Variability of Image Features Computed from Conventional and Respiratory-Gated PET/CT Images of Lung Cancer

Abstract

Radiomics is being explored for potential applications in radiation therapy. How various imaging protocols affect quantitative image features is currently a highly active area of research. To assess the variability of image features derived from conventional [three-dimensional (3D)] and respiratory-gated (RG) positron emission tomography (PET)/computed tomography (CT) images of lung cancer patients, image features were computed from 23 lung cancer patients. Both protocols for each patient were acquired during the same imaging session. PET tumor volumes were segmented using an adaptive technique which accounted for background. CT tumor volumes were delineated with a commercial segmentation tool. Using RG PET images, the tumor center of mass motion, length, and rotation were calculated. Fifty-six image features were extracted from all images consisting of shape descriptors, first-order features, and second-order texture features. Overall, 26.6% and 26.2% of total features demonstrated less than 5% difference between 3D and RG protocols for CT and PET, respectively. Between 10 RG phases in PET, 53.4% of features demonstrated percent differences less than 5%. The features with least variability for PET were sphericity, spherical disproportion, entropy (first and second order), sum entropy, information measure of correlation 2, Short Run Emphasis (SRE), Long Run Emphasis (LRE), and Run Percentage (RPC); and those for CT were minimum intensity, mean intensity, Root Mean Square (RMS), Short Run Emphasis (SRE), and RPC. Quantitative analysis using a 3D acquisition versus RG acquisition (to reduce the effects of motion) provided notably different image feature values. This study suggests that the variability between 3D and RG features is mainly due to the impact of respiratory motion.

The Impact of Optimal Respiratory Gating and Image Noise on Evaluation of Intratumor Heterogeneity on 18F-FDG PET Imaging of Lung Cancer

“…Furthermore, the statistical quality of PET images was shown to affect textural parameters to a lesser extent than respiratory motion, with no significant differences found between images of different statistical quality. The blurring effect of respiratory motion on quantification of intratumor heterogeneity was shown in studies by Yip et al (13), and Oliver et al (21). Although our results are in line with theirs, the observed differences between the respiratory gated and nongated PET images were usually small.…”

Characterization of PET/CT images using texture analysis: the past, the present… any future?

“…More recently, the effects of respiratory motion have been investigated in two studies by comparing TA features on PET images of lung cancer patients with and without respiratory gating, and the studies showed that TA features may be affected in standard nongated acquisitions, particularly in the lower lung lobes [81, 82]. It has also been shown that the use of a respiration-averaged CT scan instead of a helical CT scan for attenuation correction of the PET data has a greater effect on SUV and total lesion glycolysis than on TA metrics [83].…”

Evaluating stability of histomorphometric features across scanner and staining variations: prostate cancer diagnosis from whole slide images

“…A feature is stable if the mean and shape of its distribution is consistent among cohorts of patients who share disease or clinical profiles or outcomes. While feature stability has been examined in the radiology space, [14][15][16][17] relatively little work has been done in the context of QH or in digital pathology.…”