Review: Cardiorenal Scintigraphy with Tc-99m Tetrofosmin

By: Nathaniel Burnett


Clinical Question: Can we assess a myocardial perfusion and renal function simultaneously during Tc99m gated SPECT myocardial perfusion imaging?
History: Cardiac and renal pathophysiology is closely linked. An abnormality in one system frequently leads to an abnormality in the other system. Measuring both at the same time may lead to a deeper understanding of this relationship. This may have important clinical and economic ramifications.
Objectives: the objective of this study was to see if Tc99m tetrofosmin renal scintigraphy could be performed accurately (compared to Tc-99m DTPA renal scintigraphy) when don in conjunction with gated SPECT myocardial perfusion imaging. The study also looked at renal function after adenosine stress as compared to rest renal function.
Study Design: prospect evaluation of a cohort.
Participants: there were a total of 30 patients referred for clinical reasons for myocardial gated SPECT imaging. Of these, there were 24 with hypertension (including 7 with renovascular hypertension), 7 with diabetes, and 6 with dilated cardiomyopathy.
Methods: The patients had gated SPECT stress-rest myocardial perfusion imaging performed. A two-day, single isotope protocol utilizing Tc-99m tetrofosmin was performed. Then, a week later, 24 of the original 30 patients underwent standard dynamic planar 99m-Tc DTPA renal scintigraphy.
The rest acquisition started out with planar dynamic and function renal imaging for 30 minutes. Then, gated SPECT myocardial perfusion images were obtained. Patient dosage of the Tc-99m was about 10 mCi (370 MBq).
Stress imaging consisted of a standard adenosine infusion, with renal images starting to be acquired at 3 minutes into the infusion. This was followed immediately by the nuclear myocardial perfusion imaging.
The renal scans consisted of dynamic and functional imaging over 30 minutes. Values obtained included split renal function, time to peak uptake, and the uptake index for the radiotracer.
Results: On visual analysis, the renal images from 99m-Tc tetrofosmin were of higher quality due to the higher uptake index of tetrofosmin compared to DTPA. The split renal function as determined by 99m-Tc tetrofosmin was comparable to that obtained by Tc99m DTPA. Time to peak activity also was comparable for the two tracers.
In those patients that also had stress renal imaging using adenosine, there was a statistically significant decrease in the Tc-99m tetrofosmin uptake index when compared the the uptake index at rest. This suggests decreased kidney function or perfusion.
Conclusion: 99m-Tc tetrofosmin imaging can assess at a single setting both cardiac and renal function utilizing a single injection of the isotope.
Source: Fommei E, Bruselli L, Ripoli A et al. Single-shot cardiorenal scintigraphy with Tc-99m tetrofosmin: a dynamic characterization at rest and during adenosine infusion. J Nucl Med. 2009 Jul 17. [Epub ahead of print]. Medline Abstract.

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