Sentinel lymph node biopsy using indocyanine green fluorescence in early-stage breast cancer: a meta-analysis

Use of indocyanine green fluorescence compared to radioisotope for sentinel lymph node biopsy in early-stage breast cancer: systematic review and meta-analysis

BACKGROUND

In early-stage breast cancer, indocyanine green (ICG)-fluorescence based sentinel lymph node (SLN) detection is being considered. This is a meta-analysis of SLN detection rates and sensitivity of ICG-fluorescence compared to radioisotope (RI), to evaluate its clinical applicability.

DATA SOURCES

Systematic review of full-text articles from PubMed and Scopus, of women with early breast cancer who underwent SLN mapping using ICG and RI concurrently was performed. The meta-analysis was performed using the Mantel-Haenszel method.

RESULTS

2301 patients from 19 studies were included. No significant difference was observed between ICG and RI for SLN detection (OR0.90,95%CI0.66-1.24) or sensitivity (OR1.23,95%CI0.73-2.05) with heterogeneity between studies (I² = 58%,P = 0.003). Sensitivity of dual mapping (ICG + RI) was significantly better compared to single mapping with RI (OR3.69,95%CI1.79-7.62) or ICG (OR3.32,95%CI1.52-7.24) alone with no heterogeneity between studies (I² = 0%,P = 0.004).

CONCLUSION

ICG-fluorescence could complement RI method or provide alternative in centers with poor accessibility to RI lymphoscintigraphy.

Preliminary study of contrast-enhanced ultrasound in combination with blue dye vs. indocyanine green fluorescence, in combination with blue dye for sentinel lymph node biopsy in breast cancer

Background

This preliminary study aimed to examine the feasibility of sentinel lymph node biopsy (SLNB) using contrast-enhanced ultrasound (CEUS) vs. indocyanine green fluorescence (ICG), combined with blue dye in patients with breast cancer.

Methods

This was a retrospective study of consecutive female patients with invasive stage I-III (based on pre-operative physical examination and imaging) primary breast cancer at the Peking Union Medical College Hospital between 01/2013 and 01/2015 who underwent preoperative SLNB by ICG + blue dye or CEUS + blue dye. The numbers of detected SLNs, detection rates, and recurrence-free survival (RFS) rates were compared between the two groups.

Results

A total of 443 patients were included. The detection rates of SLNs in the CEUS + blue dye and ICG + blue dye groups were 98.4 and 98.1%, respectively (P = 0.814). The average numbers of SLNs detected per patient showed no significant difference between the two groups (3.06 ± 1.33 and 3.12 ± 1.31 in the CEUS + blue dye and ICG + blue dye groups, respectively; P = 0.659). After a median follow-up of 46 months, five patients in the CEUS + blue dye group and 15 in the ICG + blue dye group had recurrence. RFS rates showed no significant difference (P = 0.55).

Conclusion

This preliminary study suggests that CEUS + blue dye and ICG + blue dye are both feasible for SLN detection in breast cancer.

Randomized comparison between indocyanine green fluorescence plus 99mtechnetium and 99mtechnetium alone methods for sentinel lymph node biopsy in breast cancer

Use of both patent blue and a radioisotope to locate, and reduce the risk of sentinel lymph node (SLN) detection failure in breast cancer is recommended, but drawbacks commonly lead to using only a radioisotope. An alternative method would therefore be valuable. This randomized, controlled study in 99 patients compared SLN detection using ^99mtechnetium (Tc) alone versus Tc combined with indocyanine green (ICG). The primary endpoint was the SLN identification rate. The primary outcome measure was the number of patients with <2 SLN detected. One SLN was detected in 44.0% of patients in the dual detection group and 40.8% in the ^99mTc alone group (RR = 1.08 (95% CI 0.68; 1.72), p = 0.84). A mean (±SD) of 2.14 ± 1.23 SLN were identified in the dual detection group vs. 1.77 ± 0.85 using Tc alone (p = 0.09). Eight-five (78.7%) SLN were both ICG+ and TC+, 15 (13.9%) ICG+ and Tc−, and 7 (6.5%) ICG− and Tc+. SLN detected were ICG-positive in 92.6% of patients and ^99mTc-positive in 85.2% with. No adverse event related to ICG injection was recorded. Dual detection of SLN using ICG and radioisotope is reliable and sensitive but was not superior to isotope alone in successfully locating SLN in our pilot randomized trial.

Pylorus-preserving pancreatoduodenectomy preserving the right gastroepiploic vessels following proximal gastrectomy: report of two cases

BACKGROUND

Blood flow of the remnant stomach is supplied via the right gastric and right gastroepiploic vessels after proximal gastrectomy (PG). Whether the remnant stomach can be safely preserved in patients who undergo pylorus-preserving pancreatoduodenectomy (PPPD) after PG remains unclear. We herein report two cases in which the remnant stomach was safely preserved by performing PPPD.

CASE PRESENTATION

The first patient, a 76-year-old man, was diagnosed with cancer of the common bile duct and underwent PPPD 2 years after PG for gastric cancer. The remnant stomach and right gastroepiploic vessels were safely preserved. The second patient, a 56-year-old man with a history of PG for gastric cancer 20 years previously, was diagnosed with cancer of the common bile duct and underwent PPPD. We could safely preserve the remnant stomach and right gastroepiploic vessels.

CONCLUSION

The remnant stomach could be preserved in performing PPPD following PG by preserving the right gastroepiploic vessels.

Usability of Intraoperative Fluorescence Imaging with Indocyanine Green During Laparoscopic Cholecystectomy After Percutaneous Transhepatic Gallbladder Drainage

BACKGROUND

Patients with persistent symptoms of acute cholecystitis for >72 h who cannot undergo urgent laparoscopic cholecystectomy (LC) often undergo percutaneous transhepatic gallbladder drainage (PTGBD) and delayed LC. However, intraoperative near-infrared fluorescence with indocyanine green (ICG) has recently become available in various surgical settings. Therefore, we evaluated the usability of intraoperative fluorescence imaging with ICG for LC after PTGBD in patients with acute cholecystitis.

METHODS

The preoperative and postoperative clinical characteristics of patients who underwent LC after PTGBD were retrospectively analyzed.

RESULTS

In total, 130 patients were reviewed. Intraoperative ICG fluorescence imaging was used in 39 (30.0%) patients, and none developed adverse reactions. Patients with ICG fluorescence imaging had a significantly shorter operative time (129 ± 46 vs. 150 ± 56 min, p = 0.0455), markedly lower conversion rate (2.6% vs. 22.0%, p = 0.0017), and lower proportion of subtotal cholecystectomy (0.0% vs. 6.6%, p = 0.0359) than patients without ICG fluorescence imaging. Independent risk factors for conversion to laparotomy during LC after PTGBD were the performance of PTGBD after 48 h from onset (OR 3.52; 95% CI 1.11-12.21; p = 0.0322), an unremoved PTGBD tube on LC (4.48, 1.46-15.00, p = 0.0084), and surgery without ICG (8.00, 1.28-159.47, p = 0.0231).

CONCLUSION

Intraoperative ICG fluorescence imaging produced better surgical outcomes without any adverse reactions. Early performance of PTGBD and intraoperative ICG fluorescence imaging can reduce the surgical difficulties in LC after PTGBD for acute cholecystitis.

Near Infrared Fluorescent Lymph Node Mapping with Indocyanine Green in Breast Cancer Patients: A Prospective Trial

BACKGROUND

Near infrared (NIR) fluorescence imaging is an emerging modality that can enable real-time image-guided procedures. Indocyanine green (ICG) is an FDA-approved, inexpensive, and widely available NIR dye. We hypothesized that axillary lymphatic mapping with ICG is equivalent to lymphatic mapping with technetium 99m (^99mTc) in breast cancer patients.

STUDY DESIGN

Breast cancer patients (cT1-2, N0) were prospectively enrolled. Patients underwent lymphatic mapping with ^99mTc preoperatively and ICG mapping intraoperatively (0.8 mL). Sentinel lymph node (SLN) biopsy was guided by NIR camera and gamma probe. Rate of failed mapping, number of SLNs identified, and rate of identifying pathologically positive SLNs were compared between the 2 techniques (p < 0.05 was considered statistically significant).

RESULTS

Ninety-two female patients were enrolled (median age 59 years). Mean transit time from ICG injection in the breast to localization in the axilla was 5 minutes (range 2 to 29 minutes). No adverse reactions to ICG were noted. Mean number of SLNs identified with ICG and ^99mTc was 2.4 (SD 1.42) and 2.2 (SD 1.23), respectively (p = 0.34). Pathologically positive SLNs were identified in 18 (19.8%) patients. A total of 24 pathologically positive SLNs in 18 patients were identified by ICG in 24 of 24 (100%) patients and by ^99mTc in 23 of 24 (96%) patients (p = 0.99).

CONCLUSIONS

Indocyanine green with NIR fluorescence imaging can be safely and efficiently used for real-time intraoperative lymphatic mapping in breast cancer patients. Indocyanine green performs similarly to ^99mTc with regard to the number of SLNs identified, rate of failed mapping, and identification of pathologically positive SLNs.

A Novel Indocyanine Green Fluorescence-Guided Video-Assisted Technique for Sentinel Node Biopsy in Breast Cancer

BACKGROUND

The equipment to detect indocyanine green (ICG) fluorescence for sentinel lymph node (SLN) biopsy in breast cancer is not widely accessible nor optimal. The fluorescence appears as a poorly defined white shine on a black background, and dimmed lighting is required. The aim of this study was to assess the feasibility, accuracy and healthcare costs of a novel approach for SLN biopsy by a video-assisted ICG-guided technique.

METHODS

The technique for detecting SLN was radioisotope (RI) in 194 cases, video-assisted ICG-guided in 70 cases and a combined method in 71 cases. In the video-assisted ICG group, a full HD laparoscopic system equipped with xenon lamps was used for a laser-free detection of ICG within a colored and magnified high-resolution image.

RESULTS

Detection of ICG fluorescence using a laparoscope with a near-infrared filter provided a highly defined and colored image during SLN biopsy. SLN was identified in 100% of patients in all groups. Multiple SLNs were identified in 0.5% of RI patients, in 12.9% of ICG patients and in 14.1% of ICG + RI patients (p < 0.0001). In ICG + RI group, 95.1% of lymph nodes were radioactive and 92.7% were fluorescent. Operative times and healthcare costs were equivalent between groups.

CONCLUSIONS

Video-assisted ICG-guided technique is a feasible and surgeon-friendly method for SLN biopsy, with equivalent efficacy compared to RI, providing an accurate staging of the axilla.

New Technologies for Sentinel Lymph Node Detection

The 'standard of care' method for sentinel node mapping is the combination technique using radioisotope and blue dye although some centres use radioisotope or blue dye alone. Radioisotope usage requires licensing, has regulatory issues around handling and disposal of waste, and logistically may be unavailable or difficult to implement in some centres or less developed country. This has led to the development of alternative methods such as superparamagnetic iron oxide (SPIO), fluorescence techniques using indocyanine green (ICG) or fluorescein, computed tomography lymphography, and contrast-enhanced ultrasound scan (CEUS) using microbubbles. The newer techniques will potentially enable a more widespread adoption of this procedure; however, a common barrier for these techniques is the lack of standardisation and no randomised trials to evaluate their effectiveness against the current standard of care. Furthermore, many of these techniques are more costly and may become redundant in node-negative patients with small tumours if ongoing trials show that sentinel node biopsy offers no additional benefit to grey-scale axillary ultrasound. This review discusses the new techniques for sentinel node mapping that have emerged including their pros and cons.

Near-infrared fluorescence for detection of sentinel lymph nodes in women with cervical and uterine cancers (FILM): a randomised, phase 3, multicentre, non-inferiority trial

BACKGROUND

Accurate identification of sentinel lymph nodes in patients with cancer improves detection of metastatic disease and decreases surgical morbidity. We sought to establish whether indocyanine green fluorescent dye is non-inferior to isosulfan blue dye in detecting sentinel lymph nodes in women with cervical and uterine cancers.

METHODS

In this non-inferiority, within-patient comparison study, patients aged 18 years or older with clinical stage I endometrial or cervical cancer undergoing curative surgery were randomly assigned 1:1 to lymphatic mapping with isosulfan blue dye (visualised by white light) followed by indocyanine green (visualised by near-infrared imaging), or indocyanine green followed by isosulfan blue dye. Permuted block randomisation with stratification by study site was done with a computerised random number generator. All participants were masked to their randomisation assignment until after the procedure; however, investigators were not masked to the procedure used. Laparoscopic surgery with the PINPOINT near-infrared fluorescence imaging system (Stryker, Kalamazoo, MI, USA) was used in all cases. The primary outcome was efficacy of intraoperative indocyanine green with near-infrared fluorescence imaging versus that of isosulfan blue dye in the identification of lymph nodes, defined as the number of lymph nodes identified by indocyanine green and isosulfan blue dye, respectively (and confirmed as lymphoid tissue by histology), divided by the number of lymph nodes identified intraoperatively and excised. The study had a 5% non-inferiority margin needed to show non-inferiority of the frequency of lymph node detection with indocyanine green to that with isosulfan blue dye with 80% power at a 5% two-sided significance level. Analyses were done in both per-protocol and modified intention-to-treat populations. The trial was registered with ClinicalTrials.gov, number NCT02209532, and is completed and closed.

FINDINGS

Between Dec 21, 2015, and June 19, 2017, 180 patients were enrolled and randomly assigned to the two groups (90 to each group); 176 patients received the intervention and were evaluable (modified intention-to-treat population). 13 patients with major protocol violations were subsequently excluded from the per-protocol population. 517 sentinel nodes were identified in the per-protocol population (n=163), of which 478 (92%) were confirmed to be lymph nodes on pathological processing: 219 (92%) of 238 nodes that were both blue and green, all seven nodes that were blue only, and 252 (95%) of 265 nodes that were green only (p=0·33). Seven sentinel lymph nodes were neither blue nor green but were removed for appearing suspicious or enlarged on visual examination. In total, 471 (97%) of 485 lymph nodes were identified with the green dye and 226 (47%) with the blue dye (difference 50%, 95% CI 39-62; p<0·0001). In the modified intention-to-treat population (n=176), 545 nodes were identified, of which 513 (94%) were confirmed to be lymph nodes on pathological processing: 229 (92%) of 248 nodes that were both blue and green, all nine nodes that were blue only, and 266 (95%) of 279 nodes that were green only (p=0·30). Nine sentinal lymph nodes were neither blue nor green but were removed for appearing suspicious or enlarged on visual examination. 495 (96%) of 513 nodes were identified with the green dye and 238 (46%) with the blue dye (50%, 39-61; p<0·0001).

INTERPRETATION

Indocyanine green dye with near-infrared fluorescence imaging identified more sentinel nodes than isosulfan blue dye in women with cervical and uterine cancers, with no difference in the pathological confirmation of nodal tissue between the two mapping substances.

FUNDING

Novadaq.

Real-time navigation system for sentinel lymph node biopsy in breast cancer patients using projection mapping with indocyanine green fluorescence

BACKGROUND

Inability to visualize indocyanine green fluorescence images in the surgical field limits the application of current near-infrared fluorescence imaging (NIR) systems for real-time navigation during sentinel lymph node (SLN) biopsy in breast cancer patients. The aim of this study was to evaluate the usefulness of the Medical Imaging Projection System (MIPS), which uses active projection mapping, for SLN biopsy.

METHODS

A total of 56 patients (59 procedures) underwent SLN biopsy using the MIPS between March 2016 and November 2017. After SLN biopsy using the MIPS, residual SLNs were removed using a conventional NIR camera and/or radioisotope method. The primary endpoint of this study was identification rate of SLNs using the MIPS.

RESULTS

In all procedures, at least one SLN was detected by the MIPS, giving an SLN identification rate of 100% [95% confidence interval (CI) 94-100%]. SLN biopsy was successfully performed without operating lights in all procedures. In total, 3 positive SLNs were excised using MIPS, but were not included in the additional SLNs excised by other methods. The median number of SLNs excised using the MIPS was 3 (range 1-7). Of procedures performed after preoperative systemic therapy, the median number of SLNs excised using the MIPS was 3 (range 2-6).

CONCLUSIONS

The MIPS is effective in detecting SLNs in patients with breast cancer, providing continuous and accurate projection of fluorescence signals in the surgical field, without need for operating lights, and could be useful in real-time navigation surgery for SLN biopsy.

Shortwave infrared fluorescence imaging with the clinically approved near-infrared dye indocyanine green

Fluorescence imaging is a method of real-time molecular tracking in vivo that has enabled many clinical technologies. Imaging in the shortwave IR (SWIR; 1,000-2,000 nm) promises higher contrast, sensitivity, and penetration depths compared with conventional visible and near-IR (NIR) fluorescence imaging. However, adoption of SWIR imaging in clinical settings has been limited, partially due to the absence of US Food and Drug Administration (FDA)-approved fluorophores with peak emission in the SWIR. Here, we show that commercially available NIR dyes, including the FDA-approved contrast agent indocyanine green (ICG), exhibit optical properties suitable for in vivo SWIR fluorescence imaging. Even though their emission spectra peak in the NIR, these dyes outperform commercial SWIR fluorophores and can be imaged in the SWIR, even beyond 1,500 nm. We show real-time fluorescence imaging using ICG at clinically relevant doses, including intravital microscopy, noninvasive imaging in blood and lymph vessels, and imaging of hepatobiliary clearance, and show increased contrast compared with NIR fluorescence imaging. Furthermore, we show tumor-targeted SWIR imaging with IRDye 800CW-labeled trastuzumab, an NIR dye being tested in multiple clinical trials. Our findings suggest that high-contrast SWIR fluorescence imaging can be implemented alongside existing imaging modalities by switching the detection of conventional NIR fluorescence systems from silicon-based NIR cameras to emerging indium gallium arsenide-based SWIR cameras. Using ICG in particular opens the possibility of translating SWIR fluorescence imaging to human clinical applications. Indeed, our findings suggest that emerging SWIR-fluorescent in vivo contrast agents should be benchmarked against the SWIR emission of ICG in blood.

Sentinel Lymph Node Biopsy in Breast Cancer Patients by Means of Indocyanine Green Using the Karl Storz VITOM® Fluorescence Camera

Currently, the use of radioisotope and blue dye for sentinel lymph node biopsy (SLNB) for axillary staging in breast cancer is common. Recently, indocyanine green (ICG) has been proposed as an alternative sentinel lymph node (SLN) tracking agent. We evaluated the clinical value of ICG as an additional tracer in combination with Technetium^99m and as an alternative to Technetium^99m for the identification of SLN in 104 breast cancer patients. 21 patients had at least 1 histologically tumor-positive SLN. All 21 patients were detected by ICG; in one of these 21 sentinel-positive patients, Technetium^99m was unable to identify lymph node involvement. Our results show that ICG is as effective as the radioisotope for SLNB. In addition, as a near-infrared dye, it has the advantages of real-time visualization, lower cost, and wider availability, since no radioactive material needs to be handled. This trial is registered with German Clinical Trial Register Main ID: DRKS00013606.

Comparison of sentinel lymph node detection performances using blue dye in conjunction with indocyanine green or radioisotope in breast cancer patients: a prospective single-center randomized study

Objective:

This randomized study aimed to compare the clinical efficacy between the novel dual tracer composed of indocyanine green (ICG) and blue dye (BD) and the conventional dual tracer composed of radioisotope and BD for sentinel lymph node (SLN) mapping in patients with breast cancer.

Methods:

This study enrolled 471 clinically lymph node-negative patients with primary breast cancer. All patients underwent mastectomy, and those undergoing sentinel lymph node biopsy (SLNB) were randomized to receive blue dye plus radioisotope (RB group) or BD plus ICG (IB group). The detection performances on SLN identification rate, positive SLN counts, detection sensitivity, and false-negative rate were compared between the two groups.

Results:

In the IB group, 97% (194/200) of the patients who underwent the ICG and BD dual tracer injection showed fluorescent-positive lymphatic vessels within 2–5 min. The identification rate of SLNs was comparable between the IB group (99.0%, 198/200) and the RB group (99.6%, 270/271) (P = 0.79). No significant differences were observed in the identification rate of metastatic SLNs (22.5% vs. 22.9%, P > 0.05, RB group vs. IB group, the same below), positive SLN counts (3.72 ± 2.28 vs. 3.91 ± 2.13, P > 0.05), positive metastatic SLN counts (0.38 ± 0.84 vs. 0.34 ± 0.78, P > 0.05), SLNB detection sensitivity (94.4% vs. 92.5%, P > 0.05), or false-negative rate (5.6% vs. 7.5%, P > 0.05) between the two groups.

Conclusions:

ICG can be used as a promising alternative tracer for radioisotope in SLN mapping, and when it is combined with BD in lymphangiography, it offers comparable detection sensitivity compared to the conventional lymphatic mapping strategies that are widely used in clinical practice.

Role of Indocyanine Green in Fluorescence Imaging with Near-Infrared Light to Identify Sentinel Lymph Nodes, Lymphatic Vessels and Pathways Prior to Surgery - A Critical Evaluation of Options

Modern surgical strategies aim to reduce trauma by using functional imaging to improve surgical outcomes. This reviews considers and evaluates the importance of the fluorescent dye indocyanine green (ICG) to visualize lymph nodes, lymphatic pathways and vessels and tissue borders in an interdisciplinary setting. The work is based on a selective search of the literature in PubMed, Scopus, and Google Scholar and the authors' own clinical experience. Because of its simple, radiation-free and uncomplicated application, ICG has become an important clinical indicator in recent years. In oncologic surgery ICG is used extensively to identify sentinel lymph nodes with promising results. In some studies, the detection rates with ICG have been better than the rates obtained with established procedures. When ICG is used for visualization and the quantification of tissue perfusion, it can lead to fewer cases of anastomotic insufficiency or transplant necrosis. The use of ICG for the imaging of organ borders, flap plasty borders and postoperative vascularization has also been scientifically evaluated. Combining the easily applied ICG dye with technical options for intraoperative and interventional visualization has the potential to create new functional imaging procedures which, in future, could expand or even replace existing established surgical techniques, particularly the techniques used for sentinel lymph node and anastomosis imaging.

Comparison of sentinel lymph node biopsy guided by indocyanine green, blue dye, and their combination in breast cancer patients: a prospective cohort study

BACKGROUND

Recent studies show that near-infrared (NIR) fluorescence imaging using indocyanine green (ICG) has the potential to improve the performance of sentinel lymph node (SLN) mapping. The current cohort study was designed to assess the value of the combination of ICG and methylene blue (MB) dye in patients undergoing SLN biopsy.

METHODS

A prospective self-controlled trial was designed to detect the difference in the detection efficacies of ICG, MB, and combined ICG and MB (ICG + MB) navigation methods. Between 2010 and 2013, 198 consecutive early breast cancer patients eligible for sentinel lymph node biopsy were enrolled and 200 biopsy procedures were performed by injection of both ICG and MB. SLNs were searched and removed under the guidance of fluorescence and/or blue dye. The mapping characteristics, the detection rate of SLNs and positive SLNs, and the number of SLNs of ICG, MB, and ICG + MB were compared. Injection safety of ICG and MB was evaluated.

RESULTS

Fluorescence imaging of lymphatic flow, which is helpful to locate the incision site, could be seen in 184 of 200 procedures. The nodal detection rate of ICG, MB, and ICG + MB samples was 97, 89, and 99.5% (χ 2 = 26.2, p < 0.001), respectively, with the combination method yielding a superior identification result. The addition of ICG to the MB method resulted in the identification of more lymph nodes (median 3 versus 2) and more positive axillas (22.7% involved axillas were discovered by fluorescence only) than either method alone. No acute or chronic allergic reaction was observed in this study. However, 23 patients (23/82) who received breast-conserving therapy reported temporary skin staining, and 5 patients had permanent tattooing. Palpable subcutaneous nodules at the injection sites were reported in nine patients. There were no reports of skin necrosis.

CONCLUSIONS

The lymphatic navigation by ICG fluorescence detects SLNs at a high detection rate and improves the mapping performance when added to the MB method. The novel ICG + MB dual tracing modality, without involvement of radioactive isotopes, exhibits great potential as an alternative to traditional standard mapping methods.

TRIAL REGISTRATION

ACTRN12612000109808 . Retrospectively registered on 23 January 2012.

Sensitivity and specificity of indocyanine green near-infrared fluorescence imaging in detection of metastatic lymph nodes in colorectal cancer: Systematic review and meta-analysis

This review aimed to determine the overall sensitivity and specificity of indocyanine green (ICG) near-infrared (NIR) fluorescence in sentinel lymph node (SLN) detection in Colorectal cancer (CRC). A systematic search in electronic databases was conducted. Twelve studies including 248 patients were reviewed. The median sensitivity, specificity, and accuracy rates were 73.7, 100, and 75.7. The pooled sensitivity and specificity rates were 71% and 84.6%. In conclusion, ICG-NIR fluorescence is a promising technique for detecting SLNs in CRC.