Synthetic temporal bone CT generation from UTE-MRI using a cycleGAN-based deep learning model: advancing beyond CT-MR imaging fusion

Abstract

ObjectivesThe aim of this study is to develop a deep-learning model to create synthetic temporal bone computed tomography (CT) images from ultrashort echo-time magnetic resonance imaging (MRI) scans, thereby addressing the intrinsic limitations of MRI in localizing anatomic landmarks in temporal bone CT.Materials and methodsThis retrospective study included patients who underwent temporal MRI and temporal bone CT within one month between April 2020 and March 2023. These patients were randomly divided into training and validation datasets. A CycleGAN model for generating synthetic temporal bone CT images was developed using temporal bone CT and pointwise encoding-time reduction with radial acquisition (PETRA). To assess the model's performance, the pixel count in mastoid air cells was measured. Two neuroradiologists evaluated the successful generation rates of 11 anatomical landmarks.ResultsA total of 102 patients were included in this study (training dataset, n = 54, mean age 58 +/- 14, 34 females (63%); validation dataset, n = 48, mean age 61 +/- 13, 29 females (60%)). In the pixel count of mastoid air cells, no difference was observed between synthetic and real images (679 +/- 342 vs 738 +/- 342, p = 0.13). For the six major anatomical sites, the positive generation rates were 97-100%, whereas those of the five major anatomical structures ranged from 24% to 83%.ConclusionWe developed a model to generate synthetic temporal bone CT images using PETRA MRI. This model can provide information regarding the major anatomic sites of the temporal bone using MRI.Clinical relevance statementThe proposed algorithm addresses the primary limitations of MRI in localizing anatomic sites within the temporal bone.Key Points...