Formulation of lyophilized single vial kit of N-N-Ethylene-L-Dicysteine 99m [EC] for labeling with Tc. II: Radiochemical and clinical evaluation 99mr as a renal tubular agent in comparison with Tc-MAG[3]

A Technetium[99m]Tc labeled lyophilized single component kit of N-N-ethylene-I-dicysteine [EC] is developed to replace multiple step kit developed by others. The aim of study is to formulate a radionuclide that is easy to prepare, has rapid plasma clearance, produce high quality images and is an affective alternative to radioiodine labeled orthoiodohippurate, which has been remained the physiological 'gold standard' since long time. To achieve this goal, the systematically varied key parameters such as pH, the use of reducing agents, stabilizers and additives are optimized to obtain maximum radiochemical purity and optimum bio distribution in non human and human primates. Various pH levels of EC showed equally good results in animal experiments but only pH 10 was suitable for human use. Dynamic and renal Scintigraphic studies are carried out with[99m]Tc-EC at pH 8 in 12 volunteers and at pH 10 in 18 volunteers and compared with[99m]Tc-MAG[3], Background ratios, renograms, relative renal function and semi quantitative parameters are available in all studies. The background ratios [mean +/- SD] at 30[th] minute are 0229+/-0.024 and 0.236+/-0.018 for[99m]Tc-EC at pH 10 and[99m]c-MAG[3] respectively. The mean +/- standard error of mean [SEM] values of T[M]X and time to half activity [T[12]] for[99m]Tc-EC [pHIO] are 3.7+/-0.6 and 7.3+/-1.0 respectively while for [99m]Tc-MAG[3], they are 4.0+/-0.8 and 7.9+/-1.4 with p values 0.001 and 0.049 respectively. The values of relative renal function [RRF] for[99m]Tc-EC and[99m]Tc-MAG[3] are 50.8+/-3.11 and 51.2+/-3.4 respectively with p value of 0.822. The residual activity at 25[th] minute [A[25] / A[MAX]] and renal uptake are 0. 209+/-12.67+/-2.80 for[99m]Tc-EC and 0.218+/-0.035 and 1053+/-2.98 for[99m]Tc-MAG[3] [p=0.031 an 0.0003] respectively. The correlation coefficient [R] for T[max], T1/2, A[2]5/A[Max] and renal uptake are 0.96, 0.69, 0.93 and 0.85 respectively

Assessment of cerebral perfusion in chronic tobacco users through spect [single photon emission computed tomography] using tc-99m hmpao [metastable technetium-99 labelled hexa-methyl propylene amine oxime]

To determine an association between chronic tobacco use and changes in cerebral perfusion through semi-quantitative scintigraphic assessment employing metastable Technetium-99 labelled hexa-methyl propylene amine oxime single photon emission computed tomography [Tc-99m HMPAO SPECT]. Design: Case-control study. Place and duration of study: The study was conducted at the Department of Medical Sciences, Pakistan Institute of Engineering and Applied Sciences [PIEAS], Nilore, Islamabad, from Oct 2001 to May 2002. Regional cerebral perfusion in 48 chronic tobacco users was evaluated, utilising a normal database created by HMPAO brain scans of 20 non-tobacco users. Subjects were classified into chronic tobacco users and non-tobacco users through the use of the smoking index [SI]. [Smoking Index = Number of years of tobacco use x Number of cigarettes smoked per day]. SI value of 100 was taken as the cut-off value. Regions of interest [ROIs] were declared hypoperfused or hyperperfused if their percentage perfusion values relative to the average perfusion per pixel of the whole slice under evaluation did not fall within + 2 standard deviation [SD] of the mean regional perfusion in the corresponding ROI, in the normal control group. Result: Chronic tobacco users showed 164 hypoperfused ROIs [6.57%] and 138 hyperperfused ROIs [5.53%] out of 2496 ROIs assessed, whereas the normal controls showed only 15 hypoperfused [1.44%] and 27 hyperperfused [2.60%] ROIs out of 1040 ROIs assessed [P < 0.001]. Cerebral perfusion in chronic tobacco users was found to be significantly decreased compared to the non-tobacco users