Fluorescence lifetime and intensity detection of water-soluble hypericin accumulation in ex-vivo glioma, meningioma, and brain metastasis tissue

Abstract

Abstract Fluorescence-guided surgery improves intraoperative brain tumor visualization, but currently available agents remain unreliable for several common entities, particularly lower-grade gliomas and lesions without visible 5-aminolevulinic acid (5-ALA)-induced fluorescence. We prospectively analyzed 69 surgically obtained tumor specimens from 61 patients with WHO grade 4 gliomas, WHO grade 2/3 gliomas, meningiomas, and brain metastases before and after ex vivo incubation in 4 µM water-soluble high-load hypericin-polyvinylpyrrolidone complex (HHL-PVP). Fluorescence lifetime and intensity were quantified using a dual-tap CMOS camera system with a hypericin-specific 575–615 nm bandpass filter. HHL-PVP incubation significantly increased both fluorescence intensity and lifetime in all tumor entities, including specimens without visible 5-ALA fluorescence. An independently derived combined lifetime/intensity regression model discriminated pre- from post-incubation measurements with an area under the receiver operating characteristic curve of 0.975, sensitivity of 98.6%, and specificity of 82.6%; entity-specific areas under the curve ranged from 0.933 to 1.000. These findings support robust hypericin-associated signal detection across major brain tumor entities after ex vivo incubation and provide a rationale for future in vivo evaluation of HHL-PVP in fluorescence-guided neuro-oncological surgery.