Functional connectivity changes in patients with brain tumours—A systematic review on resting state-fMRI

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AimResting-state functional magnetic resonance imaging (rs-fMRI) has been utilised to explore the brain's functional changes in patients with brain tumours. However, it remains unclear how such alterations affect functional connectivity (FC) and thus lead to changes in behaviour. To better understand the present state of knowledge, we conducted a systematic review. Material and methodsA systematic literature search of patients with brain tumours with rs-fMRI methods was conducted using the PubMed/MEDLINE and Cochrane Library electronic databases following PRISMA guidelines. References and citations were checked in Scopus database. ResultsTen independent studies were identified, comprising of 361 adult participants (218 had brain tumours; and the remainder were healthy controls). In comparison to healthy controls, patients with brain tumours demonstrated network distortions, alterations, and associated changes in the resting state networks (RSNs). Location and types of tumour affected RSNs integrity, particularly in the Default Mode Network (DMN). The left hemisphere was reported to have the largest effect on RSNs regardless of size or type of tumour. Result also demonstrate significant alterations to the local networks (decreases in the intra-hemispheric and inter-hemispheric FC). Studies also demonstrated that alterations in rs-fMRI were related to poorer neuropsychological task performance. ConclusionHowever, more studies utilising rs-fMRI to investigate effects of brain tumours on different types of RSNs are needed to draw clear conclusions about effects of tumour growth on properties of brain functional networks. Notably, not all studies have used the same nodes or regions for the networks, even though tumour locations often overlap.