Evaluation of Myocardial Cell Membrane Integrity by Using 201Thallium - Gik Infusion: Is it the Effect of Insulin; High Dose 201Thallium Chlorideor Rate of Radiop harm aceutical Infusion?

Introduction: There are many trials that used 201 thalliumglucose insulin potassium ( 201 Tl-GIK) as a radiopharmaceutical material to detect the myocardial cells viability which is an important step before taking the decision of revascularization procedure. These trials showed an improvement in the detection of the myocardial cells viability by more than 30%, in comparison to the traditional techniques used before for the same purpose, but the question that shines in minds is whether this improvement could be attributed to the higher dose of 201 Tl-chloride used in this technique or due to the rate of injection (infusion) of the radiopharmaceutical, or lastly the effect of insulin that used in the GIK combination. In this study, we tried to get answers for these questions. Methods: Sixty male non diabetic patients with previous history of myocardial infarction (MI) were included in this study. All of them were subjected to thorough history taking, clinical examination, ECG evaluation and echocardiography imaging to detect the extent of dysfunctional left myocardial ventricle segments. Our patients were then subjected to two SPECT studies: The first study was a 201 Tl-SPECT stress myocardial perfusion study, followed by a second study, a 201 Tl-SPECT reinjection (rest) myocardial perfusion study, which evaluates the extent of underlying ischemia as well as the infarcted segments to be evaluated afterwards. These patients were then divided into two groups: The first group was subjected to a third SPECT study by using 201 Tl-GIK infusion (111MBq) over 30 minutes on a separate day. The second group was subjected to a third SPECT study by using 201 Tl-G infusion (111MBq) over 30 minutes on a separate day. Results: Our work showed that the first group of patients showed 42% improvement in detection of viable segments {110 segments of 378 initially diagnosed as scar segments (29%) showed complete improvement (normalized), and 49 segments (13%) of these 378 showed partial improvement} whereas; the second group showed only 12% improvement in detection of viable segments {28 segments of 328 initially Correspondence to: Dr. Fouad Khalil, The Department of Radiology, Faculty of Medicine, Minia University, Minia, Egypt Email: [email protected] diagnosed scar segments (9%) showed complete improvement (normalized), and 12 segments of these 328 segments (3%), showed partial improvement}. This means that the insulin component of the radiopharmaceutical ( 201 Tl-GIK) can enhance the detection of viable myocardial cells (cells with intact cell membranes). This could be attributed to the effect of insulin which enforces the 201 Tl to enter inside the cells through the intact cell membrane via the Na-K channels. This occurs due to the similarity in kinetics between potassium and thallium inside the body. Conclusion: Our results recommend that using TL-201 (GI K) infusion is considered as a safe, simple, tolerable and reliable study that can significantly improve detection of viable myocardial segments by three folds in comparison to other used techniques. Aim of the study: Creating a new imaging protocols with improved sensitivity and specificity in detection of viable myocardial segments, with figures near to the other highly sensitive but more expensive and less widely distributed imaging modalities like PET studies.