Peri-tumoral fractional anisotropy mapping as a prognosticator and treatment guidance of brain tumors: A feasibility study

Peri-tumoral signal abnormalities of brain tumors contain varieties of tissues. A better delineation of the tissue contents may facilitate therapeutic strategy and improve clinical outcome. Six patients (3 meningiomas, 3 high-grade gliomas) were recruited in this study. Magnetic resonance (MR) diffusion tensor imaging (DTI) was acquired before and after tumor resection. Pre- and post-surgical fractional anisotropy (FA) of peri-tumoral signal abnormality was calculated. Three meningiomas were totally removed. Their pre-surgical peri-tumoral mean FA was 0.246 ± 0.046. Peri-tumoral signal abnormality in two meningiomas vanished completely after surgery (FA recovered to 0.402 ± 0.045) but not in the patient who had been previously treated by radiation. For the three high-grade gliomas, their pre-surgical peri-tumoral mean FA was 0.180 ± 0.027. Complete tumor resection could not be achieved in any of them. Post-surgical peri-tumoral mean FA of an anaplastic astrocytoma was 0.191 ± 0.018. Pathological, surgical and imaging correlative analysis confirmed vasogenic edema of peri-tumoral tissues in meningioma and tumor infiltration in high grade-glioma. Peri-tumoral signal abnormality of meningiomas with higher FA (≧ 0.2) had higher chance to recover in a shorter time interval after tumor resection, and the clinical outcome was better. High-grade gliomas contain lower FA (<0.2) in the peri-tumoral region. Their post-surgical peri-tumoral high signal on T2W remained mostly. High FA may indicate better tissue integrity, and low FA may indicate interstitial tumor infiltration and tissue injury. DTI can be used not only as pre-surgical trajectory guidance but also used as a predictor of post-surgical outcome.