Generating Synthetic T2*-Weighted Gradient Echo Images of the Knee with an Open-source Deep Learning Model.
Authors
Affiliations (4)
Affiliations (4)
- Artificial Intelligence and Translational Imaging (ATI) Lab, Department of Radiology, School of Medicine, University of Crete, Voutes Campus, Heraklion 71003, Greece (K.V., A.H.K., M.E.K.).
- Department of Medical Imaging, University Hospital of Heraklion, Heraklion, Crete 71110, Greece (E.E.V., G.V., A.H.K., M.E.K.).
- Artificial Intelligence and Translational Imaging (ATI) Lab, Department of Radiology, School of Medicine, University of Crete, Voutes Campus, Heraklion 71003, Greece (K.V., A.H.K., M.E.K.); Department of Medical Imaging, University Hospital of Heraklion, Heraklion, Crete 71110, Greece (E.E.V., G.V., A.H.K., M.E.K.); Computational BioMedicine Laboratory, Institute of Computer Science, Foundation for Research and Technology Hellas (ICS-FORTH), Heraklion, Crete 70013, Greece (A.H.K., M.E.K.).
- Artificial Intelligence and Translational Imaging (ATI) Lab, Department of Radiology, School of Medicine, University of Crete, Voutes Campus, Heraklion 71003, Greece (K.V., A.H.K., M.E.K.); Department of Medical Imaging, University Hospital of Heraklion, Heraklion, Crete 71110, Greece (E.E.V., G.V., A.H.K., M.E.K.); Computational BioMedicine Laboratory, Institute of Computer Science, Foundation for Research and Technology Hellas (ICS-FORTH), Heraklion, Crete 70013, Greece (A.H.K., M.E.K.); Division of Radiology, Department for Clinical Science, Intervention and Technology (CLINTEC), Karolinska Institutet, Huddinge 141 52, Sweden (M.E.K.). Electronic address: [email protected].
Abstract
Routine knee MRI protocols for 1.5 T and 3 T scanners, do not include T2*-w gradient echo (T2*W) images, which are useful in several clinical scenarios such as the assessment of cartilage, synovial blooming (deposition of hemosiderin), chondrocalcinosis and the evaluation of the physis in pediatric patients. Herein, we aimed to develop an open-source deep learning model that creates synthetic T2*W images of the knee using fat-suppressed intermediate-weighted images. A cycleGAN model was trained with 12,118 sagittal knee MR images and tested on an independent set of 2996 images. Diagnostic interchangeability of synthetic T2*W images was assessed against a series of findings. Voxel intensity of four tissues was evaluated with Bland-Altman plots. Image quality was assessed with the use of root mean squared error (NRMSE), structural similarity index (SSIM) and peak signal-to-noise ratio (PSNR). Code, model and a standalone executable file are provided on github. The model achieved a median NRMSE, PSNR and SSIM of 0.5, 17.4, and 0.5, respectively. Images were found interchangeable with an intraclass correlation coefficient >0.95 for all findings. Mean voxel intensity was equal between synthetic and conventional images. Four types of artifacts were identified: geometrical distortion (86/163 cases), object insertion/omission (11/163 cases), a wrap-around-like (26/163 cases) and an incomplete fat-suppression artifact (120/163 cases), which had a median 0 impact (no impact) on the diagnosis. In conclusion, the developed open-source GAN model creates synthetic T2*W images of the knee of high diagnostic value and quality. The identified artifacts had no or minor effect on the diagnostic value of the images.