Label-free fluorescence lifetime imaging for rapid discrimination of high-grade prostate cancer in fresh biopsy cores: a feasibility study.

[SIGNIFICANCE] Prostate biopsy remains the gold standard for prostate cancer (PCa) diagnosis and treatment planning. However, current techniques suffer from low cancer detection rates, with most biopsy cores sampling benign tissue, leading to undergrading and repeat procedures. Label-free fluorescence lifetime imaging (FLIm) offers a potential solution by enabling real-time discrimination between malignant and benign tissue during biopsy collection, potentially reducing both the number of cores required and the repeat biopsy rates.

[AIM] This pilot study evaluates the feasibility of label-free FLIm for rapid discrimination of malignant from benign prostate tissue in freshly obtained core needle biopsies.

[APPROACH] Twenty patients undergoing prostate biopsy were enrolled. FLIm measurements were performed immediately after sample collection ( ) using a custom fiber-optic probe. For each point measurement, FLIm parameters from four spectral bands associated with the emission of distinct endogenous fluorophores including structural proteins and metabolic cofactors (e.g., NADH and FAD) were entered in the analysis. Each FLIm point measurement was labeled based on histological annotation. These data were analyzed to characterize tissue-type differences and to train and evaluate support vector machine (SVM) classifiers for malignancy detection.

[RESULTS] Separation between benign tissue and Gleason pattern can already be observed using just 2 out of 56 FLIm-derived parameters. The SVM classifier, using all parameters, achieved a receiver operating characteristic of 0.88 for identifying Gleason pattern 4 PCa. A shorter lifetime value observed in the NADH-associated band was observed for Gleason pattern 4 PCa relative to benign tissue, consistent with increased free NADH from upregulated glycolysis, supporting the biochemical basis for optical differentiation.

[CONCLUSIONS] FLIm demonstrates strong potential for identifying high-grade PCa. Because measurements were performed using a single fiber optic, this approach can be readily integrated into standard prostate biopsy devices to enable FLIm-guided and real-time tissue characterization during the biopsy procedure and to inform targeted tissue collection.