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Pretreatment Normal WM Magnetization Transfer Ratio Predicts Risk of Radiation Necrosis in Patients with
J H Harreld1,2, P Zou3, N D Sabin3
1From the Department of Radiology (J.H.H.), Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire Julie.H.Harreld@Hitchcock.org.
Background And Purpose:
Radiation necrosis, for which abnormal WM enhancement is a hallmark, is an uncommon complication of craniospinal irradiation in children with medulloblastoma. The magnetization transfer ratio measures macromolecular content, dominated by myelin in the WM. We investigated whether the pretreatment supratentorial (nonsurgical) WM magnetization transfer ratio could predict patients at risk for radiation necrosis after radiation therapy for medulloblastoma.
Materials And Methods:
Ninety-five eligible patients with medulloblastoma (41% female; mean age, 11.0 [SD, 5.4] years) had baseline balanced steady-state free precession MR imaging before proton or photon radiation therapy. Associations among baseline supratentorial magnetization transfer ratio, radiation necrosis (spontaneously resolving/improving parenchymal enhancement within the radiation field)3, age, and the presence of visible brain metastases were explored by logistic regression and parametric/nonparametric techniques as appropriate.
Results:
Twenty-three of 95 (24.2%) children (44% female; mean age, 10.7 [SD, 6.7] years) developed radiation necrosis after radiation therapy (19 infratentorial, 1 supratentorial, 3 both). The mean pretreatment supratentorial WM magnetization transfer ratio was significantly lower in these children (43.18 versus 43.50, P = .03). There was no association between the supratentorial WM magnetization transfer ratio and age, sex, risk/treatment stratum, or the presence of visible brain metastases.
Conclusions:
A lower baseline supratentorial WM magnetization transfer ratio may indicate underlying structural WM susceptibility to radiation necrosis and may identify children at risk for developing radiation necrosis after craniospinal irradiation for medulloblastoma.
Insights
A lower magnetization transfer ratio in white matter before radiation therapy may identify children at risk for developing radiation necrosis after medulloblastoma treatment. This finding aids in predicting and potentially preventing this complication.
Area of Science:
- Neuroimaging
- Radiation Oncology
- Pediatric Oncology
Background:
- Radiation necrosis is an uncommon complication of craniospinal irradiation in pediatric medulloblastoma patients.
- Abnormal white matter (WM) enhancement is a hallmark of radiation necrosis.
- Magnetization transfer ratio (MTR) measures macromolecular content, primarily myelin in WM.
Purpose of the Study:
- To investigate if pretreatment supratentorial WM MTR can predict radiation necrosis risk in children with medulloblastoma.
- To assess the association between baseline WM MTR and the development of radiation necrosis post-radiation therapy.
Main Methods:
- Ninety-five pediatric medulloblastoma patients underwent baseline MR imaging before radiation therapy.
- Logistic regression and statistical techniques explored associations between supratentorial WM MTR, radiation necrosis, age, and brain metastases.
- Radiation necrosis was defined as spontaneously resolving/improving parenchymal enhancement within the radiation field.
Main Results:
- Twenty-three of 95 patients (24.2%) developed radiation necrosis.
- A significantly lower mean pretreatment supratentorial WM MTR was observed in children who developed radiation necrosis (43.18 vs 43.50, P=.03).
- No association was found between supratentorial WM MTR and age, sex, risk/treatment stratum, or brain metastases.
Conclusions:
- Lower baseline supratentorial WM MTR may indicate susceptibility to radiation necrosis.
- Pretreatment supratentorial WM MTR can help identify children at risk for radiation necrosis after craniospinal irradiation for medulloblastoma.
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