Fatigue and Cognitive Dysfunction After Allogeneic Stemcell Transplantation, Prospective PET Study

This study is the academic study and continuation and further development of a prior project under the leadership of Professor LeBlanc. Patients undergoing allogenic stem cell transplantation are followed up in the outpatient clinic. Here, patients are offered participation the fatigue study measuring both fatigue and cognitive impairment systematically by international standard. Previous study by Boberg et al suggested distinct mRNA and proteomic profiles segregating fatigued from non-fatigued patients as well as patients with or without cognitive impairment. A larger well-defined patient cohort is necessary to confirm these results. Investigators aim to identify specific sets of proteins in the CSF that can serve as potential biomarkers of cognitive dysfunction and/or fatigue. This will be performed with two methods: * by using mass spectrometry-based proteomics approaches * Olink technology PET examinations will be performed on both fatigued and non-fatigued. We will utilize the second generation TSPO radioligand \[ 11C\]PBR28 as well as the SV2A radioligand \[ 11C\]UCB-J, both showing high signal-to-noise ratio and adequate test-retest properties.