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PET CT evaluation of glomerular filtration rate (GFR) in rats

We have established a new method to use Positron emission tomography CT (PET CT) to evaluate Glomerular Filtration Rate (GFR) in rats. GFR is a pivotal parameter for kidney function. The traditional method to evaluate GFR is cumbersome with several time-points for blood and urine sampling. Imaging modalities are ideal to evaluate small animal kidney function due to the non-invasive and repeatable nature. PET-CT can give high quality of the total activity acquisition by the small animal.

Abodominal aorta acts as a reference for the input function.Tracer distribution mostly in the kidney cortex.
A. Abodominal aorta acts as a reference for the input function. B. Tracer distribution mostly in the kidney cortex.
Photo:
Jianhua Han

Glomerular Filtration Rate (GFR) is a pivotal parameter for kidney function. Because of the non-invasive and repeatable nature, imaging modalities are ideal to evaluate the small animal kidney function. Positron emission tomography CT (PET-CT) can give high quality of the total activity acquisition by the small animal. In this study, we used PET/CT and radioactivity tracer labeling of a small molecular tracer that is cleared exclusively by glomerular filtration to evaluate GFR in male Wistar rats. After anesthesia with isoflurane, a CT scan was performed, followed by injection of 5-10 MBq of the labeled tracer in the tail vein. The rats were scanned by dynamic PET for 10 minutes. Further, a chronic kidney disease (CKD) rat model were made and scanned with the dynamic PET CT every second week. GFR was calculated by total signal intensity on the kidney / area under the blood vessel signal curve.  Standard GFR measurement by iohexol clearance were tested on all rats. The PET CT and iohexol GFR have good correlation. Individual kidney GFR can also be measured with the PET dynamic scanning. PET CT and iohexol both identified kidney dysfunction reflected as reduced GFR. The creatinine concentration is less sensitive than the PET CT GFR measurement to detect kidney dysfunction. We established new method for GFR measurement, enabling single kidney function monitoration.

 

Data presented at the Scandinavian Physiological Society conference on Iceland 8.-11. August. 2019