Single-Shot Cardiorenal Scintigraphy with ^99mTc-Tetrofosmin: A Dynamic Characterization at Rest and During Adenosine Infusion

¹ "Gabriele Monasterio" Foundation, CNR Institute of Clinical Physiology, Pisa, Italy; Department of Internal Medicine, University of Pisa, Pisa, Italy
² Department of Nuclear Medicine, University of Pisa, Pisa, Italy
³ "Gabriele Monasterio" Foundation, CNR Institute of Clinical Physiology, Pisa, Italy

^* To whom correspondence should be addressed. E-mail: fommei{at}ifc.cnr.it.

	Abstract

Renal function is known to be a strong predictor of cardiovascular prognosis, and cardiorenal disease is increasingly investigated in medical research. In this study, we tested the hypothesis that a single combined cardiorenal scintigraphy examination with the perfusion tracer ^99mTc-tetrofosmin is feasible and may allow the simultaneous investigation of cardiac and renal pathology in cardiovascular patients. Methods: Thirty patients scheduled for dual-day gated SPECT also gave their informed consent for a renal acquisition after a single injection of 370 MBq of ^99mTc-tetrofosmin, at rest (30 patients) or with adenosine (21 patients), and to undergo an additional standard renal study with the glomerular tracer ^99mTc-diethylenetriaminepentaacetic acid (DTPA) (74 MBq) after 1 wk (24 patients). Kidney images and renograms were obtained. Renal uptake index, expressed as the percentage ratio of kidney counts cumulated over the second minute after injection to the administered dose, was calculated as a functional renal parameter. Time to peak activity and separate kidney percentage uptake (as the percentage contribution of each kidney to total renal uptake) were also calculated. Results: Compared with ^99mTc-DTPA, ^99mTc-tetrofosmin provided better-quality kidney images, with a higher uptake index (13.17% ± 4.76% vs. 8.33% ± 2.45%, P < 0.001) and with comparable separate kidney percentage uptake and times to peak activity. ^99mTc-tetrofosmin uptake index was significantly lower in the patients who were more compromised according to renal and cardiovascular functional parameters, and correlated with ^99mTc-DTPA uptake index (r = 0.77, P < 0.001), serum creatinine (r = 0.59, P < 0.005), log brain natriuretic peptide N-terminal levels (r = -0.65, P < 0.005), myocardial and carotid intima-media wall thickness (for both, r = -0.61, P < 0.005), and the Doppler index of renal vascular resistance (r = -0.60, P < 0.005). In the 21 patients who underwent the provocative test, adenosine induced a significant decrease in renal ^99mTc-tetrofosmin uptake index (from 14.12% ± 4.50% to 11.81% ± 3.33%, P < 0.005) suggesting a decrement in renal perfusion or function. Conclusion: ^99mTc-tetrofosmin cardiorenal scintigraphy is feasible at low cost as a single-shot study and may allow both the evaluation of renal morphology and renograms during a cardiac study and the calculation of renal functional parameters.

Key Words: cardiorenal disease, myocardial scintigraphy, renal scintigraphy