[Calculation of the partial function of the kidney with DMSA in pediatrics: is the evaluation of the geometric mean necessary?].
For assessment of differential renal function (PF) by means of static renal scintigraphy with Tc-99m-dimercaptosuccinic acid (DMSA) the calculation of the geometric mean of counts from the anterior and posterior view is recommended.


OBJECTIVE
Of this retrospective study was to find out, if the anterior view is necessary to receive an accurate differential renal function by calculating the geometric mean compared to calculating PF using the counts of the posterior view only.


METHODS
164 DMSA-scans of 151 children (86 f, 65 m) aged 16 d to 16 a (4.7 +/- 3.9 a) were reviewed. The scans were performed using a dual head gamma camera (Picker Prism 2000 XP, low energy ultra high resolution collimator, matrix 256 x 256, 300 kcts/view, Zoom: 1.6-2.0). Background corrected values from both kidneys anterior and posterior were obtained. Using region of interest technique PF was calculated using the counts of the dorsal view and compared with the calculated geometric mean [SQR(Ctsdors x Ctsventr)].


RESULTS
The differential function of the right kidney was significantly less when compared to the calculation of the geometric mean (p < 0.01). The mean difference between the PFgeom and the PFdors was 1.5 +/- 1.4%. A difference > or = 5% (5.0-9.5%) was obtained in only 6/164 scans (3.7%). Three of 6 patients presented with an underestimated PFdors due to dystopic kidneys on the left side in 2 patients and on the right side in one patient. The other 3 patients with a difference > 5% did not show any renal abnormality.


CONCLUSIONS
The calculation of the PF from the posterior view only will give an underestimated value of the right kidney compared to the calculation of the geometric mean. This effect is not relevant for the calculation of the differential renal function in orthotopic kidneys, so that in these cases the anterior view is not necessary. However, geometric mean calculation to obtain reliable values for differential renal function should be applied in cases with an obvious anatomical abnormality.
Porn
U
U
Klinik und Poliklinik für Nuklearmedizin, Klinikum der Ludwig-Maximilians-Universität München, Innenstadt, Deutschland. uporn@nuk.med.uni-muenchen.de
Rossmüller
B
B
Alalp
S
S
Fischer
S
S
Dresel
S
S
Hahn
K
K
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007668:Kidney / Q000000981:diagnostic imaging* / Q000502:physiology* / Q000503:physiopathology; D007674:Kidney Diseases / Q000000981:diagnostic imaging* / Q000503:physiopathology; D007677:Kidney Function Tests; D008297:Male; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D012044:Regression Analysis; D015203:Reproducibility of Results; D019783:Technetium Tc 99m Dimercaptosuccinic Acid / Q000493:pharmacokinetics
D019275:Radiopharmaceuticals; D019783:Technetium Tc 99m Dimercaptosuccinic Acid