Diagnostic Performance of Arterial Spin Labeling for Grading Nonenhancing Astrocytic Tumors.

PURPOSE

We evaluated the utility of arterial spin labeling (ASL) imaging of tumor blood flow (TBF) for grading non-enhancing astrocytic tumors.

MATERIALS AND METHODS

Thirteen non-enhancing astrocytomas were divided into high-grade (n = 7) and low-grade (n = 6) groups. Both ASL and conventional sequences were acquired using the same magnetic resonance machine. Intratumoral absolute maximum TBF (TBF), absolute mean TBF (TBF), and corresponding values normalized to cerebral blood flow (TBF and TBF ratios) were measured. The Mann-Whitney U test and receiver operating characteristic (ROC) curve analysis were used to assess the accuracy of TBF variables for tumor grading.

RESULTS

Compared with low-grade astrocytoma, high-grade astrocytoma exhibited significantly greater absolute TBF (90.93 ± 24.96 vs 46.94 ± 20.97 ml/100 g/min, P < 0.001), TBF (58.75 ± 19.89 vs 31.16 ± 17.63 ml/100 g/min, P < 0.001), TBF ratio (3.34 ± 1.22 vs 1.35 ± 0.5, P < 0.001), and TBF ratio (2.15 ± 0.94 vs 0.88 ± 0.41, P < 0.001). The TBF ratio yielded the highest diagnostic accuracy (sensitivity 100%, specificity 86.3%), while absolute TBF yielded the lowest accuracy (sensitivity 85.7%, specificity 70.1%) by ROC analysis.

CONCLUSION

Parameters from ASL perfusion imaging, particularly TBF ratio, may be useful for distinguishing high-grade from low-grade astrocytoma in cases with equivocal conventional MRI findings.