Validation of automated computed tomography segmentation software to assess body composition among cancer patients

Assessing body composition using computed tomography (CT) can help predict the clinical outcomes of cancer patients, including surgical complications, chemotherapy toxicity, and survival. However, manual segmentation of CT images is labor-intensive and can lead to significant inter-observer variability. In this study, we validate the accuracy and reliability of automatic CT-based segmentation using the Data Analysis Facilitation Suite (DAFS) Express software package, which rapidly segments single CT slices.

The study analyzed single-slice images at the third lumbar vertebra (L3) level (n = 5973) of patients diagnosed with non-metastatic colorectal (n = 3098) and breast cancer (n = 2875) at Kaiser Permanente Northern California. Manual segmentation used SliceOmatic with Alberta protocol HU ranges; automated segmentation used DAFS Express with identical HU limits. The accuracy of the automated segmentation was evaluated using the DICE index, the reliability was assessed by intra-class correlation coefficients (ICC) with 95 % CI, and the agreement between automatic and manual segmentations was assessed by Bland-Altman analysis. DICE scores below 20 % and 70 % were considered failed and poor segmentations, respectively, and underwent additional review. The mortality risk associated with each tissue's area was generated using Cox proportional hazard ratios (HR) with 95 % CI, adjusted for patient-specific variables including age, sex, race/ethnicity, cancer stage and grade, treatment receipt, and smoking status. A blinded review process categorized images with various characteristics for sensitivity analysis.

The mean (standard deviation, SD) ages of the colorectal and breast cancer patients were 62.6 (11.4) and 56 (11.8), respectively. Automatic segmentation showed high accuracy vs. manual segmentation, with mean DICE scores above 96 % for skeletal muscle (SKM), visceral adipose tissue (VAT), and subcutaneous adipose tissue (SAT), and above 77 % for intermuscular adipose tissue (IMAT), with three failures, representing 0.05 % of the cohort. Bland-Altman analysis of 5973 measurements showed mean cross-sectional area differences of -5.73, -0.84, -2.82, and -1.02 cm² for SKM, VAT, SAT and IMAT, respectively, indicating good agreement, with slight underestimation in SKM and SAT. Reliability Coefficients ranged from 0.88 to 1.00 for colorectal and 0.95-1.00 for breast cancer, with Simple Kappa values of 0.65-0.99 and 0.67-0.97, respectively. Additionally, mortality associations for automated and manual segmentations were similar, with comparable hazard ratios, confidence intervals, and p-values. Kaplan-Meier survival estimates showed mortality differences below 2.14 %.

DAFS Express enables rapid, accurate body composition analysis by automating segmentation, reducing expert time and computational burden. This rapid analysis of body composition is a prerequisite to large-scale research that could potentially enable use in the clinical setting. Automated CT segmentations may be utilized to assess markers of sarcopenia, muscle loss, and adiposity and predict clinical outcomes.