During breast conserving surgery (BCS), which is the preferred approach to treat most early stage breast cancers, the
surgeon attempts to excise the tumor volume, surrounded by thin margin of normal tissue. The intra-operative
assessment of cancerous areas is a challenging procedure, with the surgeon usually relying on visual or tactile guidance.
This study evaluates whether time-resolved fluorescence spectroscopy (TRFS) presents the potential to address this
problem. Point TRFS measurements were obtained from 19 fresh tissue slices (7 patients) and parameters that
characterize the transient signals were quantified via constrained least squares deconvolution scheme. Fibrotic tissue
(FT, n=69), adipose tissue (AT, n=76), and invasive ductal carcinoma (IDC, n=27) were identified in histology and
univariate statistical analysis, followed by multi-comparison test, was applied to the corresponding lifetime data.
Significant differentiation between the three tissue types exists at 390 nm and 500 nm bands. The average lifetime is
3.23±0.74 ns for AT, 4.21±0.83 ns for FT and 4.71±0.35 ns (p<0.05) for IDC at 390 nm. Due to the smaller contribution
of collagen in AT the average lifetime value is different from FT and IDC. Additionally, although intensity
measurements do not show difference between FT and IDC, lifetime can distinguish them. Similarly, in 500 nm these
values are 7.01±1.08 ns, 5.43±1.05 ns and 4.39±0.88 ns correspondingly (p<0.05) and this contrast is due to
differentiation in retinol or flavins relative concentration, mostly contributing to AT. Results demonstrate the potential of
TRFS to intra-operatively characterize BCS breast excised tissue in real-time and assess tumor margins.