Department of Radiology, University of Chicago Hospitals, Chicago, IL 60637, USA.
Acad Radiol. 2010 Jan;17(1):39-47. doi: 10.1016/j.acra.2009.07.004. Epub 2009 Sep 5.
Flat lesions in the colon may result in false-negative computed tomography colonography interpretations. It is unknown whether flat lesions are better measured on two-dimensional (2D) or three-dimensional (3D) images and which settings are optimal for enhanced reproducibility and decreased variability. We evaluated these factors to determine whether 2D or 3D is best for flat lesion measurements.
Eighty-eight lesions in 66 patients from a previously published clinical trial were analyzed. Lesions were viewed with four methods including 2D at three window/level settings and 3D endoluminal view. Lesions in either supine or prone were counted as one dataset. Long axis and height were measured. Criteria of "height" (<or=3 mm high) or "ratio" (height <or=half the long axis) were applied. A subset of lesions was subject to inter- and intra-observer variability analysis.
With the "height" criterion, more datasets were classified as flat in 2D flat (n = 76), 2D soft tissue (n = 82), and 3D (n = 73) views than in the 2D lung (n = 49) view. If long axis is used as the key metric, endoluminal 3D (12.1%) views significantly showed the least inter-observer variability compared to lung (18.9%) or soft tissue (20.2%) views. Intra-observer variability was low overall for all methods.
When characterizing lesions as flat, a consistent viewing method should be used. To minimize inter-observer variability (such as when following a patient over time), it is best to use the ratio criterion for flat lesion definition incorporating the single longest dimension on 3D views as the key metric.
结肠扁平病变可能导致计算机断层结肠成像出现假阴性结果。目前尚不清楚在二维（2D）或三维（3D）图像上测量扁平病变时，哪种方法更好，以及哪种设置可实现最佳的可重复性和最小的变异性。我们评估了这些因素，以确定 2D 或 3D 哪种方法最适合扁平病变的测量。
分析了先前发表的临床试验中 66 名患者的 88 个病变。病变通过 4 种方法进行观察，包括 3 种窗宽/窗位的 2D 以及腔内 3D 视图。仰卧位或俯卧位的病变均视为一个数据集。测量长轴和高度。应用“高度”（<或=3 毫米高）或“比例”（高度<或=长轴的一半）标准进行病变分类。部分病变进行了观察者内和观察者间可变性分析。
使用“高度”标准，与 2D 肺视图（n = 49）相比，更多的数据集在 2D 平坦视图（n = 76）、2D 软组织视图（n = 82）和 3D 视图（n = 73）中被归类为扁平病变。如果以长轴作为关键指标，腔内 3D 视图（12.1%）与肺（18.9%）或软组织（20.2%）视图相比，观察者间的变异性显著最小。所有方法的观察者内变异性总体较低。
在对病变进行平坦特征描述时，应使用一致的观察方法。为了最小化观察者间的变异性（例如在随时间观察患者时），最好使用比例标准来定义扁平病变，将 3D 视图上的单个最长维度作为关键指标。
