Identification of Metastatic Lymph Nodes Using Indocyanine Green Fluorescence Imaging

A Tumor-Activatable Liposomal Nanoprobe for Selective Visualization of Metastatic Lymph Nodes

The precise identification of sentinel lymph nodes (SLNs) during surgery and assessment of their benign status is crucial for accurate tumor staging and optimal treatment strategizing. Currently, a deficiency exists in non-invasive in vivo diagnostic techniques that can accurately pinpoint SLNs during surgery while simultaneously evaluating their benign status. Here, a tumor-activatable liposomal nanoprobe (nTAL) is developed, remotely loaded with clinically approved photosensitizer, methyl aminolevulinate (MAL), to noninvasively visualize the tumor metastasis lymph nodes (LNs) with precision. Benefited from the highly efficient LNs draining of nanosized liposome and tumor cell-specific transformation of the non-fluorescent MAL to fluorescent protoporphyrin IX (PPIX), nTAL succeeded in targeting the SLNs and differentiated the metastatic from the benign ones with a positive correlation between PPIX generation and tumor cell infiltration in LNs. Moreover, the nTAL technology is capable of probing the early metastatic stage with a primary tumor size of 50 mm3. This study provides a new strategy for intraoperative visualization of real-time sentinel node dissection.

Comparison of Postoperative Outcomes Between Near-Infrared Fluorescent Imaging-Guided Mediastinal Lymphadenectomy and Conventional Surgery for Esophageal Cancer

BACKGROUND

The study aimed to evaluate the efficacy of using near-infrared fluorescent imaging (NIRF) imaging with indocyanine green as an intraoperative tool for achieving complete mediastinal lymph node (LN) resection.

PATIENTS AND METHODS

Between September 2019 and July 2021, patients with potential for esophagectomy due to middle and lower thoracic esophageal cancer were enrolled in this study. All patients were scheduled for NIRF-guided mediastinal lymphadenectomy during esophageal cancer surgery and were appropriately assigned to the NIRF group. Patients who underwent esophagectomy between September 2017 and September 2019 were assigned to the historical control group upon satisfying the inclusion/exclusion criteria. Surgical outcomes and the number of removed LNs were compared between the two groups using 1:1 propensity score matching.

RESULTS

Of 67 eligible patients, 59 patients were included in the NIRF group after postsurgical exclusions. The operative time was significantly shorter in the NIRF group than in the historical control group [180 (140-420) min versus 202 (137-338) min; P < 0.001]. The incidence of postoperative chylothorax and hoarseness were significantly lower in the NIRF group than in the historical control group (0% versus 10.2 %; P = 0.036, 3.4% versus 13.6%; P = 0.047). The number of dissected total LNs, mediastinal LNs, and negative LNs was significantly larger in the NIRF group than in the historical control group. The number of overall metastatic LNs and abdominal LNs was comparable between the two groups.

CONCLUSIONS

NIRF imaging can assist in the thorough and complete mediastinal LNs dissections without increasing complications in patients undergoing esophagectomy.

A preliminary investigation of precise visualization, localization, and resection of pelvic lymph nodes in bladder cancer by using indocyanine green fluorescence-guided approach through intracutaneous dye injection into the lower limbs and perineum

Objective

This study aimed to investigate the feasibility and effectiveness of using indocyanine green (ICG) injected intracutaneously through the lower limbs and perineum for visualized tracking, localization, and qualitative assessment of pelvic lymph nodes (LNs) in bladder cancer to achieve their accurate resection.

Methods

First, ICG was injected into the LN metastasis model mice lower limbs, and real-time and dynamic in vivo and ex vivo imaging was conducted by using a near-infrared fluorescence imaging system. Additionally, 26 patients with bladder cancer were enrolled and divided into intracutaneous group and transurethral group. A near-infrared fluorescence imaging device with internal and external imaging probes was used to perform real-time tracking, localization, and resection of the pelvic LNs.

Results

The mice normal LNs and the metastatic LNs exhibited fluorescence. The metastatic LNs showed a significantly higher signal-to-background ratio than the normal LNs (3.9 ± 0.2 vs. 2.0 ± 0.1, p < 0.05). In the intracutaneous group, the accuracy rate of fluorescent-labeled LNs was 97.6%, with an average of 11.3 ± 2.4 LNs resected per patient. Six positive LNs were detected in three patients (18.8%). In the transurethral group, the accuracy rate of fluorescent-labeled LNs was 84.4%, with an average of 8.6 ± 2.3 LNs resected per patient. Two positive LNs were detected in one patient (12.5%).

Conclusion

Following the intracutaneous injection of ICG into the lower limbs and perineum, the dye accumulates in pelvic LNs through lymphatic reflux. By using near-infrared fluorescence laparoscopic fusion imaging, physicians can perform real-time tracking, localization, and precise resection of pelvic LNs.