多层螺旋CT灌注成像对部分颅脑肿瘤和瘤样病变的评估

目的探讨多层螺旋CT灌注成像在脑肿瘤和瘤样病变诊断与鉴别诊断中的临床价值。方法56例患者中,脑内肿瘤38例,其中胶质瘤29例(低级组12例,高级组17例),室管膜瘤2例,血管母细胞瘤2例,髓母细胞瘤1例,转移瘤2例,畸胎瘤和淋巴瘤各1例;脑外肿瘤8例,其中脑膜瘤5例,神经鞘瘤2例,生殖细胞瘤1例;非肿瘤性病变10例,其中海绵状血管瘤6例,非特异性炎性肉芽肿2例,结核瘤1例,脉络丛增生1例。采用GElightspeed 16 slice多层螺旋CT机,行头部横断面平扫确定病灶中心层面,采用电影模式5-10 mm/2～4层,120 kV,180 mA,使用高压注射器经肘静脉注射非离子型造影剂,50～70 ml(300 mgI/ml),速率3～5 ml/s,延迟7 s,数据采集50 s。研究数据采用Perfusion(GE)软件包(去卷积算法)处理。结果胶质瘤高级组肿瘤的T-D曲线多呈尖蜂状,低级组则较平滑;脑膜瘤灌注曲线为速升缓降型,有较长的高位平台期。各级胶质瘤平均脑血液量(CBF)、脑血容量(CBV)和表面通透性(PS)值随肿瘤分级的升高而呈增加趋势,其中PS值相对值最显著,在伪彩图上可以确定肿瘤的边界,特别是合并出血时,具有独特价值。脑膜瘤的CBF低于胶质瘤高级组,其他灌注值与胶质瘤高级组比较,差异均无统计学意义。颅内海绵状血管瘤的灌注具有多样性,MTT的大幅延长、灌注曲线的多样性及0灌注区的出现,是其区别于其他肿瘤的特征。生殖细胞瘤和松果体区畸胎瘤CBF和CBV相对较低,而PS显著增高,灌注曲线呈快速上升后继续缓慢上扬。神经鞘瘤的灌注特征符合病理学表现,炎性病变的灌注表现不具特征性。结论多层螺旋CT灌注成像可在一定程度上反映肿瘤和瘤样病变的组织学特征及血液动力学改变,为诊断与鉴别诊断脑肿瘤和瘤样病变提供有价值的信息。

Multi-slice helical CT perfusion imaging in evaluating intracranial neoplasms and tumor-like lesions

Objective To investigate the clinical value of CT perfusion in diagnosing and assessing intracranial neoplasms and tumor-like lesions. Methods 16-slice helical CT perfusion imaging was performed in 56 patients who were clinically suspected to have intracranial neoplasm or tumor-like lesion. With a GE-Light Speed 16-slice helical CT scanner, routine plain-CT scanning was performed to localize the central slice of the lesion. Perfusion imaging was then carried out using cine scan technique to maintain a slice thickness of 5-10 mm, a total dose of 50-70 ml of contrast-medium at an injection flow rate of 3-5 ml/s, a delay time of 7 s and a total scan time of 50 s. The images were processed using perfusion software in an ADW 4. 0 workstation, meanwhile, time-density curves (TDC) of different kinds of lesions were also produced and analyzed. Results The pathological types in this series included; 29 gliomas (12 low-grade and 17 high-grade) , 2 ependemomas, 2 hemangioblastomas, 1 medulloblastoma, 2 metastatic tumors, 1 lymphoma, 5 meningiomas, 2 schwannomas, 1 germinoma, 1 teratoma in the pineal region, 6 cavernous hemangiomas, 2 inflammatory granulomas, 1 tuberculoma, and 1 hyperplasia of the choroid plexus. TDC of high-grade glioma, low-grade glioma and meningioma was different from each other. The cerebral blood flow (CBF) .cerebral blood volume(CBV), particularly, the permeability surface(PS)value of glioma was found to increase significantly with the escalation of tumor differentiation grade. In PS map, margin of the tumor could be clearly showed, which was very useful when hemorrhaging within the tumor occurred. CBF in meningioma was lower than that in high-grade glioma, but there was no statistical difference in CBV, MTT and PS between these two types of tumor. The features of intracranial cavernous hemangioma such as significant prolongation of MTT, different TDCs, and zero perfused areas were diverse on CTP image, which was helpful in differentiating it from the other lesions. The germinoma and teratoma had rather low CBF and CBV value, but a remarkably high PS value, furthermore, they showed a rapid escalated TDC with a slowly and continuously elevated platform. The perfusion features of schwannoma was concordant with its pathological findings. However, no visible specific feature of inflammatory lesion was found on CTP image in this series. Conclusion Multi-slice helical CT perfusion imaging may be helpful in revealing histopathological features and hemodynamic changes as well as differential diagnosis of intracranial neoplasms and tumor-like lesions. When combined with other image and clinical information, CTP can play an important role in pre-operative diagnosis and treatment planning for intracranial neoplasms and tumor-like lesions.