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Uher D, Drenthen GS, Poser BA, Hofman PAM, Wagner LG, van Lanen RHGJ, Hoeberigs CM, Colon AJ, Schijns OEMG, Jansen JFA, Backes WH. DeepFLAIR: A neural network approach to mitigate signal and contrast loss in temporal lobes at 7 Tesla FLAIR images. Magn Reson Imaging 2024; 110:57-68. [PMID: 38621552 DOI: 10.1016/j.mri.2024.04.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Revised: 04/04/2024] [Accepted: 04/10/2024] [Indexed: 04/17/2024]
Abstract
BACKGROUND AND PURPOSE Higher magnetic field strength introduces stronger magnetic field inhomogeneities in the brain, especially within temporal lobes, leading to image artifacts. Particularly, T2-weighted fluid-attenuated inversion recovery (FLAIR) images can be affected by these artifacts. Here, we aimed to improve the FLAIR image quality in temporal lobe regions through image processing of multiple contrast images via machine learning using a neural network. METHODS Thirteen drug-resistant MR-negative epilepsy patients (age 29.2 ± 9.4y, 5 females) were scanned on a 7 T MRI scanner. Magnetization-prepared (MP2RAGE) and saturation-prepared with 2 rapid gradient echoes, multi-echo gradient echo with four echo times, and the FLAIR sequence were acquired. A voxel-wise neural network was trained on extratemporal-lobe voxels from the acquired structural scans to generate a new FLAIR-like image (i.e., deepFLAIR) with reduced temporal lobe inhomogeneities. The deepFLAIR was evaluated in temporal lobes through signal-to-noise (SNR), contrast-to-noise (CNR) ratio, the sharpness of the gray-white matter boundary and joint-histogram analysis. Saliency mapping demonstrated the importance of each input image per voxel. RESULTS SNR and CNR in both gray and white matter were significantly increased (p < 0.05) in the deepFLAIR's temporal ROIs, compared to the FLAIR. The gray-white matter boundary sharpness was either preserved or improved in 10/13 right-sided temporal regions and was found significantly increased in the ROIs. Multiple image contrasts were influential for the deepFLAIR reconstruction with the MP2RAGE second inversion image being the most important. CONCLUSIONS The deepFLAIR network showed promise to restore the FLAIR signal and reduce contrast attenuation in temporal lobe areas. This may yield a valuable tool, especially when artifact-free FLAIR images are not available.
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Affiliation(s)
- Daniel Uher
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Centre, Maastricht, the Netherlands; Mental Health and Neuroscience Institute (MHeNs), Maastricht University, Maastricht, the Netherlands; Department of Neurosurgery, Maastricht University Medical Center, Maastricht, the Netherlands
| | - Gerhard S Drenthen
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Centre, Maastricht, the Netherlands; Mental Health and Neuroscience Institute (MHeNs), Maastricht University, Maastricht, the Netherlands
| | - Benedikt A Poser
- Faculty of Psychology and Neuroscience (FPN), Maastricht University, the Netherlands
| | - Paul A M Hofman
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Centre, Maastricht, the Netherlands; Academic Center for Epileptology, Kempenhaeghe and Maastricht University Medical Centre, Heeze/Maastricht, the Netherlands
| | - Louis G Wagner
- Academic Center for Epileptology, Kempenhaeghe and Maastricht University Medical Centre, Heeze/Maastricht, the Netherlands
| | - Rick H G J van Lanen
- Mental Health and Neuroscience Institute (MHeNs), Maastricht University, Maastricht, the Netherlands; Department of Neurosurgery, Maastricht University Medical Center, Maastricht, the Netherlands
| | - Christianne M Hoeberigs
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Centre, Maastricht, the Netherlands; Academic Center for Epileptology, Kempenhaeghe and Maastricht University Medical Centre, Heeze/Maastricht, the Netherlands
| | - Albert J Colon
- Academic Center for Epileptology, Kempenhaeghe and Maastricht University Medical Centre, Heeze/Maastricht, the Netherlands; Department of Epileptology, CHU-Martinique, Fort-de-France, France
| | - Olaf E M G Schijns
- Mental Health and Neuroscience Institute (MHeNs), Maastricht University, Maastricht, the Netherlands; Department of Neurosurgery, Maastricht University Medical Center, Maastricht, the Netherlands; Academic Center for Epileptology, Kempenhaeghe and Maastricht University Medical Centre, Heeze/Maastricht, the Netherlands
| | - Jacobus F A Jansen
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Centre, Maastricht, the Netherlands; Mental Health and Neuroscience Institute (MHeNs), Maastricht University, Maastricht, the Netherlands; Academic Center for Epileptology, Kempenhaeghe and Maastricht University Medical Centre, Heeze/Maastricht, the Netherlands; Department of Electrical Engineering, Eindhoven University of Technology, Eindhoven, the Netherlands
| | - Walter H Backes
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Centre, Maastricht, the Netherlands; Mental Health and Neuroscience Institute (MHeNs), Maastricht University, Maastricht, the Netherlands; Cardiovascular Diseases Institute (CARIM), Maastricht University, Maastricht, the Netherlands.
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