Determination of glomerular filtration rate in anesthetized pigs by use of three-phase whole-kidney computed tomography and Patlak plot analysis.
OBJECTIVE
To develop a whole-kidney computed tomography (CT) technique that would allow 3-point Patlak plot determination of glomular filtration rate (GFR) and assess the correlation of GFR determined via CT (CT-GFR) with GFR determined via renal plasma clearance of inulin (Inu-GFR) in pigs.


METHODS
6 healthy anesthetized pigs.


METHODS
Each pig underwent 3-phase whole-kidney helical CT (arterial, early, and late parenchymal phases) before and after contrast medium administration. After contrast medium administration, corrected Hounsfield unit values were determined for each kidney and the aorta. A 3-point Patlak plot for each kidney was generated, and plasma clearance per unit volume was multiplied by renal volume to obtain whole-animal CT-GFR. Correlations of mean Inu-GFR for the left and right kidneys (and combined [total] values) with the corresponding CT-GFRs were assessed via linear regression and Bland-Altman analyses.


RESULTS
Left kidney, right kidney, and total CT-GFRs were good predictors of the respective Inu-GFR values (r(2) = 92.3%, r(2) = 85.5%, and r(2) = 93.7%, respectively). For the left kidney, no significant bias between Inu-GFR and CT-GFR was detected. Right kidney and total CT-GFRs underestimated the corresponding Inu-GFRs (mean underestimation, -8.4 mL*min(1) and -12.6 mL*min(1), respectively).


CONCLUSIONS
Three-phase whole-kidney CT with Patlak plot analysis of GFR may underestimate right kidney and total Inu-GFRs in pigs. The Patlak plot generated may be sensitive to nonlinearity caused by temporal variation in GFR. Nonetheless, the 3-phase CT approach offers some practical advantages for simultaneous evaluation of renal morphology and measurement of GFR.
Alexander
Kate
K
Department of Clinical Sciences, Faculty of Veterinary Medicine, Université de Montréal, St-Hyacinthe, QC J2S 7C6, Canada.
Ybarra
Norma
N
del Castillo
Jérôme R E
JR
Morin
Valérie
V
Gauvin
Dominique
D
Bichot
Sylvain
S
Beauchamp
Guy
G
Troncy
Eric
E
D000818:Animals; D005919:Glomerular Filtration Rate / Q000662:veterinary*; D007444:Inulin; D007668:Kidney / Q000000981:diagnostic imaging*; D016014:Linear Models; D010121:Oxytocin; D034421:Sus scrofa; D014057:Tomography, X-Ray Computed / Q000662:veterinary
D010121:Oxytocin; D007444:Inulin