The Applied Physics Department, The Jerusalem College of Technology, Jerusalem, Israel.
Radiology Department, Haddasah Medical Center, Jerusalem, Israel.
Abdom Radiol (NY). 2021 Jun;46(6):2647-2655. doi: 10.1007/s00261-020-02880-1. Epub 2021 Jan 2.
Partial obstruction of the upper urinary tract is a common urological pathology that leads to progressive atrophy and dysfunction of the kidney. Most methods for evaluating the urine drainage rate, to assess the severity of partial obstruction, involve injection of markers into the blood stream and therefore the filtration rate from the blood effects the drainage rate. This study presents a novel method for assessing the drainage rate from the upper urinary tract by analyzing sequential fluoroscopic images from a routine nephrostogram, in which contrast material is introduced directly into the renal collecting system.
Fluoroscopic images from 36 nephrostograms, following percutaneous nephrolithotomy, were retrospectively evaluated, 19 with a dilated renal pelvis. A radiological model for calculating the radiopacity of the renal pelvis, which reflects the amount of contrast material in each sequential image, was developed. Using this model, an algorithm was designed for generating a drainage curve and calculating the "drainage time" t in which half of the contrast material has drained from the renal pelvis.
Analysis of images of a step-wedge phantom made of an increasing number of contrast material layers showed that the calculated radiopacity of each step was proportional to the amount of contrast material, independent of the background attenuation. Analysis of the nephrostograms showed that the drainage curves highly fitted an exponential function (R = 0.961), with a significantly higher t for dilated cases.
The developed method may be used for a quantitative and accurate estimation of the urine drainage rate.
上尿路部分梗阻是一种常见的泌尿科病理，可导致肾脏进行性萎缩和功能障碍。大多数评估尿液排出率的方法，以评估部分梗阻的严重程度，都涉及将标志物注入血流中，因此滤过率会影响排出率。本研究提出了一种通过分析常规肾盂造影术的连续荧光透视图像来评估上尿路排出率的新方法，其中直接将造影剂引入肾集合系统。
回顾性评估了 36 例经皮肾镜碎石术后的肾盂造影术的荧光透视图像，其中 19 例肾盂扩张。开发了一种用于计算肾盂放射密度的放射学模型，该模型反映了每个连续图像中的造影剂量。使用该模型，设计了一种算法来生成排出曲线并计算“排出时间”t，即一半的造影剂从肾盂中排出。
对由越来越多的造影剂层组成的阶跃楔形体的图像进行分析表明，每个阶跃的计算放射密度与造影剂的量成正比，与背景衰减无关。对肾盂造影术的分析表明，排出曲线高度拟合指数函数（R=0.961），扩张病例的 t 值明显更高。
所开发的方法可用于定量和准确估计尿液排出率。
