Infrared (IR) spectroscopic imaging is potentially useful
for digital
histopathology as it provides spatially resolved molecular absorption
spectra, which can subsequently yield useful information by powerful
artificial intelligence methods. A typical analysis pipeline in using
IR imaging data for chemical pathology often involves iterative processes
of segmentation, evaluation, and analysis that necessitate rapid data
exploration. Here, we present a fast, reliable, and intuitive method
based on a phasor representation of spectra and discuss its unique
applicability for IR imaging data. We simulate different features
extant in IR spectra and discuss their influence on the phasor waveforms;
similarly, we undertake IR image analysis in the transform space to
understand spectral similarity and variance. We demonstrate the potential
of phasor analysis for biomedical tissue imaging using a variety of
samples, using fresh frozen surgical prostate resections and formalin-fixed
paraffin-embedded breast cancer tissue microarray samples as model
systems that span common histopathology practice. To demonstrate further
generalizability of this approach, we apply the method to data from
different experimental conditionsincluding standard (5.5 μm
× 5.5 μm pixel size) and high-definition (1.1 μm
× 1.1 μm pixel size) Fourier transform IR (FTIR) spectroscopic
imaging using transmission and transflection modes. Quantitative segmentation
results from our approach are compared to previous studies, showing
good agreement and quick visualization. The presented method is rapid,
easy to use, and highly capable of deciphering compositional differences,
presenting a convenient tool for exploratory analysis of IR imaging
data.