Imagerie des métastases cérébrales

The therapeutic management of brain metastases depends upon their diagnosis and characteristics. It is therefore imperative that imaging provides accurate diagnosis, identification, size and localization information of intracranial lesions in patients with presumed cerebral metastatic disease. MRI exhibits superior sensitivity to CT for small lesions identification and to evaluate their precise anatomical location. The CT-scan will be made only in case of MRI's contraindication or if MRI cannot be obtained in an acceptable delay for the management of the patient. In clinical practice, the radiologic metastasis evaluation is based on visual image analyses. Thus, a particular attention is paid to the imaging protocol with the aim to optimize the diagnosis of small lesions and to evaluate their evolution. The MRI protocol must include: 1) non-contrast T1, 2) diffusion, 3) T2* or susceptibility-weighted imaging, 4) dynamic susceptibility contrast perfusion, 5) FLAIR with contrast injection, 6) T1 with contrast injection preferentially using the 3D spin echo images. The role of the nuclear medicine imaging is still limited in the diagnosis of brain metastasis. The Tc-sestamibi brain imaging or PET with amino acid tracers can differentiate local brain metastasis recurrence from radionecrosis but still to be evaluated.