A deep learning-based approach for the diagnosis of adrenal adenoma: A new trial using CT.

Abstract

OBJECTIVES To develop and validate deep convolutional neural network (DCNN) models for the diagnosis of adrenal adenoma (AA) using CT. METHODS This retrospective study enrolled 112 patients who underwent abdominal CT (non-contrast, early, and delayed phases) with 107 adrenal lesions (83 AAs and 24 non-AAs) confirmed pathologically and with eight lesions confirmed by follow-up as metastatic carcinomas. Three patients had adrenal lesions on both sides. We constructed 6 DCNN models from 6 types of input images for comparison: non-contrast images only (Model A), delayed Phase images only (Model B), three phasic images merged into a 3-channel (Model C), relative-washout-rate (RWR) image maps only (Model D), non-contrast and RWR maps merged into a 2-channel (Model E), and delayed phase and RWR maps merged into a 2-channel (Model F). These input images were prepared manually with cropping and registration of CT images. Each DCNN model with six convolutional layers was trained with data augmentation and hyper-parameter tuning. The optimal threshold values for binary classification were determined from the receiver-operating characteristic curve analyses. We adopted the nested cross-validation method, in which the outer 5-fold cross-validation was used to assess the diagnostic performance of the models and the inner 5-fold cross-validation was used to tune hyperparameters of the models. RESULTS The AUCs with 95% confidence intervals of Models A-F were 0.94 [0.90, 0.98], 0.80 [0.69, 0.89], 0.97 [0.94, 1.00], 0.92 [0.85, 0.97], 0.99 [0.97, 1.00] and 0.94 [0.86, 0.99], respectively. Model E showed high AUC greater than 0.95. CONCLUSION DCNN models may be a useful tool for the diagnosis of AA using CT. ADVANCES IN KNOWLEDGE The current study demonstrates a deep learning-based approach could differentiate adrenal adenoma from non-adenoma using multiphasic CT.