Quantitative evaluation of spatial distribution of line structure in the lung for computer‐aided diagnosis of pulmonary nodules
Hidenori Shikata, Hiroko Kitaoka, Yoshinobu Sato, Takeshi Johkou, Hironobu Nakamura, Shinichi Tamura · Systems and Computers in Japan · 2003
Abstract In the discrimination of benign and malignant pulmonary nodules, it is considered very important to evaluate the spatial distribution of the line structure around the nodule. For quantitative evaluation, a computer must be used. This paper proposes a method in which line structures, such as vessels, in the chest CT image are extracted, and their spatial distribution is quantitatively evaluated. First, the line structures in the three‐dimensional CT image are extracted, and the direction of the central line is estimated from the eigenvector of the Hessian matrix. The angle between the direction vector of a point on the central line and the vector directed from that point to the nodule center is defined as the “centripetal angle.” By a statistical analysis of the distribution of the centripetal angle, the spatial distribution of the line structure is estimated. In the proposed method, only the variation of the nodule center can affect the result. Consequently, stable operation is expected with a simple manipulation. The method is applied to 20 clinical cases, and satisfactory classification results are obtained. The effects of the image reconstruction algorithm and of parameter values such as the threshold of line structure extraction on the results of the proposed method are examined, and its robustness and range of application are determined. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(9): 58–70, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/scj.10222