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Artificial Intelligence in Health                                       ViT for neurodegeneration diagnosis




            Table 4. The performance comparison of our model with others in the literature
            Model                             Class  Sensitivity  Specificity  Precision  F1 score  F1 score (micro‑average)
            Ding et al.  (model CNN)          CN       0.59       0.75     0.60      0.59          0.64
                   5
                                              MCI      0.54       0.68     0.55      0.55
                                              AD       0.81      0.94 a    0.76      0.78
            Etminani et al.  (model CNN)*     CN       0.88       0.90     0.81      0.84          0.63
                      4
                                              MCI      0.17      0.94 a    0.20      0.18
                                              AD       0.91 a     0.92     0.83 a    0.87 a
            Etminani et al.  (consensus of human readers)*   †  CN  0.70  0.81  0.64  0.67         0.45
                      4
                                              MCI      0.25       0.75     0.08      0.12
                                              AD       0.47       0.90     0.68      0.56
            Our model (ViT)                   CN       0.90 a    0.95 a    0.90 a    0.90 a        0.81 a
                                              MCI      0.65 a     0.90     0.76 a    0.70 a
                                              AD       0.90       0.88     0.78      0.84
            Notes: All results were obtained using  F-FDG PET brain scans from the ADNI dataset. Besides acquiring a significantly higher F1 score, our model
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            outperforms others in classifying MCI cases by a considerable margin. *The authors considered an additional DLB class in their paper and tested the
            model and human readers in a four-class classification task (CN, MCI, AD, DLB).  Four professional nuclear medicine physicians with 3, 8, 13, and 16
                                                                 †
            years of experience.  The highest values per each metric and class.
                         a
            Abbreviations: AD: Alzheimer’s disease; ADNI: Alzheimer’s Disease Neuroimaging Initiative; CN: Cognitively normal; CNN: Convolutional neural network;
            DLB: Dementia with Lewy bodies;  F-FDG:  F-fluorodeoxyglucose; MCI: Mild cognitive impairment; PET: Positron emission tomography; ViT: Vision
                                 18
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            transformer.
            impact on its decision and a heatmap of the input scan, in   applicable models that can assist experts in NDD diagnosis.
            which the pixels’ intensities illustrate their importance in
            the model’s prediction. Furthermore, we conducted a study   6. Conclusion
            to  reveal  regions’  significance  in  the  model’s  decisions,   We believe  this  research  showcases  the extraordinary
            showing some brain areas are of utmost importance in   potential of the ViT architecture in NDDs classification,
            predicting various conditions.                     which surpasses other methods, including CNNs. Apart
                                                               from their excellent performance, ViTs allow computer
            5.1. Limitations
                                                               vision researchers to benefit from advancements in NLP
            A key goal of this study was to ensure that the model can   due to the sharing of the same transformer architecture.
            distinguish and classify all stages of AD. Therefore, we   Furthermore, ViTs make developing explainable models
            decided to develop the model solely on MCI cases that   more feasible by leveraging the attention mechanism.
            later progressed to AD. However, this sample selection
            might introduce some bias in the dataset regarding the   Acknowledgments
            MCI class and result in the model becoming a prognostic   None.
            MCI-to-AD classifier. In addition, we exclusively relied
            on the ADNI dataset in this research, which may restrict   Funding
            the model’s out-of-distribution generalization.    Data collection and sharing for this project was funded
              Although the critical regions suggested by the proposed   by the ADNI (National Institutes of Health Grant U01
            model are consistent with the literature to a significant   AG024904) and DOD ADNI (Department of Defense
            extent, our findings require more examination and   award  number  W81XWH-12-2-0012).  ADNI  is  funded
            validation by medical domain experts.              by the National Institute on Aging, the National Institute
                                                               of Biomedical Imaging and Bioengineering, and through
              Finally, we should stress that while DNNs demonstrate   generous contributions from the following: AbbVie,
            promising results in NDD classification, they are limited to   Alzheimer’s Association; Alzheimer’s Drug Discovery
            their  datasets,  substantially  affecting  their  generalization   Foundation; Araclon Biotech; BioClinica, Inc.; Biogen;
            performance. In addition, unlike clinical procedures, DNNs   Bristol-Myers Squibb Company; CereSpir, Inc.; Cogstate;
            do not consider all medical factors and base their predictions   Eisai Inc.; Elan Pharmaceuticals, Inc.; Eli Lilly and
            on limited data. Therefore, vast improvements and training on   Company; EuroImmun; F. Hoffmann-La Roche Ltd and
            diverse datasets are critical to designing robust and clinically
                                                               its affiliated company Dec 5, 2024 12:30 PM Genentech,

            Volume 2 Issue 4 (2025)                         43                          doi: 10.36922/AIH025140026
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