Radiographic patterns of recurrence and pathologic correlation in malignant gliomas treated with bevacizumab

Area of Science:

• Neuro-oncology
• Radiology
• Pathology

Background:

• Interpreting MRI abnormalities in bevacizumab-treated malignant gliomas (MG) is challenging.
• Differentiating tumor recurrence from treatment necrosis using standard MRI is difficult.
• Quantitative diffusion-weighted imaging (DWI) may offer insights but is not standard.

Purpose of the Study:

• To correlate radiographic recurrence patterns on MRI with histopathologic findings in bevacizumab-treated MG patients.
• To evaluate the utility of DWI in distinguishing tumor recurrence from necrosis.

Main Methods:

• Retrospective review of 32 bevacizumab-treated MG patients who underwent surgery or autopsy.
• Analysis of radiographic recurrence patterns (local enhancing, distant enhancing, nonenhancing, leptomeningeal).
• Correlation of imaging findings with histopathologic diagnoses (tumor, mixed tumor/necrosis, necrosis).

Main Results:

• Tumor was present in 94% of cases, irrespective of the radiographic recurrence pattern.
• Local enhancing recurrence was the most common pattern (n=23).
• Restricted diffusion on DWI correlated with necrosis, not tumor recurrence.

Conclusions:

• Histopathologic confirmation of tumor is crucial in bevacizumab-treated MG, as MRI patterns can be misleading.
• The presence of restricted diffusion on DWI in this context is suggestive of necrosis.
• Further investigation into advanced imaging techniques may improve diagnostic accuracy.