A recent meeting was held on March 22, 2019, among the U.S. Food and Drug Administration (FDA), clinical scientists, pharmaceutical and biotech companies, clinical trials cooperative groups, and patient advocacy groups to discuss challenges and potential solutions for increasing development of therapeutics for central nervous system (CNS) metastases. A key issue identified at this meeting was the need for consistent tumor measurement for reliable tumor response assessment, including the first step of standardized image acquisition with an MRI protocol that could be implemented in multicenter studies aimed at testing new therapeutics. This document builds upon previous consensus recommendations for a standardized brain tumor imaging protocol (BTIP) in high-grade gliomas and defines a protocol for brain metastases (BTIP-BM) that addresses unique challenges associated with assessment of CNS metastases. The “minimum standard” recommended pulse sequences include: 1) parameter matched pre- and post-contrast inversion-recovery (IR)-prepared, isotropic 3D T1-weighted gradient echo (IR-GRE); 2) axial 2D T2-weighted turbo spin echo acquired after gadolinium-based contrast agent (GBCA) injection and before post-contrast 3D T1-weighted images; 3) axial 2D or 3D T2-weighted FLAIR; 4) axial 2D, 3-directional diffusion-weighted images; and 5) post-contrast 2D T1-weighted spin echo images for increased lesion conspicuity. Recommended sequence parameters are provided for both 1.5T and 3T MR systems. An “ideal” protocol is also provided, which replaces IR-GRE with 3D TSE T1-weighted imaging pre- and post-gadolinium, is best performed at 3T, and for which DSC perfusion is included. Recommended DSC perfusion parameters are given.
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