Determination of the Relative Glomerular Filtration Rate of Each Kidney in Man

Abstract

Iohexol and 99mTc-DTPA were used in 43 patients to determine the relative glomerular filtration rate (GFR), i.e., the GFR of each kidney in percent of total GFR. The amount of any GFR marker accumulating in Bowman's space, tubuli and renal pelvis within a few minutes after i.v. injection, before any marker had left the kidney via the ureter, was defined as proportional to the GFR of that kidney. The renal accumulation of iohexol was determined by CT using 10 slices of 8-mm thickness 1 to 4 minutes after injection. The renal accumulation of 99mTc-DTPA was determined with a gamma camera within 2 minutes after injection. The correlation coefficient between the two methods was 0.98. Due to the higher radiation dose from CT than from 99mTc-DTPA injection, relative GFR determination with CT should be performed when there is also a diagnostic need to reveal morphology.

Determination of Split Renal Function by 3D Reconstruction of CT Angiograms: A Comparison with Gamma Camera Renography

“…Algebraic determination of split renal function followed the form put forward by Frennby, Almen, and Lilja, et al in 1995, modified only to account for volume instead of cross-sectional area [10]. For each side the difference between the mean attenuation in the arterial series (Art Att) and the pre-contrast series (Pre Att) was multiplied by the mean of the respective parenchymal volumes (Art Vol and Pre Vol) to measure the accumulation (Art Acc) of contrast in each individual kidney during the arterial phase.…”

“…CT Angiography (CTA) has been examined by several groups as a possible method for evaluating split renal function. These studies [10-14] were small, but each showed that various 2D CT methods for the calculation of split renal function produce results only slightly different from those obtained by the current radionuclide renogram standard in populations with suspected or known renal disease including renal artery stenosis, hydronephrosis, stones, renal artery embolization, renal TB, and hematuria. However, slow CT scan speeds with older equipment as well as anatomic differences in the location of the renal artery origin, renal parenchymal size and pathologic conditions of the kidneys make estimation of total renal volume and attentuation from individual 2D slices problematic.…”

Determination of Single-Kidney Glomerular Filtration Rate in Human Subjects by Using CT

“…Absolute GFR was initially quantified by using CT scanners with modest spatial and temporal resolution (5)(6)(7)(8). Yet, the advent of subsecond helical CT scanners with improved spatial and temporal resolution, in conjunction with application of the indicator dilution theory, allows calculation of renal perfusion and GFR from the same time-attenuation curves.…”

“…We have shown that timeattenuation modeling provides more robust estimates of GFR (9). In addition, Frennby et al previously defined GFR from the accumulation of nonionic contrast material in the kidney within a few minutes after intravenous injection and compared it with radiolabeled scintigraphy (6,24). This method was simple, but the assumption that contrast agents must all be contained within the kidney at these times may cause underestimation of GFR (25).…”

“…Previous studies were conducted to investigate the feasibility of assessing CT GFR by using other methods (3,(5)(6)(7)(8)(24)(25)(26)(27)(28). The Patlak method is a twocompartment technique in which it is assumed that the contrast agent is fully trapped within the system at the time of measurement (29), but the complexity of tubular anatomy is neglected.…”