Neurosurgery Center for Research, Training and Education, Loma Linda University, Loma Linda, California 92354, USA.
Magn Reson Med. 2011 Jun;65(6):1592-601. doi: 10.1002/mrm.22745. Epub 2010 Dec 16.
Brain microbleeds (BMB) are associated with chronic and acute cerebrovascular disease and present a source of pathologic iron to the brain proportional to extravasated blood. Therefore, BMB iron content is potentially a valuable biomarker. We tested noninvasive phase image methods to quantify iron content and estimate true source diameter (i.e., unobscured by the blooming effect) of BMB in postmortem human tissue. Tissue slices containing BMB were imaged using a susceptibility weighted imaging protocol at 11.7T. BMB lesions were assayed for iron content using atomic absorption spectrometry. Measurements of geometric features in phase images were related to lesion iron content and source diameter using a mathematical model. BMB diameter was estimated by image feature geometry alone without explicit relation to the magnetic susceptibility. A strong linear relationship (R(2) = 0.984, P < 0.001) predicted by theory was observed in the experimental data, presenting a tentative standardization curve where BMB iron content in similar tissues could be calculated. In addition, we report BMB iron mass measurements, as well as upper bound diameter and lower bound iron concentration estimates. Our methods potentially allows the calculation of brain iron load indices based on BMB iron content and classification of BMB by size unobscured by the blooming effect.
脑微出血 (BMB) 与慢性和急性脑血管疾病有关，是大脑中与外渗血液成比例的病理性铁的来源。因此，BMB 铁含量可能是一个有价值的生物标志物。我们测试了非侵入性的相位图像方法来量化铁含量，并估计人体组织死后 BMB 的真实源直径（即不受blooming 效应影响）。使用 11.7T 的磁化率加权成像方案对含有 BMB 的组织切片进行成像。使用原子吸收光谱法测定 BMB 病变中的铁含量。使用数学模型将相位图像中的几何特征测量值与病变铁含量和源直径相关联。通过图像特征几何形状来估计 BMB 直径，而不与磁化率有明确的关系。理论预测的强线性关系（R²=0.984，P<0.001）在实验数据中得到了观察，提出了一个初步的标准化曲线，其中可以计算类似组织中的 BMB 铁含量。此外，我们还报告了 BMB 铁质量测量值，以及上限直径和下限铁浓度估计值。我们的方法可能允许根据 BMB 铁含量计算脑铁负荷指数，并通过不受 blooming 效应影响的大小对 BMB 进行分类。
