Novel 99mTc(III)-azide complexes [99mTc(N3)(CDO)(CDOH)2B-R] (CDOH2 = cyclohexanedione dioxime) as potential radiotracers for heart imaging
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2016
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Introduction In this study, novel 99mTc(III)-azide complexes [99mTc(N3)(CDO)(CDOH)2B-R] (99mTc-ISboroxime-N3: R = IS; 99mTc-MPboroxime-N3: R = MP; 99mTc-PAboroxime-N3: R = PA; 99mTc-PYboroxime-N3: R = PY; and 99mTc-Uboroxime-N3: R = 5U) were evaluated as heart imaging agents. Methods Complexes [99mTc(N3)(CDO)(CDOH)2B-R] (R = IS, MP, PA, PY and 5U) were prepared by ligand exchange between NaN3 and [99mTcCl(CDO)(CDOH)2B-R]. Biodistribution and imaging studies were carried out in Sprague–Dawley rats. Image quantification was performed to compare their initial heart uptake and myocardial retention. Results 99mTc-ISboroxime-N3, 99mTc-PYboroxime-N3 and 99mTc-Uboroxime-N3 were prepared with high RCP (93–98%) while the RCP of 99mTc-MPboroxime-N3 and 99mTc-PAboroxime-N3 was 80–85%. The myocardial retention curves of 99mTc-ISboroxime-N3, 99mTc-PYboroxime-N3 and 99mTc-Uboroxime-N3 were best fitted to the bi-exponential decay function. The half-time of the fast component was 1.6 ± 0.4 min for 99mTc-ISboroxime-N3, 0.7 ± 0.1 min for 99mTc-PYboroxime-N3 and 0.9 ± 0.4 min for 99mTc-Uboroxime-N3. The 2-min heart uptake from biodistribution studies followed the ranking order of 99mTc-ISboroxime-N3 (3.60 ± 0.68%ID/g) > 99mTc-PYboroxime-N3 (2.35 ± 0.37%ID/g) ≫ 99mTc-Uboroxime-N3 (1.29 ± 0.06%ID/g). 99mTc-ISboroxime-N3 had the highest 2-min heart uptake among 99mTc radiotracers revaluated in SD rats. High quality SPECT images were obtained with the right and left ventricular walls being clearly delineated. The best image acquisition window was 0–5 min for 99mTc-ISboroxime-N3. Conclusion Both azide coligand and boronate caps had significant impact on the heart uptake and myocardial retention of complexes [99mTc(N3)(CDO)(CDOH)2B-R]. Among the radiotracers evaluated in SD rats, 99mTc-ISboroxime-N3 has the highest initial heart uptake with the heart retention comparable to that of 99mTc-Teboroxime. 99mTc-ISboroxime-N3 is a promising alternative to 99mTc-Teboroxime for SPECT MPI. © 2016 Elsevier Inc.
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Animals , Heart , Image Processing, Computer-Assisted , Myocardium , Organotechnetium Compounds , Oximes , Radioactive Tracers , Radiochemistry , Rats , Rats, Sprague-Dawley , Tissue Distribution , Tomography, Emission-Computed, Single-Photon , 99mTc 1h pyrazol 3 ylboronic acid boroxime , 99mTc 1h pyrazol 3 ylboronic acid boroxime n3 , 99mTc 3 pyridineboronic acid boroxime , 99mTc 3 pyridineboronic acid boroxime n3 , 99mTc isoxazole 4 boronic acid boroxime , 99mTc isoxazole 4 boronic acid boroxime n3 , 99mTc n methylpyridinium 4 boronic acid iodide boroxime , 99mTc n methylpyridinium 4 boronic acid iodide boroxime n3 , 99mTc teboroxime , 99mTc teboroxime n3 , 99mTc trioxime , 99mTc trioxime n3 , 99mTc uracil 5 boronic acid boroxime , 99mTc uracil 5 boronic acid boroxime n3 , tracer , unclassified drug , oxime , technetium complex , tracer , animal experiment , Article , cardiac imaging , controlled study , dynamic planar imaging , heart left ventricle wall , heart right ventricle , image reconstruction , nonhuman , nuclear magnetic resonance imaging , radiochemistry , rat , right ventricular wall , single photon emission computer tomography , Sprague Dawley rat , animal , cardiac muscle , chemistry , diagnostic imaging , heart , image processing , metabolism , procedures , single photon emission computed tomography , tissue distribution