Research on Medical Imaging Technology Applied to Early Diagnosis of Alzheimer’s Disease

ABSTRACT

Alzheimer's disease (AD) is a central nervous system disease and causes most cases of dementia. Due to the pathogenesis of AD is still not understood well, the clinical diagnosis of AD is mainly based on patients' clinical manifestations currently, but the sensitivity and specificity of this diagnostic method is limited. With the rapid development of modern medicine, medical imaging plays an increasingly important role in clinical diagnosis. The maturity of various imaging technologies and the improvement of various medical imaging analysis software have brought a new way to the early diagnosis of AD to better detect and monitor brain changes in AD. Medical imaging techniques can be used for early diagnosis of AD to improve the accuracy and sensitivity of diagnosis.

Key words: Alzheimer's disease; Early diagnosis; Medical imaging technology

Introduction

Senile dementia is a general term for all types of dementia that occur in the elderly, including AD, vascular dementia, mixed dementia and other dementia caused by other causes. The prevalence of AD accounts for 60%~70% of senile dementia [1]. As a neurodegenerative disease, the pathogenesis of AD is not completely clear [2]. Its characteristic pathological changes are atrophy of the cerebral cortex, accompanied by deposition of beta-amyloid, neurofibrillary tangles and a decrease in the number of neurons [3-4]. AD is divided into several stages based on cognitive level, and patients with mild cognitive impairment (MCI) may deteriorate to AD or present a stable non-progressive symptom [5]. It will be important for disease awareness and early intervention that accurately predicting whether MCI will be further transformed into AD. This article reviews the current advances in medical imaging technology studies of AD.

Positron emission computed tomography

Positron emission computed tomography (PET) is a three-dimensional imaging technique that injects positron isotope-labeled compounds into the interior of organisms and measures their spatial distribution and temporal characteristics in vitro. It is the latest development in nuclear medicine imaging [6]. Many PET studies have shown that the early stage of AD is mainly characterized by a decrease in glucose metabolism rate in the dome region [7], which is an indicator of early AD diagnosis superior to ordinary MR and can predict disease progression. PET can be used repeatedly in a short period of time by using a short half-life nuclide and has good image contrast and spatial resolution. However, due to its low time resolution and high price, it is not easy to promote.

Magnetic resonance imaging

Magnetic resonance imaging (MRI) is a technique that uses a signal generated by resonance of a nucleus in a magnetic field to be imaged after reconstruction. The most widely used MRI volumetric measurement technique is the semi-automatic threshold tracking technique [8]. MRI is divided into structure magnetic resonance imaging (sMRI) and functional magnetic resonance imaging (fMRI). The sMRI can reflect the morphological changes of the gray matter and effectively detect structural changes such as brain atrophy [9]. MRI is sensitive to the patient's body motion and is prone to artifacts. AD patients are generally difficult to cooperate with the examination, which often leads to examination failure.

Computerized tomography

Computerized tomography (CT) reconstructs a two- or three-dimensional image on a specific level of an object without destroying the structure of it based on projection data of a certain physical quantity (such as wave speed, X-ray intensity, etc.) acquired about the object [10]. CT can show calcification sensitivity [11], easy and safe inspection and high tissue density resolution and is a common means for clinicians to perform imaging examinations on patients with dementia. Brain CT is mainly used to show the anatomical structure and morphological changes of brain tissue, and it is difficult to show brain function and brain metabolism. In recent years, reports on the use of CT to diagnose AD have been gradually reduced.

Discussion and Conclusion

Imaging techniques such as PET, MRI, and CT have their own characteristics in the diagnosis of AD. The combination of structure and functional neuroimaging improves the accuracy of predicting AD [12]. So far, there is no clear standard for the imaging diagnosis of AD. Any of the above imaging techniques cannot independently diagnose AD. Although neuroimaging studies of AD have made great progress, there are still many shortcomings in the early diagnosis of AD individualization.

Acknowledgments

I a new here and I don't have a complete experimental study. Hence, I choose to write this review. Through this process, I learned a lot of medical imaging technology applied to early diagnosis of Alzheimer's disease. This is my time to write a review article in English completely, so thank everyone gives me a hand during my writing. I also want to thank Dr. Karen, who taught me techniques in English writing.

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