The value of contrast?enhanced T1 mapping technique in differentiating recurrence and radiation necrosis of brain metastases after gamma knife treatment / 中华放射学杂志

ABSTRACT

Objective To explore the value of contrast?enhanced T1 mapping technique in differentiating between recurrence and radiation necrosis of brain metastases after gamma knife treatment. Methods From March 2016 to June 2017,56 patients with brain metastases treated by gamma knife and confirmed by pathology or follow?up in Shandong Provincial Hospital were prospectively collected. Routine MRI and contrast?enhanced T1 mapping sequence scan were performed. T1 value was obtained 5 mins (T1 5 min) and 60 mins (T1 60 min) after injection of contrast agent. The Differences betweenT1 60 min and T1 5 min (T1 differ) was calculated,and relative cerebral blood volume (rCBV) value was obtained. Patients were divided into radiation necrosis group and tumor recurrence group according to imaging follow?up results or pathological results. Two?sides unpaired t test was used to compare the differences in T1 5 min,T1 60 min,T1 differ and rCBV between the 2 groups. Pearson correlation analysis was used to evaluate the correlation between T1 differ and rCBV, and the receiving operating curve (ROC) was used to evaluate the diagnostic efficiency of MRI quantitative parameters,and Z test was used to compare the differences of area under curve (AUC) between T1 differ and rCBV values. Results Of the 56 patients,27 had tumor recurrence and 29 had radiation necrosis. The differences in T1 5 min,T1 60 min,T1 differ and rCBV between the 2 groups was statistically significant (P<0.05). T1 differ and rCBV values were significantly correlated, r=0.58, P<0.01. The differential diagnosis of AUC between radiation necrosis and tumor recurrence were 0.66,0.73,0.97 and 0.95 respectively in T1 5 min,T1 60 min, T1 differ and rCBV, and there was no significant differences between AUC in T1 differ and rCBV (P=0.274). Conclusion The contrast?enhanced T1 mapping image can be used for differential diagnosis between radiation necrosis and recurrence after gamma knife treatment of brain metastases. T1 differ value has high differential efficiency.