BACKGROUND Clot contraction reinforces hemostasis by providing an impermeable barrier and contractile force. Since computed tomography attenuation of intracerebral hemorrhage is largely determined by the density of red blood cells, clot contraction can be reflected in an increase of Hounsfield unit (HU) of hematoma. AIMS We hypothesized that hematoma expansion is inversely associated with mean HU of intracerebral hemorrhage at presentation. METHODS Eighty-nine consecutive spontaneous intracerebral hemorrhage patients with onset to first computed tomography within 24 h were included. Hematomas were segmented using semiautomated planimetry to measure the volume and mean HU. Hematoma expansion was defined as an increase in hematoma volume by over 33% or 6 mL. Multivariable logistic regression was performed for hematoma expansion. The discrimination power of mean HU for hematoma expansion was assessed using C-statistic. RESULTS The computed tomography attenuation of hematoma at presentation was 57.5 ± 3.3 HU and the volume was 16.9 ± 23.2 mL. Hematoma expansion occurred in 37.1% of patients. The computed tomography attenuation of hematoma was lower in patients with hematoma expansion than with no expansion (55.7 ± 2.9 HU vs. 58.6 ± 3.1 HU, p-value < 0.01). Multivariable logistic regression revealed that the mean HU of hematoma was inversely associated with hematoma expansion (adjusted odds ratio, 0.64; 95% confidence interval, 0.51-0.80). The C-statistic of the model with four known predictors increased from 0.66 to 0.84 after incorporating mean HU (p-value < 0.01). CONCLUSIONS Intracerebral hemorrhage with lower mean HU of hematoma at presentation is more likely to undergo hematoma expansion. This finding suggests the potential presence of clot contraction process that reinforces hemostasis in intracerebral hemorrhage.

中文翻译：

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血肿 Hounsfield 单位和脑内出血的扩大：止血凝块收缩的潜在标志。

背景凝块收缩通过提供不可渗透的屏障和收缩力来加强止血。由于脑出血的计算机断层扫描衰减很大程度上取决于红细胞的密度，因此血凝块收缩可以反映为血肿的亨斯菲尔德单位（HU）的增加。目的 我们假设血肿扩大与就诊时脑出血的平均 HU 呈负相关。方法 共纳入 89 名在 24 小时内首次进行计算机断层扫描的自发性脑出血患者。使用半自动面积测量法对血肿进行分割，以测量体积和平均 HU。血肿扩大定义为血肿体积增加超过 33% 或 6 mL。对血肿扩大进行多变量逻辑回归。使用 C 统计量评估平均 HU 对血肿扩大的区分能力。结果 就诊时血肿的计算机断层扫描衰减为 57.5 ± 3.3 HU，体积为 16.9 ± 23.2 mL。37.1% 的患者发生血肿扩大。血肿扩张患者的血肿计算机断层扫描衰减低于未扩张患者（55.7 ± 2.9 HU vs. 58.6 ± 3.1 HU，p 值 < 0.01）。多变量逻辑回归显示血肿的平均 HU 与血肿扩大呈负相关（调整后的优势比，0.64；95% 置信区间，0.51-0.80）。在纳入平均 HU（p 值 < 0.01）后，具有四个已知预测变量的模型的 C 统计量从 0.66 增加到 0.84。结论 就诊时血肿平均 HU 较低的脑出血更可能发生血肿扩大。这一发现表明凝块收缩过程的潜在存在，可加强脑出血中的止血。