Preoperative MR imaging of 6 patients with suspected glioma recurrence. In 3 cases (1, 2, and 3), histopathology revealed treatment-related lesions, and in the other 3 cases (4, 5, and 6), recurrent tumor. T1-weighted postcontrast (A) and DWI (B) are shown in each case. Treatment-related lesions (1, 2, and 3) show reduced diffusion predominantly in the central necrotic region. Lesions corresponding to progressive tumor (4, 5, and 6), on the other side, show reduced diffusion mainly in the solid-lesion components.

Differentiating between treatment-related lesions and tumor progression remains one of the greatest dilemmas in neuro-oncology. Diffusion MR imaging characteristics may provide useful information to help make this distinction. The aim of the study was to assess the diagnostic accuracy of the centrally reduced diffusion sign for differentiation of treatment-related lesions and true tumor progression in patients with suspected glioma recurrence.


The images of 231 patients who underwent an operation for suspected glioma recurrence were reviewed. Patients with susceptibility artifacts or without central necrosis were excluded. The final diagnosis was established according to histopathology reports. Two neuroradiologists classified the diffusion patterns on preoperative MR imaging as the following: 1) reduced diffusion in the solid component only, 2) reduced diffusion mainly in the solid component, 3) no reduced diffusion, 4) reduced diffusion mainly in the central necrosis, and 5) reduced diffusion in the central necrosis only. Diagnostic accuracy metrics and the area under the receiver operating characteristic curve were estimated for the diffusion patterns.


One hundred three patients were included (22 with treatment-related lesions and 81 with tumor progression). The diagnostic accuracy results for the centrally reduced diffusion pattern as a predictor of treatment-related lesions (“mainly central” and “exclusively central” patterns versus all other patterns) were as follows: 64% sensitivity (95% CI, 41%–83%), 84% specificity (95% CI, 74%–91%), 52% positive predictive value (95% CI, 37%–66%), and 89% negative predictive value (95% CI, 83%–94%).


The centrally reduced diffusion sign is associated with the presence of treatment effect. The probability of a histologic diagnosis of a treatment-related lesion is low (11%) in the absence of centrally reduced diffusion.

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Jeffrey Ross

• Mayo Clinic, Phoenix

Dr. Jeffrey S. Ross is a Professor of Radiology at the Mayo Clinic College of Medicine, and practices neuroradiology at the Mayo Clinic in Phoenix, Arizona. His publications include over 100 peer-reviewed articles, nearly 60 non-refereed articles, 33 book chapters, and 10 books. He was an AJNR Senior Editor from 2006-2015, is a member of the editorial board for 3 other journals, and a manuscript reviewer for 10 journals. He became Editor-in-Chief of the AJNR in July 2015. He received the Gold Medal Award from the ASSR in 2013.

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