Correlation coefficient based supervised locally linear embedding for pulmonary nodule recognition.
OBJECTIVE
Dimensionality reduction techniques are developed to suppress the negative effects of high dimensional feature space of lung CT images on classification performance in computer aided detection (CAD) systems for pulmonary nodule detection.


METHODS
An improved supervised locally linear embedding (SLLE) algorithm is proposed based on the concept of correlation coefficient. The Spearman's rank correlation coefficient is introduced to adjust the distance metric in the SLLE algorithm to ensure that more suitable neighborhood points could be identified, and thus to enhance the discriminating power of embedded data. The proposed Spearman's rank correlation coefficient based SLLE (SC(2)SLLE) is implemented and validated in our pilot CAD system using a clinical dataset collected from the publicly available lung image database consortium and image database resource initiative (LICD-IDRI). Particularly, a representative CAD system for solitary pulmonary nodule detection is designed and implemented. After a sequential medical image processing steps, 64 nodules and 140 non-nodules are extracted, and 34 representative features are calculated. The SC(2)SLLE, as well as SLLE and LLE algorithm, are applied to reduce the dimensionality. Several quantitative measurements are also used to evaluate and compare the performances.


RESULTS
Using a 5-fold cross-validation methodology, the proposed algorithm achieves 87.65% accuracy, 79.23% sensitivity, 91.43% specificity, and 8.57% false positive rate, on average. Experimental results indicate that the proposed algorithm outperforms the original locally linear embedding and SLLE coupled with the support vector machine (SVM) classifier.


CONCLUSIONS
Based on the preliminary results from a limited number of nodules in our dataset, this study demonstrates the great potential to improve the performance of a CAD system for nodule detection using the proposed SC(2)SLLE.
School of Electronic and Information Engineering, Hebei University of Technology, Tianjin, 300401, China; Department of Electrical and Computer Engineering, University of Massachusetts Lowell, Lowell, MA 01854, USA.
Panpan
P
Wu
School of Electronic and Information Engineering, Hebei University of Technology, Tianjin, 300401, China.
Kewen
K
Xia
Department of Electrical and Computer Engineering, University of Massachusetts Lowell, Lowell, MA 01854, USA. Electronic address: hengyong-yu@ieee.org.
Hengyong
H
Yu
D006801:Humans; D008962:Models, Theoretical; D012680:Sensitivity and Specificity; D003074:Solitary Pulmonary Nodule / Q000175:diagnosis*
Dimensionality reduction; Pulmonary nodule recognition; Spearman's rank correlation coefficient; Supervised locally linear embedding
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