Assessment of MRI parameters as imaging biomarkers for radiation necrosis in the rat brain

Silun Wang, Erik Tryggestad, Tingting Zhou, Michael Armour, Zhibo Wen, De Xue Fu, Eric Ford, Peter C.M. Van Zijl, Jinyuan Zhou

Research output: Contribution to journalArticlepeer-review

Abstract

Purpose: Radiation necrosis is a major complication of radiation therapy. We explore the features of radiation-induced brain necrosis in the rat, using multiple MRI approaches, including T 1, T 2, apparent diffusion constant (ADC), cerebral blood flow (CBF), magnetization transfer ratio (MTR), and amide proton transfer (APT) of endogenous mobile proteins and peptides. Methods and Materials: Adult rats (Fischer 344; n = 15) were irradiated with a single, well-collimated X-ray beam (40 Gy; 10 × 10 mm 2) in the left brain hemisphere. MRI was acquired on a 4.7-T animal scanner at ∼25 weeks' postradiation. The MRI signals of necrotic cores and perinecrotic regions were assessed with a one-way analysis of variance. Histological evaluation was accomplished with hematoxylin and eosin staining. Results: ADC and CBF MRI could separate perinecrotic and contralateral normal brain tissue (p < 0.01 and < 0.05, respectively), whereas T 1, T 2, MTR, and APT could not. MRI signal intensities were significantly lower in the necrotic core than in normal brain for CBF (p < 0.001) and APT (p < 0.01) and insignificantly higher or lower for T 1, T 2, MTR, and ADC. Histological results demonstrated coagulative necrosis within the necrotic core and reactive astrogliosis and vascular damage within the perinecrotic region. Conclusion: ADC and CBF are promising imaging biomarkers for identifying perinecrotic regions, whereas CBF and APT are promising for identifying necrotic cores.

Original languageEnglish (US)
Pages (from-to)e431-e436
JournalInternational Journal of Radiation Oncology Biology Physics
Volume83
Issue number3
DOIs
StatePublished - Jul 1 2012

Keywords

  • APT imaging
  • Biomarker
  • MRI
  • Molecular imaging
  • Radiation necrosis

ASJC Scopus subject areas

  • Radiation
  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Cancer Research

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