Value of amide proton transfer magnetic resonance imaging and apparent diffusion coefficient in grading of meningioma

Abstract

Background: Meningioma is the most common intracranial extra-axial tumor in general populations with world health organization (WHO) grading ranging from grade 1 to grade 3 depending on subtypes which indicate the prognosis and management plan. Amide proton transfer (APT) is the new molecular MRI technique based on chemical exchange saturation transfer mechanism while apparent diffusion coefficient (ADC) is a conventional technique measuring of the magnitude of diffusion of water molecule within tissue.

Aim: To study whether the APT and ADC values correlate with meningioma WHO grading.

Materials and methods: A cross-sectional study was conducted at Department of Radiology, Srinagarind Hospital, Faculty of Medicine, Khon Kaen University, Thailand between July 2021 and December 2021. We performed MRI in patients with extra-axial tumors using conventional, APT and DWI sequences. Two experienced neuroradiologists placed the ROIs within the solid portion of the tumor those showed highest APT value and lowest ADC value in consensus manner and blinded to clinical data. The patients were later classified into groups based on pathological results. APT and ADC values were compared between groups.

Results: A total 23 patients with presumptive diagnosis of meningioma on pre-operative MRI were included with 20 patients who had pathological confirmed meningioma (17 patients with typical meningiomas WHO grade 1, two patients with atypical meningiomas WHO grade 2 and one anaplastic meningioma WHO grade 3). The mean and maximal APT values in an atypical meningioma group (WHO grade 2-3) were significantly higher than in a typical meningioma group with p-values of 0.023 and 0.024, respectively. There was no significant difference in mean and minimum ADC values and ADC ratios among the typical and atypical meningioma groups. The multivariate logistic regression analysis showed that higher APT values increased relative risk of high-grade tumors by a factor of 2.51 using mean APT (95%CI 0.81-7.74, p value 0.001, area under ROC curve 0.9097) and 2.48 using maximum APT (95%CI 0.75-8.1, p value 0.001, area under ROC curve 0.9064). A mean APT cut point of 3.52 provides good specificity in differentiating low and high grade meningiomas (sensitivity 67%, specificity 94% and area under ROC curve 0.8021)

Conclusion: The APT-weighted image offers an additional technique in differentiating low and high grades meningioma, while there is no difference of ADC values among the meningioma grades.