Brain Tumors: Evaluation of Perfusion Using 3D-FSE-Pseudo-Continuous Arterial Spin Labeling

In this chapter, the advantages and disadvantages of 3D fast spin echo (FSE) pCASL as a measure of brain tumor perfusion are reviewed. In addition, we compare pCASL with other perfusion techniques and discuss future ASL approaches. A prospective study of 28 patients with contrast-enhancing brain tumors was performed at 3 T using dynamic susceptibility contrast (DSC) MRI and pCASL. The visual qualitative evaluation of signal enhancement in tumor was scored from 0 to 3 (0 = no signal enhancement compared with white matter (WM), 3 = pronounced signal enhancement with similar or higher signal intensity than in gray matter (GM)/basal ganglia). The extent of susceptibility artifacts in the tumor was scored from 0 to 2 (0 = no susceptibility artifacts, 2 = extensive susceptibility artifacts (maximum diameter >2 cm). Absolute ASL cerebral blood flow (CBF) values in tumor, GM, WM, and cerebellum were also measured. Using normalized tumor blood flow values (ASL nTBF, DSC nTBF), tumor-to-healthy tissue perfusion ratios were calculated by dividing the mean value of tumor ROI by the mean value in ROIs in the two cerebellar hemispheres. ASL had in comparison with DSC-MRI both a lower signal enhancement score (p = 0.02) and a lower susceptibility artifact score (p < 0.01). The highest absolute ASL CBF values were measured in tumor tissue and the lowest in WM. There was a good correlation between DSC nTBF and ASL nTBF values, with a correlation coefficient of 0.82.