Perfusion CT imaging of brain tumors: an overview

Abstract

Perfusion imaging of brain tumors has been performed by using various tracer and nontracer modalities and can provide additional physiologic and hemodynamic information, which is not available with routine morphologic imaging. Tumor vascular perfusion parameters obtained by using CT or MR perfusion have been used for tumor grading, prognosis, and treatment response in addition to differentiating treatment/radiation effects and non-neoplastic lesions from neoplasms. This article is an overview of the utility of PCT for assessment of brain tumors and describes the technique, its advantages, and limitations.

Fig 1.

CBV and PS perfusion CT maps in a 45-year-old woman with WHO grade II astrocytoma show low blood volume (CBV = 0.70 mL/100 g) and low permeability (PS = 0.65 mL/100 g/min) within the tumor (arrows). Inset: Postcontrast T1-weighted image shows a nonenhancing left temporal tumor with no surrounding perilesional edema.

Fig 2.

PCT maps in a 50-year-old man with glioblastoma multiforme. The CBV map shows high blood volume (CBV = 4.56 mL/100 g), and the PS map shows high permeability (PS = 3.78 mL/100 g/min) along the enhancing nodular margins of the tumor (arrow). Inset: Postcontrast T1-weighted image shows a heterogeneously enhancing mass with irregular central necrosis in the right parietal region.

Fig 3.

PCT maps in a 39-year-old woman with heterogeneously enhancing grade III glioma involving the left temporal lobe. CBV and PS maps show an enhancing region laterally. Region of interest 7 demonstrates the highest PS (8.52 mL/100 g/min), but not the highest CBV (4.73 mL/100 g) within the tumor; whereas region of interest 8 shows relatively lower PS (1.14 mL/100 g/min) but the highest CBV within the tumor (11.65 mL/100 g), suggesting that there is marked heterogeneity within high-grade gliomas, which could be due to the heterogeneity of tumor angiogenesis. Inset: Postcontrast T1-weighted axial images show a heterogeneously enhancing left temporal lobe tumor.

Fig 4.

A, A 56-year-old man who was previously treated for a right occipital anaplastic astrocytoma, shows a progressive enhancing lesion in the medial aspect of the surgical resection cavity (inset) and PCT CBV map shows high CBV (CBV = 3.5 ml/100 g), suggesting recurrent/progressive tumor (arrows). B, Histopathology proven radiation/treatment necrosis (arrows) in a 34-year-old woman who underwent radiation and chemotherapy for a right fronto-parietal anaplastic astrocytoma shows low CBV (CBV = 1.1 ml/100 g) in a recurrent/progressive enhancing lesion (inset).

Fig 5.

A, Same case as in Fig 4A. PCT PS map shows high PS (PS = 4.2 ml/100 g/min) in the medial aspect of the surgical resection cavity (arrows) in a histopathology proven recurrent/progressive tumor (inset). B, A 41-year-old man with initial diagnosis of WHO grade II astrocytoma received chemotherapy and radiation. A 33 month follow-up MR image (inset) shows development of a recurrent enhancing lesion. PCT PS map shows low PS (PS = 1.1 ml/100 g/min) suggesting radiation necrosis. The patient underwent open biopsy and histopathology revealed radiation necrosis without viable tumor cells.

Fig 6.

Histopathology-proved TDL in a 45-year-old woman who presented with a very heterogeneously enhancing large lesion in the left frontoparietal periventricular region (inset). PCT CBV and PS maps show low to minimally increased blood volume (CBV = 1.01 mL/100 g) and permeability (PS = 0.40 mL/100 g/min), unlike a high-grade tumor that it was mimicking on postcontrast images, hence, suggesting a non-neoplastic lesion.

Fig 7.

MR image (inset) shows a large nonenhancing mass lesion in the left frontal lobe in a 65-year-old man who presented with headaches. PCT CBV and PS maps show low blood volume and permeability (arrows), suggesting either a low-grade glioma (however, this is slightly unusual considering the associated edema and mass effect) or, more likely, a non-neoplastic lesion. The patient underwent open biopsy, which showed amyloid angiopathy.