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Differentiation between Supratentorial Single Brain Metastases and High Grade Astrocytic Tumors: An Evaluation of Different DSC MRI Measurements

This study evaluated the role of different perfusion MRI measurements in the pre-operative differentiation between single brain metastases and high grade astrocytic tumors. 24 high-grade astrocytic tumors and 29 single metastases were studied. A gradient echo-planar sequence was used for DSC MRI. Relative cerebral blood volume, cerebral blood flow and mean transit time in both tumor parenchyma (T rCBV, T rCBF and T rMTT) and peritumoral edema (P rCBV, P rCBF and P rMTT) were measured. Mann-Whitney tests were used to assess differences between single brain metastases and high grade astrocytic tumors. Receiver operating characteristic analyses were performed to determine optimum thresholds for tumor differentiation. Sensitivity, specificity and accuracy for identifying brain metastases were calculated. Mean T rCBV, T rCBF, P rCBV and P CBF of brain metastases (2.75±1.72, 2.51±2.09, 1.05±0.53, 0.87±0.40) differed statistically (P <0.05) from those of high grade astrocytic tumors (6.00±2.17, 5.68±2.35, 1.77±1.19 and 1.58±0.99). No statistical difference was found between mean rMTTs of these two entities (P >0.05). Based on the area under the ROC curves (AUC), the efficiency of T rCBV and T rCBF for correct diagnosis of brain metastases is almost identical (AUC: 0.899, 0.890 respectively) and superior to other measurements. A threshold value of 3.50 for T rCBF provided the same specificity (86.7) as that of T rCBV but higher sensitivity (86.2) and accuracy (86.3). Different perfusion measurements can be used to differentiate single metastases from high-grade astrocytic tumors. T rCBF showed the highest diagnostic efficiency among these measurements.