路易体痴呆和阿尔茨海默病：DTI 特征的神经退行性模式。
Dementia with Lewy bodies and Alzheimer disease: neurodegenerative patterns characterized by DTI.
机构信息
Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
出版信息
Neurology. 2010 Jun 1;74(22):1814-21. doi: 10.1212/WNL.0b013e3181e0f7cf.
OBJECTIVE
To identify the patterns of diffusivity changes in patients with dementia with Lewy bodies (DLB) and Alzheimer disease (AD) and to determine whether diffusion tensor MRI (DTI) is complementary to structural MRI in depicting the tissue abnormalities characteristic of DLB and AD.
METHODS
We studied clinically diagnosed age-, gender-, and education-matched subjects with DLB (n = 30), subjects with AD (n = 30), and cognitively normal (CN) subjects (n = 60) in a case-control study. DTI was performed at 3T with a fluid-attenuated inversion recovery-based DTI sequence that enabled cortical diffusion measurements. Mean diffusivity (MD) and gray matter (GM) density were measured from segmented cortical regions. Tract-based diffusivity was measured using color-coded fractional anisotropy (FA) maps.
RESULTS
Patients with DLB were characterized by elevated MD in the amygdala and decreased FA in the inferior longitudinal fasciculus (ILF). ILF diffusivity was associated with the presence of visual hallucinations (p = 0.007), and amygdala diffusivity was associated with Unified Parkinson's Disease Rating Scale (r = 0.50; p = 0.005) in DLB. In contrast, patients with AD were characterized by elevated MD in the medial temporal, temporal, and parietal lobe association cortices and decreased FA in the fornix, cingulum, and ILF. Amygdala diffusivity was complementary to GM density in discriminating DLB from CN; hippocampal and parahippocampal diffusivity was complementary to GM density in discriminating AD from CN.
CONCLUSION
Increased amygdalar diffusivity in the absence of tissue loss in dementia with Lewy bodies (DLB) may be related to microvacuolation, a common pathology associated with Lewy body disease in the amygdala. Diffusivity measurements were complementary to structural MRI, demonstrating that measures of diffusivity on diffusion tensor MRI are valuable tools for characterizing the tissue abnormalities characteristic of Alzheimer disease and DLB.
目的
确定路易体痴呆（DLB）和阿尔茨海默病（AD）患者的弥散变化模式，并确定弥散张量 MRI（DTI）是否可补充结构 MRI 来描绘 DLB 和 AD 特有的组织异常。
方法
我们在病例对照研究中，对 30 名临床诊断的年龄、性别和教育相匹配的 DLB 患者、30 名 AD 患者和 60 名认知正常（CN）患者进行了研究。使用基于液体衰减反转恢复的 DTI 序列在 3T 上进行 DTI，该序列可实现皮质弥散测量。从分割的皮质区域测量平均弥散度（MD）和灰质（GM）密度。使用彩色编码的各向异性分数（FA）图测量基于束的弥散度。
结果
DLB 患者的特征是杏仁核 MD 升高和下纵束（ILF）FA 降低。ILF 弥散度与视觉幻觉的存在相关（p = 0.007），而 DLB 患者的杏仁核弥散度与统一帕金森病评定量表（r = 0.50；p = 0.005）相关。相比之下，AD 患者的特征是内侧颞叶、颞叶和顶叶联合皮质的 MD 升高和穹窿、扣带和 ILF 的 FA 降低。杏仁核弥散度与 GM 密度结合可区分 DLB 与 CN；海马和海马旁回弥散度与 GM 密度结合可区分 AD 与 CN。
结论
在没有组织丢失的情况下，DLB 中杏仁核弥散度增加可能与微空泡化有关，这是与杏仁核路易体疾病相关的常见病理学。弥散度测量可补充结构 MRI，表明弥散张量 MRI 上的弥散度测量是描述 AD 和 DLB 特有的组织异常的有价值的工具。
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