The variability of processing of technetium-99m DTPA renography. Role of interpolative background subtraction.
In quantitative renography, observer-dependent selection of renal outlines and background regions may account for considerable variability. This study of differential renal function with Tc-99m DTPA scintigraphy compares interpolative background subtraction with the authors' routine techniques; the latter involves background-subtracted uptake on data integrated over 1-3 minutes after injection. Other techniques considered were omission of background subtraction and use of 1-2 minute integration. The normal range was established in 24 hypertensive patients who had a normal angiogram and a normal radiometric glomerular filtration rate. The test set of 52 other hypertensive patients included 27 with renal artery stenosis. All techniques correlated well with the routine method (r > or = 0.98); however the interpolative background technique was unique in preserving the depiction of renal asymmetry but reducing the variability of replicate measurements (P < 0.05). Reduced renal function increased the variability of routine measurements, but the interpolative background subtraction method performed better in this instance (P < 0.01). Thus, the new technique appears to improve the definition of renal outlines and increase the reliability of measurements of differential renal function.
Hurwitz
G A
GA
Department of Diagnostic Radiology/Nuclear Medicine, University of Western Ontario, London, Canada.
Champagne
C L
CL
Gravelle
D R
DR
Smith
F J
FJ
Powe
J E
JE
D000465:Algorithms; D006801:Humans; D006978:Hypertension, Renovascular / Q000000981:diagnostic imaging*; D007091:Image Processing, Computer-Assisted; D007668:Kidney / Q000000981:diagnostic imaging*; D011866:Radioisotope Renography / Q000379:methods*; D012016:Reference Values; D015203:Reproducibility of Results; D013382:Subtraction Technique; D016284:Technetium Tc 99m Pentetate
D016284:Technetium Tc 99m Pentetate