The prostate-specific membrane antigen (PSMA)–targeted radiotracers ⁶⁸Ga/¹⁷⁷Lu-PSMA-I&T and ^99mTc-PSMA-I&S (for imaging and surgery) are currently successfully used for clinical PET imaging, radionuclide therapy, and radioguided surgery of metastatic prostate cancer. To additionally exploit the high sensitivity and spatial resolution of fluorescence imaging for improved surgical guidance, a PSMA-I&T–based hybrid tracer, PSMA-I&F (DOTAGA-k(Sulfo-Cy5)-y-nal-k-Sub-KuE), has been developed and evaluated. Methods: The in vitro PSMA-targeting efficiency of PSMA-I&F, the reference PSMA-I&T, and their corresponding ^natGa-/⁶⁸Ga- and ^natLu/¹⁷⁷Lu counterparts was determined in LNCaP cells via competitive binding assays (IC₅₀) and dual-tracer radioligand and fluorescence internalization studies. Biodistribution and small-animal PET imaging studies were performed in CB17 SCID and LNCaP xenograft–bearing SHO mice, respectively, and complemented by intraoperative far-red fluorescence imaging using a clinical laparoscope. Additionally, fully automated serial cryosectioning and fluorescence imaging of 1 tumor-bearing animal as well as PSMA immunohistochemistry and fluorescence microscopy of organ cryosections (tumor, kidney, spleen) were also performed. Results: Compared with the parent PSMA-I&T analogs, the PSMA affinities of PSMA-I&F and its ^natGa-/^natLu-complexes remained high and unaffected by dye conjugation (7.9 < IC₅₀ < 10.5 nM for all ligands). The same was observed for the internalization of ⁶⁸Ga- and ¹⁷⁷Lu-PSMA-I&F. In vivo, blood clearance of ⁶⁸Ga- and ¹⁷⁷Lu-PSMA-I&F was only slightly delayed by high plasma protein binding (94%–95%), and very low accumulation in nontarget organs was observed already at 1 h after injection. Dynamic PET imaging confirmed PSMA-specific (as demonstrated by coinjection of 2-PMPA) uptake into the LNCaP xenograft (4.5% ± 1.8 percentage injected dose per gram) and the kidneys (106% ± 23 percentage injected dose per gram). Tumor-to-background ratios of 2.1, 5.2, 9.6, and 9.6 for blood, liver, intestines, and muscle, respectively, at 1 h after injection led to excellent imaging contrast in ⁶⁸Ga-PSMA-I&F PET and in intraoperative fluorescence imaging. Furthermore, fluorescence imaging of tissue cryosections allowed high-resolution visualization of intraorgan PSMA-I&F distribution in vivo and its correlation with PSMA expression as determined by immunohistochemistry. Conclusion: Thus, with its high PSMA-targeting efficiency and favorable pharmacokinetic profile, ⁶⁸Ga/¹⁷⁷Lu-PSMA-I&F serves as an excellent proof-of-concept compound for the general feasibility of PSMA-I&T–based hybrid imaging. The PSMA-I&T scaffold represents a versatile PSMA-targeted lead structure, allowing relatively straightforward adaptation to the different structural requirements of dedicated nuclear or hybrid imaging agents.

Due to loss of tactile feedback the assessment of tumor margins during robotic surgery is based only on visual inspection, which is neither significantly sensitive nor specific. Here we demonstrate time-resolved fluorescence spectroscopy (TRFS) as a novel technique to complement the visual inspection of oral cancers during transoral robotic surgery (TORS) in real-time and without the need for exogenous contrast agents. TRFS enables identification of cancerous tissue by its distinct autofluorescence signature that is associated with the alteration of tissue structure and biochemical profile. A prototype TRFS instrument was integrated synergistically with the da Vinci Surgical robot and the combined system was validated in swine and human patients. Label-free and real-time assessment and visualization of tissue biochemical features during robotic surgery procedure, as demonstrated here, not only has the potential to improve the intraoperative decision making during TORS but also other robotic procedures without modification of conventional clinical protocols.

The study of structured light is an important field of investigation in both the quantum and classical regimes.^1,2 In particular, light carrying orbital angular momentum (OAM) different from zero has been used in many applications ranging from quantum simulation^3,4 and quantum engineering^5,6 to quantum and classical communications.^{7 – 14} Recently, OAM modes have been particularly studied for their uses in biomedical applications of imaging and diagnosis.^{15 – 17} In particular, they have been exploited for the development of noninvasive diagnostics on tissues. In this regard, studies comparing the transmittance to the Gaussian spatial mode on scattering media simulating real tissue properties have been carried out.^{18 – 20} In this context, it becomes of fundamental importance to investigate how the structure of OAM modes can be degraded by scattering and turbulent media. In particular, this has been investigated in communications through scattering media,²¹ atmospheric turbulence,^{22 – 24} and underwater.^25,26

Significance: Early detection by white-light endoscopy (WLE) is the key procedure used in clinical care to prevent colorectal cancer (CRC). In high-risk patients to develop CRC, like in inflammatory bowel disease, the miss-rate of dysplastic lesions is three times higher compared to healthy individuals. In this study we explored the use of a near-infrared probe with fluorescence endoscopy as an adjunct to WLE to highlight adenomas. We demonstrated in clinically relevant animal models of colorectal carcinogenesis and ulcerative colitis that our strategy enabled improved detection using near-infrared fluorescence-guided colonoscopy without interfering in the clinical workflow. Since combined near-infrared fluorescent/WLE systems are already being clinically translated, our approach could result in improving the adenoma detection rate during colonoscopy particularly in high-risk patients.

Fluorescence imaging has been considered for over a half-century as a modality that could assist surgical guidance and visualization. The administration of fluorescent molecules with sensitivity to disease biomarkers and their imaging using a fluorescence camera can outline pathophysiological parameters of tissue invisible to the human eye during operation. The advent of fluorescent agents that target specific cellular responses and molecular pathways of disease has facilitated the intraoperative identification of cancer with improved sensitivity and specificity over nonspecific fluorescent dyes that only outline the vascular system and enhanced permeability effects. With these new abilities come unique requirements for developing phantoms to calibrate imaging systems and algorithms. We briefly review herein progress with fluorescence phantoms employed to validate fluorescence imaging systems and results. We identify current limitations and discuss the level of phantom complexity that may be required for developing a universal strategy for fluorescence imaging calibration. Finally, we present a phantom design that could be used as a tool for interlaboratory system performance evaluation.

Fluorescence imaging in surgery allows for visualization of biologically relevant markers that are indicated to guide rapid decision-making during the procedure.^{1 – 3} The use of fluorescence-guided surgery (FGS) has been growing at a steady pace over the past 70 years, with rapid expansion over the last decade as the imaging technologies have matured to enable seamless integration into the clinical workflow.² Indocyanine green (ICG) is by far the most widely used tissue perfusion agent and cardiac flow indicator within FGS.⁴ The success of ICG within fluorescence imaging can be attributed to its absorption and emission in the near-infrared (NIR) range, its low toxicity, and its history of use within medicine for over half a century.^{2,4 – 6} As the field of FGS expands, there is a wider range of imaging systems that are indicated for the same uses, such that there is a compelling need for standards that enable system characterization, performance monitoring, and intersystem comparisons or calibration.^{7 – 10} The performance of imaging systems can affect surgical decision making,⁷ so knowledge of their performance capabilities is especially relevant given the real-time decisions that are made with these systems during surgical procedures.