摘要目的 研究弥散峰度成像(DKI)对脑组织灰质和白质的描述以及在脑中风诊断中的应用.方法 采用2例正常人以及15例脑中风患者(包含9例脑梗死,急性、亚急性和陈旧性各占3例)的脑部核磁共振图像作为试验数据.针对每例数据各个像素位置,分别对9个不同弥散梯度场下各个信号强度进行非线性拟合得到弥散系数(D值)和弥散峰度(K值),进而做出ADC图和DKI图.观察比较分析各例在ADC图和DKI图的表现.结果 DKI成像具有更多的纹理细节,包含更丰富的组织特征.急性、亚急性脑梗死病灶在DKI图呈现高信号,陈旧性脑梗死病灶在DKI图呈现低信号,平均峰度相对值(rMK)分别为2.193±0.166,1.789±0.162,0.564±0.069.结论 DKI对脑组织尤其是灰质以及一些脑中风病灶的描述相对于ADC图包含更多的组织信息.脑梗死病灶的rMK值具有特征性演变规律.

abstractsObjective To investigate diffuse kurtosis imaging (DKI) in the description of cerebral white and grey matter and application for diagnosis of stroke.Methods The profiles of cerebral magnetic resonance imaging (MRI) in 2 normal controls and 15 patients with stroke (9 with cerebral infarction,including 3 respective cases of acute,subacute and old infarction) were analyzed. Diffusion coefficient (D value) and diffusion kurtosis (K value) of each signal were obtained via nonlinear fitting corresponding to the location of individual pixel in 9 diffusion gradient fields for depiction of ADC and DKI maps.The images of ADC and DKI maps were studied and compared.Results DKI map contained more texture details and abundant tissue characters.Acute and subacute cerebral infarction presented hyperintensity signals in DKI,while old infarction presented hypointensity signals,with mean relative MK value (rMK) of (2.193±0.166),(1.789 ± 0.162) and (0.564± 0.069),respectively.Conclusion DKI offers more information of brain tissue,particularly in terms of grey matter and stroke foci,as compared with ADC that mainly focuses in tissues.Features of variation in rMK value of cerebral infarction can be captured.