From a single instrument to an imaging system: the trend towards integration in mass spectrometry imaging

Early mass spectrometry imaging often consisted of a makeshift combination of ‘one mass spectrometer + one homemade ionisation probe + a set of self-written scripts’. Whilst this could result in published papers, it was difficult to replicate and difficult to commercialise. A clear trend in recent years is that this capability is moving away from disparate components towards standardised, commercially available imaging systems. The most critical component of this integration is the imaging source.

What constitutes a system?

A mass spectrometry imaging system capable of producing stable images comprises at least four components:

• Imaging ion source — responsible for ionising molecules whilst maintaining their retention positions. Neo Source INSTRUMENT’s MSI DPI and MSI LDPI fall into this category; the former covers 20–200 μm and the latter 2–3 μm, covering different scales.

• Mass spectrometer – responsible for separating ions by m/z and recording the data. Taking the time-of-flight (TOF) configuration as an example, Neo Source’s ProC series of online time-of-flight mass spectrometers utilise a dual-field reflection design, with a resolution better than 2000 (at m/z = 92).

• Imaging control and stage — responsible for moving the probe point by point according to coordinates and capturing the spectrum for each pixel.

• Reconstruction and visualisation software — reconstructs the ‘pixel × m/z’ data into a visualised molecular distribution map.

In the past, these four components were often pieced together by different people; now, integrating them into a cohesive whole with synchronised alignment and linked parameters is at the heart of product development.

Why the ‘source’ has become the key to integration

Analysers (mass spectrometer main units) are already in place at many institutions. The real gap lies in the ‘front end’: how to ensure stable ionisation of samples at atmospheric or near-atmospheric pressure, how to accurately map positions to the spectrum, and how to communicate with the main unit. The imaging source fits precisely into this gap, thus becoming the hub of system integration.

Xinceyuan has designed the imaging source to be compatible with mainstream mass spectrometers from Agilent, AB SCIEX and Thermo, essentially standardising ‘the missing piece’—users do not need to repurchase a main unit to obtain a properly aligned imaging front-end.

Three changes brought about by integration

• From ‘usable’ to ‘user-friendly’: parameter linkage and automatic coordinate binding reduce errors caused by manual alignment.

• From one-off to reproducible: the same method can be repeated across different batches of samples, facilitating scientific research and quality control.

• From research to industry: stable, commercially available modules enable pharmaceutical companies, food producers and traditional Chinese medicine organisations to utilise imaging, rather than it being the exclusive preserve of high-level laboratories.

The missing pieces of the puzzle

Greater integration does not mean everything is in place. Data volume remains an unavoidable constraint: a single high-resolution imaging run often generates gigabytes of data, and the ‘second half’ of the system—storage, pre-processing and visualisation—must keep pace; otherwise, whilst the data may be ‘clearly acquired’, it becomes ‘unreadable’.

It is clear that the next stage in mass spectrometry imaging is not an arms race over individual parameters, but rather system-level coordination: whoever integrates the four components—‘source, detector, platform and software’—more tightly and stably will come closer to the goal of ‘making imaging a routine tool’.