(ChemotherapyAdvisor) – Retinoblastoma chemotherapy is associated with decreased visual cortex activation among children, according to findings from a functional magnetic resonance imaging (fMRI) study presented at the Radiological Society of North America (RSNA)’s 2012 Scientific Assembly and Annual Meeting in Chicago, IL.

“Functional neuroimaging will be useful to evaluate the impact of disease and treatment on visual system development in children with retinoblastoma,” reported lead author Kathleen Helton, MD, of the St Jude Children’s Research Hospital Radiology Department in Memphis, TN, and her coauthors.

Retinoblastoma is the most common form of eye tumor diagnosed among children. Fatal if untreated, its chemotherapy coincides with the timing of rapid eye and visual neurodevelopment. The effects of chemotherapy on visual system development during childhood has been little studied, however.

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The clinical decision whether to enucleate or preserve the child’s eye(s) is a difficult one, Dr. Helton noted.

“Understanding chemotherapy effects on vision is critical,” she said.

Dr. Helton’s team longitudinally assessed fMRI of visual cortex responses to light stimulation among 60 children undergoing chemotherapy for retinoblastoma (median age at diagnosis, 13.3 months).

The team found “a significant effect of chemotherapy on both the peak fMRI response (P<0.001) and the volume of the cortex activated (P=0.002),” Dr. Helton reported. Activated visual cortex volumes correlated with tumor stage (early, advanced bilateral retinoblastoma, and advanced unilateral retinoblastoma), which correlated with chemotherapy regimen intensity.

“Primary visual cortex fMRI response was decreased after exposure to chemotherapy in children treated for retinoblastoma,” Dr. Helton concluded. “Functional MRI can clarify visual function.”

Further research is needed to “clarify the effects of chemotherapy on cortical activation and the neural-hemodynamic coupling that mediates fMRI signals,” she noted.