Expressing kidney uptake during 99Tcm-MAG3 renography in terms of administered activity.
In a study of gamma-camera renography, a digitized time-activity curve, or renogram, was standardized in terms of absolute renal uptake. The algorithm for standardization of the renogram was based on a gamma-camera uptake method employed by Gates and Schlegel et al. All count rates for the background-corrected renograms were converted to percent renal uptake per injected dose per minute (%RU). The maximum value for the scale on the y-axis was set at 20% RU. The renograms were generated from 66 kidneys in 35 patients (27 males, 8 females) aged 19-80 years. Using the newly developed computer program, the shape of the renograms was considered abnormal between 8/52 (15%) and 10/53 (19%) kidneys, depending on the observer, all of which were classified as normal when displayed conventionally. All the renograms for 4 patients with one poorly functioning kidney, and between 8 (28%) and 10 (32%) renograms for 31 patients with two poorly performing kidneys, exceeded the maximum g-axis value of 20% RU. Expression of the renograms based on absolute uptake is helpful in avoiding the potential problem of two poorly functioning kidneys, which may be considered near-normal in terms of count rate. The maximum value on the y-axis in 99Tcm-MAG3 renography should be fixed between 25 and 30% RU, while the actual amplitude of the standardized renogram may depend on the method used for quantification.
Itoh
K
K
Department of Nuclear Medicine, Hokkaido University School of Medicine, Sapporo, Japan.
Kato
C
C
Shiga
T
T
D000328:Adult; D000368:Aged; D005260:Female; D015902:Gamma Cameras; D006801:Humans; D007668:Kidney / Q000000981:diagnostic imaging* / Q000378:metabolism*; D007674:Kidney Diseases / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011866:Radioisotope Renography; D015203:Reproducibility of Results; D012984:Software; D017263:Technetium Tc 99m Mertiatide / Q000493:pharmacokinetics*; D014570:Urologic Diseases / Q000000981:diagnostic imaging*
D017263:Technetium Tc 99m Mertiatide