Brain 17 Vienna

IMAGING of TREATMENT RESPONSE PSEUDO-RESPONSE

PSEUDO-RESPONSE: Angiogenetic inhibitors can cause a decrease in contrast enhancement due to reduction in blood-brain barrier permeability rather then true reduction in volume ( Clarke JL et al. Curr Neurol Neurosci Rep 2009).

A 47-year-old man with GBM. A reduction of the enhancing portion of the lesion is observed 1 day after initiation of cediranib treatment. Four weeks later, besides a continuing reduction in the enhancing portion, an expansion is observed in the FLAIR images. Expansions in both the enhancing area and abnormal hyperintense areas consistent with tumor progression were observed subsequently (L.C. Hygino da Cruz Jr et al. AJNR 2011)

Pseudo-response might be an indicator of subsequent favourable response

RANO Criteria for pseudoresponse: greater than 50% reduction in contrast enhancement without a significant decrease in nonenhancing tumour. Decreased enhancement should persist more than 4 weeks to be considered true response.