CT灌注对表现为局限性低密度的脑肿瘤与非肿瘤性病变的鉴别诊断

Differential diagnosis of brain tumors and non-neoplastic diseases which manifested as local hypodensity on precontrast CT:a priliminary study with CT perfusion

目的:探讨CT灌注(CTP)参数在鉴别颅内局限性低密度病变中肿瘤及非肿瘤性病变的价值。方法:60例经手术病理及临床证实的局限性低密度病变分为肿瘤组(29例)与非肿瘤组(31例)。肿瘤组29例包括低级别星形细胞瘤13例(Ⅰ级1例,Ⅱ级12例),高级别星形细胞瘤7例(Ⅲ级2例,Ⅳ级5例),转移瘤7例,颅内淋巴瘤2例。非肿瘤组31例包括脑梗死21例,多发性硬化3例,外伤及放疗后脑软化7例。60例均行常规CT平扫、CT增强及CTP检查,测量病变区灌注参数,包括脑血流量(CBF)、脑血容量(CBV)、平均通过时间(MTT)及脑血管表面通透性(PS),并进行统计学分析。结果:肿瘤组及非肿瘤组CBF值(中位数与四分位间距值)分别为42.18mL/(min.100g)、32.12和10.15mL/(min.100g)、2.56;CBV值分别为3.54mL/100g、2.85和0.99mL/100g、0.59;PS值分别为3.79mL/(min.100g)、2.24和0.46mL/(min.100g)、0.28。两组间CBF、CBV、PS值差异有统计学意义(P<0.05)。肿瘤组和非肿瘤组MTT值分别为9.22s、5.97和11.21s、8.53,差异无统计学意义(P>0.05);CTP及CT增强扫描鉴别肿瘤组与非肿瘤组的准确率分别为77%和55%,差异有统计学意义(P<0.05)。肿瘤组病理:星形细胞瘤可见异形细胞及血管不同程度异常增生;转移瘤可见与原发灶相似的肿瘤细胞及血管结构;淋巴瘤可见肿瘤细胞围绕血管呈"套袖"状排列。非肿瘤组病理:脑梗死可见正常的胶质细胞肿胀,部分破裂伴有周围水肿;多发性硬化可见髓鞘脱失,血管周围可见炎性细胞。结论:表现为局限性颅内低密度的病变中肿瘤组及非肿瘤组的CBF、CBV、PS值有明显差异,CTP鉴别诊断肿瘤组及非肿瘤组的准确率高于CT增强扫描。CTP可为确定脑局限性低密度病灶是否为肿瘤性病变提供重要信息。

Objective：To probe the clinical value of CT perfusion （CTP） in differentiating brain tumors and non-neoplastic lesions which manifested as local hypoattenuation on pre-contrast CT. Methods： 29 cases of brain tumors and 31 cases of non-neoplastic diseases with their diagnosis confirmed by surgery and follow-up underwent CT perfusion of the brain. Brain tumor group included 13 cases with low-grade astrocytoma （2 cases with WHO Grade Ⅰ ,11 cases with Grade Ⅱ） ,7 high-grade astrocytoma （Grade Ⅲ 2, Grade Ⅳ 5）, 7 metastases and 2 lymphoma. Non-neoplastic group included 21 cases with cerebral infarction,3 multiple sclerosis,7 malacia after radiotherapy and injury. All patients underwent pre and postcontrast CT and CT perfusion （CTP） examinations. Cerebral blood flow （CBF）, cerebral blood volume （CBV）, mean transit time （MTT） and cerebral vascular permeability surface （PS） values were measured.. Results.. The values （median, interquartile range） of CBF,CBV,or PS of brain tumors versus non-neoplastic diseases were [42.18mL/（min. 100g） ,32.12] vs [10.15mL/（min·100g）,2. 56]; （3. 54mL/100g,2. 85） vs （0. 99mL/100g,0. 59）; [3. 79mL/（min·100g）, 2. 24] vs [0.46mL/（min·100g）, 0.28] respectively, which showing significant difference between the two groups （P〈0.05, respectively） ,but no significant difference found for MTT （P〉0.05）. The accuracy of CTP and enhanced CT for discriminating patients in the two group were 77% or 55% （P〈0.05,respectively）. Histologically, scattered tumor cells and angiogenesis could be detected for astrocytoma, tumor cells and vascular structures similar with primary lesions for metastases, tumor ceils arranged about the vascular space as ＂sleeve＂ for lymphoma. In non-neoplastic group,swelling neuroglia ceils and part of them broken were found for cerebral infarctions, demyelination and inflammatory cytokines surrounding vascular for multiple sclerosis. Conclusion： CTP can detect the differences between brain tumors and non-neoplastic lesions manifested as local hypoattenuation on pre-contrast CT. The CTP parameters will play certain role in the differential diagnosis between patients belonging to this two groups.