Table 1.

Contraction between MALDI-MSI and AFADESI-MSI.

MSI technique	MALDI-MSI	DESI-MSI	AFADESI-MSI
Ionization method	Matrix-assisted laser desorption ionization (MALDI)	Desorption electrospray ionization (DESI)	Air flow-assisted desorption electrospray ionization (AFADESI)
Type of MSI	Vacuum	Ambient	Ambient
Max spatial resolution	Lowest at around 1.4 µm Currently, most cancer metabolomics papers conduct experiments at around 10 µm	Lowest at 10-20 µm 50-200 µm for most of the current studies	Around 100 µm
Sample preparation	Frozen tissue or FFPE Matrix deposition	Frozen tissue or FFPE	Frozen tissue or FFPE
Key advantages	High spatial resolution and mass resolution Good for examining small samples Reliable results	High throughput Ambient operating conditions Minimum sample preparations Quick results	Ambient operating conditions Minimum sample preparations Wide field and large coverage Improve sensitivity and spatial resolution from DESI
Major limitations	Extra preparation steps Vacuum condition	Lower spatial resolution and sensitivity	Low reproducibility of results due to complex parameters