1First Department of Internal Medicine Hirosaki University School of Medicine, 2Second Department of Surgery Hirosaki University School of Medicine, 3Department of Surgery, Kizukuri Adult Disease Center Hospital
Thyroid nodules, Brightness analysis, Determination of the nodule border, Clarity of the nodule border
Using an image processor, we defined the border of a thyroid nodule on an ultrasonic image as a set of points, where the local brightness gradient (隆B) indicates a maximal value. The determined border line appeared to be compatible with the visual one. Furthermore, we introduced a clarity index (CI), defined as the ratio of the number of points indicating a high 隆B value to the number of points indicating a low 隆B value, in order to quantify border clarity. The CI exhibited a value of more than 5, 0.5 to 2, and 2.58 in thyroid nodules presenting a cystic pattern, solid pattern, and mixed pattern, respectively. The border determination process, which we call brightness analysis, can be extensively applied to estimate nodular lesions in other organs.