Introduction: For renal scintigraphy, different radiopharmaceuticals like 99mTc-DMSA and 99mTc-EC can be used. Although these methods are accurate, some differences can be observed among them. These radiopharmaceuticals have different levels of reproducibility and repeatability. This study aimed to evaluate the level of inter and intra observer variability in 99mTc-DMSA scintigraphy. We also compared the renal function, measured with 99mTc-EC, with the one measured using 99mTc-DMSA scintigraphy to determine if 99mTc-EC can be used instead of 99mTc-DMSA in this regard.Methods: The sample volume consisted of 81 patients underwent both 99mTc-DMSA and 99mTc-EC in Imam Reza Health Center in 2008. These scans were interpreted by two observers. One of the observers interpreted the scans after one month for the second time. The data were analyzed with SPSS.Results: There was a close correlation between these two methods with respect to DRF (P = 0.51). Estimating intra observer variability showed close correlation between DMSA (r = 0.997) and EC (r = 0.996). The evaluation of inter observer variability also revealed high correlation between DMSA (r = 0.995) and EC (r = 0.996).Conclusion: Since the comparison between these two methods in measuring renal function showed the same results, 99mTc-EC can be used as a substitute for 99mTc-DMSA. In addition, Tc-99m EC scintigraphy can be a reliable single-modality study to evaluate renal cortical defects, perfusion, and drainage of the urinary system and indirect evidence of vesicoureteric reflux with the added advantage of low radiation exposure to the patient. Also good reproducibility and repeatability were reported according to this study.

Objectives: 99mTc-MAG3 is a standard radiotracer for renal dynamic functional study. Despite its properties for clinical uses, it has numerous technical limitations. 99mTc-EC is also a tubular radiotracer for renal imaging, which has not been used worldwide. In this study, the use of 99mTc-EC and 99mTc-MAG3 for renal functional study were compared.Methods: Thirty five patients (20 male, 15 female; mean age of 34.63 ±10.69 years) were entered in the study. About 10 mCi of 99mTc-EC and 99mTc-MAG3 were administered in different days within 7 days intervals and serial images were obtained for 30 minutes. Serum creatinine and visual scintigraphic findings of all patients were within normal limits.Results: In this study, the renal uptake of 99mTc-EC was significantly higher than 99mTc-MAG3 (6.20% vs 4.39% of the injected dose), while the hepatic activity of 99mTc-EC was significantly lower (307 vs 439 mean pixel count, p<0.0001). Also the absolute values for some other quantitative parameters such as right and left kidney transit times and ERPF were different for each radiotracer. In spite of these differences most quantitative parameters (except for right kidney transit time, liver uptake and Tmax of both kidneys) showed good correlations for both agents.Conclusion: The calculated ERPF with 99mTc-EC as compared to 99mTc-MAG3 is in closer proximity to the true values. Also the use of 99mTc-EC compared to 99mTc-MAG3 in clinic due to simplicity of preparation, higher stability, higher renal uptake, and lower hepatobiliary activity is better. Therefore the use of 99mTc-EC as an appropriate substitute or ever preferred radiopharmaceutical for 99mTc-MAG3 radiopharmaceutical for renal function studies is recommended.

Introduction: This article as the first clinical prospective study was conducted to use of Tc-IgG as compared with autologous Tc-RBC in gated blood pool ventriculography. Moreover, two objectives were followed: (a) assess the feasibility of this radiotracer in routine practice; (b) appraise its in vivo steadiness over time by measurement of organs activity ratios and the image quality.Methods: the study population included 12 patients who referred for evaluation of liver hemangioma or infection process. Six patients underwent gated planar blood pool (GPBP) acquisition using Tc-RBC and remaining 6 cases underwent GPBP with Tc-IgG. Additionally, to evaluate the activity ratios in different organs, ROIs were manually drawn over the LV, RV, right lung, left lung, aorta, liver and spleen on the static anterior datasets in 20 minute (early) and also delayed (180 minutes) post injection of Tc-RBC and Tc-IgG.Ratios of activity between the early and delayed images were compared for each ROI.Results: The mean time of acquisition following injection of each radiotracer (RBC; 75.83±11.75 minute Vs IgG; 80.00±7.09 minute) was not different [p value>0.05]. Observer 1 and 2 were classified good quality for both radiotracers in all participants. The mean ejection fraction (EF) of patients with Tc-RBC and Tc-IgG wan not significantly different (59.00±7.64 % vs.58.33±16.03 %) [P value>0.05]. The ratio of LV to crescent background in GBP was not statistically difference between two agents (RBC; 2.55±0.99 Vs IgG; 2.11±0.78) The mean activity of LV and RV to backgrounds ratios in patients with Tc-IgG was more (although nonsignificant) relative to cases radiolabeled with in vitro Tc-RBC on early and delayed views (P>0.05). In addition, the relevant constancy of biodistribution of both radiotracers over time was also compared in the organs activities between the early and delayed studies.Conclusion: This data showed that the use of Tc-IgG in cardiac blood pool studies might led to comparable images as Tc-RBC. Therefore, 99mTc-IgG, readily accessible and needing a single injection, might be an attractive alternative to Tc-RBC for the estimation of LV function, especially in subjects with poor vein quality or busy departments.