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<p>Purpose: To develop a novel voxel-based radiomics extraction technique, and to
investigate the potential association between spatially-encoded radiomics features
of the lungs and pulmonary function.</p><p>Methods: We developed a voxel-based radiomics
feature extraction platform to generate radiomics filtered images. Specifically, for
each voxel in the image, 62 radiomics features were calculated in a rotationally-invariant
3D neighbourhood to capture spatially-encoded information. In general, such an approach
results in an image tensor object, i.e., each voxel in the original image is represented
by a 62-dimensional radiomics feature vector. Two digital phantoms are then designed
to validate the technique's ability to quantify regional image information. To test
the technique as a potential pulmonary biomarker, we generated radiomics filtered
images for 25 lung CT image and are subsequently evaluated against corresponding Galligas
PET images, as the ground truth for pulmonary function, using voxel-wise Spearman
correlation (r). The Canonical Correlation Analysis (CCA)-based feature fusion method
is also implemented to enhance such a correlation. Finally, the Spearman distributions
were compared with 37 individual CT ventilation image (CTVI) algorithms to assess
the overall performance relative to conventional CT-based techniques.</p><p>Results:
Several radiomics filtered images were identified to be correlated with Galligas PET
lung imaging. The most robust association was found to be the Run Length Encoding
feature, Run-Length Non-uniformity (0.21<r<0.65, median=0.45). this association can
be substantially improved (from 0.21<r<0.65 to 0.32<r<0.73) following CCA-based feature
fusion. Furthermore, The association comparison with 37 individual CTVI algorithms
reveals that our voxel-based CT radiomics analysis outperforms most CTVI algorithms
in characterizing the regional lung functions. </p><p>Conclusions: This preliminary
study indicates that spatially-encoded lung texture and lung density are potentially
associated with pulmonary function as measured via Galligas PET ventilation images.
Collectively, low density, heterogeneous coarse lung texture was often associated
with lower Galligas radiotracer amounts.</p>
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