PT - JOURNAL ARTICLE AU - Andrew T. Taylor AU - Malgorzata Lipowska AU - Hui Cai TI - <sup>99m</sup>Tc(CO)<sub>3</sub>(NTA) and <sup>131</sup>I-OIH: Comparable Plasma Clearances in Patients with Chronic Kidney Disease AID - 10.2967/jnumed.112.108357 DP - 2013 Apr 01 TA - Journal of Nuclear Medicine PG - 578--584 VI - 54 IP - 4 4099 - http://jnm.snmjournals.org/content/54/4/578.short 4100 - http://jnm.snmjournals.org/content/54/4/578.full SO - J Nucl Med2013 Apr 01; 54 AB - The pharmacokinetics of the tricarbonyl core radiopharmaceutical 99mTc(CO)3-nitrilotriacetic acid (99mTc(CO)3(NTA)) in rats and subjects with normal renal function are comparable to those of 131I-o-iodohippuran (131I-OIH), the radiopharmaceutical gold standard for the measurement of effective renal plasma flow. Our objective was to compare the pharmacokinetics of these 2 tracers in subjects with renal failure. Methods: 99mTc(CO)3(NTA) was prepared with commercially available NTA and a commercially available labeling kit and isolated by reversed-phase high-performance liquid chromatography. Approximately 74 MBq (2.0 mCi) of 99mTc(CO)3(NTA) were coinjected with approximately 11.1 MBq (300 μCi) of 131I-OIH in 8 subjects with stage 3–4 renal failure; simultaneous images were obtained for 24 min, followed by an anterior image over the gallbladder and abdomen. Plasma clearances were determined from 10 blood samples obtained 3–180 min after injection using the single-injection, 2-compartment model. Plasma protein binding, red cell uptake, and percentage injected dose in the urine at 30 and 180 min were determined. Results: There was no difference in the plasma clearances of 99mTc(CO)3(NTA) and 131I-OIH (177 ± 63 vs. 171 ± 66 mL/min/1.73 m2, respectively) (P = 0.41). The plasma protein binding and red cell uptake of 99mTc(CO)3(NTA) were 35% ± 7% and 6% ± 3%, respectively; both values were significantly lower than the plasma protein binding (71% ± 5%) and red cell uptake (16% ± 2%) of 131I-OIH (P &lt; 0.001). There was no significant difference in the percentage injected dose in the urine at 30 min (P = 0.24) and at 3 h (P = 0.82); for comparison, the percentage dose in the urine at 3 h was 77% ± 9% for 99mTc(CO)3(NTA) and 78% ± 11% for 131I-OIH. Image quality with 99mTc(CO)3(NTA) was excellent and no activity was identified in the gallbladder or intestine. Conclusion: Results in patients with renal failure show the clearance and rate of urine excretion of 99mTc(CO)3(NTA) to be equivalent to that of 131I-OIH.