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Parenchymal changes after radiosurgery of cerebral arteriovenous malformations. Preliminary report of a proposed
F Nataf1, M Ghossoub, O Missir
1Department of Neurosurgery, Centre Hospitalier Sainte-Anne, Paris, France.
Abstract:
Radiosurgery of cerebral arteriovenous malformations (cAVM) can induce parenchymal changes seen on MRI. The purpose of this study was to classify these changes and to correlate them to clinical outcome and obliteration of the cAVM. 142 patients with cAVM underwent radiosurgery with a linear accelerator between 1994 and 1995. 60 clinical records, MR images, and postradiation angiograms were reviewed. Signal abnormalities and contrast enhancements were correlated with clinical deterioration and size decrease of the AVM. The Spearman nonparametric test was used for statistical correlation. MR findings allowed to differentiate between four grades: grade 1 = no parenchymal changes; grade 2 = hypersignal on T2-weighted sequences, grade 3 = grade 2 + contrast enhancement on T1-weighted sequences; grade 4 = grade 3 + central hyposignal (necrosis-like) + peripheral hyposignal surrounding the AVM on T1-weighted sequences. Grade 4 was significantly related (p < 0.001) to clinical deterioration (deficit, seizures, increased intracranial pressure). All grade 4 patients, and only them, had clinical symptoms. Most of these symptoms regressed with corticoid treatment. Grade 4 was also related to the proportion of obliteration of the cAVM at 1 year after radiotherapy: mean proportion of obliteration was 12.5% for grade 2, 25% for grade 3 and 82.2% for grade 4 (p < 0.01). The size of T2-weighted MR images was related to clinical symptom appearance (p < 0.001). Finally, contrast enhancement was not predictive of the occurrence of the clinical symptoms. This proposed classification allows one to differentiate between the various MR images, and seems to predict clinical complications and response to radiotherapy of the cAVM.
Insights
Radiosurgery for cerebral arteriovenous malformations (cAVM) causes MRI changes. A new grading system predicts clinical outcomes and treatment response in cAVM patients after radiosurgery.
Area of Science:
- Neurosurgery
- Radiology
- Neuroradiology
Background:
- Radiosurgery for cerebral arteriovenous malformations (cAVM) can lead to parenchymal changes detectable by MRI.
- Understanding these post-radiosurgery changes is crucial for patient management and outcome prediction.
Purpose of the Study:
- To classify MRI-detected parenchymal changes following radiosurgery for cAVM.
- To correlate these classified changes with clinical outcomes and the obliteration rates of cAVM.
Main Methods:
- Review of clinical records, MR images, and postradiation angiograms from 142 patients treated with linear accelerator radiosurgery for cAVM.
- Correlation of MRI signal abnormalities and contrast enhancement with clinical deterioration and AVM size decrease using the Spearman nonparametric test.
- Development of a four-grade classification system (grades 1-4) based on MRI findings.
Main Results:
- A four-grade classification system for MRI changes was established.
- Grade 4 changes (hypersignal on T2, contrast enhancement, central/peripheral hyposignal) were significantly associated with clinical deterioration (p < 0.001) and AVM obliteration rates (p < 0.01).
- The size of T2-weighted MR images correlated with clinical symptom onset (p < 0.001).
Conclusions:
- The proposed MRI classification system effectively differentiates post-radiosurgery changes in cAVM.
- This classification appears to predict clinical complications and the therapeutic response to radiotherapy for cAVM.