Functional Renal Imaging with 2-Deoxy-2-¹⁸F-Fluorosorbitol PET in Rat Models of Renal Disorders

Precise regional quantitative assessment of renal function is limited with conventional ^99mTc-labeled renal radiotracers. A recent study reported that the PET radiotracer 2-deoxy-2-¹⁸F-fluorosorbitol (¹⁸F-FDS) has ideal pharmacokinetics for functional renal imaging. Furthermore, ¹⁸F-FDS is available via simple reduction from routinely used ¹⁸F-FDG. We aimed to further investigate the potential of ¹⁸F-FDS PET as a functional renal imaging agent using rat models of kidney disease. Methods: Two different rat models of renal impairment were investigated: induction of acute renal failure by intramuscular administration of glycerol in the hind legs, and induction of unilateral ureteral obstruction by ligation of the left ureter. At 24 h after these procedures, dynamic 30-min ¹⁸F-FDS PET data were acquired using a dedicated small-animal PET system. Urine ¹⁸F-FDS radioactivity 30 min after radiotracer injection was measured together with coinjected ^99mTc-diethylenetriaminepentaacetic acid urine activity. Results: Dynamic PET imaging demonstrated rapid ¹⁸F-FDS accumulation in the renal cortex and rapid radiotracer excretion via the kidneys in healthy control rats. On the other hand, significantly delayed renal radiotracer uptake (continuous slow uptake) was observed in acute renal failure rats and unilateral ureteral obstruction kidneys. Measured urine radiotracer concentrations of ¹⁸F-FDS and ^99mTc-diethylenetriaminepentaacetic acid correlated well with each other (R = 0.84, P < 0.05). Conclusion:¹⁸F-FDS PET demonstrated favorable kinetics for functional renal imaging in rat models of kidney diseases. ¹⁸F-FDS PET imaging, with its advantages of high spatiotemporal resolution and simple tracer production, could potentially complement or replace conventional renal scintigraphy in select cases and significantly improve the diagnostic performance of renal functional imaging.