Diagnostic Accuracy of Perfusion MRI and MR Spectroscopy in Differentiating Tumor Recurrence from Radiation Necrosis

Background: Differentiating tumor recurrence from radiation necrosis after treatment of intracranial tumors is challenging because both conditions often appear similar on conventional MRI. Advanced imaging techniques such as perfusion MRI and magnetic resonance spectroscopy (MRS) may improve diagnostic accuracy. The aim is to evaluate the diagnostic accuracy of perfusion MRI and MRS in differentiating tumor recurrence from radiation necrosis. Material and Methods: This prospective observational study included 100 patients with suspected post-treatment intracranial lesions who underwent perfusion MRI and MRS. Imaging findings were compared with the final clinical or histopathological diagnosis. Results: Tumor recurrence was confirmed in 62% of patients and radiation necrosis in 38%. Recurrent tumors showed significantly higher relative cerebral blood volume and elevated Cho/NAA and Cho/Cr ratios, whereas radiation necrosis demonstrated reduced perfusion and prominent lipid-lactate peaks (p<0.001). Combined perfusion MRI and MRS achieved 94.0% diagnostic accuracy, with 95.2% sensitivity and 92.1% specificity. Conclusion: Combined perfusion MRI and MRS reliably differentiate tumor recurrence from radiation necrosis and enhance post-treatment neuroimaging assessment.

Keywords: Perfusion MRI; Magnetic resonance spectroscopy; Tumor recurrence; Radiation necrosis; Brain tumors; Diagnostic accuracy.