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Advanced Neurology                                                Diffusion model for brain tumor classification



            1. Introduction                                    Geometry Group (VGG)16, VGG19, and InceptionV3, and
                                                               the generalizability of models trained on DDM-generated
            Brain tumors are among the most complex and life-  datasets was assessed. By integrating DDM with CDCNN,
            threatening forms of cancer, with significant impacts   this approach addresses both the need for robust diagnostic
            on morbidity and mortality worldwide.  According to   accuracy and the ethical imperative of patient data privacy.
                                              1
            the Globocan 2022 estimates, brain tumors accounted   The proposed method demonstrates improved predictive
            for over 321,000 new cases and approximately 248,500   performance, supporting its potential as a reliable, privacy-
            deaths globally in 2022.  These tumors may be malignant,   preserving  tool  for  brain  tumor  classification  in  clinical
                               2
            exhibiting rapid proliferation and potential for metastasis,   and research applications.
            or benign, with slower growth and generally favorable
                                  1,3
            outcomes after treatment.  The most common types   1.1. Related research
            include gliomas, meningiomas, and pituitary tumors, each   Over the past couple of years, considerable efforts have
            with distinct biological behaviors and clinical challenges. 4,5
                                                               been directed toward the development of classification
              Accurate diagnosis of brain tumors is essential for   systems aimed at achieving precise and efficient distinction
            effective treatment planning, yet remains challenging due   of brain tumors. Research designs have relied on
            to tumor heterogeneity, overlapping imaging features,   various methodological frameworks, including classical
            and variability in radiological interpretation.  Magnetic   supervised learning and DL structures, such as CNNs
                                                6-8
            resonance imaging (MRI) is the primary diagnostic tool,   and transfer learning designs. To date, most published
            offering  detailed  structural  and  functional  information   works have focused on binary classification, which is
            through  sequences,  such  as T1,  T1c,  T2,  and fluid-  generally feasible given the exaggerated morphology of
                                                9,10
            attenuated inversion recovery (FLAIR).  Despite    many tumors. This evidential burden, however, increases
            these advancements, conventional diagnosis remains   severity-fold when classifiers are required to discriminate
            labor-intensive, prone to inter-observer variability, and   among multiple tumor types, a challenge further
            dependent on specialized expertise.  Computer-aided   complicated by the highly similar morphologies shared by
                                          4,11
            diagnosis systems, driven by machine learning and   numerous neoplasms.
            deep learning (DL), have shown promise in improving
            tumor detection, segmentation, and classification. 12,13    Traditional machine-learning workflows usually
            Convolutional neural networks (CNNs), in particular,   proceed through sequential  phases  ending with the
            outperform traditional machine learning techniques in   generation and identification of handcrafted features.
            complex classification tasks. However, their performance is   Vastly differing techniques, such as the discrete wavelet
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            hindered by the scarcity of large, diverse, and high-quality   transform,  gray-level co-occurrence matrix,  and
                                                               evolutionary algorithms, specifically genetic algorithms,
            datasets. 14,15  Furthermore, data availability is also limited   have been integrated into such pipelines to enhance
            by privacy regulations, as medical images often contain
            identifiable patient information. 16,17            descriptive power. Support vector machines (SVMs)
                                                               remain the most widely employed classifiers due to their
              Synthetic data augmentation offers a potential solution   near-optimal predictive accuracy, although alternative
            to both data scarcity and privacy concerns. Generative   models, such as random forests, extreme learning
            adversarial networks (GANs) have been widely used to   machines, and sequential minimal optimization, have also
            create realistic medical images while preserving patient   been considered. 21,22
                     18
            anonymity.  However, GAN-based augmentation can
                                                                 Despite their utility, manual feature extraction
            suffer from mode collapse, training instability, and limited   introduces pragmatic and methodological limitations: The
            variability.  Recently, denoising diffusion models (DDMs)
                    8
            have emerged as a powerful alternative, generating   process is time-consuming, error-prone, and dependent on
            high-fidelity  synthetic  images  through  a  progressive   structured, human-defined functions whose effectiveness
            noise removal process that offers more stable training   is constrained by prior knowledge of tumor characteristics,
            and greater diversity in outputs.  This study proposed a   particularly spatial localization. Therefore, it is of utmost
                                      19
            conditional deep CNN (CDCNN) model that uses DDM-  importance to develop classification systems that minimize
            based synthetic augmentation to enhance brain tumor   reliance on highly curated, manually defined features.
            classification. The primary objective is to evaluate whether   DL techniques have been extensively utilized in medical
            DDM-based   augmentation  improves  classification  imaging and brain tumor classification. They do not rely
            accuracy compared to traditional GAN-based approaches.   on manually engineered features; however, pre-processing
            The performance of CDCNN was further compared with   steps and careful selection of appropriate architectures are
            established CNN architectures, such as ResNet50, Visual   often needed to enhance classification accuracy.  In the
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            Volume 4 Issue 4 (2025)                         89                           doi: 10.36922/AN025130025
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