Meningioma Consistency: Correlation Between Magnetic Resonance Imaging Characteristics, Operative Findings, and Histopathological Features

Abstract

Introduction: Intracranial meningiomas account for 30% of all primary intracranial tumors. Surgical resection remains the mainstay of the treatment for meningiomas. The magnetic resonance of intracranial meningiomas has been largely discussed in many reports of the radiological and neurosurgical literature. To date, a few studies have been attempted to differentiate the tumor characteristics of meningiomas based on magnetic resonance imaging (MRI) studies.

Objective: The objective of the study is to evaluate the relationship between MRI signal characteristics of intracranial meningiomas and consistency of tumor using objective measures.

Materials and methods: A prospective study included all the patients who were admitted for surgery with an MRI finding suggestive of meningioma. All patients were subjected to routine radiological investigations. Surgical resection was performed for patients eligible for surgery using cavitron ultrasonic aspirator (CUSA). The relationship and correlation between the radiological, intraoperative measurements and the histopathological diagnosis were studied. The tumor consistency was measured using mean CUSA level. Intensity on T2, fluid-attenuated inversion recovery (FLAIR), and diffusion-weighted imaging (DWI) was measured using circular regions of interest (ROI) on the MRI. Multiple ROIs were placed initially on the lesions avoiding the obvious blood vessels, if any, then on the brain cortex to avoid the vasogenic edema. The mean ROI (mROI) results from the lesion were subtracted from the mean ROI from the brain cortex for each lesion to achieve normalized ratio. The results of lesion mROI-cortex mROI were compared to the operative and histopathology results using Pearson's correlation test and linear regression test.

Results: The total number of patients was seventy. The mean age of the patients was 51 ± 14.8, with 72% of them being females and 28% males. There was a strong statistically significant (P = 0.046) and (P = 0.003) correlation between mean CUSA and FLAIR mROI difference or T2 mROI difference, respectively. On the other hand, there was an inversely proportional relationship between mean CUSA and FLAIR mROI difference and mean CUSA and T2 mROI difference. The value of the regression test (r) shows that there was a slight linear relationship between FLAIR mROI difference or T2 mROI difference and mean CUSA values, in which the mean CUSA value = 50.1 + (-0.088) × FLAIR mROI difference (r = -0.273, P = 0.046) or mean CUSA value = 50.8 + (-0.055) × T2 mROI difference (r = 0.4, P = 0.003). There was no statistical significance in the relation between CUSA values and tumor histological subtypes, DWI values, age, or gender.

Conclusion: This study presents a new objective method to measure the consistency of intracranial meningiomas based on a simple algorithmic formula. Such information will aid in planning surgery and assessing the resectability of the tumor. To date, this is the first objective measurement of meningioma consistency based on MRI studies and objective intraoperative evaluation.

Keywords: Brain imaging; magnetic resonance imaging; meningioma; neurostimulation; neurosurgery.

Figure 1

Sample of regions of interest selection on the workstation

Figure 2

Regression test (r) showed that there is a slight linear relationship between fluid-attenuated inversion recovery mean regions of interest difference mean CUSA values. In which mean CUSA value = 50.1 + (−0.088 × fluid-attenuated inversion recovery mean regions of interest difference) (r = −0.273, P = 0.046)

Figure 3

Regression test (r) showed that there is a slight linear relationship between T2 mean regions of interest difference and mean CUSA values. In which mean CUSA value = 50.8 + (−0.055 × T2 mean regions of interest difference) (r = 0.4, P = 0.003)