Multiphase convolutional dense network for the classification of focal liver lesions on dynamic contrast-enhanced computed tomography

Figure 1 Four-phase images processing pipeline for multiphase convolutional dense network. AP: Arterial phase; DP: Delayed phase; HU: Hounsfield unit; MD-CDN: Multiphase convolutional dense network; PP: Precontrast phase; PVP: Portal venous phase; ROI: Region of interest.

Figure 2 Architecture of the proposed multiphase convolutional dense network. AP: Arterial phase; DP: Delayed phase; FLLs: Focal liver lesions; HCC: Hepatocellular carcinoma; PP: Precontrast phase; PVP: Portal venous phase.

Figure 3 The representative correctly classified and misclassified categories. For each patient, axial four-phase (PP, AP, PVP, DP) computed tomography images were obtained and focal liver lesions were diagnosed by histopathologic evaluation after biopsy or surgery. A: A 33-year-old man with focal nodular hyperplasia was correctly classified as category C; B: A 54-year-old woman with hemangioma was misclassified as category D; C: A 52-year-old man with hepatic abscess was correctly classified as category D; D: An 82-year-old woman with hepatic abscess was misclassified as category B; E: A 55-year-old man with HCC was correctly classified as category A; F: A 38-year-old woman with HCC was misclassified as category C; G: A 75-year-old man with liver metastases derived from colorectal cancer was correctly classified as category B. And there was no misclassification for the metastasis group. AP: Arterial phase; DP: Delayed phase; PP: Precontrast phase; PVP: Portal venous phase.

Figure 4 The receiver operating characteristic analysis of model's classification performance on test set and calibration curve of model's classification probability for each category. A: The receiver operating characteristic analysis of model's classification performance on test set; B: Calibration curve of model's classification probability for each category. FLLs: Focal liver lesions; HCC: Hepatocellular carcinoma; ROC: Receiver operating characteristic.

Figure 5 Predicted probability heatmaps. The top color bar represents the classification probability of the model from 0 to 1, which corresponds to dark blue to bright yellow. A: Shows the results from normal four-phase input; B: Shows the results from different “phase cheating” sets as indicated in the policy of input data; C: Shows the representative examples. AP: Arterial phase; DP: Delayed phase; PP: Precontrast phase; PVP: Portal venous phase.