The invention provides for a magnetic resonance imaging system (100) for acquiring MRF magnetic resonance data (144) from a subject (118) within a region of interest (109). The magnetic resonance imaging system comprises a processor (130) for controlling the magnetic resonance imaging system and a memory (134) for storing machine executable instructions (140) and MRF pulse sequence commands (142). The MRF pulse sequence commands are configured for controlling the magnetic resonance imaging system to acquire the MRF magnetic resonance data according to a magnetic resonance fingerprinting protocol. Execution of the machine executable instructions causes the processor to: acquire (200) the MRF magnetic resonance data for the region of interest by controlling the magnetic resonance imaging system with the MRF pulse sequence commands; receive (202) at least one magnetic resonance image (152) descriptive of the region of interest; identify (204) anatomical regions (156) within the region of interest using an anatomical model (154); select (206) a local magnetic resonance fingerprinting dictionary (158) from a set of magnetic resonance fingerprinting dictionaries for each of the anatomical regions, wherein the local magnetic resonance fingerprinting dictionary comprises a listing of calculated MRF signals for a set of predetermined substances specific to each of the anatomical regions; and calculate (208) a composition mapping (160) of the predetermined substances for each of the anatomical regions using the MRF magnetic resonance data and the local magnetic resonance fingerprinting dictionary, wherein the composition mapping is a spatial average within each of the anatomical regions.