title: Restriction-Spectrum Imaging of Bevacizumab-Related Necrosis in a Patient with GBM.
abstract: OBJECTIVE
  With the increasing use of antiangiogenic agents in the treatment of high-grade gliomas, we are becoming increasingly aware of distinctive imaging findings seen in a subset of patients treated with these agents. Of particular interest is the development of regions of marked and persistent restricted diffusion. We describe a case with histopathologic validation, confirming that this region of restricted diffusion represents necrosis and not viable tumor.
  
  
  METHODS
  We present a case report of a 52-year-old man with GBM treated with temozolomide, radiation, and concurrent bevacizumab following gross total resection. The patient underwent sequential MRI's which included restriction-spectrum imaging (RSI), an advanced diffusion-weighted imaging (DWI) technique, and MR perfusion. Following surgery, the patient developed an area of restricted diffusion on RSI which became larger and more confluent over the next several months. Marked signal intensity on RSI and very low cerebral blood volume (CBV) on MR perfusion led us to favor bevacizumab-related necrosis over recurrent tumor. Subsequent histopathologic evaluation confirmed coagulative necrosis.
  
  
  CONCLUSIONS
  Our report increases the number of pathologically proven cases of bevacizumab-related necrosis in the literature from three to four. Furthermore, our case demonstrates this phenomenon on RSI, which has been shown to have good sensitivity to restricted diffusion.
authors.affiliation: Department of Radiology, University of California San Diego , San Diego, CA , USA ; Multimodal Imaging Laboratory, University of California San Diego , San Diego, CA , USA.
authors.forename: Nikdokht
authors.initials: N
authors.lastname: Farid
authors.forename: Daniela B
authors.initials: DB
authors.lastname: Almeida-Freitas
authors.forename: Nathan S
authors.initials: NS
authors.lastname: White
authors.forename: Carrie R
authors.initials: CR
authors.lastname: McDonald
authors.forename: Karra A
authors.initials: KA
authors.lastname: Muller
authors.forename: Scott R
authors.initials: SR
authors.lastname: Vandenberg
authors.forename: Santosh
authors.initials: S
authors.lastname: Kesari
authors.forename: Anders M
authors.initials: AM
authors.lastname: Dale
keywords: bevacizumab; diffusion-weighted imaging; glioblastoma multiforme; necrosis; restriction-spectrum imaging