Can amide proton transfer-weighted imaging differentiate tumor grade and predict Ki-67 proliferation status of meningioma?

OBJECTIVES: To determine the utility of the amide proton transfer-weighted MR imaging in differentiating the WHO grade and predict proliferative activity of meningioma.

METHODS: Fifty-three patients with WHO grade I meningiomas and 26 patients with WHO grade II meningiomas underwent conventional and APT-weighted sequences on a 3.0 Tesla MR before clinical intervention. The APT-weighted (APTw) parameters in the solid tumor region were obtained and compared between two grades using the t test; the receiver operating characteristic (ROC) curve was used to assess the best parameter for predicting the grade of meningiomas. Pearson's correlation coefficient was calculated between the APTwmax and Ki-67 labeling index in meningiomas.

RESULTS: The APTwmax and APTwmean values were not significantly different between WHO grade I and grade II meningiomas (p = 0.103 and p = 0.318). The APTwmin value was higher and the APTwmax-min value was lower in WHO grade II meningiomas than in WHO grade I tumors (p = 0.027 and p = 0.019). But the APTwmin was higher and the APTwmax-min was lower in microcystic meningiomas than in WHO grade II meningiomas (p = 0.001 and p = 0.006). The APTwmin combined with APTwmax-min showed the best diagnostic performance in predicting the grade of meningiomas with an AUC of 0.772. The APTwmax value was positively correlated with Ki-67 labeling index (r = 0.817, p < 0.001) in meningiomas; the regression equation for the Ki-67 labeling index (%) (Y) and APTwmax (%) (X) was Y = 4.9 × X - 12.4 (R2  = 0.667, p < 0.001).

CONCLUSION: As a noninvasive imaging method, the ability of APTw-MR imaging in differentiating the grade of meningiomas is limited, but the technology can be used to predict the proliferative activity of meningioma.

KEY POINTS: • The APTw min value was higher and the APTw max-min value was lower in WHO grade II meningioma than in grade I tumors. • The APTw min value was higher and the APTw max-min value was lower in microcystic meningiomas than in WHO grade II meningiomas. • The APTw max value was positively correlated with meningioma proliferation index.