Reproducibility of 99mTc-mercaptoacetyltriglycine renography: population comparison

To evaluate reproducibility of diuretic renography, performed according to current guidelines in adult and pediatric patient populations.

Fifty adult and 50 pediatric renograms were processed twice by each of three observers. For differential renal function (DRF) assessment, intraclass correlation coefficient (ICC), standard deviation of DRF calculation and the repeatability parameter were calculated. For drainage assessment, ICC was calculated. Intraobserver and interobserver analysis was performed for both parameters. Patient groups and subgroups (age, DRF asymmetry, drainage) were compared by analysis of variance.

Interobserver analysis, adult patient group: DRF-repeatability 4.20%, ICC 0.99. Drainage-ICC 0.92/1.00 (left/right kidney). Pediatric patient group: DRF-repeatability 7.80%, ICC 0.97. Drainage-ICC 0.93/0.85 (left/right kidney). Intraobserver analysis, adult patient group: DRF-repeatability 2.61%, ICC 0.99. Drainage-ICC 0.92/1.00 (left/right kidney). Pediatric patient group: DRF-repeatability 4.76%, ICC 0.98. Drainage-ICC 0.92/0.88 (left/right kidney). Highest repeatability and thus highest DRF dispersion was found in the subgroup of patients with poor/impaired kidney drainage and reduced DRF (repeatability 11.3%, analysis of variance, P<0.001).

Reproducibility of DRF estimation was excellent in adults in both intraobserver and interobserver analysis. In pediatric patients, intraobserver DRF reproducibility was very good, whereas variation in interobserver analysis was rather high with a potential influence on patient management, but occurred mainly in a subgroup of patients with impaired drainage and ipsilaterally reduced DRF. Drainage assessment was highly reproducible in both patient groups; factors confounding drainage interpretation in discordant patient cases remained unidentified.