The overall aim is to combine intraoperative MRI and optical techniques for multimodal guidance in neurosurgery in patients undergoing brain tumor resection and biopsies. Further, in neurointensive care patients with subarachnoid hemorrhage or traumatic brain injury different MR modalities will be combined with optical techniques for measurement of cerebral perfusionand blood flow. The optical techniques will be transferred and integrated for use with a 3T MR scanner (Skyra, Siemens) and a new operation room (OR). Brain tumor resection: The blue-light neurosurgical microscope has been evaluated together with the in-house developed 5-ALA induced fluorescence probe-technique which helps identify the infiltrative high-grade tumor border. Up till now the fluorescence technique has been used in more than 50 tumor resections at the Neurosurgical clinic (Richter et al., 2017). Further development by combing the fluorescence method with laser Doppler flowmetry (LDF) for biopsy procedures can help indicate vessels structure along the insertion trajectory. As a nextstep probes will be adapted for iMRI together with frameless intraoperative navigation. Neurointensive care: A thin optical probe and corresponding software module for a LDF has been developed and adapted for use in the human brain (Rejmstad et al., 2018). Cerebral microvascular monitoring in the neurointensive care unit (NICU) has so far been done in two patients (EPN, 2099-01032). Each monitoring covered LDF information from more than four days and data was presented in real time in the NICU. Signal analysis methodology development for reduction of movement artifacts, and extracting signals representing e.g.vasomotion, microvascular level is ongoing. Correlation to routine parameters like intracranialpressure, microdialysis and EEG will be the next step in the development chain, together with monitoring of brain perfusion and blood flow in single vessels using MR techniques like ASL,BOLD and NOVA.