Limited Performance of Estimated Total Kidney Volume for Follow-up of ADPKD

Abstract

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Evaluating the Safety and effectivenesS in adult KorEaN patients treated with Tolvaptan for management of autosomal domInAnt poLycystic kidney disease (ESSENTIAL): short-term outcomes during the titration period

“…The second limitation is that the change of 1.3% in htTKV is close to the range of measurement error in the ellipsoid method. Mean bias of reproducibility between observers was 0.9% in the ellipsoid method [ 32 ]. However, a decrease of 1.7% including increased htTKV in this study could be significant over 4 weeks.…”

Clinical Quality Control of MRI Total Kidney Volume Measurements in Autosomal Dominant Polycystic Kidney Disease

“…CT and MRI both produce cross-sectional kidney images that can be manually contoured for organ volume measurements [ 8 ], but MR is commonly recommended because it avoids the risks of ionizing radiation, which can become considerable in patients having serial CT scans [ 9 ]. MR-based TKV, calculated by ellipsoidal estimation from length, width, and depth measurements, has limited repeatability [ 10 , 11 ]. Manually contouring the renal boundaries on every slice appears to have achieved high intra-observer repeatability with a percent difference of 0.8–3.5% and high inter-observer repeatability of 1.2–7.1% [ 10 , 11 , 12 , 13 , 14 , 15 ].…”

“…MR-based TKV, calculated by ellipsoidal estimation from length, width, and depth measurements, has limited repeatability [ 10 , 11 ]. Manually contouring the renal boundaries on every slice appears to have achieved high intra-observer repeatability with a percent difference of 0.8–3.5% and high inter-observer repeatability of 1.2–7.1% [ 10 , 11 , 12 , 13 , 14 , 15 ]. Moreover, several artificial intelligence (AI)—assisted segmentation algorithms showed high agreement with manual segmentation results with noninferior repeatability and substantial time savings [ 16 , 17 ].…”

Size Matters: How to Characterize ADPKD Severity by Measuring Total Kidney Volume

“…The ellipsoidal method of estimating volume (TKV = (length × width × depth × pi/6) is easy to perform and readily available to clinicians who do not have imaging expertise. But this method has poor inter-reader reproducibility, with a coefficient of variation of 7 to 17% [ 4 , 5 ]. Considering that the average annual TKV growth rate in TEMPO 3:4, a clinical trial of tolvaptan treatment in ADPKD, was only 2.8% to 5.5%, with or without tolvaptan treatment, respectively, the ht-TKV measurement reproducibility needs to be well under 2.8% to be useful for annual follow-up assessments.…”

“…Manually contouring kidney outlines on every slice of the MRI has better reproducibility, ~3.4% to 6%, but is still not sufficient for monitoring individual subjects [ 4 , 5 ]. Manual contouring is also tedious, time-consuming, and therefore costly because kidney borders on every slice of an MR series of images must be outlined.…”