Patlak plot analysis CT‐GFR for the determination of renal function: comparison of normal dogs with autologous kidney transplant dogs

Abstract

Glomerular filtration rate (GFR) can be determined using Patlak plot analysis with single-slice dynamic computed tomography (CT). Acute autologous graft failure has several causes, all of which induce a measurable decrease in glomerular filtration rate. This study demonstrated in an experimental model of canine autologous renal transplant that CT-derived renal plasma clearance was significantly lower (p = 0.002) in dogs having undergone transplant (0.077 +/- 0.058 ml min(-1) ml renal tissue(-1)) compared with control dogs (0.396 +/- 0.139 ml min(-1) ml renal tissue(-1)). A significant negative curvilinear relationship was seen between serum creatinine and total renal plasma clearance (R(2) = 0.84, p = 0.0001). Alterations in renal time attenuation curve shape in dogs having undergone transplant may have been related to increased renal vascular resistance related to tubular necrosis. CT-GFR may be a useful experimental tool in the evaluation of renal dysfunction in transplant models.

ESTIMATION OF GLOMERULAR FILTRATION RATE IN HEALTHY CATS USING SINGLE‐SLICE DYNAMICCTANDPATLAK PLOT ANALYSIS

“…The shape of the aortic and renal TACs was similar for each cat and similar to those previously reported in dogs and pigs . After the recirculation peaks occurred, the aortic TAC had a mildly negative slope indicating decreasing iohexol concentration over time.…”

“…Alterations in attenuation (Hounsfield units, HU) are directly proportional to GFR. Dynamic CT has been used to quantify GFR in humans, pigs, and dogs . The iohexol dose required for the GFR analysis using dynamic CT (CTGFR) is less than one‐fourth of the dose required for standard CT contrast procedures and for serum analysis of iohexol as a tracer in humans, dogs, and pigs .…”

“…Dynamic CT has been used to quantify GFR in humans, pigs, and dogs . The iohexol dose required for the GFR analysis using dynamic CT (CTGFR) is less than one‐fourth of the dose required for standard CT contrast procedures and for serum analysis of iohexol as a tracer in humans, dogs, and pigs . Many of these studies have found a close correlation between CTGFR and GFR measured by traditional means, but with underestimation of traditional reference values when measured by CTGFR.…”

“…A Patlak plot is a graphical analysis technique based on pharmacokinetic principles of a two‐compartment model developed originally for nuclear medicine . The model requires that a tracer leaves one compartment (blood) and enters a second compartment irreversibly (filtrate) . Iohexol behaves in this manner in the kidney during the first 2 min after injection, before it exits via the ureters .…”

“…This method of determining regional blood flow and GFR is well described in several species using targeted ROIs and is the basis of the Patlak plot analysis …”