In-vivo assessment of a rat rectal tumor using optical-resolution photoacoustic endoscopy.

Optical-resolution photoacoustic endoscopy (OR-PAE) has been proven to realize imaging on the vascular network in the gastrointestinal (GI) tract with high sensitivity and spatial resolution, providing morphological information. Various photoacoustic endoscopic catheters were developed to improve the resolution and adaptivity of in-vivo imaging. However, this technology has not yet been validated on in-vivo GI tumors, which generally feature angiogenesis. The tumor causes thickened mucosa and neoplasia, requiring large depth-of-field (DOF) in imaging, which contradicts to high-resolution imaging. In this work, a novel catheter was developed with a high resolution of ∼27 µm, providing a matched DOF of ∼400 µm to cover the vessels up to the submucosa layer. Optical-resolution photoacoustic endoscopic imaging was first performed on in-vivo rat rectal tumors. In addition, to further characterize the vessel morphology, tumor-suspected regions and normal regions were selected for quantification and analysis of vessel dimension distribution and tortuosity. All the results suggest that the OR-PAE has great application potential in tumor diagnosis, evaluation, and monitoring of therapeutic efficacy.

Second Near-Infrared Macrophage-Biomimetic Nanoprobes for Photoacoustic Imaging of Neuroinflammation.

Neuroinflammation is a significant pathological event involving the neurodegenerative process associated with many neurological disorders. Diagnosis and treatment of neuroinflammation in its early stage are essential for the prevention and management of neurological diseases. Herein, we designed macrophage membrane-coated photoacoustic (PA) probes (MSINPs), with targeting specificities based on naturally existing target-ligand interactions for the early diagnosis of neuroinflammation. The second near-infrared dye, IR1061, was doped into silica as the core and was encapsulated with a macrophage membrane. In vitro as well as in vivo, the MSINPs could target inflammatory cells via the inflammation chemotactic effect. PA imaging was used to trace the MSINPs in a neuroinflammation mouse model and showed a great targeted effect of MSINPs in the prefrontal cortex. Therefore, the biomimetic nanoprobe prepared in this study offers a new strategy for PA molecular imaging of neuroinflammation, which can enhance our understanding of the evolution of neuroinflammation in specific brain regions.

Efficacy of hepatectomy for hepatolithiasis using 3D visualization combined with ICG fluorescence imaging: A retrospective cohort study.

BACKGROUND: Hepatolithiasis is a complex condition that poses challenges and difficulties in surgical treatment. Three-dimensional visualization technology combined with fluorescence imaging (3DVT-FI) enables accurate preoperative assessment and real-time intraoperative navigation. However, the perioperative outcomes of 3DVT-FI in hepatolithiasis have not been reported. We aim to evaluate the efficacy of 3DVT-FI in the treatment of hepatolithiasis. METHODS: A retrospective analysis was performed on 128 patients who underwent hepatectomy for hepatolithiasis at the Department of Hepatobiliary Surgery, Zhujiang Hospital, between January 2017 and December 2022. Among them, 50 patients underwent hepatectomy using 3DVT-FI (3DVT-FI group), while 78 patients underwent conventional hepatectomy without 3DVT-FI (CH group). The operative data, postoperative liver function indices, complication rates and stone residue were compared between the two groups. RESULTS: There were no significant differences in preoperative baseline data between the two groups (p > 0.05). Compared with the CH group, the 3DVT-FI group exhibited lower intraoperative blood loss (140.00 ± 112.12 vs. 225.99 ± 186.50 mL, p = 0.001), and a lower intraoperative transfusion rate (8.0% vs. 23.1%, p = 0.027). The overall incidence of postoperative complications did not differ significantly (22.0% vs. 35.9%, p = 0.096). The 3DVT-FI group was associated with a lower immediate residual stone rate (16.0% vs. 34.6%, p = 0.021). There were no perioperative deaths in the 3DVT-FI group, while one perioperative death occurred in the CH group. CONCLUSIONS: The 3DVT-FI may offer significant benefits in terms of surgical safety, reduced intraoperative bleeding and decreased stone residue during hepatectomy for hepatolithiasis.

Targeted Cyclo[8]pyrrole-Based NIR-II Photoacoustic Tomography Probe for Suppression of Orthotopic Pancreatic Tumor Growth and Intra-abdominal Metastases.

Pancreatic cancer is highly lethal. New diagnostic and treatment modalities are desperately needed. We report here that an expanded porphyrin, cyclo[8]pyrrole (CP), with a high extinction coefficient (89.16 L/g·cm) within the second near-infrared window (NIR-II), may be formulated with an αvß3-specific targeting peptide, cyclic-Arg-Gly-Asp (cRGD), to form cRGD-CP nanoparticles (cRGD-CPNPs) with promising NIR-II photothermal (PT) therapeutic and photoacoustic (PA) imaging properties. Studies with a ring-array PA tomography system, coupled with analysis of control nanoparticles lacking a targeting element (CPNPs), revealed that cRGD conjugation promoted the delivery of the NPs through abnormal vessels around the tumor to the solid tumor core. This proved true in both subcutaneous and orthotopic pancreatic tumor mice models, as confirmed by immunofluorescent studies. In combination with NIR-II laser photoirradiation, the cRGD-CPNPs provided near-baseline tumor growth inhibition through PTT both in vitro and in vivo. Notably, the combination of the present cRGD-CPNPs and photoirradiation was found to inhibit intra-abdominal metastases in an orthotopic pancreatic tumor mouse model. The cRGD-CPNPs also displayed good biosafety profiles, as inferred from PA tomography, blood analyses, and H&E staining. They thus appear promising for use in combined PA imaging and PT therapeutic treatment of pancreatic cancer.

Relief of tumor hypoxia using a nanoenzyme amplifies NIR-II photoacoustic-guided photothermal therapy.

Hypoxia is a critical tumor microenvironment (TME) component. It significantly impacts tumor growth and metastasis and is known to be a major obstacle for cancer therapy. Integrating hypoxia modulation with imaging-based monitoring represents a promising strategy that holds the potential for enhancing tumor theranostics. Herein, a kind of nanoenzyme Prussian blue (PB) is synthesized as a metal-organic framework (MOF) to load the second near-infrared (NIR-II) small molecule dye IR1061, which could catalyze hydrogen peroxide to produce oxygen and provide a photothermal conversion element for photoacoustic imaging (PAI) and photothermal therapy (PTT). To enhance stability and biocompatibility, silica was used as a coating for an integrated nanoplatform (SPI). SPI was found to relieve the hypoxic nature of the TME effectively, thus suppressing tumor cell migration and downregulating the expression of heat shock protein 70 (HSP70), both of which led to an amplified NIR-II PTT effect in vitro and in vivo, guided by the NIR-II PAI. Furthermore, label-free multi-spectral PAI permitted the real-time evaluation of SPI as a putative tumor treatment. A clinical histological analysis confirmed the amplified treatment effect. Hence, SPI combined with PAI could offer a new approach for tumor diagnosing, treating, and monitoring.

NIR-II Photoacoustic Imaging-Guided Oxygen Delivery and Controlled Release Improves Photodynamic Therapy for Hepatocellular Carcinoma.

Hypoxia, a prominent hallmark of hepatocellular carcinoma (HCC), undermines curative outcomes, elevates recurrence rates, and fosters metastasis, particularly during photodynamic therapy (PDT) in clinical settings. Studies indicate that alleviating tumor hypoxia enhances PDT efficacy. However, persistent challenges, including suboptimal oxygen delivery efficiency and absence of real-time feedback on blood oxygen fluctuations during PDT, considerably impede therapeutic efficacy in tumor treatment. This study addresses these issues using near-infrared-II (NIR-II) photoacoustic (PA) imaging for tumor-targeted oxygen delivery and controlled release. For this purpose, a biomimetic oxygen delivery system designated BLICP@O2 is developed, which utilizes hybrid tumor cell membranes and thermosensitive liposomes as oxygen carriers, incorporating the NIR-II dye IR1048, photosensitizer chlorin e6 (Ce6), and perfluorohexane. Upon sequential irradiation at 1064 and 690 nm, BLICP@O2 exhibits significant photothermal and photodynamic effects. Photothermal heating triggers oxygen release, enhancing the photodynamic effect of Ce6. Blood oxygen changes during PDT are tracked by multispectral PA imaging. Enhanced PDT efficacy, mediated by hypoxia relief, is convincingly demonstrated both in vitro and in vivo. This work presents an imaging-guided, dual-wavelength programmed cascaded treatment strategy for tumor-targeted oxygen delivery and controlled release, with real-time efficacy monitoring using PA imaging, offering valuable insights for overcoming challenges in PDT-based cancer therapy.

Review and Application of Integrin Alpha v Beta 6 in the Diagnosis and Treatment of Cholangiocarcinoma and Pancreatic Ductal Adenocarcinoma.

Integrin Alpha v Beta 6 is expressed primarily in solid epithelial tumors, such as cholangiocarcinoma, pancreatic cancer, and colorectal cancer. It has been considered a potential and promising molecular marker for the early diagnosis and treatment of cancer. Cholangiocarcinoma and pancreatic ductal adenocarcinoma share genetic, histological, and pathophysiological similarities due to the shared embryonic origin of the bile duct and pancreas. These cancers share numerous clinicopathological characteristics, including growth pattern, poor response to conventional radiotherapy and chemotherapy, and poor prognosis. This review focuses on the role of integrin Alpha v Beta 6 in cancer progression. It addition, it reviews how the marker can be used in molecular imaging and therapeutic targets. We propose further research explorations and questions that need to be addressed. We conclude that integrin Alpha v Beta 6 may serve as a potential biomarker for cancer disease progression and prognosis.

Handheld photoacoustic imaging of indocyanine green clearance for real-time quantitative evaluation of liver reserve function.

Preoperative assessment of liver function reserve (LFR) is essential for determining the extent of liver resection and predicting the prognosis of patients with liver disease. In this paper, we present a real-time, handheld photoacoustic imaging (PAI) system-based noninvasive approach for rapid LFR assessment. A linear-array ultrasound transducer was sealed in a housing filled with water; its front end was covered with a plastic wrap. This PAI system was first implemented on phantoms to confirm that the photoacoustic (PA) intensity of indocyanine green (ICG) in blood reflects the concentration of ICG in blood. In vivo studies on normal rabbits and rabbits with liver fibrosis were carried out by recording the dynamic PA signal of ICG in their jugular veins. By analyzing the PA intensity-time curve, a clear difference was identified in the pharmacokinetic behavior of ICG between the two groups. In normal rabbits, the mean ICG clearance rate obtained by PAI at 15 min after administration (PAI-R15) was below 21.6%, whereas in rabbits with liver fibrosis, PAI-R15 exceeded 62.0% because of poor liver metabolism. The effectiveness of the proposed method was further validated by the conventional ICG clearance test and pathological examination. Our findings suggest that PAI is a rapid, noninvasive, and convenient method for LFR assessment and has immense potential for assisting clinicians in diagnosing and managing patients with liver disease.

Photoacoustic image-guided biomimetic nanoparticles targeting rheumatoid arthritis.

The high level of reactive oxygen species (ROS) in the rheumatoid arthritis (RA) microenvironment (RAM) and its persistent inflammatory nature can promote damage to joints, bones, and the synovium. Targeting strategies that integrate effective RAM regulation with imaging-based monitoring could lead to improvements in the diagnosis and treatment of RA. Here, we report the combined use of small interfering RNAs (siRNAsT/I) and Prussian blue nanoparticles (PBNPs) to silence the expression of proinflammatory cytokines TNF-α/IL-6 and scavenge the ROS associated with RAM. To enhance the in vitro and in vivo biological stability, biocompatibility, and targeting capability of the siRNAsT/I and PBNPs, macrophage membrane vesicles were used to prepare biomimetic nanoparticles, M@P-siRNAsT/I. The resulting constructs were found to suppress tumor necrosis factor-α/interleukin-6 expression and overcome the hypoxic nature of RAM, thus alleviating RA-induced joint damage in a mouse model. The M@P-siRNAsT/I of this study could be monitored via near-infrared photoacoustic (PA) imaging. Moreover, multispectral PA imaging without the need for labeling permitted the real-time evaluation of M@P-siRNAsT/I as a putative RA treatment. Clinical microcomputed tomography and histological analysis confirmed the effectiveness of the treatment. We thus suggest that macrophage-biomimetic M@P-siRNAsT/I and their analogs assisted by PA imaging could provide a new strategy for RA diagnosis, treatment, and monitoring.

Depth-extended acoustic-resolution photoacoustic microscopy based on a two-stage deep learning network.

Acoustic resolution photoacoustic microscopy (AR-PAM) is a major modality of photoacoustic imaging. It can non-invasively provide high-resolution morphological and functional information about biological tissues. However, the image quality of AR-PAM degrades rapidly when the targets move far away from the focus. Although some works have been conducted to extend the high-resolution imaging depth of AR-PAM, most of them have a small focal point requirement, which is generally not satisfied in a regular AR-PAM system. Therefore, we propose a two-stage deep learning (DL) reconstruction strategy for AR-PAM to recover high-resolution photoacoustic images at different out-of-focus depths adaptively. The residual U-Net with attention gate was developed to implement the image reconstruction. We carried out phantom and in vivo experiments to optimize the proposed DL network and verify the performance of the proposed reconstruction method. Experimental results demonstrated that our approach extends the depth-of-focus of AR-PAM from 1mm to 3mm under the 4 mJ/cm2 light energy used in the imaging system. In addition, the imaging resolution of the region 2 mm far away from the focus can be improved, similar to the in-focus area. The proposed method effectively improves the imaging ability of AR-PAM and thus could be used in various biomedical studies needing deeper depth.

Visualizing tumor angiogenesis and boundary with polygon-scanning multiscale photoacoustic microscopy.

Recently, we developed an integrated optical-resolution (OR) and acoustic-resolution (AR) PAM, which has multiscale imaging capability using different resolutions. However, limited by the scanning method, a tradeoff exists between the imaging speed and field of view, which impedes its wider applications. Here, we present an improved multiscale PAM which achieves high-speed wide-field imaging based on a homemade polygon scanner. Encoder trigger mode was proposed to avoid jittering of the polygon scanner during imaging. Distortions caused by polygon scanning were analyzed theoretically and compared with traditional types of distortions in optical-scanning PAM. Then a depth correction method was proposed and verified to compensate for the distortions. System characterization of OR-PAM and AR-PAM was performed prior to in vivo imaging. Blood reperfusion of an in vivo mouse ear was imaged continuously to demonstrate the feasibility of the multiscale PAM for high-speed imaging. Results showed that the maximum B-scan rate could be 14.65 Hz in a fixed range of 10 mm. Compared with our previous multiscale system, the imaging speed of the improved system was increased by a factor of 12.35. In vivo imaging of a subcutaneously inoculated B-16 melanoma of a mouse was performed. Results showed that the blood vasculature around the melanoma could be resolved and the melanoma could be visualized at a depth up to 1.6 mm using the multiscale PAM.

Background-suppressed tumor-targeted photoacoustic imaging using bacterial carriers.

Photoacoustic (PA) imaging offers promise for biomedical applications due to its ability to image deep within biological tissues while providing detailed molecular information; however, its detection sensitivity is limited by high background signals that arise from endogenous chromophores. Genetic reporter proteins with photoswitchable properties enable the removal of background signals through the subtraction of PA images for each light-absorbing form. Unfortunately, the application of photoswitchable chromoproteins for tumor-targeted imaging has been hampered by the lack of an effective targeted delivery scheme; that is, photoswitchable probes must be delivered in vivo with high targeting efficiency and specificity. To overcome this limitation, we have developed a tumor-targeting delivery system in which tumor-homing bacteria (Escherichia coli) are exploited as carriers to affect the point-specific delivery of genetically encoded photochromic probes to the tumor area. To improve the efficiency of the desired background suppression, we engineered a phytochrome-based reporter protein (mDrBphP-PCMm/F469W) that displays higher photoswitching contrast than those in the current state of the art. Photoacoustic computed tomography was applied to achieve good depth and resolution in the context of in vivo (mice) imaging. The present system effectively integrates a genetically encoded phytochrome-based reporter protein, PA imaging, and synthetic biology (GPS), to achieve essentially background-suppressed tumor-targeted PA monitoring in deep-seated tissues. The ability to image tumors at substantial depths may enable target-specific cancer diagnoses to be made with greater sensitivity, fidelity, and specificity.

Importance of Microvascular Invasion Risk and Tumor Size on Recurrence and Survival of Hepatocellular Carcinoma After Anatomical Resection and Non-anatomical Resection.

Purpose: To establish a valid prediction model to prognose the occurrence of microvascular invasion (MVI), and to compare the efficacy of anatomic resection (AR) or non-anatomic resection (NAR) for hepatocellular carcinoma (HCC). Methods: Two hundred twenty-eight patients with HCC who underwent surgical treatment were enrolled. Their hematological indicators, MRI imaging features, and outcome data were acquired. Result: In the multivariable analysis, alpha-fetoprotein >15 ng/mL, neutrophil to lymphocyte ratio >3.8, corona enhancement, and peritumoral hypointensity on hepatobiliary phase were associated with MVI. According on these factors, the AUROC of the predictive model in the primary and validation cohorts was 0.884 (95% CI: 0.829, 0.938) and 0.899 (95% CI: 0.821, 0.967), respectively. Patients with high risk of MVI or those with low risk of MVI but tumor size >5 cm in the AR group were associated with a lower rate of recurrence and death than patients in the NAR group; however, when patients are in the state of low-risk MVI with tumor size >5 cm, there is no difference in the rate of recurrence and death between AR and NAR. Conclusion: Our predictive model for HCC with MVI is convenient and accurate. Patients with high-risk of MVI or low-risk of MVI but tumor size >5 cm executing AR is of great necessity.

[Application of 3D visualization and 3D printing in individualized precision surgery for Bismuth-Corlette type â ¢ and â £ hilar cholangiocarcinoma].

OBJECTIVE: To explore the application of 3D visualization and 3D printing in individualized precision surgical treatment of Bismuth-Corlette type Ⅲ and Ⅳ hilar cholangiocarcinoma. METHODS: We retrospectively analyzed the data of 10 patients with hilar cholangiocarcinoma undergoing surgeries under the guidance of 3D visualization and 3D printing in the Department of Hepatobiliary Surgery, Zhujiang Hospital from May 2016 to March 2019. Thin-section CT data of the patients were collected for 3D reconstruction and 3D printing, and the 3D printed models were used for observing the 3D relationship of tumor with the intrahepatic bile duct, hepatic artery, portal vein and hepatic vein system and for performing preoperative simulated surgery and surgical planning. The 3D printed models were subsequently used for real-time intraoperative navigation to guide surgeries in the operating room. RESULTS: 3D visualization models were successfully reconstructed for all the 10 patients and printed into 3D models. The 3D visualization types in Bismuth-Corlette classification included type Ⅲa (4 cases), type Ⅲb (4 cases), and type Ⅳ (2 cases); 4 patients showed portal vein variation, 3 had hepatic artery variation, and 2 had both portal vein and hepatic artery variations. Two patients were found to have trifurcation type of portal vein variation, one had "I-shaped" variation, and one showed the absence of the right anterior branch of the portal vein; 3 patients had hepatic artery variations with the left hepatic artery originating from the left gastric artery (1 case) and the right hepatic artery originating from the superior mesenteric artery (2 cases). Four patients with type Ⅲb underwent left hepatectomy; 4 with type Ⅲa received right hepatectomy; 1 patient with of type Ⅳ received peripheral hepatic resection and another underwent left hepatectomy. The results of preoperative 3D reconstruction, 3D printed model and preoperative planning were consistent with the intraoperative findings. The operative time was 452±75.12 min with a mean intraoperative blood loss of 356±62.35 mL and a mean hospital stay of 15 ± 4.61 days in these cases. One patient had bile leakage and 3 patients had pleural effusion postoperatively, and they were discharged after drainage and medications. No liver failure or death occurred in these cases perioperatively. CONCLUSIONS: 3D visualization and 3D printing can facilitate accurate preoperative assessment, surgical planning and surgical procedure optimization for Bismuth-Corlette type Ⅲ and Ⅳ hilar cholangiocarcinoma to improve surgical safety and reduce surgical risks especially in cases of intrahepatic vascular variations.

[Three-dimensional visualization combined with indocyanine green fluorescence imaging in diagnosis and treatment of primary hepatocellular carcinoma].

OBJECTIVE: To explore the value of three-dimensional visualization technology (3DVT) combined with indocyanine green (ICG) fluorescence imaging in the diagnosis and treatment of primary hepatocellular carcinoma (HCC). METHODS: We retrospectively analyzed the clinical data of 154 patients with HCC admitted to the Department of Hepatobiliary Surgery, Zhujiang Hospital, Southern Medical University between January, 2016 and November, 2018. In 57 of the patients (3DVT group), preoperative CT and Gd-EOB-DTPA-enhanced MRI were performed and 3D visualization and surgical planning was carried out before the operation; intraoperative ICG florescence imaging was performed for real-time detection of the tumor location and demarcation, intrahepatic satellite lesions and metastases. According to the intraoperative fluorescent signals and 3D visualization-based surgical planning, the final surgical plan was determined. In the other 97 patients (control group), conventional surgical assessment and surgical resection of the tumor was carried out. The preoperative imaging findings, intraoperative tumor detection, postoperative laboratory results, pathological reports, and follow-up data of the patients were analyzed. RESULTS: In 3DVT group, 63 and 70 lesions were detected by preoperative CT and MRI, respectively; compared with CT examination, intraoperative ICG florescence imaging revealed additional 17 lesions, among which 10 were pathologically confirmed as HCC and 7 as cirrhosis nodules. The median volume of bleeding was 300 mL in 3DVT group, significantly less than that in the control group (400 mL; Z=2.291, P=0.022). In both groups, serious complications or perioperative death occurred in none of the patients. The incidence of postoperative complications was significantly lowed in 3DVT group than in the control group [21% (12/57) vs 48.4% (47/97); χ2=11.406, P=0.001]. The overall disease-free survival rate at 2 years after the operation was significantly higher in 3DVT group than in the control group (74.9% vs 28.9%, P=0.022). CONCLUSIONS: 3DVT combined with ICG fluorescence imaging allows precise preoperative diagnosis, surgical planning and implementation, intraoperative detection of small liver cancers and precise navigation for HCC treatment, thereby helping to reduce postoperative complications and improve the disease-free survival rate of the patients.