Quantification of Vessel Permeability Using Dynamic Contrast Enhanced and Arterial Spin Labeling MRI in Brain Tumors
HL Liu1,2*, TT Chang1, FX Yan1, YS Lin1,3, AM Wong2, (1) Chang Gung University, Taiwan,(2)Chang Gung Memorial Hospital-Linko, Taiwan,(3)Chang Gung Memorial Hospital-Keelung, TaiwanSU-E-CAMPUS-I-2 Sunday 3:00PM - 6:00PM Room: Exhibit Hall
Purpose: The transfer constant (Ktrans) obtained from DCE-MRI data is commonly used as an indicator for vessel permeability in tumors. However, it is known that Ktrans is also weighted by blood flow. This study proposed to combine the cerebral blood flow (CBF) measurement, by using the pseudo-continuous arterial spin labeling (PCASL) technique, and the DCE-MRI to estimate PS in brain tumors.
Methods: Eleven pediatric patients with brain tumors participated in this study. The CBF maps were acquired at a 3T clinical scanner using a 3D FSE PCASL sequence with spiral acquisition (TR/TE = 4500ms/10 ms, post-labeling delay = 1525 ms, matrix = 128 x 128, slice thickness = 5mm, 23 slices). Before the DCE-MRI, T1 maps were acquired by using a 3D SPGR sequence with multiple flip angles. DCE-MRI were performed by using a T1-weighted 3D SPGR sequence (TR/TE/FA=4.9ms/1.3ms/30°, matrix = 256 x 128, slice thickness = 5mm, 8 slices, 60 dynamics), following the injection of contrast agents. The Ktrans, Ve, and Vp maps were obtained by using the mTK model. The PS map was calculated using the equation PS = -CBFxln(1-Ktrans /CBF).
Results: The mean tumor Ktrans, CBF and PS values were 0.045+/-0.031 1/min, 52.3+/-20.9 ml/100g/min and 0.048+/-0.036 1/min, respectively. Similar patterns were found between Ktrans and PS maps, with slightly higher PS values in some patients. Significant positive correlations were found between Ktrans and PS (p<0.05). When Ktrans values were greater, they became increasingly underestimated than the PS values. The largest discrepancy between Ktrans and PS in this study was 13% in a patient with mean tumor Ktrans of 0.10 min-1.
Conclusion: This study proposed to utilize the PCASL technique for separating the flow weighting from the Ktrans measurement by DCE-MRI in brain tumors. The results demonstrated that the Ktrans well approximated vessel permeability in the patient group.