Measurement of single kidney contrast media clearance by multiphasic spiral computed tomography: preliminary results.
OBJECTIVE
We present preliminary results of a new method (hereinafter called 'CT-clearance') to measure single kidney contrast media clearance by performing multiphasic helical CT of the kidneys. CT-clearance was calculated according to an extension of the Patlak-Plot. In contrast to prior investigators, who repeatedly measured a single slice, this method makes it possible to calculate single kidney clearance from at least three spiral CTs, utilizing the whole kidney volume.


METHODS
Spiral CT of the kidneys was performed unenhanced and about 30 and 100 s after administration of about 120 ml iopromide. Sum-density of the whole kidneys and aortic density was calculated from this data. Using this data, renal clearance of contrast media was calculated by CT-clearance in 29 patients. As reference, Serum-clearance was calculated in 24 patients by application of a modified one-exponential slope model. Information on the relative kidney function was gained by renal scintigraphy with Tc99m-MAG-3 or Tc99m-DMSA in 29 patients.


RESULTS
Linear regression analysis revealed a correlation coefficient of CT-clearance with Serum-clearance of r=0.78 with Cl (CT) [ml/min]=22.2+1.03 * Cl (serum), n=24. Linear regression of the relative kidney function (rkf) of the right kidney calculated by CT-clearance compared to scintigraphy results provided a correlation coefficient r=0.89 with rkf(CT)[%]=18.6+0.58 * rkf(scintigraphy), n=29.


CONCLUSIONS
The obtained results of contrast media clearance measured by CT-clearance are in the physiological range of the parameter. Future studies should be performed to improve the methodology with the aim of higher accuracy. More specifically, better determination of the aortic density curve might improve the accuracy.
Hackstein
N
N
Department of Diagnostic Radiology, Justus-Liebig Universität Giessen, Klinikstrasse 36, 35385 Giessen, Germany. nils.hackstein@radiol.med.uni-giessen.de
Puille
M F
MF
Bak
B H
BH
Scharwat
O
O
Rau
W S
WS
D003287:Contrast Media / Q000493:pharmacokinetics*; D006801:Humans; D007472:Iohexol / Q000031:analogs & derivatives / Q000493:pharmacokinetics*; D007668:Kidney / Q000000981:diagnostic imaging* / Q000502:physiology; D016014:Linear Models; D011866:Radioisotope Renography; D019783:Technetium Tc 99m Dimercaptosuccinic Acid; D017263:Technetium Tc 99m Mertiatide; D014057:Tomography, X-Ray Computed / Q000379:methods*
D003287:Contrast Media; D017263:Technetium Tc 99m Mertiatide; D007472:Iohexol; D019783:Technetium Tc 99m Dimercaptosuccinic Acid; C038192:iopromide