Radiomics for differentiating tumor deposits from lymph node metastasis in rectal cancer

Figure 1 Flowchart of patients’ recruitment pathway. RC: Rectal cancer; CT: Computed tomography; TDs: Tumor deposits; LNM: Lymph node metastasis.

Figure 2 Radiomics workflow. 3D VOI: Three-dimensional volume of interest; GLCM: Gray level co-occurrence matrix; GLSZM: Gray level size zone matrix; GLRLM: Gray level run length matrix; GLDM: Gray level dependence matrix; NGTDM: Neighbouring gray tone difference matrix; ROC: Receiver operating characteristic curve.

Figure 3 Comparisons of the receiver operating characteristic curves, and fit and usefulness evaluation of Rad-score 2. A: In the training set: Area under the curve (AUC) = 0.768 for Rad-score 1, 0.955 for the combined model, and 0.940 for Rad-score 2; B: In the validation set: AUC = 0.700 for Rad-score 1, 0.930 for the combined model, and 0.918 for Rad-score 2; C: The calibration curve of Rad-score 2 shows good agreement between the predicted and observed risks in the training cohort; D: The decision curve demonstrates that Rad-score 2 obtains more benefit than “treat all”, “treat none”, and Rad-score 1. Rad-score 1: Rad-score of the main tumor; Rad-score 2: Rad-score of the largest peritumoral nodule; AUC: Area under the curve.

Figure 4 Case presentation. A: A 56-year-old man with upper RC, the nodule of TDs (size: 24 mm × 16 mm) had an irregular shape; B: A 44-year-old man with lower RC, the nodule of TDs (size: 14 mm × 11 mm) had a regular oval shape. It is difficult to distinguish TDs and LNM from conventional imaging findings. For these two patients, Rad-score of the largest peritumoral nodule achieved correct diagnosis (values = 0.98 and 0.97, respectively). RC: Rectal cancer; TDs: Tumor deposits; LNM: Lymph node metastasis.