Pathological and molecular assessment of sentinel lymph nodes in solid tumors

Sentinel Node Biopsy in Laryngeal Cancer: A Systematic Review and Meta-Analysis

Background: Sentinel lymph node (SLN) biopsy offers a minimally invasive approach to staging lymph node involvement in laryngeal squamous cell carcinoma (SCC). Despite its adoption in other cancers, its accuracy in laryngeal SCC remains under investigation. This systematic review and meta-analysis evaluates the diagnostic performance of SLN mapping in laryngeal cancer. Methods: A systematic search of MEDLINE, Scopus, and Google Scholar was conducted using the keywords "(larynx OR laryngeal) AND sentinel", with no date or language restrictions. Studies reporting SLN detection rates and/or sensitivity in laryngeal SCC were included. A random-effects model was applied for data pooling, and subgroup analyses were performed based on tumor location (supraglottic versus transglottic) and mapping material (radiotracer versus blue dye). Publication bias was assessed using funnel plots and statistical methods. Results: Nineteen studies, encompassing 366 patients, were analyzed. The overall pooled SLN detection rate was 90.8% (95% CI: 86-94.1), and sensitivity was 88% (95% CI: 81-94). Supraglottic tumors demonstrated superior outcomes (detection rate: 93.7%, sensitivity: 96%) compared to transglottic tumors (detection rate: 84.7%, sensitivity: 71%). Radiotracers significantly outperformed blue dye, with detection rates of 90.8% versus 81.5% and sensitivities of 88% versus 77%. Conclusions: SLN mapping is a reliable technique for staging laryngeal SCC, particularly for supraglottic tumors, where high detection rates and sensitivity were observed. Radiotracers offer superior performance compared to blue dye, underscoring their clinical value. These findings support the feasibility and accuracy of SLN biopsy in laryngeal cancer, while emphasizing the importance of tumor location and mapping material.

Intra-operative lymphatic mapping and sentinel node biopsy in laryngeal carcinoma using radiotracer injection

OBJECTIVE

The purpose of this study was to determine the value of sentinel lymph node biopsy (SLNB) in the laryngeal SCC, using intra-operative peri-tumoral injection of Tc-99m-phytate.

METHODS

Patients with biopsy-proven squamous cell carcinoma of the larynx were included. On the day of surgery, after anesthesia induction, suspension laryngoscopy was performed to inject 74 MBq/0.4 ml Tc-99m-phytate in four aliquots into the sub-mucosal peri-tumoral location. After a 10-min wait, a portable gamma probe was used to locate sentinel nodes. Subsequently, all patients underwent laryngectomy and neck dissection. Both sentinel nodes and non-sentinel nodes were examined using hematoxylin and eosin (H&E) staining.

RESULTS

Twenty-six patients with a diagnosis of laryngeal carcinoma were included in the study. The SLN detection rate was 65.4%, with a 100% detection rate in the supraglottic region and a 52.6% detection rate for glottis/transglottic patients. Permanent pathology results showed lymph node involvement in four patients, but only one patient had a negative result in the SLNB, resulting in an overall false negative rate of 25%. The sensitivity of the SLN technique was 75% overall, 100% in the supraglottic region, and 67% in the glottis/transglottic region.

CONCLUSION

The accuracy and feasibility of SLNB may be related to the location of the tumors in the larynx. For supraglottic tumors, the technique seems to be feasible with a low false negative rate. For glottis/transglottic tumors, both the detection rate and false negative rate seem to be suboptimal. Further studies are needed to validate our results.

Lymph Node Cellular Dynamics in Cancer and HIV: What Can We Learn for the Follicular CD4 (Tfh) Cells?

Lymph nodes (LNs) are central in the generation of adaptive immune responses. Follicular helper CD4 T (Tfh) cells, a highly differentiated CD4 population, provide critical help for the development of antigen-specific B cell responses within the germinal center. Throughout the past decade, numerous studies have revealed the important role of Tfh cells in Human Immunodeficiency Virus (HIV) pathogenesis as well as in the development of neutralizing antibodies post-infection and post-vaccination. It has also been established that tumors influence various immune cell subsets not only in their proximity, but also in draining lymph nodes. The role of local or tumor associated lymph node Tfh cells in disease progression is emerging. Comparative studies of Tfh cells in chronic infections and cancer could therefore provide novel information with regards to their differentiation plasticity and to the mechanisms regulating their development.

The inextricable axis of targeted diagnostic imaging and therapy: An immunological natural history approach

In considering the challenges of approaches to clinical imaging, we are faced with choices that sometimes are impacted by rather dogmatic notions about what is a better or worse technology to achieve the most useful diagnostic image for the patient. For example, is PET or SPECT most useful in imaging any particular disease dissemination? The dictatorial approach would be to choose PET, all other matters being equal. But is such a totalitarian attitude toward imaging selection still valid? In the face of new receptor targeted SPECT agents one must consider the remarkable specificity and sensitivity of these agents. (99m)Tc-Tilmanocept is one of the newest of these agents, now approved for guiding sentinel node biopsy (SLNB) in several solid tumors. Tilmanocept has a Kd of 3×10(-11)M, and it specificity for the CD206 receptor is unlike any other agent to date. This coupled with a number of facts, that specific disease-associated macrophages express this receptor (100 to 150 thousand receptors), that the receptor has multiple binding sites for tilmanocept (>2 sites per receptor) and that these receptors are recycled every 15 min to bind more tilmanocept (acting as intracellular "drug compilers" of tilmanocept into non-degraded vesicles), gives serious pause as to how we select our approaches to diagnostic imaging. Clinically, the size of SLNs varies greatly, some, anatomically, below the machine resolution of SPECT. Yet, with tilmanocept targeting, the SLNs are highly visible with macrophages stably accruing adequate (99m)Tc-tilmanocept counting statistics, as high target-to-background ratios can compensate for spatial resolution blurring. Importantly, it may be targeted imaging agents per se, again such as tilmanocept, which may significantly shrink any perceived chasm between the imaging technologies and anchor the diagnostic considerations in the targeting and specificity of the agent rather than any lingering dogma about the hardware as the basis for imaging approaches. Beyond the elements of imaging applications of these agents is their evolution to therapeutic agents as well, and even in the neo-logical realm of theranostics. Characteristics of agents such as tilmanocept that exploit the natural history of diseases with remarkably high specificity are the expectations for the future of patient- and disease-centered diagnosis and therapy.

The feasibility of sentinel lymph node biopsy with a multidisciplinary cooperative team approach for the management of koreans with cutaneous malignant melanoma

BACKGROUND

The regional lymph nodal status is the most powerful independent predictor of survival for patients with clinical N0 primary cutaneous malignant melanoma.

OBJECTIVE

We wanted to evaluate the feasibility and morbidity of the sentinel lymph node biopsy (SLNB) staging using a multidisciplinary team approach, in cooperation with other surgical departments, at a university hospital setting.

METHODS

Twenty two patients with cutaneous melanoma and who were treated at Kyungpook National University Hospital were included in this study. They all received SLNB, which was done by the Departments of Dermatology and General Surgery. We evaluated the feasibility and side effects of SLNB.

RESULTS

Pathologically-positive sentinel nodes were found in 7 of the 22 cases (31.8%) and all 7 patients were consequently upstaged. The whole process involved in SLNB was well tolerated by nearly all the patients, with only mild and transient complications being observed.

CONCLUSION

We suggest that in a Korean setting, utilizing SLNB with a multi-disciplinary team approach is a technically feasible procedure that is able to detect occult nodal metastasis with low morbidity rates in patients with cutaneous malignant melanoma.

Molecular markers of breast axillary lymph node metastasis

In breast cancer, axillary lymph node status is one of the most important prognostic variables and a crucial component to the staging system. Several clinico-histopathological parameters are considered to be strong predictors of metastasis; however, they fail to accurately classify breast tumors according to their clinical behavior and to predict which patients will have disease recurrence. Methods based on genome-wide microarray analyses have been used to identify molecular markers with respect to the development of axillary lymph node metastasis. Most of these markers can be detected in the primary tumors, which can potentially lead to the ability to identify patients at the time of diagnosis who are at high risk for lymph node metastasis, allowing for early intervention and more suitable adjuvant treatments.

[Feasibility and technical problems of sentinel node analysis in melanoma]

BACKGROUND

Development of the sentinel lymph node (SLN) biopsy the last 10 years has changed surgical approach of solid tumor treatment and particularly of melanoma. The aim of our study was to analyze in our hospital, the feasibility of the SLN biopsy technique in order to define a better prognostic classification of melanomas.

PATIENTS AND METHODS

Between July 1999 and October 2003, 97 patients were included in this study in our center. Criteria for inclusion were cutaneo-mucosal melanoma of Breslow >or=1,5 mm, and/or Clarck >or=IV, and/or ulceration, and/or signs of regression, before any surgical margins.

RESULTS

Lymphoscintigraphy (LS) identified at least 1 SLN in 94 cases/97 (97%), thus permitting intraoperative SLN mapping and sentinel node biopsy of at least 1 lymph node in 88 cases/94 (94%). Failure of the SLN procedure was noted in 9 cases: in 3 cases, no lymph node was individualized by LS, in 1 patient, intraoperative SLN mapping failed to find the previously identified SLN and in 5 cases, a SLN was identified by LS and intraoperative mapping but could not be removed because of its deep location and difficulty of dissection. In 17 patients, removal of one or two "non sentinel lymph node(s)" was (were) made by the surgeon because of its (their) suspected aspect (black or large). Among the 88 patients who had dissection of at least 1 SLN, a micrometastasis was detected by standard histological evaluation and/or immunohistochemical stains in 14 cases (16%) and into a "non SLN" in 2 cases (2,3%). The median follow up of patients was 16 months (1- 48 months). Among the 14 patients with positive SLN, 6 (43%) relapsed. The other eight were in complete remission of their melanoma with a mean follow up of 11,44 months . Among the 74 patients with negative SLN, 7 (9,5%) developed a recurrence. Among the 9 patients in whom any sentinel lymph node have been removed, 3 had a relapse (one in transit than on lymph nodes, and two on lymph nodes).

CONCLUSION

Our results are in accordance with the literature, and confirm the feasibility of SLN mapping and of SLN histological analysis in our center. We described in this study technical problems we encountered. Our study also show the prognostic value of this technique. However, advantage in global survey of sentinel node dissection and regional lymph node dissection in cases of micrometastases has still to be demonstrated.

Molecular diagnostics in melanoma

Molecular pathology is rapidly evolving, featuring continuous technologic improvements that offer novel clinical opportunities for the recognition of disease predisposition, for identifying sub-clinical disease, for more accurate diagnosis, for selecting efficacious and non-toxic therapy, and for monitoring of disease outcome. Currently, the identification and prognosis of primary cutaneous melanoma is based on histologic factors (tumor depth and ulceration) and clinical factors (number of lymph node and/or distant metastases). However, metastasis can occur in patients with thin melanomas, and sentinel lymph node biopsy does not identify all patients at risk for distant metastasis. New markers exist that correlate with melanoma progression, which may aid in melanoma identification, prognostication, and detection of minimal residual disease/early recurrence. Moreover, not many therapeutic options exist for melanoma as no regimen prolongs survival. Emerging data with investigational therapies suggest that certain markers might play a crucial role in identifying patients who will respond to therapy or show utility in the monitoring the response to therapy. Herein, molecular diagnostics that can potentially benefit the individual melanoma patient will be discussed.

Cutaneous melanoma: therapeutic lymph node and elective lymph node dissections, lymphatic mapping, and sentinel lymph node biopsy

Early clinical observation in cancer patients suggested that tumors spread in a methodical, stepwise fashion from the primary site, to the regional lymphatics, and only then to distant locations. Based on these observations, the regional lymphatics were believed to be mechanical barriers, at least temporarily preventing the widespread dissemination of tumor. Despite evidence now available disputing its validity, this barrier theory has guided the surgical management of the regional lymphatics in cancer patients for more than a century, influencing the use of such surgical modalities as therapeutic lymph node dissection, elective lymph node dissection, and most recently lymphatic mapping and sentinel lymph node biopsy. No published randomized controlled trial exists that demonstrates improved overall patient survival for cancer of any type, including melanoma, after surgical excision of regional lymphatics. This article will review the biology of lymphatics as it relates to regional tumor metastasis, and based on available information, offer practical recommendations for the clinical dermatologist and their patients who have cutaneous melanoma.

[Sentinel lymph node biopsy in malignant melanoma--an update]

Ten years after the introduction of the sentinel lymph node biopsy technique in the management of malignant melanoma, it is time to take stock. The complex method has proved itself sufficiently sensitive, although a certain percentage of false-negative histological results have to be taken into account. Presently, it is still a point at issue whether sentinel lymph node biopsy should be regarded as the standard of care in high-risk patients. Three prospective multicentre trials have failed to demonstrate a survival benefit resulting from elective lymph node dissection. In contrast, a retrospective multicentre study has recently shown that patients with node metastases diagnosed by the sentinel procedure benefit from early excision of their nodal disease in terms of overall survival, as compared to patients with delayed dissection of palpable nodes. Studies worldwide have established the pathologic status of the sentinel lymph node biopsy as the most important prognostic factor for recurrence and survival after the excision of primary melanoma. As with any invasive staging procedure, sentinel lymph node biopsy should have demonstrated therapeutic consequences. Unfortunately, an unequivocally acknowledged adjuvant therapy is lacking. Moreover, the impact of complete lymph node dissection after positive sentinel biopsy on survival or local disease control has not yet been clarified.

Évaluation du taux de récidive ganglionnaire après ganglion sentinelle négatif chez les patients porteurs de mélanome, et analyse des résultats. L’expérience de l’hôpital Saint-Louis, Paris

Melanoma is a malignant tumor, with dominant lymphatic extension. Sentinel lymph node is the first lymph node touched by melanoma. Our retrospective and monocentric study is about 87 patients, between July 1999 and July 2003. The inclusion criteria were malignant melanoma with Breslow level superior or equal 1.5 mm, and/or Clark level superior or equal IV, and/or ulcerated, and/or in regression. Sentinel lymph node has been negative on histological analysis in 75 patients (86.2%). About these 75 patients, we found five metastatic lymph node recurrence (6.66%) in a short notice (median 10.2 months). For the five patients with recurrence, the original slides and tissue blocks were available for reexamination. Then, we found micrometastasis in two patients (40% of occult metastasis). Our rate of lymph node recurrence in patients with sentinel lymph node negative is about 6.66%. Our analysis make us believe that early recurrence are essentially linked to histological analysis limits, and maybe to skip metastasis existence.

Clinical breast lymphoscintigraphy: optimal techniques for performing studies, image atlas, and analysis of images

Breast lymphoscintigraphy is increasingly performed before surgery to delineate the drainage to the sentinel node (SN) in the axilla. On the basis of the histologic status of harvested SNs, the disease status of the entire axilla can be predicted. This prediction allows a more limited dissection to be performed while maintaining staging accuracy comparable with that of classic axillary lymph node dissection. Lymphoscintigraphy assists surgeons in harvesting the SN during gamma probe-assisted axillary biopsy or dissection and provides a wide field of view survey, among other benefits. When certain injection protocols are used, lymphoscintigraphy can be performed in the afternoon before surgery the next morning, thus minimizing disruptions of tight surgical schedules. Image acquisition can be optimized and SN activity can be maximized by means of such factors as parameters for preparation of the radiotracer, injection techniques, energy settings for the gamma camera, breast displacement maneuvers, and techniques for marking and outlining the patient's body. The ultimate goals are to delineate the true SN, maximize activity in the node for facilitated removal (even at next-day surgery), and deliver the information to the surgeon without delaying the surgical schedule.

J, Lewin S, Marone MMS. Pesquisa do linfonodo sentinela em pacientes com melanoma: experiência com fitato marcado com Tecnécio-99m e revisão da literatura

FUNDAMENTOS: A progressão linfática do melanoma maligno habitualmente se inicia pelo linfonodo sentinela (LNS), cuja análise histopatológica permite predizer o acometimento de toda a cadeia. OBJETIVO: O trabalho tem por objetivo descrever a utilização do 99mTc-Fitato na detecção do LNS em pacientes com melanoma maligno, revisando as indicações e informações fornecidas por sua biópsia. MÉTODO: A pesquisa de LNS foi realizada por meio da linfocintilografia com 99mTc-Fitato em 92 pacientes com melanoma (54,0±14,3 anos). Após 18-24 horas, 88 pacientes foram submetidos à localização intra-operatória com detector portátil, seguida da ressecção e análise histopatológica do LNS. RESULTADOS: A linfocintilografia permitiu a identificação do LNS em todos os estudos, havendo detecção intra-operatória em 98,8% dos casos. O LNS estava acometido em 23 pacientes (26%). O valor preditivo negativo foi de 100% e não se observaram reações adversas pelo uso do 99mTc-Fitato. CONCLUSÃO: A detecção do LNS pode ser realizada com diferentes radiofármacos, incluindo o 99mTc-Fitato, que apresenta vantagens de custo e disponibilidade no Brasil. A pesquisa de LNS resulta em maior acurácia e menor morbidade no estadiamento de pacientes com melanoma maligno

Laparoscopic sentinel node mapping in early-stage cervical cancer

OBJECTIVE

We aimed to determine the feasibility and accuracy of sentinel node (SN) mapping and its ability to predict the status of the regional nodal basin.

METHODS

From October 2000 to September 2002, 70 patients undergoing radical surgery for early-stage cervical cancer (stage IA, IB, and IIA) were offered lymph node mapping for identification of the sentinel node. All patients underwent SN identification laparoscopically followed by a complete laparoscopic pelvic node and parametrial dissection. The SN mapping was done after intracervical blue dye injection in all cases and was combined with preoperative lymphoscintigraphy following intracervical Tc-99 injection and intraoperative SN detection with a miniaturized laparoscopic gamma probe in 29 cases (42%).

RESULTS

The blue dye technique alone (n = 70) identified at least 1 SN in 61 (87%) of the patients. The rate of SN detection by side of dissection was 74%, 70% on the left side and 77% on the right side. Bilateral SN were identified in 60% of cases. In the subgroup of patients who had the combined technique (n = 29), the rate of SN detection increased from 79 to 93% (P = 0.04). The bilateral SN detection rate increased from 55 to 72% when adding lymphoscintigraphy (P = 0.03). In the last 15 cases of the series, the SN detection rate reached 93% (14/15) and this was statistically significant compared to the detection rate of the first 55 cases (P < 0.01). A total of 135 SN were identified, with the majority (88%) being located at three main sites: the external iliac, obturator, and bifurcation. Thirty-six patients (51%) had 2 SN identified, and 16 (24%) had 3 SN or more. Twelve (17%) patients had positive lymph nodes. In those cases, the rate of SN detection per side of dissection in patients with normal appearing nodes at laparoscopy was 75%, whereas it was only 56% in patients with macroscopically involved lymph nodes (P = NS). The false negative rate was 0. The negative predictive value of SN mapping was 100% and the sensitivity was 93% with the combined technique. Two patients had allergic reactions to the blue dye (3%).

CONCLUSION

Sentinel node mapping with the combined blue dye technique and lymphoscintigraphy in patients with cervical cancer is laparoscopically feasible and is highly accurate. The detection rate improves significantly with experience and with the use of lymphoscintigraphy.

Candidate???s Thesis: The Application of Sentinel Node Radiolocalization to Solid Tumors of the Head and Neck: A 10-Year Experience

OBJECTIVES/HYPOTHESIS

The goals of the research study were to develop an easily mastered, accurate, minimally invasive technique of sentinel node radiolocalization with biopsy (SNRLB) in the feline model; to compare it with blue-dye mapping techniques; and to test the applicability of sentinel node radiolocalization biopsy in three head and neck tumor types: N0 malignant melanoma, N0 Merkel cell carcinoma, and N0 squamous cell carcinoma.

STUDY DESIGN

Prospective consecutive series studies were performed in the feline model and in three head and neck tumor types: N0 malignant melanoma (43 patients), N0 Merkel cell carcinoma (8 patients), and N0 squamous cell carcinoma (20 patients).

METHODS

The technique of sentinel node radiolocalization with biopsy was analyzed in eight felines and compared with blue-dye mapping. Patterns of sentinel node gamma emissions were recorded. Localization success rates were determined for blue dye and sentinel node with radiolocalization biopsy. In the human studies, all patients had sentinel node radiolocalization biopsy performed in a similar manner. On the morning of surgery, each patient had sentinel node radiolocalization biopsy of the sentinel lymph node performed using an intradermal or peritumoral injection of technetium Tc 99m sulfur colloid. Sentinel nodes were localized on the skin surface using a handheld gamma detector. Gamma count measurements were obtained for the following: 1) the "hot" spot/node in vivo before incision, 2) the hot spot/node in vivo during dissection, 3) the hot spot/node ex vivo, 4) the lymphatic bed after hot spot/node removal, and 5) the background in the operating room. The first draining lymph node(s) was identified, and biopsy of the node was performed. The radioactive sentinel lymph node(s) was submitted separately for routine histopathological evaluation. Preoperative lymphoscintigrams were performed in patients with melanoma and patients with Merkel cell carcinoma. In patients with head and neck squamous cell carcinoma, the relationship between the sentinel node and the remaining lymphatic basin was studied and all patients received complete neck dissections. The accuracy of sentinel node radiolocalization with biopsy, the micrometastatic rate, the false-negative rate, and long-term recurrence rates were reported for each of the head and neck tumor types. In the melanoma study, the success of sentinel node localization was compared for sentinel node radiolocalization biopsy, blue-dye mapping, and lymphoscintigraphy. In the Merkel cell carcinoma study, localization rates were evaluated for sentinel node radiolocalization biopsy and lymphoscintigraphy. In the head and neck squamous cell carcinoma study, the localization rate of sentinel node radiolocalization biopsy and the predictive value of the sentinel node relative to the remaining lymphatic bed were determined. All results were analyzed statistically.

RESULTS

Across the different head and neck tumor types studied, sentinel node radiolocalization biopsy had a success rate approaching 95%. Sentinel node radiolocalization biopsy was more successful than blue-dye mapping or lymphoscintigraphy at identifying the sentinel node, although all three techniques were complementary. There was no instance of a sentinel node-negative patient developing regional lymphatic recurrence. In the head and neck squamous cell carcinoma study, there was no instance in which the sentinel node was negative and the remaining lymphadenectomy specimen was positive.

CONCLUSION

In head and neck tumors that spread via the lymphatics, it appears that sentinel node radiolocalization biopsy can be performed with a high success rate. This technique has a low false-negative rate and can be performed through a small incision. In head and neck squamous cell carcinoma, the histological appearance of the sentinel node does appear to reflect the regional nodal status of the patient.

The management of regional lymph nodes in cancer

Early clinical observation in cancer patients suggested that tumours spread in a methodical, stepwise fashion from the primary site to the regional lymphatics, and only then to distant locations. Based on these observations, the regional lymphatics were believed to be mechanical barriers preventing the widespread dissemination of tumour. Despite evidence now available disputing its validity, this barrier theory has guided the surgical management of the regional lymphatics for more than a century, influencing the use of such surgical modalities as therapeutic lymph node dissection, elective lymph node dissection and most recently sentinel lymph node biopsy. No published randomized controlled trial exists that demonstrates improved overall survival for patients with cancer of any type undergoing surgery of the regional lymphatics. We believe the presence of tumour in the regional lymphatics indicates the presence of systemic disease, and therapeutic interventions should be directed accordingly.

Biomarkers in melanoma: staging, prognosis and detection of early metastases

Currently, melanoma remains a surgical disease since early detection and excision of thin melanomas offers the best chance of a cure. Despite intensive clinical investigation, no effective systemic therapies exist for metastatic melanoma. Sentinel lymph node biopsy has greatly aided the staging and prognostic evaluation of primary cutaneous melanoma, however, approximately a third of patients diagnosed with metastatic melanomas present without prior regional lymph node involvement. Additional prognostic biomarkers exist which help determine the risk of advanced melanoma but the accuracy for each current marker is less than 100%. A greater understanding of the biology of melanomas and the development of new methods to identify patients with early (subclinical) metastatic disease may allow for selective and more effective therapy for patients at-risk for advanced disease. In this paper, current and novel potentially more accurate biomarkers for the staging and prognostic evaluation of melanoma patients, and for the detection of subclinical metastases are reviewed.

Interstitial CT lymphography-guided localization of breast sentinel lymph node: preliminary results

BACKGROUND

Accurate localization of the breast sentinel lymph node (SLN) can be challenging as a minimally invasive approach to the treatment of early-stage breast cancer. We tested the potential capability of interstitial computed tomographic lymphography (CT-LG) using a conventional contrast agent (iopamidol) for SLN mapping.

METHODS

In 14 female dogs, 0.5 and 1 mL of undiluted iopamidol was injected subcutaneously into the 2 skin areas overlying the mammary gland. Contiguous, 2 mm-thick multidetector helical CT images were obtained through the upper breast and axilla before, and for 60 minutes after, gentle massage at the injection site. Three-dimensional (3D) CT images were obtained from the postcontrast images showing the greatest SLN enhancement. This CT-LG with 2 mL of iopamidol was also evaluated in 5 human female volunteers.

RESULTS

The direct connection of SLN and lymphatic vessels draining from the injection sites in the animal models was clearly visualized, even with 0.5 mL of iopamidol. With this dose, the SLN attenuation was maximally enhanced, with a mean of 274 Hounsfield units (HU) on the first postcontrast images. The topographic 3D images provided the comprehensive anatomy of these lymphatic pathways. Of the 28 SLNs and 184 distant nodes visualized on CT images, all of the SLNs (100%) and 161 (87.5%) of the distant nodes could be resected at premortem and/or postmortem, with a good correlation in the locations and sizes with those on the CT images. The CT-LG effectively localized 5 SLNs with averaged maximum attenuation of 223 HU in the human volunteers, without any significant adverse effects.

CONCLUSION

Interstitial CT-LG using small volumes of iopamidol can sufficiently visualize breast lymphatic drainage and may have potential utility for breast SLN mapping.