Cerebral blood flow changes after radiation therapy identifies pseudoprogression in diffuse intrinsic pontine gliomas

BACKGROUND: The interval between progression and death in diffuse intrinsic pontine glioma (DIPG) is usually 6 months following so-called pseudoprogression, with a median of 8.9 months and a maximum of 35.6 months. All 43 patients exhibited increased blood volume and flow after radiotherapy, but the 90th percentile of those with signs of pseudoprogression had a greater increase of ASL-CBF (P < 0.001). Survival between the 2 groups did not differ significantly. During true progression, DSCrCBF and DSCrCBV values increased only in patients who had not experienced pseudoprogression. CONCLUSIONS: Pseudoprogression is a frequent phenomenon in DIPG patients. This condition needs to be recognized before considering treatment discontinuation. In this study, the larger increase of the ASL-CBF ratio after radiotherapy accurately distinguished pseudoprogression from true progression.