Magnetic resonance spectroscopy (MRS) for differentiating tumour recurrence from radiation necrosis in treated intra-axial brain tumours.

This is a protocol for a Cochrane Review (diagnostic). The objectives are as follows: The primary objective of this review is to determine the diagnostic accuracy of magnetic resonance spectroscopy (MRS) for detecting tumour recurrence or progression in people with primary or secondary intra-axial brain tumours who have previously undergone radiotherapy or radiosurgery and who present with new or enlarging contrast-enhancing lesions suggestive of recurrence. Secondary objectives The secondary objective of this review is to explore potential sources of heterogeneity in the diagnostic performance of MRS and to investigate the existence of clinically meaningful diagnostic cut-offs or thresholds. In this context, heterogeneity refers to differences between studies, such as technical parameters of the test (e.g. MRS acquistion technique), participants (e.g. primary tumour or metastases), types of treatment modalities, and variations in reference standard (e.g. diagnostic thresholds) that may influence how well the test performs.