Rapid in vivo measurement of single-kidney extraction fraction and glomerular filtration rate with MR imaging.
OBJECTIVE
To compare the accuracy of a noninvasive magnetic resonance (MR) imaging method to rapidly determine single-kidney glomerular filtration rate (GFR) relative to findings with an accepted standard of reference.


METHODS
Simultaneous inulin and MR imaging measurements of renal excretory function were performed in six small swine. Renal extraction fraction of gadopentetate dimeglumine was determined with T1 measurements of flowing blood in the renal vein and in a systemic vessel 10-300 minutes after administration. These data were correlated with standard inulin-derived measurements of single-kidney GFR obtained during the same intervals as the MR imaging measurements. Gradient-echo (GRE) and echo-planar imaging were investigated for in vivo measurement of extraction fraction.


RESULTS
The MR imaging-derived measurements of extraction fraction and single-kidney GFR were not significantly different from the inulin-determined measures (P > .18). The MR imaging extraction fraction and single-kidney GFR measurements correlated with inulin-derived measurements of the same parameters (r = .74 to .89, P < .0007).


CONCLUSIONS
T1 measurement methods with GRE and echo-planar imaging are acceptable techniques with which to measure renal excretory function in a rapid and noninvasive manner in this model. Rapid measurements of single-kidney GFR should enable studies of the response of renal hemodynamics to pharmaceutical manipulation.
Niendorf
E R
ER
Department of Medical Physics, University of Wisconsin-Madison 53792, USA.
Grist
T M
TM
Lee
F T
FT
Brazy
P C
PC
Santyr
G E
GE
D000818:Animals; D003287:Contrast Media; D017352:Echo-Planar Imaging / Q000379:methods; D019786:Gadolinium DTPA; D005919:Glomerular Filtration Rate; D007444:Inulin; D007668:Kidney / Q000033:anatomy & histology / Q000502:physiology*; D007677:Kidney Function Tests; D008279:Magnetic Resonance Imaging / Q000379:methods*; D013552:Swine
D003287:Contrast Media; D007444:Inulin; D019786:Gadolinium DTPA