MSIWarp

MSIWarp performs label-free m/z alignment and recalibration of centroid mass spectra in mass spectrometry imaging (MSI) to improve spectral matching and compound identification across datasets.

Key Features:

• Label-free m/z alignment: Recalibrates spectra without requiring labeled standards by aligning m/z peaks between spectra.
• Similarity score optimization: Maximizes a similarity score that considers both peak intensity and m/z position of matched peaks to determine recalibration.
• Centroid-only requirement: Determines the recalibration function using only centroid spectra.
• RANSAC-based outlier handling: Incorporates a tailored random sample consensus (RANSAC) procedure to detect and exclude spurious peak matches.
• Instrument compatibility: Implemented to work across multiple instrument types, including time-of-flight (TOF) and Orbitrap instruments.
• Validation on public datasets: Evaluated on four publicly available datasets, reporting improvements in m/z alignment of up to 88%.
• Composition-agnostic: Operates without assumptions regarding the molecular composition of the sample.
• Authorship: Developed by Horvatovich et al.

Scientific Applications:

• Compound identification: Improves accuracy of compound identification by reducing m/z shifts across spectra.
• Reproducible MSI analysis: Enhances reproducibility when analyzing and sharing MSI datasets through public repositories.
• Cross-instrument data integration: Facilitates alignment of spectra from different instruments such as TOF and Orbitrap for comparative studies.

Methodology:

MSIWarp recalibrates centroid MSI spectra by maximizing a similarity score that accounts for both peak intensity and m/z position of matched peaks, determines a recalibration function from centroid spectra, and optionally applies a tailored RANSAC procedure to detect and exclude spurious peak matches.