Feasibility and diagnostic performance of dual-tracer-guided sentinel lymph node biopsy in cT1-2N0M0 gastric cancer: a systematic review and meta-analysis of diagnostic studies

Feasibility of intraoperative pathologic examination for sentinel lymph nodes during sentinel node navigation surgery in early gastric cancer: results of pathologic protocol for SENORITA trial

BACKGROUND

During sentinel node navigation surgery in patients with gastric cancer, intraoperative pathologic examination of sentinel nodes is crucial in determining the extent of surgery. In this study, we evaluated the feasibility and accuracy of intraoperative pathologic protocols using data from a prospective, multicenter, randomized trial.

METHODS

A retrospective analysis was conducted using data from the SEntinel Node ORIented Tailored Approach trials from 2013 to 2016. All sentinel lymph nodes were evaluated during surgery with hematoxylin-eosin (HE) staining using a representative section at the largest plane for lymph nodes. For permanent histologic evaluation, sentinel basin nodes were stained with HE and cytokeratin immunohistochemistry in formalin-fixed, paraffin-embedded (FFPE) sections and examined with HE for three deeper-step sections at 200-μm intervals. The failure rate of identification by frozen section and the metastasis rate in non-sentinel basins were investigated.

RESULTS

Of the 237 patients who underwent sentinel node basin dissection, 30 had lymph node metastases on permanent pathology. Thirteen patients had macrometastasis confirmed in frozen sections as well as FFPE sections (failure rate: 0%). Patients with negative sentinel nodes in frozen sections but micrometastasis in FFPE sections had no lymph node recurrence during the follow-up period (0%, 0/6). However, in cases with tumor-positive nodes in frozen sections, metastases in non-sentinel basins were detected in the paraffin blocks (8.3%, 2/24).

CONCLUSIONS

The single-section HE staining method is sufficient for detecting macrometastasis via intraoperative pathological examination. If a negative frozen-section result is confirmed, sentinel basin dissection can be performed safely. Otherwise, standard surgery is required.

Sentinel Node Navigation Surgery for Early Gastric Cancer: A Narrative Review

Early gastric cancer (EGC) refers to malignant tumor lesions that are limited to the mucosa and submucosa layers, regardless of the presence of lymph node metastasis. Typically, EGC has a low rate of perigastric lymph node metastasis, and long-term survival outcomes are good after radical surgical treatment. The primary objective of surgical treatment for EGC is to achieve functional preservation while ensuring a radical cure. Sentinel node navigation surgery (SNNS) is a surgical technique used in the treatment of EGC. This approach achieves functional preservation by limiting lymph node dissection and performing restrictive gastrectomy guided by intraoperative negative sentinel node (SN) biopsy. Despite the apparent improvement in the detection rate of SN with the emergence of various tracing dyes and laparoscopic fluorescence systems, the oncological safety of SNNS remains a controversial research topic. SNNS, as a true form of stomach preservation surgery that enhances the quality of life, has become a topic of interest in the EGC field. In recent years, scholars from Japan and South Korea have conducted extensive research on the feasibility and safety of SNNS in the treatment of EGC. This article aims to provide reference choices for surgeons treating EGC by reviewing relevant research on SNNS for EGC in recent years.

Current applications of indocyanine green (ICG) in abdominal, gynecologic and urologic surgery: a meta-review and quality analysis with use of the AMSTAR 2 instrument

BACKGROUND

Indocyanine green (ICG) is an injectable fluorochrome that has recently gained popularity as a means of assisting intraoperative visualization during laparoscopic and robotic surgery. Many systematic reviews and meta-analyses have been published. We conducted a meta-review to synthesize the findings of these studies.

METHODS

PubMed and Embase were searched to identify systematic reviews and meta-analyses coping with the uses of ICG in abdominal operations, including Metabolic Bariatric Surgery, Cholecystectomy, Colorectal, Esophageal, Gastric, Hepato-Pancreato-Biliary, Obstetrics and Gynecology (OG), Pediatric Surgery, Surgical Oncology, Urology, (abdominal) Vascular Surgery, Adrenal and Splenic Surgery, and Interdisciplinary tasks, until September 2023. We submitted the retrieved meta-analyses to qualitative analysis based on the AMSTAR 2 instrument.

RESULTS

We identified 116 studies, 41 systematic reviews (SRs) and 75 meta-analyses (MAs), spanning 2013-2023. The most thoroughly investigated (sub)specialties were Colorectal (6 SRs, 25 MAs), OG (9 SRs, 15 MAs), and HPB (4 SRs, 12 MAs). Interestingly, there was high heterogeneity regarding the administered ICG doses, routes, and timing. The use of ICG offered a clear benefit regarding anastomotic leak prevention, particularly after colorectal and esophageal surgery. There was no clear benefit regarding sentinel node detection after OG. According to the AMSTAR 2 tool, most meta-analyses ranked as "critically low" (34.7%) or "low" (58.7%) quality. There were only five meta-analyses (6.7%) that qualified as "moderate" quality, whereas there were no "high" quality reviews.

CONCLUSIONS

Regardless of the abundance of pertinent literature and reviews, surgeons should be cautious when interpreting their results on ICG use in abdominal surgery. Future reviews should focus on ensuring methodological vigor; establishing clear protocols of ICG dose, route of administration, and timing; and improving reporting quality. Other sources of data (e.g., registries) and novel methods of data analysis (e.g., machine learning) might also contribute to an enhanced role of ICG as a decision-making tool in surgery.

Impact of tumor stage and neoadjuvant chemotherapy in fluorescence-guided lymphadenectomy during laparoscopic gastrectomy for gastric cancer: A propensity score-matched study in a western center

BACKGROUND

The use of indocyanine green fluorescence has been shown to be a safe and effective method for improving lymph node retrieval in patients with gastric cancer. However, previous studies have focused on early-stage tumors and/or the Asian population and excluded patients who received neoadjuvant treatment.

METHODS

In this study, 142 patients with gastric adenocarcinoma underwent laparoscopic gastrectomy at a Spanish hospital between January 2017 and December 2022. Of these, 42 patients received preoperative indocyanine green injection to guide lymphadenectomy. Their outcomes were compared to a retrospective cohort of 42 patients after 1:1 propensity score matching.

RESULTS

The feasibility of indocyanine green lymphatic mapping was 95.5%. No complications associated with indocyanine green injection were observed. The indocyanine green group had a significantly higher number of retrieved lymph nodes than the non-indocyanine green group (32.67 vs 25.14; P = .013). This statistically significant difference was maintained across subgroups of neoadjuvant treatment, non-obese patients, pT0 to 2 stage, and pN0 stage. In 47.6% of patients from the indocyanine green group, lymphadenectomy was extended outside the standard D2 dissection area based on indocyanine green uptake, but none of the retrieved lymph nodes were metastatic. There were no differences in postoperative complications and length of hospital stay between the 2 groups.

CONCLUSION

Indocyanine green-guided lymphadenectomy is safe and feasible and increases the number of retrieved lymph nodes compared to conventional lymphatic dissection, as well as in patients receiving neoadjuvant chemotherapy. The use of indocyanine green should be routine if available for guiding lymph node dissection in gastric cancer, regardless of tumor stage or previous neoadjuvant treatment. However, further studies are needed to determine the impact of this technique on disease-free and overall survival.

[Fluorescence lymphoscopy with sentinel lymph node biopsy in research of lymphatic flow in early gastric cancer]

OBJECTIVE

To analyze the incidence and risk factors of regional lymph node metastatic lesions, as well as patterns of lymphatic drainage in early gastric cancer using indocyanine green (ICG).

MATERIAL AND METHODS

A prospective single-center non-randomized study included 67 patients with early gastric cancer between 2016 and 2019. All patients underwent endoscopic dissection or surgical resection with sentinel lymph node biopsy.

RESULTS

Regional lymph node metastatic lesions were detected in 12 (20.2%) out of 59 patients with examined lymph nodes. Of these, 11 out of 12 patients had sentinel lymph node lesion, and only 1 patient had metastasis outside this lymph node. The proposed technique for sentinel lymph node biopsy demonstrated high sensitivity, specificity and accuracy (93.2%, 100% and 98.3%, respectively). Risk factors for metastasis of early gastric cancer to regional lymph nodes were high grade adenocarcinoma (p=0.038) and tumor of anterior gastric wall (p=0.013). All patients with tumors of the upper third of the stomach had sentinel lymph node in the left gastric artery basin. Lymph flow was multidirectional in patients with tumors of the middle third of the stomach. In tumors of the lower third of the stomach, sentinel lymph node was located in the right gastroepiploic artery (50%) and left gastric artery basins (36.84%) (p=0.002). Sentinel lymph node was located in the left gastric artery basin in 84% of patients with tumors of the lesser curvature (p<0.001). Lymphatic drainage was multidirectional if tumors were localized on anterior and posterior walls, as well as on the greater curvature.

CONCLUSION

The proposed technique for sentinel lymph node biopsy demonstrated high sensitivity, specificity and accuracy (93.2%, 100% and 98.3%, respectively). ICG is valuable to identify the first lymph node in lymphatic drainage pathway in 83.6% of cases that makes it possible to assess the regional lymphatic collector. In addition, sentinel lymph node biopsy with ICG contributes to analysis of lymphatic drainage in early gastric cancer. The last one has both scientific and practical significance.

Endoscopic Resection of Early Gastric Cancer and Pre-Malignant Gastric Lesions

Early gastric cancer comprises gastric malignancies that are confined to the mucosa or submucosa, irrespective of lymph node metastasis. Endoscopic resection is currently pivotal for the management of such early lesions, and it is the recommended treatment for tumors presenting a very low risk of lymph node metastasis. In general, these lesions consist of two groups of differentiated mucosal adenocarcinomas: non-ulcerated lesions (regardless of their size) and small ulcerated lesions. Endoscopic submucosal dissection is the technique of choice in most cases. This procedure has high rates of complete histological resection while maintaining gastric anatomy and its functions, resulting in fewer adverse events than surgery and having a lesser impact on patient-reported quality of life. Nonetheless, approximately 20% of resected lesions do not fulfill curative criteria and demand further treatment, highlighting the importance of patient selection. Additionally, the preservation of the stomach results in a moderate risk of metachronous lesions, which underlines the need for surveillance. We review the current evidence regarding the endoscopic treatment of early gastric cancer, including the short-and long-term results and management after resection.

Korean Practice Guidelines for Gastric Cancer 2022: An Evidence-based, Multidisciplinary Approach

Gastric cancer is one of the most common cancers in Korea and the world. Since 2004, this is the 4th gastric cancer guideline published in Korea which is the revised version of previous evidence-based approach in 2018. Current guideline is a collaborative work of the interdisciplinary working group including experts in the field of gastric surgery, gastroenterology, endoscopy, medical oncology, abdominal radiology, pathology, nuclear medicine, radiation oncology and guideline development methodology. Total of 33 key questions were updated or proposed after a collaborative review by the working group and 40 statements were developed according to the systematic review using the MEDLINE, Embase, Cochrane Library and KoreaMed database. The level of evidence and the grading of recommendations were categorized according to the Grading of Recommendations, Assessment, Development and Evaluation proposition. Evidence level, benefit, harm, and clinical applicability was considered as the significant factors for recommendation. The working group reviewed recommendations and discussed for consensus. In the earlier part, general consideration discusses screening, diagnosis and staging of endoscopy, pathology, radiology, and nuclear medicine. Flowchart is depicted with statements which is supported by meta-analysis and references. Since clinical trial and systematic review was not suitable for postoperative oncologic and nutritional follow-up, working group agreed to conduct a nationwide survey investigating the clinical practice of all tertiary or general hospitals in Korea. The purpose of this survey was to provide baseline information on follow up. Herein we present a multidisciplinary-evidence based gastric cancer guideline.

Use of fluorescence imaging and indocyanine green during colorectal surgery: Results of an intercontinental Delphi survey

BACKGROUND

Fluorescence imaging with indocyanine green is increasingly being used in colorectal surgery to assess anastomotic perfusion, and to detect sentinel lymph nodes.

METHODS

In this 2-round, online, Delphi survey, 35 international experts were asked to vote on 69 statements pertaining to patient preparation and contraindications to fluorescence imaging during colorectal surgery, indications, technical aspects, potential advantages/disadvantages, and effectiveness versus limitations, and training and research. Methodological steps were adopted during survey design to minimize risk of bias.

RESULTS

More than 70% consensus was reached on 60 of 69 statements, including moderate-strong consensus regarding fluorescence imaging's value assessing anastomotic perfusion and leak risk, but not on its value mapping sentinel nodes. Similarly, although consensus was reached regarding most technical aspects of its use assessing anastomoses, little consensus was achieved for lymph-node assessments. Evaluating anastomoses, experts agreed that the optimum total indocyanine green dose and timing are 5 to 10 mg and 30 to 60 seconds pre-evaluation, indocyanine green should be dosed milligram/kilogram, lines should be flushed with saline, and indocyanine green can be readministered if bright perfusion is not achieved, although how long surgeons should wait remains unknown. The only consensus achieved for lymph-node assessments was that 2 to 4 injection points are needed. Ninety-six percent and 100% consensus were reached that fluorescence imaging will increase in practice and research over the next decade, respectively.

CONCLUSION

Although further research remains necessary, fluorescence imaging appears to have value assessing anastomotic perfusion, but its value for lymph-node mapping remains questionable.

Mapping Lymph Node during Indocyanine Green Fluorescence-Imaging Guided Gastric Oncologic Surgery: Current Applications and Future Directions

Huge strides have been made in the navigation of gastric cancer surgery thanks to the improvement of intraoperative techniques. For now, the use of indocyanine green (ICG) enhanced fluorescence imaging has received promising results in detecting sentinel lymph nodes (SLNs) and tracing lymphatic drainages, which make it applicable for limited and precise lymphadenectomy. Nevertheless, issues of the lack of specificity and unpredictable false-negative lymph nodes were encountered in gastric oncologic surgery practice using ICG-enhanced fluorescence imaging (ICG-FI), which restrict its application. Here, we reviewed the current application of ICG-FI and assessed potential approaches to improving ICG-FI.

The oncologic safety and accuracy of indocyanine green fluorescent dye marking in securing the proximal resection margin during totally laparoscopic distal gastrectomy for gastric cancer: a retrospective comparative study

Background

Securing the proximal resection margin in totally laparoscopic distal gastrectomy for gastric cancer is related to curability and recurrence, while reducing the operation time is related to patient safety. This study aimed to investigate the role of indocyanine green (ICG) fluorescent dye marking in totally laparoscopic distal gastrectomy, whether it is an oncologically safe and accurate procedure that can be conducted in a single centre.

Methods

The data of 93 patients who underwent laparoscopic-assisted distal gastrectomy (non-ICG group) or totally laparoscopic distal gastrectomy using ICG (ICG group) between 2010 and 2020 were retrospectively reviewed. To correct for confounding factors, a propensity score matching was performed.

Results

Proximal resection margin did not vary with the ICG injection site after the propensity score matching (lower ICG, 3.84 cm vs. lower non-ICG, 4.42 cm, p = 0.581; middle ICG, 3.34 cm vs. middle non-ICG, 3.20 cm; p = 0.917), while the operation time was reduced by a mean of 34 min in the ICG group (ICG, 239.3 [95% confidence interval, 220.1–258.5 min]; non-ICG, 273.0 [95% confidence interval, 261.6–284.4] min; p = 0.006).

Conclusions

ICG injection for securing the proximal resection margin in totally laparoscopic distal gastrectomy is an oncologically safe and accurate procedure, with the advantage of reducing the operation time of gastric cancer surgery while it has the benefit of locating the tumour or clips when it is impossible to locate the tumour during surgery due to the inability to perform an endoscopic examination or when it is hard to directly palpate the tumour or clips in the operating theatre; this can be performed at a single centre.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12957-022-02494-5.

Pathologic Lymph Node Staging of Gastric Cancer

OBJECTIVES

The TNM classification is the main tool for lymph node (LN) staging in gastric cancer (GC). However, alternative LN staging systems have been proposed, and the role of features other than the number of metastatic LNs is being investigated. Our aim is to discuss the main challenges of LN assessment in GC.

METHODS

Comprehensive review of the literature on alternative LN staging systems, examined LNs, sentinel LN (SLN) biopsy, LN micrometastases (LNMIs), extracapsular extension (ECE), and tumor deposits (TDs) in GC.

RESULTS

Many controversies exist regarding LN assessment in GC. The TNM classification shows excellent prognostic performance, but alternative prognostic methods such as the LN ratio or log odds of positive LNs have demonstrated to be better than the TNM system in terms of prognostic accuracy. The value of SLN biopsy and LNMIs in GC is still unclear, and several challenges concerning their clinical impact and pathologic analysis must be overcome before their introduction in clinical practice. Most authors have identified ECE and TDs as independent prognostic factors for survival in GC.

CONCLUSIONS

Further studies should be performed to evaluate the impact of these features on the TNM classification and patient outcomes, as well as to standardize alternative LN staging systems.

The short-term and long-term outcomes of indocyanine green tracer-guided laparoscopic radical gastrectomy in patients with gastric cancer

Background

The safety and efficacy of indocyanine green (ICG) imaging navigational laparoscopic gastrectomy remain controversial. This study is to evaluate the short-term and long-term outcomes of ICG-guided laparoscopic radial gastrectomy in patients with gastric cancer.

Methods

Consecutive patients with definitive diagnosis of gastric cancer that underwent laparoscopic radical gastrectomy were collected retrospectively. Propensity score matching (PSM) at 1:1 ratio was performed to compare the outcomes of two groups.

Results

A total of 122 qualified patients were divided into ICG group (n = 34) and non-ICG group (n = 88). PSM yielded 28 patients with comparable baseline characteristics into each group. The number of retrieved lymph node in ICG group was significantly higher than that in non-ICG group (P = 0.0196). There was no statistical difference of perioperative, short-term, and long-term complications between the two groups.

Conclusion

ICG-guided laparoscopic radical gastrectomy is safe and effective, and ICG-navigated lymphadenectomy improves the number of retrieved lymph nodes for patients with gastric cancer.

Integrating No.3 lymph nodes and primary tumor radiomics to predict lymph node metastasis in T1-2 gastric cancer

BACKGROUND

This study aimed to develope and validate a radiomics nomogram by integrating the quantitative radiomics characteristics of No.3 lymph nodes (LNs) and primary tumors to better predict preoperative lymph node metastasis (LNM) in T1-2 gastric cancer (GC) patients.

METHODS

A total of 159 T1-2 GC patients who had undergone surgery with lymphadenectomy between March 2012 and November 2017 were retrospectively collected and divided into a training cohort (n = 80) and a testing cohort (n = 79). Radiomic features were extracted from both tumor region and No. 3 station LNs based on computed tomography (CT) images per patient. Then, key features were selected using minimum redundancy maximum relevance algorithm and fed into two radiomic signatures, respectively. Meanwhile, the predictive performance of clinical risk factors was studied. Finally, a nomogram was built by merging radiomic signatures and clinical risk factors and evaluated by the area under the receiver operator characteristic curve (AUC) as well as decision curve.

RESULTS

Two radiomic signatures, reflecting phenotypes of the tumor and LNs respectively, were significantly associated with LN metastasis. A nomogram incorporating two radiomic signatures and CT-reported LN metastasis status showed good discrimination of LN metastasis in both the training cohort (AUC 0.915; 95% confidence interval [CI] 0.832-0.998) and testing cohort (AUC 0.908; 95% CI 0.814-1.000). The decision curve also indicated its potential clinical usefulness.

CONCLUSIONS

The nomogram received favorable predictive accuracy in predicting No.3 LNM in T1-2 GC, and the nomogram showed positive role in predicting LNM in No.4 LNs. The nomogram may be used to predict LNM in T1-2 GC and could assist the choice of therapy.

Does near-infrared fluorescent cholangiography with indocyanine green reduce bile duct injuries and conversions to open surgery during laparoscopic or robotic cholecystectomy? - A meta-analysis

BACKGROUND

Bile duct injury and conversion-to-open-surgery rates remain unacceptably high during laparoscopic and robotic cholecystectomy. In a recently published randomized clinical trial, using near-infrared fluorescent cholangiography with indocyanine green intraoperatively markedly enhanced biliary-structure visualization. Our systematic literature review compares bile duct injury and conversion-to-open-surgery rates in patients undergoing laparoscopic or robotic cholecystectomy with versus without near-infrared fluorescent cholangiography.

METHODS

A thorough PubMed search was conducted to identify randomized clinical trials and nonrandomized clinical trials with ≥100 patients. Because all near-infrared fluorescent cholangiography studies were published since 2013, only studies without near-infrared fluorescent cholangiography published since 2013 were included for comparison. Incidence estimates, weighted and unweighted for study size, were adjusted for acute versus chronic cholecystitis, and for robotic versus laparoscopic cholecystectomy and are reported as events/10,000 patients. All studies were assessed for bias risk and high-risk studies excluded.

RESULTS

In total, 4,990 abstracts were reviewed, identifying 5 near-infrared fluorescent cholangiography studies (3 laparoscopic cholecystectomy/2 robotic cholecystectomy; n = 1,603) and 11 not near-infrared fluorescent cholangiography studies (5 laparoscopic cholecystectomy/4 robotic cholecystectomy/2 both; n = 5,070) for analysis. Overall weighted rates for bile duct injury and conversion were 6 and 16/10,000 in near-infrared fluorescent cholangiography patients versus 25 and 271/10,000 in patients without near-infrared fluorescent cholangiography. Among patients undergoing laparoscopic cholecystectomy, bile duct injuries, and conversion rates among near-infrared fluorescent cholangiography versus patients without near-infrared fluorescent cholangiography were 0 and 23/10,000 versus 32 and 255/10,000, respectively. Bile duct injury rates were low with robotic cholecystectomy with and without near-infrared fluorescent cholangiography (12 and 8/10,000), but there was a marked reduction in conversions with near-infrared fluorescent cholangiography (12 vs 322/10,000).

CONCLUSION

Although large comparative trials remain necessary, preliminary analysis suggests that using near-infrared fluorescent cholangiography with indocyanine green intraoperatively sizably decreases bile duct injury and conversion-to-open-surgery rates relative to cholecystectomy under white light alone.

Sentinel lymph node detection for gastric cancer: Promise or pitfall?

At present, optimal surgery for gastric cancer is still under debate, especially the extent of lymph node dissection. Gastrectomy with D1/D2 lymphadenectomy is standard treatment for resectable advanced gastric cancer. However, in early gastric cancer without lymph node metastasis, gastrectomy with D1/D2 lymphadenectomy may not be unnecessary, which could increases morbidity and mortality and reduces the quality of life (QOL). Therefore, the concept of sentinel lymph node could be applied in gastric cancer. But due to the complexity of gastric lymphatic drainage, there are still many issues under debate, such as suitable tracers, the method of mapping and collecting and the oncologic safety of sentinel node navigation surgery (SNNS). In addition, skip metastasis and unreliability of intraoperative pathological diagnosis are two main reasons for false negative cases. In this review, we summarize the current status and controversy of sentinel lymph node detection in gastric cancer, attempting to help with practical application. Further, we hold opinion that we should be cautious about performing sentinel lymph node detection in gastric cancer before an accurate and effective method occurs.

[Does sentinel lymph node identification has indication in digestive cancers?]

Despite being a standard of care in several cancers, sentinel lymph node (SLN) is not widespread in digestive cancers. European guidelines do not recommend its use for any digestive cancers. Particularity of the lymphatic vessel, intimately linked to blood vessel, may explain part of this phenomenon. Nevertheless, more indication could arise in the near future with the early diagnosis of tumor induced by cancer screening. Ruling out the lymphatic invasion could allow preserving the organ currently resected because of risk of lymph node positivity. This procedure is well studied in early gastric cancer in Korea and Japan. Several study have demonstrated that, a dual-tracer (isotopic and dye) allows to accurately identify the SLN. A randomized phase 3 trial is currently active in Korea to evaluate the oncological results of the procedure. Similar indication could arise for T1 tumor of the low-rectum, but currently available data are insufficient to recommend its use outside of a study. SLN may also be used to detect aberrant lymphatic drainage (rectum, ileum) but have been tested so far only in a few dozen of patients. Finally, SLN is disappointing in colon cancer, due to its low sensitivity and the absence of modification of the surgical procedure induced.

Mannan-based conjugates as a multimodal imaging platform for lymph nodes

We show that mannan-based conjugates possess exceptional features for multimodal imaging because of their biocompatibility, biodegradability and self-targeting properties. Two new mannan conjugates, containing a gadolinium complex and a fluorescent probe, one based only on polysaccharide and the other one comprising polysaccharide with poly(2-methyl-2-oxazoline) grafts, were prepared and simultaneously visualized in vitro and in vivo by magnetic resonance and fluorescence imaging. The synthesis of these mannan-based complexes was based on alkylation with allyl bromide or grafting with poly(2-methyl-2-oxazoline) chains, followed by a thiol-ene click reaction with cysteamine to introduce primary amino groups into their structure. Finally, the obtained conjugates were functionalized with contrast labels using the corresponding N-hydroxysuccinimide esters. When used to detect lymph nodes, the polymers showed better imaging properties than a commercially available contrast agent.