Intraoperative real-time elastography of gliomatous tumors of the brain

Objectives: Conventional B-mode imaging is commonly used for intraoperative localization of brain tumors and able to detect the lesion in the majority of cases. Nevertheless it might be difficult to delineate tumors with infiltrating character as it is true for gliomatous tumors. We present first experiences with intraoperative real-time elastography in order to help solving these problems.

Methods: Elastic properties of brain tissue are registered and analysed by the „Extended Combined Autocorrelation Method“ with an EUB 8500 ultrasound system (Hitachi Medical Systems). Elasticity is displayed as a colour-coded overlay to the conventional B-mode image in real-time. Ten patients with gliomatous brain tumors were analysed: 5 glioblastomas, 2 astrogliomas WHO° II, 1 pilocytic astrocytoma, 1 oligoastrocytoma WHO° II, and 1 oligoastrocytoma WHO° III.

Results: Glioblastomas as well as both astrocytomas WHO° II and both oligoastrocytomas showed a softer appearance than the surrounding tissue, and this seems to be especially true for the surrounding edema and zone of infiltrative growth, but exact histologic evaluation is still lacking. The pilocytic astrocytoma was displayed being harder than the surrounding tissue and this was confirmed by the detection of intratumoral calcification.

Conclusions: These preliminary results point to a possible value of real-time elastography in defining borders of infiltratively growing brain tumors more precisely thus ameliorating the extent of resection. Histologic confirmation of these observations is still lacking.