Diffusion-weighted MR imaging of the hippocampus and temporal white matter in Alzheimer's disease

Hanyu, Haruo; Sakurai, Hirofumi; Iwamoto, Toshihiko; Takasaki, Masaya; Shindo, Hiroaki; Abe, Kimihiko

doi:10.1016/s0022-510x(98)00043-4

Cited by 155 publications

(80 citation statements)

References 24 publications

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“…Based on the assumption that the diffusivity is maximal in the direction of fibre tracts, the voxelby-voxel determination of FA can be used in order to tract fibres at the macroscopic level (Mori and van Zijl, 2002). A number of DTI-based studies in AD patients have (Hanyu et al, 1998;Kantarci et al, 2001), anterior and posterior cingulate gyrus (Kantarci et al, 2001;Rose et al, 2000;Takahashi et al, 2002;Zhang et al, 2007), and the corpus callosum (Bozzali et al, 2002;Duan et al, 2006;Sydykova et al, 2006;Teipel et al, 2007b;Xie et al, 2006). hypothesis that the changes produced by AD neuropathology within the brain follow a network of connections that arise from the medial temporal areas (Arriagada et al, 1992a;Morrison and Hof, 2002;Morrison et al, 1986).…”

Section: Connectivity Dysfunction Due To Changes In White Mattermentioning

confidence: 99%

Assessing neuronal networks: Understanding Alzheimer's disease

Bokde

Ewers

Hampel

2009

Progress in Neurobiology

110

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Findings derived from neuroimaging of the structural and functional organization of the human brain have led to the widely supported hypothesis that neuronal networks of temporally coordinated brain activity across different regional brain structures underpin cognitive function. Failure of integration within a network leads to cognitive dysfunction. The current discussion on Alzheimer's disease (AD) argues that it presents in part a disconnection syndrome. Studies using functional magnetic resonance imaging, positron emission tomography and electroencephalography demonstrate that synchronicity of brain activity is altered in AD and correlates with cognitive deficits. Moreover, recent advances in diffusion tensor imaging have made it possible to track axonal projections across the brain, revealing substantial regional impairment in fiber-tract integrity in AD. Accumulating evidence points towards a network breakdown reflecting disconnection at both the structural and functional system level. The exact relationship among these multiple mechanistic variables and their contribution to cognitive alterations and ultimately decline is yet unknown.Focused research efforts aimed at the integration of both function and structure hold great promise not only in improving our understanding of cognition but also of its characteristic progressive metamorphosis in complex chronic neurodegenerative disorders such as AD. Page 3 of 50A c c e p t e d M a n u s c r i p t 3 IntroductionFunctional neuroimaging studies in humans and animals suggest that particular brain regions are necessary for specific cognitive functions. The activations of different brain regions, however, do not appear to occur independently from each other but may occur in a sequential spatio-temporally ordered fashion Murphy et al., 1993). The involved regions integrate into a large-scale network which forms the basis of cognition and closely relates to its complex underlying systemic structural architecture (Horwitz et al., 2005;Lee et al., 2006;Luria, 1973;McIntosh, 2004;Rogers et al., 2007). For example, successful associative learning has been shown to correlate with a change in the effective connectivity, i.e., the influence of activation of one brain region onto another, within a specific neuronal network (Buchel et al., 1999). From the neuroanatomical perspective, connectivity of brain activity is predicted to be confined towards pathways of neuroanatomical connections between specific brain regions (Greicius et al., 2008;Toosy et al., 2004). These neuroanatomical constraints allow generating useful predictive models, specific working hypotheses concerning the effect of localized lesions on specific network functions in complex chronically progressive neurodegenerative system disorders such as Alzheimer's disease (AD).Thus a failure of the regions of a network to interact at a high level of coordination may underpin the cognitive disorders which are present in AD. The failure of network function may be due to interaction failure among the region...

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Section: Connectivity Dysfunction Due To Changes In White Mattermentioning

confidence: 99%

Assessing neuronal networks: Understanding Alzheimer's disease

Bokde

Ewers

Hampel

2009

Progress in Neurobiology

110

View full text Add to dashboard Cite

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“…This was thought likely to be caused by axonal loss or demyelination in these areas, and the decrease was also correlated with the degree of cognitive impairment. In a separate study, Hanyu et al 33 also examined temporal lobe white matter in the hippocampus and temporal stem. They again attempted to assess anisotropy, although because the white matter tracts were not aligned with any of the diffusion-encoding gradient directions, this study can only be regarded as semi-quantitative.…”

Section: Alzheimer's Diseasementioning

confidence: 99%

Applications of diffusion‐weighted and diffusion tensor MRI to white matter diseases – a review

2002

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This paper reviews the current applications of diffusion-weighted and diffusion tensor MRI in diseases of the brain white matter. The contribution that diffusion-weighted imaging has made to our understanding of white matter diseases is critically appraised. The quantitative nature of diffusion MRI is one of its major attractions; however, this is offset by the more advanced hardware required to collect diffusion-weighted images reliably, and the more complex processing to produce quantitative parametric diffusion images. With the now common availability of scanners equipped to perform echo-planar imaging, the acquisition of diffusion tensor images is sure to become more widespread and routine.

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“…Normal white matter tracts exhibit strong anisotropy, while normal gray matter is isotropic. There is some early evidence that anisotropy is decreased in white matter pathways in Alzheimer's disease (Hanyu et al, 1998), depression (Taylor et al, 2004b), and schizophrenia (Buchsbaum et al, 1998), presumably due to degeneration. This study reports on preliminary findings looking at the microstructural integrity of white matter tracts in bipolar patients.…”

Section: Introductionmentioning

confidence: 99%

Cortical White Matter Microstructural Abnormalities in Bipolar Disorder

Beyer

Taylor

MacFall

et al. 2005

Neuropsychopharmacol

144

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This article reports on preliminary findings describing microstructural abnormalities in the white matter of cortical areas thought to be associated with bipolar disorder. In all, 14 patients with bipolar disorder and 21 nonpsychiatrically ill control subjects underwent MR imaging including a diffusion tensor imaging (DTI) pulse sequence (six directions, b ¼ 1000 mm 2 /s). DTI data were analyzed on a workstation using a program that allowed calculation of apparent diffusion coefficient (ADC) and fractional anisotropy (FA) within the following three white matter fiber tracts bilaterally: the orbital frontal cortex, and the superior and middle frontal gyri. These values were compared across patient groups. The left and right orbital frontal white matter exhibited significantly higher ADC values in bipolar subjects than control subjects on both the left (p ¼ 0.028) and right (p ¼ 0.011). Microstructural changes in the white matter of the orbital frontal areas as reflected by increased ADC values appear to be associated with bipolar disorder. Further research is needed to better understand the interaction of microstructural changes and bipolar symptoms and whether these changes are specific to bipolar disorder.

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Diffusion-weighted MR imaging of the hippocampus and temporal white matter in Alzheimer's disease

Cited by 155 publications

References 24 publications

Assessing neuronal networks: Understanding Alzheimer's disease

Assessing neuronal networks: Understanding Alzheimer's disease

Applications of diffusion‐weighted and diffusion tensor MRI to white matter diseases – a review

Cortical White Matter Microstructural Abnormalities in Bipolar Disorder

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