Effect of observer variability on glomerular filtration rate measurement by renal scintigraphy in dogs.
Observer variation in kidney depth measurement for correction of soft-tissue attenuation and kidney region of interest (ROI) drawing was evaluated using 60 clinical dogs with a wide range of glomerular filtration rate (GFR) for their effect on the calculated percentage uptake of 99mTc-diethylenetriamine pentaacetic acid (DTPA) and individual kidney GFR by scintigraphy. Kidney depth was measured separately on the lateral image using two color tables: a threshold and a continuous red-green-blue. Within-observer variability of the semi-automatic ROI drawing of the estimated total GFR was up to 10% for the right kidney (RK) and 9% for the left kidney (LK). The variability was lower between observers, 6% for RK and 8% for LK. Manual ROI drawing caused more within observer variation than semi-automatic: up to 14% for RK and 11% for LK. Continuous red-green-blue table caused more variation within and between observers than threshold table. Average within-observer variability from both observers of kidney depth measurement on different color tables could vary up to 5.5% and 6.5% variation of the GFR of RK and LK, respectively. Most variation affecting the DTPA percentage uptake came from the ROI drawing technique. Variations of the method because of the effects of both kidney depth and kidney ROI drawing were up to 8% and 10% for RK and LK, respectively. To minimize these variations a threshold scale should be used for the kidney depth measurement and an automatic or semi-automatic ROI should be used whenever possible. In sequential examinations the same person should make all the measurements.
Department of Biomedical Sciences and Public Health, Division of Diagnostic Imaging and Clinical Chemistry, University of Agricultural Sciences, Uppsala, Sweden.
Naruepon
N
Kampa
Peter
P
Lord
Enn
E
Maripuu
D000818:Animals; D004283:Dog Diseases / Q000000981:diagnostic imaging* / Q000503:physiopathology; D004285:Dogs; D005919:Glomerular Filtration Rate / Q000662:veterinary*; D007275:Injections, Intravenous / Q000662:veterinary; D007668:Kidney / Q000000981:diagnostic imaging / Q000378:metabolism; D007674:Kidney Diseases / Q000000981:diagnostic imaging / Q000662:veterinary*; D015588:Observer Variation; D011237:Predictive Value of Tests; D011877:Radionuclide Imaging / Q000662:veterinary; D019275:Radiopharmaceuticals / Q000008:administration & dosage; D016284:Technetium Tc 99m Pentetate / Q000008:administration & dosage
D019275:Radiopharmaceuticals; D016284:Technetium Tc 99m Pentetate