Maximized Spatial Information and Minimized Acquisition Time of Top-Hat IR-MALDESI-MSI of Zebrafish Using Nested Regions of Interest (nROIs)

Increasing the spatial resolution of a mass spectrometryimaging(MSI) method results in a more defined heatmap of the spatial distributionof molecules across a sample, but it is also associated with the disadvantageof increased acquisition time. Decreasing the area of the region ofinterest to achieve shorter durations results in the loss of potentiallyvaluable information in larger specimens. This work presents a novelMSI method to reduce the time of MSI data acquisition with variablestep size imaging: nested regions of interest (nROIs). Using nROIs,a small ROI may be imaged at a higher spatial resolution while nestedinside a lower-spatial-resolution peripheral ROI. This conserves themaximal spatial and chemical information generated from target regionswhile also decreasing the necessary acquisition time. In this work,the nROI method was characterized on mouse liver and applied to top-hatMSI of zebrafish using a novel optical train, which resulted in asignificant improvement in both acquisition time and spatial detailof the zebrafish. The nROI method can be employed with any step sizepairing and adapted to any method in which the acquisition time oflarger high-resolution ROIs poses a practical challenge.

Automated summary

This study proposes a novel method of mass spectrometry imaging (MSI) to reduce the acquisition time of MSI data using nested regions of interest (nROIs). By utilizing nROIs, a smaller region of interest can be imaged at higher spatial resolution nested within a larger region of interest at lower spatial resolution, conserving maximal spatial and chemical information while decreasing acquisition time. The nROI method was characterized on mouse liver and applied to top-hat MSI of zebrafish, resulting in significant improvements in acquisition time and spatial detail. The nROI method can be applied to any method where acquiring larger high-resolution ROIs poses a practical challenge.