Imaging Mass Spectrometry Normalization Using Common Ion Current

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Solution Overview

Problem

Current mass spectrometry preprocessing methods fail to effectively remove multiplicative noise, particularly in high molecular content samples, leading to inaccurate comparisons and analyses in fields like mass spectral imaging and chromatography.

Innovation Solution

The Ionization Efficiency Correction (IEC) method normalizes ion intensities by separating common and differential ion counts across multiple spectra, using a rank-1 approximation and non-negative matrix factorization to calculate a common ion current (CIC) for scaling, thereby minimizing the impact of differential peaks on normalization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional normalization methods (TIC-based) are used, then preprocessing is simple, but multiplicative noise is not effectively removed and measurement precision deteriorates

Engineering Contradiction:

Improvepeak height comparabilityVSAvoidnormalization process complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the total ion current into common ion current (CIC) and differential ion current components. The CIC represents the multiplicative noise component that is common across all spectra, while the differential component contains the actual analytical information. This segmentation allows selective normalization of the noise component without affecting the analytical peaks.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent extracts the common ion current (CIC) from the total ion current by identifying peaks that are common to all spectra in the dataset. This extracted CIC component is then used for normalization, separating the noise extraction process from the analytical data to improve measurement precision.

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If TIC-based normalization is used, then processing time is short, but noise-induced biases remain and reliability deteriorates

Engineering Contradiction:

Improvenormalization accuracyVSAvoidpreprocessing time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent performs preliminary identification of common peaks across all spectra before normalization. By pre-identifying which peaks belong to the CIC component, the method prepares the data structure in advance, allowing efficient normalization without excessive processing time during the actual analysis phase.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces the simple mechanical TIC-based scaling with a more sophisticated algorithmic approach that uses peak matching and CIC calculation. This substitution increases reliability by accounting for the actual noise structure in the data, while the algorithm is designed to be computationally efficient.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS11790629B2Intensity normalization in imaging mass spectrometry

Publication Date: 2023.10.17 KATHOLIEKE UNIV LEUVEN

AI summary

The present invention relates generally to a species (analyte) separation and analysis system, for instance a spectrometry system, comprising a processor for receiving and processing signals from said its detector to remove undesirable variation or noise before further processing into a spectrum, whereby the processor is programmed by a novel program for a normalization preprocessing of the signals of said separation and analysis system.