0.007), respectively. For the 12-L ECG, only the baseline normal (P-value of 0.018) and infarct findings (p-value of 0.017) were similarly associated with normal and abnormal scan results, respectively. Conclusion For patients with suspected CAD, the higher HRRs and baseline 12-L ECG of normal and infarct findings relates to the expected scan result. For scan parameters, the higher HRRs were also correlated with higher stress and rest LVEF values, and normal SRS, albeit a weak correlation. Notably, the blood pressure and post-infusion 12-L ECG changes had no significant association. In summary, the higher HRRs indicates normal scan results, normal SRS, and better LVEF values which increases the diagnostic confidence in the interpretation and management, especially in some equivocal cases.
Dipyridamole ; Myocardial perfusion scintigraphy

The study aims to determine the relationship of body mass index (BMI) and related anthropometric measurements on the image quality of Tl-201 and Tc-99m sestamibi myocardial perfusion scans (MPS). A total of 163 scans were analyzed. A blinded experienced physician performed visual analysis on the scans image quality on two different occasions. Quantitative parameter used was the heart-to-lung ratio (HLR). Regression analysis was done to determine the association of HLR with BMI and myocardial tracer uptake, ROC curves were generated to establish BMI and HLR cut-off points. Increasing BMI was associated with visually poorer images in the Tl-201 MPS group (p 0.003) but not for the Tc-99m MPS group (p 0.065). It was also associated with decrease HLR and myocardial tracer upatake for both tracers (p <0.001). ROC curves revealed BMI cut-off points of 28 (Tl-201 p 0.000; Tc99m sestamibi p 0.004) for both procedures; HR cut-off values of 3.0 for Tl-201 )p 0.295) and 2.5 for Tc-99m sestamibi (p 0.875). the image quality of Tl-201 scans begins to deteriorate at a BMI of 28 and HLR of 3.0 with myocardial count density reduction (less than or equal to 6000 counts) translating to visually poorer images. On the other hand , image quality of Tc-99m sestamibi scans also tend to deteriorate similarly at a BMI of 28. However, in contrast to Tl-201, the lower HLR cut-off of 2.5 suggests a relatively higher myocardial count density (greater than or equal to 9000 counts) rendering the image quality to be still satisfactory for subjective assessment.
Human ; Male ; Female ; Middle Aged ; Adult ; Young Adult ; Adolescent ; Child ; MYOCARDIAL PERFUSION IMAGING ; MYOCARDIAL SCINTIGRAPHY ; DIAGNOSIS ; DIAGNOSTIC TECHNIQUES AND PROCEDURES ; DIAGNOSTIC IMAGING ; CARDIAC IMAGING TECHNIQUES ; BODY MASS INDEX