Prognostic signifcance of imaging contrast enhancement for WHO grade II gliomas

Abstract

In this study, we investigated the prognostic value of MRI contrast enhancement (CE) at the time of histological diagnosis specifcally in a selected population of WHO grade II gliomas. We reviewed 927 histologically proven WHO grade II gliomas for which contrast-enhanced MR images were available at the time of histological diagnosis. CE patterns were classifed into three categories: patchy and faint, nodular-like, and ring-like. CE progression over time was recorded before oncological treatment on successive MR images, when available. CE was present in 143 cases (15.9%), with 93 patchy and faint, 50 nodular-like, and no ring-like patterns. CE areas were time progressive before oncological treatment in 35 of the 56 available cases (62.5%). Regardless of its pattern, the presence of CE was not signifcantly associated with a worsened prognosis (p 5 0.415) by u niva r iate analysis. Only the nodular-like pattern of CE (p, 0.01) and the time-progressive CE (p, 0.001) in the available subgroup proved to be statistically associated with survival since frst oncological treatment. The present results show the necessity, in cases of WHO grade II gliomas, to study CE at the time of histological diagnosis and, whenever possible, to follow its progression over time before oncological treatment. Nodular-like CE and timeprogressive CE are associated with a worsened prognosis, both suggesting malignant transformation, even though histopathological examination cannot initially disclose signs of malignancy in those areas. Neuro-Oncology 11, 176-182, 2009 (Posted to Neuro-Oncology [serial online], Doc. D07-00261, August 12, 2008. URL http://neuro -oncology.dukejournals.org; Copyright 2009 by the Society for Neuro-Oncology.