Abstract: FR-PO318

Total Kidney Volume (TKV) by Ellipsoid (EL) versus Manual Segmentation (MS) for Risk Classification in Autosomal Dominant Polycystic Kidney Disease (ADPKD): A Comparative Study

Session Information

Category: Genetic Diseases of the Kidney

  • 801 Cystic Kidney Diseases

Authors

  • Shi, Beili, University Health Network and University of Toronto, Toronto, Ontario, Canada
  • Pourafkari, Marina, University Health Network and University of Toronto, Toronto, Ontario, Canada
  • Iliuta, Ioan-Andrei, University Health Network and University of Toronto, Toronto, Ontario, Canada
  • Guiard, Elsa, University Health Network and University of Toronto, Toronto, Ontario, Canada
  • Quist, Crystal F, University Health Network and University of Toronto, Toronto, Ontario, Canada
  • Song, Xuewen, University Health Network and University of Toronto, Toronto, Ontario, Canada
  • Khalili, Korosh, Department of Medical Imaging, University Health Network and University of Toronto, Toronto, Ontario, Canada
  • Pei, York P., University Health Network and University of Toronto, Toronto, Ontario, Canada
Background

TKV derived by EL is technically simple, less laborous, and used in the Mayo Clinic Risk Classifcation (MCRC).1 However, it is less accurate than MS ("gold standard") and can result in risk misclassification. Our study aims to define the disagreement in TKV measuremnt and its resultant risk misclassification by EL vs. MS.
[1] JASN 26:160-72,2015

Methods

A single center study of 409 consecutive PKD patients who underwent standardized MRI and genetic testing between 4/2011 and 2/2017. TKV by EL and MS will be measured in all patients by a single radiologist. Bland-Atman plots are used to assess agreement.

Results

Of 203 patients who completed analyses, 33 (16%) with atypical imaging patterns were excluded. The clinical characteristics of the remaining patients are shown in Table. The MC risk classes significantly correlated with distinct mutation classes (X2=48, P<0.001, Figure 1). We found >20% disagreement in 11.2% of individual kidney volume and 5.3% of TKV, resulting in misclassification of 24 (14.1%) patients. None of the misclassified cases spanned more than one risk category.

Conclusion

Our preliminary results suggest that TKV measured by EL in a standardized setting did not result in a high rate of risk misclassification of serious clinical consequence.

Patient Characteristics
Total Number170
Gender (M/F)1:1
Age at MRI (y, mean ± SD)44.3 ± 1.1
Serum Creatinine (µmol/L, median with IQR)91.0 (69.3 – 121.2)
Estimated GFR (ml/min.1.73m2, mean ± SD)77.1 ± 2.5
Mutation Class N (%) 
PKD1 truncating + in-frame deletion61 (35.9)
PKD1 non-truncating39 (23.0)
PKD243 (25.3)
No Mutation Detected27 (15.8)

Significant difference between NMD vs. other mutation classes (P<0.001) and PKD1 PT+Indel vs. PKD2 (P=0.043).

Funding

  • Government Support - Non-U.S.