Intraoperative Ultrasonographic Elastography: A Semi-Quantitative Analysis of Brain Tumor Elasticity Patterns and Peritumoral Region

Abstract

Ultrasonographic elastography imaging visualizes the elastic properties of tissues to distinguish pathologic and healthy areas. Real-time elastography measures relative tissue hardness by evaluating changes in local strain in response to external forces. We aimed to determine the elastographic patterns of different brain tumor types and establish differences between their peritumoral regions. We prospectively enrolled patients undergoing craniotomy along with intraoperative ultrasonographic elastography for supratentorial brain tumors in March 2018-May 2019. The elastograms were semi-quantitatively analyzed offline based on the mean tissue elasticity of the tumors, peritumoral regions, and healthy parenchyma. We examined 37 lesions in 36 patients. The pathologic diagnoses comprised 11 meningiomas (29.7%), 4 low-grade gliomas (LGGs; 10.8%), 16 high-grade gliomas (HGGs; 43.2%), and 6 metastases (16.2%). The median MTE values observed after manual segmentation of the whole tumor were as follows: meningiomas, 119.9 (36.6); HGGs, 77.9 (18.9); LGGs, 91 (19.5); metastases, 103.9 (35.6); tumor types significantly differed (H= 18.2; P < 0.001). The peritumoral MTE values were as follows: meningiomas, 120.1 (36.3); HGGs, 86.3 (20.9); LGGs, 94.8 (7.38); and metastases, 116.3 (22). The intergroup differences were significant (H=17.43; P < 0.001). Using receiver operating characteristic curves, we obtained an optimal cutoff point of 92.22 (whole tumors) and 109.6 (peritumoral regions). Values below these cutoff points were correlated with a high probability of being a glioma. We objectively describe the elastographic patterns of different types of brain tumors (i.e., gliomas, metastases, and meningiomas). We have identified differences in both the tumors and the peritumoral areas of these histologic types.