Automatic lumen segmentation in IVOCT images using binary morphological reconstruction.
BACKGROUND
Atherosclerosis causes millions of deaths, annually yielding billions in expenses round the world. Intravascular Optical Coherence Tomography (IVOCT) is a medical imaging modality, which displays high resolution images of coronary cross-section. Nonetheless, quantitative information can only be obtained with segmentation; consequently, more adequate diagnostics, therapies and interventions can be provided. Since it is a relatively new modality, many different segmentation methods, available in the literature for other modalities, could be successfully applied to IVOCT images, improving accuracies and uses.


METHODS
An automatic lumen segmentation approach, based on Wavelet Transform and Mathematical Morphology, is presented. The methodology is divided into three main parts. First, the preprocessing stage attenuates and enhances undesirable and important information, respectively. Second, in the feature extraction block, wavelet is associated with an adapted version of Otsu threshold; hence, tissue information is discriminated and binarized. Finally, binary morphological reconstruction improves the binary information and constructs the binary lumen object.


RESULTS
The evaluation was carried out by segmenting 290 challenging images from human and pig coronaries, and rabbit iliac arteries; the outcomes were compared with the gold standards made by experts. The resultant accuracy was obtained: True Positive (%) = 99.29 ± 2.96, False Positive (%) = 3.69 ± 2.88, False Negative (%) = 0.71 ± 2.96, Max False Positive Distance (mm) = 0.1 ± 0.07, Max False Negative Distance (mm) = 0.06 ± 0.1.


CONCLUSIONS
In conclusion, by segmenting a number of IVOCT images with various features, the proposed technique showed to be robust and more accurate than published studies; in addition, the method is completely automatic, providing a new tool for IVOCT segmentation.
Department of Telecommunication and Control, School of Engineering of the University of São Paulo, Av, Prof, Luciano Gualberto, Travessa 3, 158 - sala D2-06, São Paulo, SP CEP 05508-970, Brazil. matheuscardosomg@hotmail.com
Matheus Cardoso
MC
Moraes
Diego Armando Cardona
DA
Cardenas
Sérgio Shiguemi
SS
Furuie
D000818:Animals; D001331:Automation; D001808:Blood Vessels / Q000166:cytology*; D006801:Humans; D007083:Iliac Artery / Q000166:cytology; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D011817:Rabbits; D041623:Tomography, Optical Coherence / Q000379:methods*; D058067:Wavelet Analysis