Investigation of apparent diffusion coefficient and diffusion tensor anisotrophy in acute and chronic multiple sclerosis lesions.
Investigation of apparent diffusion coefficient and diffusion tensor anisotrophy in acute and chronic multiple sclerosis lesions.
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发表时间：
1999-09
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通讯作者：
A. Tievsky;T. Ptak;J. Farkas
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作者：
A. Tievsky;T. Ptak;J. Farkas
背景与目的多发性硬化症（MS）不同阶段的特点是脱髓鞘和再髓鞘以及炎症。弥散磁共振成像对组织水分运动很敏感，这可能与这些病理过程相对应。我们的目的是证明表观扩散系数（ADC）和扩散张量各向异性在急性和慢性MS斑块和正常大脑中的差异。方法12例MS患者行常规和全张量弥散磁共振成像，B = 1221 s/mm2。在每个像素的基础上推导出痕量ADC并计算各向异性标量，包括偏心率、相对各向异性（RA）和分数各向异性（FA）。在共配图上确定斑块和正常结构的感兴趣区域。MS病变分为急性，亚急性，或慢性的基础上，其外观上的常规图像和相关的临床表现。结果7例急性斑块在弥散加权图像上呈高低信号强度交替的同心排列。在9个急性病变中，斑块中心具有高ADC，与边缘、正常白质（NAWM）和慢性病变相比，各向异性降低。中心周围的扩散加权高强度薄边缘显示可变ADC值和各向异性值，与NAWM无统计学差异。亚急性和慢性MS病变有中度ADC升高/各向异性降低。计算FA像元图优于偏心图或RA图；然而，质量受到信噪比的限制。结论ADC和扩散各向异性标量反映了脱髓鞘过程中基础病理的生物物理变化。
BACKGROUND AND PURPOSE The various stages of multiple sclerosis (MS) are characterized by de- and remyelination as well as by inflammation. Diffusion MR imaging is sensitive to tissue water motion, which might correspond to these pathologic processes. Our purpose was to demonstrate differences in apparent diffusion coefficient (ADC) and diffusion tensor anisotropy in acute and chronic MS plaques and in normal-appearing brain. METHODS Twelve MS patients underwent conventional and full-tensor diffusion MR imaging with B = 1221 s/mm2. Derivation of trace ADC and calculation of anisotropic scalars, including eccentricity, relative anisotropy (RA), and fractional anisotropy (FA) was performed on a per-pixel basis. Regions of interest of plaques and normal structures were determined on coregistered maps. MS lesions were classified as acute, subacute, or chronic on the basis of their appearance on conventional images and in relation to clinical findings. RESULTS Seven patients had acute plaques with a concentric arrangement of alternating high and low signal intensity on diffusion-weighted images. In nine acute lesions, plaque centers had high ADC with reduced anisotropy compared with rim, normal-appearing white matter (NAWM), and chronic lesions. The thin rim of diffusion-weighted hyperintensity surrounding the center showed variable ADC and anisotropic values, which were not statistically different from NAWM. Subacute and chronic MS lesions had intermediate ADC elevations/anisotropic reductions. Calculated FA pixel maps were superior to eccentricity or RA maps; however, quality was limited by signal-to-noise constraints. CONCLUSION ADC and diffusion anisotropic scalars reflect biophysical changes in the underlying pathology of the demyelinating process.