Fluorescence Lifetime Imaging and Intravascular Ultrasound: Co-Registration Study Using Ex Vivo Human Coronaries

AbstractMetabolic profiles vary across all levels of biological diversity, from cells to taxa. Two-photon fluorescence lifetime imaging microscopy (FLIM) facilitates metabolic characterisation of biological specimens by assaying the intrinsic autofluorescence of the ubiquitous coenzymes NAD(P)H and FAD. The potential of this method for characterising the diversity of organismal metabolism remains largely untapped. Using FLIM in Drosophila melanogaster, we show tissue-specificity in fluorescence lifetime that reflects variation in redox patterns. In particular, sperm cells exhibited elevated glycolysis relative to other tissues. We also show that sperm metabolism is phenotypically plastic: compared to male-stored sperm, sperm stored in the female’s storage organ showed a substantial reduction in the protein-bound FAD lifetime fraction but no change in the NAD(P)H profile. This study represents the first ex vivo investigation of sperm metabolism using FLIM.

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In Vivo Time Domain Optical Imaging of Renal Ischemia-Reperfusion Injury: Discrimination Based on Fluorescence Lifetime

Molecular Imaging ◽

10.2310/7290.2007.00030 ◽

2007 ◽

Vol 6 (5) ◽

pp. 7290.2007.00030 ◽

Cited By ~ 24

Author(s):

Abedelnasser Abulrob ◽

Eric Brunette ◽

Jacqueline Slinn ◽

Ewa Baumann ◽

Danica Stanimirovic

Keyword(s):

Optical Imaging ◽

Fluorescence Lifetime ◽

Fluorescence Intensity ◽

Time Domain ◽

Ex Vivo ◽

Renal Ischemia ◽

Fluorescence Lifetime Imaging ◽

Lifetime Imaging ◽

Lifetime Analysis

Fluorescence lifetime is an intrinsic parameter of the fluorescent probe, independent of the probe concentration but sensitive to changes in the surrounding microenvironment. Therefore, fluorescence lifetime imaging could potentially be applied to in vivo diagnostic assessment of changes in the tissue microenvironment caused by disease, such as ischemia. The aim of this study was to evaluate the utility of noninvasive fluorescence lifetime imaging in distinguishing between normal and ischemic kidney tissue in vivo. Mice were subjected to 60-minute unilateral kidney ischemia followed by 6-hour reperfusion. Animals were then injected with the near-infrared fluorescence probe Cy5.5 or saline and imaged using a time-domain small-animal optical imaging system. Both fluorescence intensity and lifetime were acquired. The fluorescence intensity of Cy5.5 was clearly reduced in the ischemic compared with the contralateral kidney, and the fluorescence lifetime of Cy5.5 was not detected in the ischemic kidney, suggesting reduced kidney clearance. Interestingly, the two-component lifetime analysis of endogenous fluorescence at 700 nm distinguished renal ischemia in vivo without the need for Cy5.5 injection for contrast enhancement. The average fluorescence lifetime of endogenous tissue fluorophores was a sensitive indicator of kidney ischemia ex vivo. The study suggests that fluorescence lifetime analysis of endogenous tissue fluorophores could be used to discriminate ischemic or necrotic tissues by noninvasive in vivo or ex vivo organ imaging.

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Fluorescence lifetime imaging endomicroscopy based ex-vivo lung cancer prediction using multi-scale concatenated-dilation convolutional neural networks

Medical Imaging 2021: Computer-Aided Diagnosis ◽

10.1117/12.2580467 ◽

2021 ◽

Author(s):

Qiang Wang ◽

James R. Hopgood ◽

Marta Vallejo

Keyword(s):

Lung Cancer ◽

Neural Networks ◽

Convolutional Neural Networks ◽

Fluorescence Lifetime ◽

Ex Vivo ◽

Fluorescence Lifetime Imaging ◽

Cancer Prediction ◽

Multi Scale ◽

Lifetime Imaging

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Influence of dexamethasone on visible 5-ALA fluorescence and quantitative protoporphyrin IX accumulation measured by fluorescence lifetime imaging in glioblastomas: is pretreatment obligatory before fluorescence-guided surgery?

Journal of Neurosurgery ◽

10.3171/2021.6.jns21940 ◽

2021 ◽

pp. 1-9

Author(s):

Lisa I. Wadiura ◽

David Reichert ◽

Veronika Sperl ◽

Alexandra Lang ◽

Barbara Kiesel ◽

...

Keyword(s):

Fluorescence Lifetime ◽

Aminolevulinic Acid ◽

Ex Vivo ◽

Protoporphyrin Ix ◽

Fluorescence Lifetime Imaging ◽

Lifetime Imaging ◽

Guided Surgery ◽

Fluorescence Guided Surgery ◽

Significant Difference ◽

The Mean

OBJECTIVE Fluorescence-guided surgery using 5-aminolevulinic acid (5-ALA) is nowadays widely applied for improved resection of glioblastomas (GBMs). Initially, pretreatment with dexamethasone was considered to be essential for optimal fluorescence effect. However, recent studies reported comparably high rates of visible fluorescence in GBMs despite absence of dexamethasone pretreatment. Recently, the authors proposed fluorescence lifetime imaging (FLIM) for the quantitative analysis of 5-ALA–induced protoporphyrin IX (PpIX) accumulation. The aim of this study was thus to investigate the influence of dexamethasone on visible fluorescence and quantitative PpIX accumulation. METHODS The authors prospectively analyzed the presence of visible fluorescence during surgery in a cohort of patients with GBMs. In this study, patients received dexamethasone preoperatively only if clinically indicated. One representative tumor sample was collected from each GBM, and PpIX accumulation was analyzed ex vivo by FLIM. The visible fluorescence status and mean FLIM values were correlated with preoperative intake of dexamethasone. RESULTS In total, two subgroups with (n = 27) and without (n = 20) pretreatment with dexamethasone were analyzed. All patients showed visible fluorescence independent from preoperative dexamethasone intake. Furthermore, the authors did not find a statistically significant difference in the mean FLIM values between patients with and without dexamethasone pretreatment (p = 0.097). CONCLUSIONS In this first study to date, the authors found no significant influence of dexamethasone pretreatment on either visible 5-ALA fluorescence during GBM surgery or PpIX accumulation based on FLIM. According to these preliminary data, the authors recommend administering dexamethasone prior to fluorescence-guided surgery of GBMs only when clinically indicated.

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