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Kidney Week

Abstract: SA-PO501

Standardized Image Acquisition and Measurement Methods Yield Accurate Total Kidney Volume Assessment in Polycystic Kidneys via CT or MRI

Session Information

  • ADPKD: Clinical Studies
    October 27, 2018 | Location: Exhibit Hall, San Diego Convention Center
    Abstract Time: 10:00 AM - 12:00 PM

Category: Genetic Diseases of the Kidney

  • 1001 Genetic Diseases of the Kidney: Cystic

Authors

  • Bevilacqua, Micheli U., University of British Columbia, Vancouver, British Columbia, Canada
  • Hague, Cameron, University of British Columbia, Vancouver, British Columbia, Canada
  • Romann, Alexandra, BC Provincial Renal Agency, Vancouver, British Columbia, Canada
  • Sheitt, Hana, University of British Columbia, Vancouver, British Columbia, Canada
  • Vasilescu, Dragos M., University of British Columbia, Vancouver, British Columbia, Canada
  • Yi, Tae won, University of British Columbia, Vancouver, British Columbia, Canada
  • Levin, Adeera, University of British Columbia, Vancouver, British Columbia, Canada
Background

Total Kidney Volume (TKV) assessment is a robust tool for predicting renal prognosis in autosomal dominant polycystic kidney disease (ADPKD) but is difficult to obtain outside of research settings or large academic centers. Bringing TKV measurement into routine clinical practice requires imaging protocols that are widely available and interpretation methods that are feasible for clinical radiologists.

Methods

30 participants >18 years of age with a diagnosis of ADPKD were recruited. Participants underwent 3 scans; an MRI, a low-dose CT (LD) scan and an ultra-low dose CT scan (ULD). The ULD was also reconstructed via model based iterative reconstruction (MBIR) yielding a 4th image set. The images from the 4 modalities were analyzed with three standardized TKV measurement equations and compared to the gold standard method of MRI manual planimetry. Images were interpreted by radiologists using detailed measurement instructions, but without any formal training in TKV. Accuracy, variation and reproducibility of the different imaging modalities and measurement techniques was assessed.

Results

All imaging modalities (LD, ULD and MBIR) as well as all measurement equations (‘Traditional ellipsoid’, ‘Mayo ellipsoid’ and the ‘mid-slice method’) had excellent correlation with the gold standard with r2 values for all being over 0.97. Variation was within ranges reported in previous analyses of TKV measurement, although un-reconstructed ULD and the mid-slice method showed higher variability. Intraclass Correlation Coefficients were >0.98 for all methods, demonstrating high reproducibility. The standardized measurement methods had interpretation times of 5 minutes compared to 45 minutes for the gold standard. The ULD CT scan had a mean effective radiation dose of 0.88 mSv, a value approaching average exposure for an abdominal x-ray series.

Conclusion

Accurate and reproducible TKV measurements can be obtained using time saving interpretation methods and readily available image acquisition methods including abbreviated CT protocols with minimal radiation exposure. These results confirm the accuracy of a variety of standardized TKV measurement methods which may facilitate the implementation of TKV assessment in routine clinical use across diverse practice settings.