Predicting intraoperative meningioma consistency using features from standard MRI sequences: a preoperative evaluation

Abstract

Background: Symptomatic meningiomas may require surgical resection to save or improve neurological function. The extent of tumor resection depends on multiple factors, including the tumor's consistency, its location, and the patient's overall condition. This prospective study aims to explore new criteria in combination with previously proposed tumor features on MRI to establish a rapid approach to tumor consistency characterization pre-operatively.

Methods: Forty-eight patients with meningiomas were prospectively included and underwent a dedicated MRI protocol prior to surgery. Qualitative and quantitative MRI characteristics of the tumor were correlated to a previously proposed surgical tumor consistency grading.

Results: Soft tumors were associated with homogeneous contrast enhancement, high T2 signal, absence of peritumoral edema (PTE), the presence of tumor cysts, and a uniformly dark appearance on fractional anisotropy (FA) maps. In contrast, firmer tumors were characterized by heterogeneous contrast enhancement, low T2 signal, the presence of PTE, absence of tumor cysts and a heterogeneous appearance on FA maps, requiring supranormal ultrasonic aspirator settings. Tumor signal quantification on T2 and Apparent Diffusion Coefficient maps (ADC) correlated moderately to tumor consistency. T1 sequences did not contribute in determining tumor consistency.

Conclusion: An array of simple qualitative meningioma characteristics on MRI can assist in swift discrimination of soft and hard tumors preoperatively. These have been displayed in a figure that can easily be implemented clinically for optimal surgical planning.

Keywords: Consistency; MRI; Meningioma; Tumor.

Fig. 1

Radiological tumor signal grading on T2 and FA as explained above. T2 column shows the visual range of tumor signal, (1- higher signal than contralateral insular grey matter (cGM) to 5- signal considerably lower than cGM). FA map column shows variation in FA appearance (1-uniform dark, vs 2-heterogenous, mosaic like, bright)

Fig. 2

Qualitative meningioma characteristics predictive of soft (1, 2,) and hard (3, 4, 5) tumor consistency on univariate regression analysis. Homogenous contrast enhancement, high T2 signal, absence of PTE, presence of tumor cysts, combined dark uniform FA, and ADC ROI > 6.4 × 10^–4 mm2/s were strongly predictive of soft tumors, while heterogeneous contrast enhancement, low T2 signal, presence of PTE, absence of tumor cysts, heterogeneous FA along with ADC ROI < 6.4 × 10^–4 mm2/s were predictive of intermediate and hard tumors, requiring CUSA suction power of 40 or more to remove tumor. The strength of association shown in Table 4

Fig. 3

Receiver operating characteristic (ROC) curve showing the diagnostic performance of ADC values from mean tumor ROI in predicting tumor consistency. The area under the curve (AUC) was 0.71, indicating moderate diagnostic accuracy at threshold 0.64 × 10^–4 mm²/s, with sensitivity 62%, specificity 80%. Higher values being indicative of soft tumors