Reducing the Acquisition Time for Magnetic Resonance Imaging Using Super-resolution Image Generation and Evaluating the Accuracy of Hippocampal Volumes for Diagnosing Alzheimer's Disease

Nobukiyo Yoshida^1,2Hajime Kageyama^1,3Hiroyuki Akai¹Satoshi Kasai⁴Kei Sasaki⁴Noriko Sakurai⁴Naoki Kodama^4*

• ¹Department of Radiology, Institute of Medical Science, The University of Tokyo, Tokyo, Japan
• ²Department of Radiological Technology, Faculty of Medical Technology, Niigata University of Health and Welfare, Nigata, Japan
• ³Graduate Division of Health Sciences, Komazawa University, Tokyo, Japan
• ⁴Department of Radiological Technology, Faculty of Medical Technology, Niigata University of Health and Welfare,, Nigata, Japan

Brain magnetic resonance imaging (MRI) is important for diagnosing Alzheimer's disease (AD), and MRI acquisition time should be reduced. The current study aimed to identify which Pix2Pix-based super-resolution images can reduce errors associated with brain anatomical analysis with diffeomorphic deformation examination and MRI acquisition time. Fifty patients with dementia who uderwent scanning using a 3-T MRI scanner in the OASIS-3 database were used to construct a superresolution network. Network training was performed using a scaled image (64 × 64) down-sampled from the original image as the input image and paired with the original high-resolution (256 × 256) supervised image. The hippocampal volume was measured using brain anatomical analysis with diffeomorphic deformation software, which employs machine learning algorithms and performs voxel-based morphometry. Peak signal-to-noise ratio (PSNR) and Multiscale structural similarity (MS-SSIM) score were used to objectively evaluate the generated images. At λ = e 3 , the PSNR and MS-SSIM score of the generated images were 27.91 ± 1.78 dB and 0.96 ± 0.0045, respectively. This finding indicated that the generated images had the highest objective evaluation. Using the images generated at λ = e 4 , the left and right hippocampal volumes did not significantly differ between the original and generated super-resolution images (P = 0.76, P = 0.19, respectively). With superresolution using the Pix2Pix network, the hippocampal volume can be accurately measured, and the MRI acquisition time can be reduced. The proposed method does not require special hardware and can be applied to previous images.