Feasible Method to Assess the Performance of a Lung Cancer CT Screening CAD System in Clinical Practice: Dependence on Nodule Size and Density

Abstract

Detection of small pulmonary nodules is the goal of lung cancer screening. Computer-aided detection (CAD) systems are recommended to use in lung cancer computed tomography (CT) screening to increase the accuracy of nodule detection. Size and density of lung nodules are primary factors in determining the risk of malignancy. Therefore, purpose of this study is to apply computer-simulated virtual nodules based on the point spread function (PSF) measured in same scanner (maintaining spatial resolution condition) to assess the CAD system performance dependence on nodule size and density. Virtual nodules with density differences between lung background and nodule density (∆CT) values (200, 300 and 400 HU) and different sizes (4 to 8 mm) were generated and fused on clinical images. CAD detection was performed and free-response receiver operating characteristic (FROC) curves were obtained. Results show that both density and size of virtual nodules can affect detection efficiency. Detailed results are possible to use for quantitative analysis of a CAD system performance. This study suggests that PSF-based virtual nodules could be effectively used to assess the lung cancer CT screening CAD system performance dependence on nodule size and density.

A method for evaluating the performance of computer-aided detection of pulmonary nodules in lung cancer CT screening: detection limit for nodule size and density

“…We have explored the feasibility of using this method to assess CAD performance; in this study, the virtual nodules were suggested to be useful for generating free-response receiver-operating characteristic curves for a CAD system. 16 However, in this preliminary study, the validity of the use of virtual nodules as an alternative to artificial nodules included in a lung phantom was not verified. A comparative study between virtual and artificial nodules is necessary.…”

“…In this study, we first validated the application of virtual nodules [13][14][15][16] regarding their use for the evaluation of CAD performance in place of artificial nodules included in a lung phantom. Next, as a further validation study, virtual nodules were made to appear to be comparable with real nodules with regard to size and density and were applied to the detection test of the CAD system.…”

Generation of realistic virtual nodules based on three‐dimensional spatial resolution in lung computed tomography: A pilot phantom study

“…This method potentially overcomes the limitations of previous simulation techniques for pulmonary nodules. [4][5][6][7][8][9][10][11][13][14][15][16][17][18]21 Our proposed method includes direct deconvolution by division of spatial frequencies. This analysis is essentially the same as a common image deblurring (or restoration).…”

“…The authors have explored and developed another approach to the computer generation of virtual nodules . In this method, virtual nodules are computed from object functions based on the spatial resolution characteristics measured for each CT system .…”

“…4,10,11 The authors have explored and developed another approach to the computer generation of virtual nodules. [15][16][17][18] In this method, virtual nodules are computed from object functions based on the spatial resolution characteristics measured for each CT system. [19][20][21] Once the object functions have been prepared, virtual nodules that correspond to nodule images obtained at each screening site can be generated in terms of the spatial resolution.…”