CARDIORENAL SCINTIGRAPHY WITH 99mTc-TETROFOSMIN AS AN IMAGING TOOL TO STUDY CARDIORENAL DISEASE IN ARTERIAL HYPERTENSION

Background. Renal function is a strong predictor of cardiovascular prognosis and cardiorenal disease is increasingly investigated. Cardiorenal Scintigraphy with the perfusion tracer 99mTc-Tetrofosmin was proposed as a single combined examination allowing the simultaneous investigation of heart and kidney in cardiovascular patients, including hypertensives at risk of both cardiac and renal disease (Fommei, 2009). The renal uptake index (UI) of Tetrofosmin as a percent of the injected dose was used as a renal diagnostic parameter and found to be related to clinical and scintigraphic (99mTc-DTPA) indexes of cardiorenal severity. Aim of the study. Here we tested 99mTc-Tetrofosmin renal diagnostic validity in hypertensive patients in a comparison with 123 I-Hippuran scintigraphy as a gold standard for renal function. Patients and Methods. 22 hypertensive patients (5 F, 17 M, age range 46-79 yrs) were scheduled for both 99mTc-Tetrofosmin cardiac G-SPECT and 123-I Hippuran scintigraphy in their diagnostic workup. As previously described, cardiorenal scintigraphy consisted in a dynamic renal acquisition after Tetrofosmin bolus injection, followed by standard cardiac G-SPECT. Hippuran scintigraphy was performed in a separate day following standard procedures. Renal images and renograms were obtained and renal uptake was calculated for each kidney both in Tetrofosmin and Hippuran scintigraphies. Results. Tetrofosmin UI (mean 13.13±6.9 SD%) resulted lower than Hippuran UI (23.24±12.80 % (p<0.001) reflecting different intrarenal kinetics. Positive correlations were observed between the two tracers clearances and UI (either as total or separate kidney uptake) (p<.01) and between Tetrofosmin UI and age, serum creatinine, creatinine clearance and the Doppler-renal resistive index (p<.01). Five patients with angiographically confirmed renal artery stenosis showed corresponding renographic and scintigraphic abnormalities with both tracers. Conclusions. 99mTc-Tetrofosmin cardiorenal scintigraphy may be used to obtain simultaneous renal and cardiac functional information which may be relevant for diagnosis and prognosis in states of cardiorenal diseases, with no study lenghtening nor an increase in the radiation burden to the patient compared to a standard cardiac study.