Arterial spin labeling (ASL) is a non-invasive MRI technique that could help the radiologists to distinguish brain metastasis progression versus radionecrosis following gamma-knife treatment.

The primary target of the study is to establish the diagnostic performances (specificity, sensitivity) of quantitative measures of ASL in brain metastases suspected of progression/radionecrosis after GK treatment

The metastasis progression versus radionecrosis following GK treatment can sometimes be difficult to distinguish. 60 patients will be included in this prospective, monocentric study. 3 MRI (baseline, 1month and 6 month follow-ups) will be performed. Two neuroradiologists will blindly analyse the MRIs comparing ASL sensibility and specificity to the standard morphological evaluation and T2 perfusion.

Inclusion Criteria:

• Brain metastasis from histologically proven tumor

• GK treatment within 4 month prior to the inclusion

• Lesions suspected of progression/ radionecrosis :

  i.e.≥ 25% of the size progression

• Lesion size: gadolinium enhanced part of the tumour ≥1 cm

Exclusion Criteria:

• Pregnancy
• Medical history of primitive brain tumour
• MRI incompatibility/ medical history of contrast agent allergy
• Claustrophobia
• Patient unable to consent
• Epilepsia/recent stroke
• Patients participating in other studies
• Patients without health care insurance