Ikuro Namura

Brain tissues segmentation for diagnosis of Alzheimer-type Dementia

We proposed a segmentation method of brain tissues on T2-weighted MR frontal image. In our previous work, we showed an image diagnosis support system for Alzheimer-type Dementia that extracts temporal lobe regions and an intracranial region as regions of interest (ROI) from a T2-weighted MR frontal image and uses the cerebral atrophy rates at the ROI. In this paper, we specifically discuss segmentation of brain tissues which are used for calculation of atrophy rate. We proposed a brain tissue segmentation method using two kinds of unsupervised neural networks: Self-Organizing Maps (SOMs) and Fuzzy Adaptive Resonance Theory (ART). The performance of proposed method was tested in two brain MR images used in daily diagnosis. Proposed method could segment CSF accurately with continuity of brain tissues.

Decline in the severity or the incidence of schizophrenia in Japan: A survey of university students

Clinical manifestations of schizophrenia are believed to be becoming less severe in Japan, but little evidence supports this theory. We investigated the percentages of undergraduate students attending national universities in Japan who required temporary leave and who dropped out because of schizophrenia in the academic years 1986-1987, 1994-1995, and 2013-2014. The percentages of students who required temporary leave and those who dropped out because of schizophrenia significantly decreased over time. The severity of clinical manifestations of schizophrenia may have decreased, enabling more students with schizophrenia to continue their study, or the incidence of schizophrenia might have declined.

Alcoholic brain damage and dementia viewed by MRI, with special consideration on frontal atrophy and white matter damage in dyslipidemic patients

Long‐term intake of excessive alcohol causes various forms of brain damage, most of which are now visualized by magnetic resonance imaging (MRI) and proved to be contributing to the early onset of dementia. Bi‐frontal atrophy has a unique position among these various forms of damage because of its lobar conformation localized only to the higher cortex, and because the same kind of atrophy is also seen in dyslipidemic patients like hypercholesterolemia. Multiple logistic regression analysis of 3100 subjects with MRI revealed no other significant group for this finding. Morphological features of this type of atrophy and its rate of progression are described in this paper, and computerized image analysis showed that this atrophy seems to depend mainly on the decrease of white matter. However, a common biochemical factor underlying the frontal atrophy in these two groups has not yet been identified. Importantly, dyslipidemic patients also show some type of T2 high white matter changes, which are not seen in ‘pure’ alcoholics. For dyslipidemic patients, this white matter change, which seems to be the degradation of myelin sheath, is another basis for early dementia. Although the author can propose a new concept of ‘dyslipidemic dementia’ due to frontal atrophy and white matter damage, details of its mechanism and its relation to alcoholism are left to future investigations.

Extraction of brain regions for image diagnosis of Alzheimer-type Dementia based on atrophy progress speeds

We constructed an image diagnosis support system for Alzheimer-type Dementia that extracts temporal lobe regions and an intracranial region as regions of interest (ROI) from a T2-weighted MR frontal image and uses the cerebral atrophy rates at the ROI. In this paper, we specifically discuss extraction of brain regions and diagnosis support information based on atrophy speeds of the ROI. The proposed method comprises of three steps. Step 1: A first contour that approximates a shape of the temporal lobe region to a triangle is set and Balloon model is applied. Step 2: A temporal lobe AAM is constructed and it is applied to the result obtained in Step 1. Step 3: Intracranial region is extracted using temporal lobe regions detected in Step 2. We demonstrate the potential of our method using actual diagnosis images. Additionally, we calculate atrophy rates of the ROI to consider a possibility for diagnosis of ATD using atrophy progress speeds of the ROI.