3DUS as an alternative to MRI for measuring renal volume in children with autosomal dominant polycystic kidney disease.

BACKGROUND

Total kidney volume, measured by magnetic resonance imaging (MRI), is a validated disease progression marker in adults with autosomal dominant polycystic kidney disease (ADPKD). However, in childhood, MRI is burdensome, explaining the need for alternatives.

METHODS

Kidney volume (KV) was evaluated in 30 children with ADPKD, using three-dimensional ultrasound (3DUS), applying the ellipsoid method and manual contouring (KV KV respectively); manual contouring on MRI (KV), and the ellipsoid method on two-dimensional ultrasound (2DUS, KV). Correlations and differences were evaluated using Pearson's r and Wilcoxon signed-rank tests, and variability using Bland-Altman plots.

RESULTS

All ultrasound volumetry methods showed significantly lower mean (± SD) KV (mL), compared with MRI-KV: 159 (±101); K: 169 (±105); KV: 185 (±110); KV: 206 (±130); all p < 0.001. All had a strong correlation with KV: 2DUS: r = 0.96; 3DUS-ellipsoid: r = 0.89 and 3DUS-contour: r = 0.94. Both before and after correction factor application, Bland-Altman plots showed lower variability and absolute error for KV vs KV and KV.

CONCLUSIONS

Compared with MRI, ultrasound volumetry was prone to underestimation. However, KV represents a valuable alternative for MRI in early ADPKD. Although more time-consuming, KV is recommended over KV for estimation and follow-up of KV in ADPKD children, given its smaller error.