[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.