Correlation Between Arterial Spin-labeling Perfusion and Histopathological Vascular Density of Pediatric Intracranial Tumors

Traditional MRI methods for estimation of blood flow in brain tumors require high-flow injection of contrast agents through large-bore intravenous access, which limits their pediatric utility. In contrast, arterial spin-labeling (ASL) can be used without contrast media. This study aimed to evaluate the relationship between tumor blood flow (TBF) measured by ASL and histopathological vascular density in pediatric brain tumors. Nineteen consecutive children were evaluated (10 boys, 9 girls; median age: 6 years; 8 high-grade and 11 low-grade tumors). ASL was performed with a pseudocontinuous labeling time of 1650 ms and post-labeling delay of 1525 ms. The maximal absolute (aTBF) and relative (rTBF) tumor blood flows were measured. To evaluate the relative vascular area (%Vessel), the total stained vascular area was divided by the whole tissue area. Spearman's rank-order correlation, the Mann-Whitney U test, and receiver operating characteristic analysis were used for statistical analysis. The absolute and relative TBF rates were 4.9-92.9 mL/100 g/min and 0.17-3.59 mL/100 g/min, respectively. The %Vessel was 0.6-30.2%. The %Vessel showed a significant positive correlation with TBF (aTBF: r = 0.87, P < 0.0001; rTBF: r = 0.89, P < 0.0001). The TBF rate of high-grade tumors was significantly higher than that of low-grade tumors (aTBF: P = 0.0050, rTBF: P = 0.0036). The rTBF had the best diagnostic performance (area under the curve: 0.89). ASL perfusion imaging without contrast material can be used for accurate evaluation of histopathological vascular density and may be helpful for tumor grading in children.