An overview of image registration for aligning mass spectrometry imaging with clinically relevant imaging modalities

[Display omitted] •Mass spectrometry imaging (MSI) is a powerful molecular imaging technique.•Integration with other imaging modalities is essential in clinical MSI.•Image integration is performed by image registration techniques.•Technical potential of image registration in MSI has not been fully exploited.•Roadmap proposed to improve registration accuracy. Mass spectrometry imaging (MSI) is used in many aspects of clinical research, including pharmacokinetics, toxicology, personalised medicine, and surgical decision-making. Maximising its potential requires the spatial integration of MSI images with imaging data from existing clinical imaging modalities, such as histology and MRI. To ensure that the information is properly integrated, all contributing images must be accurately aligned. This process is called image registration and is the focus of this review. In light of the ever-increasing spatial resolution of MSI instrumentation and a diversification of multi-modal MSI studies (e.g., spatial omics, 3D-MSI), the accuracy, versatility, and precision of image registration must increase accordingly. We review the application of image registration to align MSI data with different clinically relevant ex vivo and in vivo imaging techniques. Based on this, we identify steps in the current image registration processes where there is potential for improvement. Finally, we propose a roadmap for community efforts to address these challenges in order to increase registration quality and help MSI to fully exploit its multi-modal potential.