Repeatability of Ultrasound-Defined Bladder Shape Metrics in Healthy Volunteers

Kaitlyn M Maddra,1 Rui Li,2 Anna S Nagle,2 Adam P Klausner,1 John E Speich2 1Department of Surgery/Division of Urology, Virginia Commonwealth University School of Medicine, Richmond, VA, USA; 2Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University College of Engineering, Richmond, VA, USACorrespondence: John E Speich, Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University College of Engineering, Richmond, VA, USA, Tel +1 804 827 7036, Fax +1 804 827 7030, Email jespeich@vcu.eduPurpose: Recent studies demonstrate the potential value of using non-invasive abdominal ultrasound to quantify bladder shape and its association with disorders of bladder filling and voiding. The aim of the present study was to assess the repeatability of ultrasound-defined bladder shape metrics within the same individual from multiple bladder fills and study visits.Patients and Methods: Healthy volunteers completed an oral hydration protocol with two weekly visits, each with two consecutive bladder fill-void cycles, providing four total fills per participant. Throughout filling, 3-dimensional (3-D) ultrasound images were recorded at 5-minute intervals. Perimeters were manually traced in six cross-sectional planes 30° apart using GE 4D-View software. Diameters, perimeters and cross-sectional areas for the transverse, sagittal and coronal planes were interpolated at three standard bladder volumes of 200, 300, and 400mL. To quantify repeatability, intraclass correlation coefficients (ICCs) and normalized mean absolute differences were calculated for each metric at each standard volume. Moderate and good repeatability were defined as ICC ≥ 0.5 and ICC ≥ 0.75, respectively.Results: Data from 16 healthy volunteers (9 females, 7 males) were analyzed. ICCs for the transverse vertical and horizontal diameters showed good repeatability, and five of nine perimeter ICCs showed moderate or good repeatability. The mean absolute difference/mean ratio was ≤ 4% for all perimeter measurements, ...