Ajay Gupta

Robert J. Young

In this article, we investigated the utility of diffusion-weighted imaging in monitoring patients being treated for glioblastoma. We found that some treated glioblastomas developed diffusion-restricted nonenhancing lesions that subsequently transformed into enhancing lesions. We concluded that these quantitative decreases on apparent diffusion coefficient maps were probably related to increasing tumor cellularity and/or chronic ischemia. The recently proposed Revised Assessment in Neuro-Oncology (RANO) criteria did not include DWI or any advanced imaging technique; instead, determining tumor response or progression continues to rely primarily on changes in lesion enhancement. Finding an early imaging marker for tumor progression, even before changes in enhancement occur, may be beneficial for guiding clinical treatment decisions.

The imaging diagnosis of tumor progression remains a challenging problem. Enhancement patterns may be altered in the setting of pseudoprogression and other forms of radiation injury, as well as after administration of certain anti-angiogenic and immune-modulating therapies. We have ongoing projects using MRI feature/texture-based analyses, T1-weighted MRI perfusion, and PET/CT in this area. Despite the

many potential advantages of such advanced imaging techniques, however, none is as widely available or acquired as DWI. While our understanding of the role of DWI evaluation of treatment progression versus response continues to evolve, we believe that DWI will continue to play an important role in the management of patients with glioblastoma and other brain tumors.

Ajay Gupta and Robert J. Young, co-first authors

Read this article at AJNR.org . . .