J Nucl Med. 2007; 48 (Supplement 2):445P
Technologist Papers I: Cardiovascular Basic, Clinical & PET
Comparison of transient ischemic dilation (TID) ratio on myocardial perfusion imaging with dual isotope and dual Tc-99m Sestamibi protocols in females
Nabeel Hafeez1 and
1 Cardiology, Northside Hospital, Atlanta, Georgia;
2 Biomedical and Radiological Technologies, Medical College of Georgia, Atlanta, Georgia
Objectives: To evaluate the variation of transient ischemic dilation (TID) ratio with dual isotope (Tl-201 and Tc-99m Sestamibi) and dual Tc-99m Sestamibi protocols. Methods: Patients who have had an abnormal TID ratio on the routine myocardial perfusion imaging (MPI) with dual isotope protocol but otherwise considered clinically low probability for coronary artery disease on the basis of normal perfusion were selected prospectively for this study. Dual isotope imaging was performed by injecting 4.0 mCi of Thallium-201 at rest and SPECT images were done after 15 minutes. These patients were stressed either on a treadmill or using a pharmacological agent and injected with 30 mCi of Tc-99m Sestamibi at peak stress. Post stress SPECT images were done after 45 minutes for treadmill and 60 minutes for pharmacological stress. The quantitative information on TID ratio was generated by AutoQUANT program and were abnormal. These patients were brought back the next day and injected with 10 mCi of T-99m Sestamibi at rest and SPECT images were done 45 minutes post injection. These studies were reprocessed with the Tc-99m Sestamibi resting images and the TID ratio was generated again using the AutoQUANT program. Results: 8 patients referred for evaluation of ischemic heart disease (100% females, mean age 67 ± 15 years) were identified by the cardiologists who had abnormal TID ratios (mean 1.55 ± 0.18) with the dual isotope imaging (87% pharmacological) and recommended for a resting Tc-99 Sestamibi scan. The TID ratios were normal (mean 1.18 ± 0.15) when using the Sestamibi resting study. The mean TID ratio difference was statistically significant between these groups (P = .001). Conclusions: Our findings on this small group of patients suggest that dual isotope imaging has the potential to falsely elevate the TID ratio in females. This may be due to the higher scatter associated with Thallium images or the smaller heart size seen in females. These findings warrant further evaluation in a larger database.