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Kidney Week

Abstract: TH-PO830

Total Kidney Volume (TKV) Measurements in Autosomal Dominant Polycystic Kidney Disease (ADPKD) by 3D Ultrasound (3D-US) vs. Ultrasound Ellipsoid (US-EL)

Session Information

Category: Genetic Diseases of the Kidneys

  • 1001 Genetic Diseases of the Kidneys: Cystic

Authors

  • Akbari, Pedram, Toronto General Hospital UHN, Toronto, Ontario, Canada
  • Nasri, Fatemeh, Toronto General Hospital UHN, Toronto, Ontario, Canada
  • Quist, Crystal F., Toronto General Hospital UHN, Toronto, Ontario, Canada
  • Guiard, Elsa, Toronto General Hospital UHN, Toronto, Ontario, Canada
  • Iliuta, Ioan-Andrei, University Health Network and University of Toronto, Toronto, Ontario, Canada
  • Ahmed, Syed Essam, Toronto General Hospital UHN, Toronto, Ontario, Canada
  • Calvaruso, Luca, University Health Network, Toronto, Canada
  • Atri, Mostafa, University Health Network and University of Toronto, Toronto, Ontario, Canada
  • Khalili, Korosh, University Health Network and University of Toronto, Toronto, Ontario, Canada
  • Pei, York P., University Health Network and University of Toronto, Toronto, Ontario, Canada
Background

Total kidney volume (TKV) is a validated prognostic biomarker for risk assessment in ADPKD. TKV by magentic resonance imaging and manual segmentation (MRI-MS) is the “gold standard”, but is relatively expensive, time-consuming, and not readily accessible. 3D-US is a new technology which may provide greater precision and accuracy for measuring TKV than US-EL. Here, we report a comparative study of these two US techniques for TKV measurements against MRI-MS.

Methods

We conducted a prospective study of 123 patients recruited at a PKD specialty center who underwent a standardized 3D-US and MRI. Kidney volumes (i.e. single kidney and TKV) by 3D-US and US-EL measured by 5 different experienced ultrasound technicians were compared to those by MRI-MS derived from an experienced radiologist blinded to patient clinical results. Bland-Altman plots were used to assess the agreement of TKV measurements by US vs. MRI.

Results

Table 1 shows the study patient characteristics. We found the accuracy of TKV measurements by US was operator-dependent and varied between different technicians. Compared to MRI-MS, Bland-Altman plots of TKVs by 3D-US and US-EL revealed a similar bias (-9.0% vs. -10.2%), range of diagreement (-42.25 to 24.31% vs. -41.25 to 20.85%), and difference of greater than 20% (27.2% & 24.3%), respectively. Converting height and age-adjusted TKV's to the Mayo Class Imaging Class (MCIC) we found a misclassifcation rate of 22.8% and 23.5% by 3D-US and US-EL, respectively.

Conclusion

TKV measurements by 3D-US and US-EL are less accurate than MRI-MS. Both US tecniques displayed similar bias, accuracy, and are operator-dependent; however, TKV by US-EL is simpler to use and more readily available. These factors need to be considered when US-dervied TKV is used for risk assessment in ADPKD as misclassification of MCIC (esp. 1B to 1C) can have important clinical consequence.

Table 1. Patient characteristics
 N=123
Age (years) mean ± SD45 ± 15
Gender, M:F1 : 1.2
s-Cr (mg/dL) mean ± SD1.14 ± 0.48
Height (meters) mean ± SD1.69 ± 0.9
TKV (mL) mean ± SD1116 ± 822

Funding

  • Government Support - Non-U.S.