We present a novel optical sensor to acquire simultaneously functional near-infrared imaging (fNIRI) and functional magnetic resonance imaging (fMRI) data with an improved handling and direct localization in the MRI compared to available sensors. Quantitative phantom and interference
measurements showed that both methods can be combined without reciprocal adverse effects. The direct localization of the optical sensor on MR images acquired with a T1-weighted echo sequence simplifies the co-registration of NIRI and MRI data. In addition, the optical sensor
is simple to attach, which is crucial for measurements on vulnerable subjects. The fNIRI and T2*-weighted fMRI data of a cerebral activation were simultaneously acquired proving the practicability of the setup.