All MSI data was acquired in the negative polarity using a 120,000 FWHM (at m/z 400) mass resolving power and a 250 ms injection time. This resulted in a scan time of ~ 1.46 scan/sec Adjacent or nearby tissue sections were imaged using conventional MALDI to compare the effects of post-ionisation on metabolite imaging. All data was acquired using an m/z range of 100-1000 and externally recalibrated using the Xcalibur version 3.0.63 Recal Offline Software (Thermo Fisher Scientific) using the known masses of NEDC clusters (m/z 257.0618, 479.1542 and 701.2465). For MALDI-MSI and MALDI-2-MSI of mouse kidney sections, a pixel size of 60 µm x 60 µm was used. For the cancerous tissue a pixel size of 20 µm x 20 µm was used.