Woong Jae Lee MD, Presenter: Nothing to Disclose

Seung Hong Choi MD, PhD, Abstract Co-Author: Nothing to Disclose

Chul-Ho Sohn MD, Abstract Co-Author: Nothing to Disclose

Ji-Hoon Kim MD, Abstract Co-Author: Nothing to Disclose

Tae Jin Yoon MD, Abstract Co-Author: Nothing to Disclose

Ji Yeon Jang, Abstract Co-Author: Nothing to Disclose

Kee Hyun Chang MD, PhD, Abstract Co-Author: Nothing to Disclose

Moon Hee Han MD, Abstract Co-Author: Nothing to Disclose

Combination temozolomide and radiation significantly prolongs survival compared with radiation alone and has become standard treatment for high grade glioma. Response assessment in high-grade glioma is difficult as a result of the frequent occurrence of early imaging changes indistinguishable from tumor progression, termed pseudoprogression. The aim of the present study was to determine whether diffusion-weighted MR imaging (DWI) could be used to differentiate pseudoprogression from true progression in high-grade gliomas treated with radiotherapy plus concomitant temozolomide (CCRT).

The institutional review board approved this retrospective study. Informed consent was waived. We retrospectively reviewed conventional MRI and DWI obtained 1 to 2 months after completion of CCRT for histologically proved high-grade gliomas. Total of 25 patients with increase of measurable enhancing regions were identified according to the criteria of the Response Assessement in Neuro-Oncology (RANO) Working Group, which were evaluated by using contrast-enhanced MRI obtained 12 weeks after completion of CCRT. In terms of DWI findings of the enhancing regions, the patterns were qualitatively classified as no high, rim high, homogenous high, or multi-focal high. Mean ADC values were quantitatively calculated in the enhancing regions.

Pseudoprogression and true progression was noted in 12 and 13 patients, respectively. The patients with true progression showed homogeneous high (n = 8), multi-focal high (n = 4) or no high (n = 1) patterns on DWI, while rim high (n = 6) or no high (n = 6) patterns were observed in the patients with pseudoprogression, which resulted in statistical significance ( P < 0.001). The pseudoprogression group showed significantly higher ADC values (mean ± SD, 1186.86 ± 253.78) than those of true progression group (973.94 ± 159.19, P = 0.019).

The assessment of DWI for the patients with increase of measurable enhancing regions 1 to 2 months after completion of CCRT is useful in differentiating pseudoprogression from true tumor progression.

We believe that DWI may merit further development as a noninvasive biomarker potentially useful in predicting response to CCRT.

Lee, W, Choi, S, Sohn, C, Kim, J, Yoon, T, Jang, J, Chang, K, Han, M, Differentiation of Pseudoprogression from True Progression in High-Grade Glioma Treated with Radiotherapy Plus Concomitant Temozolomide Using Diffusion-weighted MR Imaging.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11011557.html