Bakker J, Olree M, Kaatee R, de Lange E E, Moons K G, Beutler J J, Beek F J
Department of Radiology, University Hospital Utrecht, The Netherlands.
Radiology. 1999 Jun;211(3):623-8. doi: 10.1148/radiology.211.3.r99jn19623.
To determine the accuracy and repeatability of ultrasonography (US) with the ellipsoid formula in calculating the renal volume.
The renal volumes in 20 volunteers aged 19-51 years were determined by using US with the ellipsoid formula and magnetic resonance (MR) imaging with the voxel-count method by two independent observers for each modality. The observers performed all measurements twice, with an interval between the first and second examinations. The voxel-count method was the reference standard. Repeatability was evaluated by calculating the SD of the difference (method of Bland and Altman).
Renal volume was underestimated with US by 45 mL (25%) on average. A comparable underestimation was found when the ellipsoid formula was applied to MR images. This indicates that the inaccuracy of US renal volume measurements (a) occurred because the kidney does not resemble an ellipsoid and (b) was not primarily related to the imaging modality. Intra- and interobserver variations in US volume measurements were poor; the SD of the difference was 21-32 mL. For comparison, the SD of the difference in reference-standard measurements was 5-10 mL.
Use of US with the ellipsoid formula is not appropriate for accurate and reproducible calculation of renal volume.
确定使用椭圆体公式的超声检查（US）在计算肾体积时的准确性和可重复性。
20名年龄在19至51岁之间的志愿者的肾体积，由两名独立观察者分别使用椭圆体公式的超声检查和体素计数法的磁共振（MR）成像来测定。观察者对所有测量进行两次，第一次和第二次检查之间有时间间隔。体素计数法为参考标准。通过计算差值的标准差（Bland和Altman方法）来评估可重复性。
超声检查平均低估肾体积45 mL（25%）。当将椭圆体公式应用于MR图像时，也发现了类似程度的低估。这表明超声测量肾体积的不准确（a）是因为肾脏并非类似椭圆体，（b）并非主要与成像方式相关。超声体积测量的观察者内和观察者间差异较差；差值的标准差为21至32 mL。相比之下，参考标准测量中差值的标准差为5至10 mL。
使用椭圆体公式的超声检查不适用于准确且可重复地计算肾体积。
