Preoperative imaging of sentinel lymph nodes in gastric cancer using CT lymphography

A path toward the clinical translation of nano-based imaging contrast agents

Recently, nanoparticles have evolved ubiquitously in therapeutic applications to treat a range of diseases. Despite their regular use as therapeutic agents in the clinic, we have yet to see much progress in their clinical translation as diagnostic imaging agents. Several clinical and preclinical studies support their use as imaging contrast agents, but their use in the clinical setting has been limited to off-label imaging procedures (i.e., Feraheme). Since diagnostic imaging has been historically used as an exploratory tool to rule out disease or to screen patients for various cancers, nanoparticle toxicity remains a concern, especially when introducing exogenous contrast agents into a potentially healthy patient population, perhaps rationalizing why several nano-based therapeutic agents have been clinically translated before nano-based imaging agents. Another potential hindrance toward their clinical translation could be their market potential, as most therapeutic drugs have higher earning potential than small-molecule imaging contrast agents. With these considerations in mind, perhaps a clinical path forward for nano-based imaging contrast agents is to help guide/manage therapy. Several studies have demonstrated the ability of nanoparticles to produce more accurate imaging preoperatively, intraoperatively, and postoperatively. These applications illustrate a more reliable method of cancer detection and treatment that can prevent incomplete tumor resection and incorrect assessment of tumor progression following treatment. The aim of this review is to highlight the research that supports the use of nanoparticles in biomedical imaging applications and offer a new perspective to illustrate how nano-based imaging agents have the potential to better inform therapeutic decisions. This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging.

Evaluation of computed tomography vascular reconstruction for the localization diagnosis of perigastric mass

BACKGROUND

The aim of this study was to evaluate the utility of computed tomography (CT) vascular reconstruction in the localization diagnosis of perigastric mass.

METHODS

Fifty-eight patients with pathologically detected perigastric mass underwent abdominal dynamic contrast-enhanced CT. CT vascular reconstructions were produced from arterial phase data using volume rendering (VR), multiplanar reconstruction (MPR), and maximal intensity projection (MIP). Image analysis was focused on the relationship between the mass, perigastric arteries, and the gastric wall. Localization diagnosis values were compared between CT vascular reconstruction and dynamic-enhanced CT images.

RESULTS

Among the 58 cases of perigastric mass, 41 cases originated from the stomach, 7 cases from the left liver lobe, 6 from the pancreas, 2 from lessor omental bursa, 1 from transverse mesocolon, and 1 from left adrenal gland. The accuracy of CT vascular reconstruction images in the localization diagnosis of perigastric mass was higher than that of dynamic-enhanced CT images (98.3% and 86.2%, respectively, P = .04). On the reference level, 35 (35/41) patients with stomach-originated masses showed the mass adjacent perigastric arteries pushed away from the stomach (arterial displacement sign), and 15 (15/17) patients with nonstomach-originated masses showed perigastric arteries between the mass and the stomach (arterial entrapment sign). The sensitivity, specificity, positive predictive value, and negative predictive value of the localization diagnosis of perigastric mass with arterial displacement sign were 85.4%, 100%, 100%, and 73.9%, respectively, and with arterial entrapment sign, 88.2%, 100%, 100%, and 95.3%, respectively.

CONCLUSION

CT vascular reconstruction can clearly depict the relationship between perigastric mass and adjacent perigastric arteries, which may help us more accurately differentiate between stomach-originated and nonstomach-originated masses compared with original dynamic-enhanced CT images.

[Imaging diagnostic methods for identification of sentinel lymph nodes in patients with early squamous cell carcinoma of the oral cavity mucosa: a literature review]

The paper describes properties of clinical visualization approaches which are applied for detection of sentinel lymph nodes in patients suffering from oral cavity squamous cell cancer. Diagnostic efficiency results and technological features of different imaging techniques are discussed.

Assessment of laparoscopic stomach preserving surgery with sentinel basin dissection versus standard gastrectomy with lymphadenectomy in early gastric cancer-A multicenter randomized phase III clinical trial (SENORITA trial) protocol

Background

Along with the marked increase in early gastric cancer (EGC) in the Eastern countries, there has been an effort to adopt the sentinel node concept in EGC to preserve gastric function and reduce the occurrence of postoperative complications. Based on promising results from a previous quality control study, this prospective multicenter randomized controlled phase III clinical trial aims to elucidate the oncologic safety of laparoscopic stomach-preserving surgery with sentinel basin dissection (SBD) compared to a standard laparoscopic gastrectomy.

Methods/Design

This trial is an investigator-initiated, open-label, multicenter randomized controlled phase III trial with a non-inferiority design. Patients diagnosed with a single lesion of clinical stage T1N0M0 gastric adenocarcinoma, with a diameter of 3 cm or less are eligible for the present study. A total of 580 patients (290 per group) will be randomized to either laparoscopic stomach-preserving surgery with SBD or standard surgery. The primary end-point is 3-year disease-free survival (DFS) and the secondary endpoints include postoperative morbidity and mortality, quality of life, 5-year DFS, and overall survival. Qualified investigators who completed the prior quality control study are exclusively allowed to participate in this phase III clinical trial.

Discussion

The proposed trial is expected to verify whether laparoscopic stomach-preserving surgery with SBD achieves similar oncologic outcomes and improved quality of life compared to a standard gastrectomy in EGC patients.

Trial registration

This study was registered at the NIH ClinicalTrial.gov database (NCT01804998) on March 4th, 2013.

Prospective Multicenter Feasibility Study of Laparoscopic Sentinel Basin Dissection for Organ Preserving Surgery in Gastric Cancer: Quality Control Study for Surgical Standardization Prior to Phase III Trial

The clinical application of sentinel node biopsies in early gastric cancer is still controversial even though it appears promising. This study was conducted as a prerequisite quality control for surgical standardization of laparoscopic sentinel basin dissection (SBD) prior to the initiation of a phase III trial.Laparoscopic SBD was performed in patients with preoperative stage T1-2N0 and tumor size <4 cm in diameter. Intraoperative endoscopic submucosal injection of a standardized dual tracer was administered. All retrieved sentinel basin nodes (SBN) were investigated with intraoperative frozen hematoxylin and eosin (H&E) staining. A strict checklist consisting of 7 essential steps was followed during laparoscopic SBD as the quality control study for a phase III trial. Completion of all essential steps in the checklist for 10 cases was used to define a qualified institution.Seven institutions participated and 112 patients were enrolled in this study. However, 4 patients were excluded owing to screening failure. The mean number of cases required for institutional qualification was 15 cases (range, 13-20 cases). Sentinel basins (SB) were detected and dissected in 100 of the 108 patients (92.6%); the median number of SB and SBN was 2 and 7, respectively. Lymph node metastases were detected in 10 patients by postoperative permanent H&E staining and they were detected by SBD in all 10 patients. Frozen results of SBN were compatible with permanent staining reports.Laparoscopic SBD is feasible and demonstrated improved sensitivity in detecting metastatic lymph nodes compared to the previous study. A future phase III randomized trial comparing laparoscopic SBD with organ-preserving gastrectomy and laparoscopic standard gastrectomy seems promising for qualified institutions.

Usefulness of CT-lymphography in sentinel lymph node navigation

BACKGROUND

There are many methods for sentinel lymph node (SLN) navigation. The methods using radioisotopes and blue dyes are performed mainly for the identification of SLN. Our current method for SLN biopsy is a combination of three techniques with 99mTc-phytate, patent blue V dye, and preoperative CT-lymphography (CTLG).

PATIENTS AND METHODS

Iomeprol (Iomeron®) as a water-soluble contrast agent is diluted twofold with 1 % lidocaine and intradermally injected into a few sites (2-5 ml at each site) around the tumor. After the injection, CT imaging is performed using a 64-row MDCT system (Siemens SOMATOM Definition AS+). We performed CTLG in 34 patients (16 men, 18 women) between September 2008 and March 2013.

RESULTS

CTLG clearly visualized the SLN and the lymphatic drainage in 21 out of 34 patients.

CONCLUSIONS

We can detect the SLN and lymphatic flow near to tumors without shine-through effect, especially in the head and neck regions. It is thought that CTLG may be useful to determine the range of lymph node dissection.

Fluorescent iodized emulsion for pre- and intraoperative sentinel lymph node imaging: validation in a preclinical model

PURPOSE

To validate the usefulness of a newly developed tracer for preoperative gastric sentinel lymph node (LN) (SLN) mapping and intraoperative navigation after a single preoperative submucosal injection in rat and beagle models.

MATERIALS AND METHODS

This study was approved by the Experimental Animal Ethical Committee of Yonsei University College of Medicine according to the eighth edition of the Guide for the Care and Use of Laboratory Animals published in 2011. An emulsion was developed that contained indocyanine green in iodized oil, which can be visualized with both computed tomography (CT) and near-infrared (NIR) optical imaging and has the property of delayed washout. This emulsion was injected into the footpad of rats (n = 6) and the gastric submucosa of beagles (n = 8). CT lymphography was performed. The degree of enhancement of popliteal LNs was measured in rats, and the enhancing LNs were identified and the degree of enhancement of the enhancing LNs was measured in beagles. Next, NIR imaging was performed in beagles during open, laparoscopic, and robotic surgery to identify LNs containing the fluorescent signals of indocyanine green. The enhanced LNs detected with CT lymphography and NIR imaging were matched to see if they corresponded.

RESULTS

Preoperative CT lymphography facilitated SLN mapping, and 26 SLNs were identified in eight beagles. NIR imaging enabled high-spatial-resolution visualization of both SLNs and the intervening lymphatic vessels and was useful for intraoperative SLN navigation.

CONCLUSION

SLN mapping with fluorescent iodized oil emulsion is effective and feasible for both CT and NIR imaging.

Clinical relevance of novel imaging technologies for sentinel lymph node identification and staging

The sentinel lymph node (SLN) concept has become a standard of care for patients with breast cancer and melanoma, yet its clinical application to other cancer types has been somewhat limited. This is mainly due to the reduced accuracy of conventional SLN mapping techniques (using blue dye and/or radiocolloids as lymphatic tracers) in cancer types where lymphatic drainage is more complex, and SLNs are within close proximity to other nodes or the tumour site. In recent years, many novel techniques for SLN mapping have been developed including fluorescence, x-ray, and magnetic resonant detection. Whilst each technique has its own advantages/disadvantages, the role of targeted contrast agents (for enhanced retention in the SLN, or for immunostaging) is increasing, and may represent the new standard for mapping the SLN in many solid organ tumours. This review article discusses current limitations of conventional techniques, limiting factors of nanoparticulate based contrast agents, and efforts to circumvent these limitations with modern tracer architecture.

Early gastric cancer: feasibility of CT lymphography with ethiodized oil for sentinel node mapping

PURPOSE

To evaluate the feasibility of CT lymphography with ethiodized oil for sentinel node mapping in porcine stomachs and in patients with early gastric cancer.

MATERIALS AND METHODS

Approval for the animal study was obtained from the authors' institutional animal use and care administrative advisory committee, the clinical study was approved by the institutional review board, and informed consent was obtained from each participant. Five pigs underwent CT lymphography 1 hour after gastric subserosal injection of 1 mL ethiodized oil and sentinel node mapping with injection of 1 mL methylene blue. Ethiodized oil retention nodes were identified on the radiographic images of the gastric specimen and removed for histopathologic examination. In addition, 10 patients with early gastric cancer underwent CT lymphography with peritumoral injection of 1 mL ethiodized oil, followed by sentinel basin extirpation with CT and routine nodal dissection. The removed sentinel basins were examined by radiography. Histopathologic examination was performed for dissected nodes, including sentinel nodes.

RESULTS

In each of the five pigs, CT showed one perigastric ethiodized oil retention node. After harvesting the ethiodized oil retention node, blue-stained areas were identified in the five removed nodes and intranodal ethiodized oil was detected on histopathologic examination. In all 10 patients, CT lymphography with ethiodized oil successfully defined the sentinel basin with ethiodized oil retention nodes. CT lymphography revealed 20 ethiodized oil retention nodes. After basin extirpation, 28 and 46 nodes were detected on radiographic and histopathologic examinations. Histopathologic examination revealed that one patient had micrometastases at two sentinel nodes and another patient had isolated tumor cells at one sentinel node. No patient had metastasis in nonsentinel nodes.

CONCLUSION

CT lymphography with ethiodized oil may be a feasible method for sentinel node mapping in patients with early gastric cancer.

Nanoscale iodized oil emulsion: a useful tracer for pretreatment sentinel node detection using CT lymphography in a normal canine gastric model

BACKGROUND

Pretreatment identification of the sentinel lymph nodes (SLNs) in gastric cancer patients may have great advantages for minimally invasive treatment. No reliable method for the detection of SLNs during the pretreatment period in gastric cancer has been established. The aim of this study was to determine whether computed tomographic (CT) lymphography using nanoscale iodized oil emulsion via endoscopic submucosal injection can visualize LNs.

METHODS

Five dogs underwent CT lymphography after endoscopic submucosal injection of 2 ml of a nanoscale iodized oil emulsion. CT images were taken before and 30, 90, and 210 min after contrast injection. Intraoperative SLN detection was performed using endoscopically injected indocyanine green lymphography for comparison.

RESULTS

Computed tomographic lymphography with nanoscale iodized oil emulsion enabled the visualization of 19 enhanced LNs (mean = 3.8/dog, range = 3-6) with a 100% SLN detection rate. The locations of the SLNs were the lesser curvature (n = 7), greater curvature (n = 1), infrapyloric (n = 3), and left gastric (n = 8) areas. Contrast enhancement of SLNs continuously increased and peaked after 210 min at 142.4 ± 42.3 HU. No green LNs were visualized in the three locations that were detected by CT lymphography. However, no additional LNs were visualized using the dye method. The concordance rate based on the LNs between the SLNs on CT lymphography and the green LNs using the ICG method was 84% (16/19), whereas the concordance rate of the stations identified by CT lymphography and the dye method was 78.6% (11/14).

CONCLUSIONS

Computed tomographic lymphography using nanoscale iodized oil emulsion is a promising tool for preoperative SLN detection for early gastric cancer if the biological safety of the nanoscale iodized oil emulsion can be established.

High rate of solitary sentinel node metastases identification by fluorescence-guided lymphatic imaging in breast cancer

BACKGROUND

The lymph node status was shown to be an important prognostic factor for breast cancer, but controversial issues remain. There has been increased focus on optimizing the visualization of lymph nodes for an accurate and selective approach to axillary lymph nodes. Fluorescence-guided lymphatic imaging is a potential candidate for further research on remaining controversies.

METHODS

Forty-seven patients were subject to injection of indocyanine green for navigation to the SLN based on fluorescent dye retention detection. In two groups, patients either received intended axillary lymph node dissection (ALND) and sentinel lymph node biopsy (SLNB) for superstaging or isolated SLNB for minimal-invasive staging. The prospective study was designed to evaluate the technical feasibility with focus on solitary positive SLN.

RESULTS

Visualization of lymphatic vessels with bright fluorescence of the SLN was feasible in 46 of 47 patients. Eighteen of 19 nodal positive patients were correctly identified with a sensitivity of 94.7% in all patients after ALND. After immunohistochemistry, in 19 of 25 overall nodal positive patients (76%) the SLN was the only positive lymph node.

CONCLUSION

Fluorescence-guided imaging using fluorescence retention detection allows transcutaneous navigation with a high rate of solitary positive SLN identification as an alternative technique for further research.

The peak-standardized uptake value (P-SUV) by preoperative positron emission tomography-computed tomography (PET-CT) is a useful indicator of lymph node metastasis in gastric cancer

BACKGROUND AND OBJECTIVES

Little data is currently available on the usefulness of peak-standardized uptake value (P-SUV) by positron emission tomography-computed tomography (PET-CT) in gastric cancer. The purpose of the present study was to evaluate the value of PET-CT for the preoperative evaluation of patients with gastric cancer. The aim of this study was to assess the relation of between primary tumor P-SUV, as determined by preoperative PET-CT, and lymph node metastasis in gastric cancer.

METHODS

From December 2007 to March 2010, we analyzed the PET-CT of 147 patients that underwent gastrectomy for gastric cancer. P-SUV in PET-CT were measured by single nuclear medicine physician. Statistical analysis was performed to determine relations between clinicopathologic parameters including P-SUV and lymph node metastasis using the chi-square test, the independent t-test, and using logistic regression analysis.

RESULTS

Age, tumor depth, tumor size, and lymph node metastasis were found to be associated with primary tumor P-SUV by PET-CT (P=0.009, <0.001, <0.001, and <0.001, respectively). No association was found between P-SUV and tumor histology or tumor location (P=0.099). Advanced gastric cancer was found to have a higher P-SUV than early gastric cancer, and a higher P-SUV was found to be associated with lymph node metastases by both univariate and multivariate analysis.

CONCLUSIONS

P-SUV of primary tumor could be an independent indicator of lymph node metastasis in gastric cancer. Gastric surgeons should pay more attention to the dissection of lymph nodes when primary tumors have higher P-SUV values by PET-CT.