Comparaison Between MRI Alone or Combined With Positron Emission Tomography for Brain Metastasis Diagnosis (ITIRR)

Inclusion Criteria:

• Male or female over 18 years of age;
• Having undergone gamma knife radiosurgery for brain metastasis;
• Presenting for a first MRI follow-up (Cohort C1);
• Presence of one or more brain metastases with increased enhancement on follow-up MRI (Cohort C2.1 and C2.2); A participant recruited for Cohort C1 could be recruited for follow-up in Cohort C2.1 or C2.2 if the MRI result is ambiguous.

Exclusion Criteria:

• Pregnancy or breastfeeding;
• Other condition that may influence the imaging result;
• Renal impairment (<30 mL/min/1.73 m2). This threshold is consistent with recent RAC recommendations; Note: For participants with intermediate renal clearance (30-60 mL/min/1.73 m2), the total gadobutrol dose injected is set at the manufacturer's recommended clinical dose. For patients with renal clearance greater than 60 mL/min/1.73 m2, a dose of 1.5x the normal dose is used. These dose values have been approved by Dr. Chénard and are consistent with the RAC recommendations.
• Inability to maintain supine position for the required duration (variable, depending on the sequence);
• Patients who have previously received full brain irradiation;
• Patients who are claustrophobic and cannot tolerate insertion into the MRI scanner;