Postradiation Imaging Changes in the CNS: How can we Differentiate Between Treatment Effect and Disease Progression?

Abstract

A familiar challenge for neuroradiologists and neuro-oncologists is differentiating between radiation treatment effect and disease progression in the CNS. Both entities are characterized by an increase in contrast enhancement on MRI and present with similar clinical signs and symptoms that may occur either in close temporal proximity to the treatment or later in the disease course. When radiation-related imaging changes or clinical deterioration are mistaken for disease progression, patients may be subject to unnecessary surgery and/or a change from otherwise effective therapy. Similarly, when disease progression is mistaken for treatment effect, a potentially ineffective therapy may be continued in the face of progressive disease. Here we describe the three types of radiation injury to the brain based on the time to development of signs and symptoms – acute, subacute and late – and then review specific imaging changes after intensity-modulated radiation therapy, stereotactic radiosurgery and brachytherapy. We provide an overview of these phenomena in the treatment of a wide range of malignant and benign CNS illnesses. Finally, we review the published data regarding imaging techniques under investigation to address this well-known problem.

Stroke‐like migraine attacks after radiation therapy: A misnomer?

“…2 It is possible that these consistently extensive hemispheric MRI changes seen in our SMART patients relate to a preexisting postradiation neuronal injury. 33 Alternatively, the preexisting vasculopathy in SMART may explain imaging findings in 2 ways. First, a disrupted blood-brain barrier can lead to gadolinium enhancement.…”

Radionécrose cérébrale après irradiation en conditions stéréotaxiques des berges opératoires : analyse de la littérature à partir de quatre cas

“…Il s'agit d'une toxicité secondaire tardive survenant dans les mois ou années qui suivent l'irradiation. Selon Walker et al, la radionécrose apparaît dans un délai de 3 ans dans 80 % des cas [13], comme pour les quatre patients présentés. L'IRM et le développement de nouvelles séquences dont la perfusion cérébrale ont conduit à employer ce terme plus largement face à une présentation radiologique « typique ».…”

Clinical Reasoning: Corpus callosum lesion with multiple strokes

“…Biopsy is the gold standard for a definitive diagnosis of radiation necrosis. 7 Though different imaging modalities like DWI/diffusion tensor imaging, magnetic resonance spectroscopy, PET, and SPECT have been used, no single imaging modality reliably differentiates between radiation necrosis and tumor recurrence.…”

“…MRI may be normal or may show diffuse brain edema. 7 The disease is usually self-limited and nonprogressive. Early delayed injury is characterized by pronounced somnolence, lethargy, and anorexia, often occurring in the setting of concomitant chemotherapy.…”

“…Radiation necrosis can occur within a few weeks to as late as 19 years after therapy, with 80% of cases occurring within 3 years. 7 It is associated with high-dose local radiation and is rare with whole brain radiation. 9 Pathologically it is thought to be due to glial and endothelial injury.…”