Expanded Imaging Classification of Autosomal Dominant Polycystic Kidney Disease

Abstract

BackgroundThe Mayo Clinic imaging classification of autosomal dominant polycystic kidney disease (ADPKD) uses height-adjusted total kidney volume (htTKV) and age to identify patients at highest risk for disease progression. However, this classification applies only to patients with typical diffuse cystic disease (class 1). Because htTKV poorly predicts eGFR decline for the 5%–10% of patients with atypical morphology (class 2), imaging-based risk modeling remains unresolved.MethodsOf 558 adults with ADPKD in the HALT-A study, we identified 25 patients of class 2A with prominent exophytic cysts (class 2Ae) and 43 patients of class 1 with prominent exophytic cysts; we recalculated their htTKVs to exclude exophytic cysts. Using original and recalculated htTKVs in association with imaging classification in logistic and mixed linear models, we compared predictions for developing CKD stage 3 and for eGFR trajectory.ResultsUsing recalculated htTKVs increased specificity for developing CKD stage 3 in all participants from 82.6% to 84.2% after adjustment for baseline age, eGFR, BMI, sex, and race. The predicted proportion of class 2Ae patients developing CKD stage 3 using a cutoff of 0.5 for predicting case status was better calibrated to the observed value of 13.0% with recalculated htTKVs (45.5%) versus original htTKVs (63.6%). Using recalculated htTKVs reduced the mean paired difference between predicted and observed eGFR from 17.6 (using original htTKVs) to 4.0 ml/min per 1.73 m2 for class 2Ae, and from −1.7 (using original htTKVs) to 0.1 ml/min per 1.73 m2 for class 1.ConclusionsUse of a recalculated htTKV measure that excludes prominent exophytic cysts facilitates inclusion of class 2 patients and reclassification of class 1 patients in the Mayo classification model.

Baseline Characteristics and Patient-Reported Outcomes of ADPKD Patients in the Multicenter TAME-PKD Clinical Trial

“…Seven participants, all female, had atypical, Mayo imaging class 2A MRI imaging with cystic involvement that was segmental, asymmetric or lopsided (36,43). In prior studies from the Mayo and HALT cohorts, the former had more males than females with class 2, while the reverse was observed in HALT (36,44).…”

Genetic identification of inherited cystic kidney diseases for implementing precision medicine: a study protocol for a 3-year prospective multicenter cohort study

“…Total kidney volume will be measured by 2 methods: the stereologic method by using semiautomatic volumetry software (ImageJ version 1.5a, https://imagej.nih.gov/ij/ ) [ 21 ] and the manual method by using the Mayo ellipsoid method [ 18 , 22 ]. Expanded imaging classification will be applied to typical and atypical polycystic kidney cases [ 23 ]. The sonographic images and their interpretations will be collected from pediatric patients.…”

Management of autosomal dominant polycystic kidney disease in the era of disease-modifying treatment options

“…The MIC has been validated in a study by Yu et al, and it was concluded that htTKV is a long-term predictor of decline in GFR [ 24 ]. In a study by Bae et al [ 25 ], htTKV was recalculated after exclusion of prominent exophytic cysts, and the imaging classification based on recalculated htTKV was more predictive of decline in eGFR. The definition of rapid progression is evolving.…”