[The sentinel node. Concepts and clinical applications in neoplasms of the breast and melanoma]

Multidisciplinary radio-guided surgery team: Alternative to change the current paradigm

INTRODUCTION

Given the constant increase in the healthcare demand for examinations related to radio-guided surgery (RGS), our hospital adopted new professional profiles in the RGS team, in order to partially reduce the time spent by nuclear medicine physicians on this task.

AIM

To analyze the process of incorporating the profiles of Diagnostic Imaging Technician (DIT) and Sentinel Node Referent Nurse (SNRN), evaluating their deployment in the procedures linked to the technique.

MATERIAL AND METHODS

Analysis of RGS activity during the period 2018-2022, focusing on pre-surgical and surgical procedures related to breast cancer (BC) and malignant melanoma (MM), as they are those pathologies on which the transfer of care competencies was concentrated. Chronological evolution of the competencies assumed by the different profiles during their integration into the RGS team.

RESULTS

RGS's healthcare activity during the analyzed period experienced an increase of 109%. BC and MM were the pathologies that accounted for by far the greatest demand for care. The transfer of competencies in these two pathologies occurred in a progressive and staggered manner, with 74% (460/622) of the administration phase being carried out by the SNRN and 64% (333/519) of the surgeries by the DIT in 2022.

CONCLUSIONS

The creation of a multidisciplinary RGS team that includes different professional profiles (nuclear medicine physician [MN], ERGC and TSID) is an effective strategy to respond to the increase in the complexity and number of all procedures related to RGS.

Use of SPECT/CT for improved sentinel lymph node localization in endometrial cancer

OBJECTIVE

To assess the usefulness of adding SPECT/CT to planar images for pre-surgical sentinel lymph node (SLN) identification in endometrial cancer (EC), a technique that could have an important clinical impact on the staging, treatment, and prognosis of EC patients.

METHODS

We compared the planar and SPECT/CT lymphoscintigraphic images of 44 patients with high-risk EC who underwent sentinel lymph node procedure (SLN) using an injection technique recently developed at our center known as TUMIR (Transvaginal Ultrasound Myometrial Injection of Radiotracer). 148 MBq (4 mCi) of 99mTc-nanocolloid were injected, guided by transvaginal ultrasound imaging. Planar and SPECT/CT images were performed in all 44 patients.

RESULTS

SLNs were seen on planar images in 32 cases (73%) and in 34 cases (77%) using SPECT/CT. A total of 88 SLNs were depicted by planar lymphoscintigraphy while SPECT/CT visualized a total of 110 SLNs. SPECT/CT changed the assessment of the SLNs visualized in planar lymphoscintigraphy in 26 cases, either by modifying the number and/or the location of the SLNs detected. External iliac chain was the most frequent location of SLN detection (71%) in the 34 cases. Fifteen of these patients (44%) showed para-aortic SLNs. One case had exclusive para-aortic drainage (3%) that was only visualized by SPECT/CT. In another case, SPECT/CT was able to localize the only pelvic metastatic lymph node not visualized by planar images.

CONCLUSIONS

SPECT/CT combined with planar imaging improves preoperative SLN detection and provides valuable anatomic information that enhances the presurgical stage of the SLN technique in endometrial cancer.

Lymphoscintigraphy for differential diagnosis of peripheral edema: diagnostic yield of different scintigraphic patterns

Edema of the limbs is a common reason for medical consultation, for which the lymphoscintigraphy is considered to be a reliable method for its differential diagnosis.

OBJECTIVE

To evaluate the usefulness of radionuclide studies in the differential diagnosis of edema, and the diagnostic yield of different scintigraphic patterns.

MATERIAL AND METHODS

A total of 61 patients, mean age 43 years, referred to our Department in the last three years for suspected lymphoedema, were considered. One patient was discarded due to lack of diagnosis, 56 had lower limb edema and 4 upper limb edema. After intradermal injection of two doses of (99m)Tc-nanocolloid, scintigraphic scans were made at 30 and 120minutes. The final diagnosis was based on imaging tests, clinical course, and response to treatment. We calculated the parameters of the diagnostic yield of four different scintigraphic patterns (presence of dermal backflow, asymmetry-alteration in inguinal/axillary nodes, presence of collateral pathways, and visualization of intermediate lymph nodes), considering them individually and jointly.

RESULTS

The best diagnostic yield was achieved by considering dermal backflow and asymmetry in inguinal/axillary nodes (accuracy 88.9%, specificity 96.4%, PPV 95.5%). Evaluation of intermediate lymph nodes and presence of collateral pathways contributed little to the diagnostic yield, showing poor sensitivity and high false positive rates.

CONCLUSION

The lymphoscintigraphy had high diagnostic yield, allowing early treatment of lymphœdema. The dermal backflow and asymmetry in inguinal/axillary nodes had the greatest diagnostic accuracy. Evaluation of intermediate lymph nodes and visualization of collateral pathways contributed little to improving the diagnosis.

[Evaluation of the sentinel lymph node combining SPECT/CT with the planar image and its importance for the surgical act]

The sentinel node biopsy procedure is based on the hypothesis of the existence of an orderly and predictable pattern of lymphatic drainage to a regional lymph node basin. This results in the consideration of all lymph nodes with direct drainage from the primary tumor as sentinel nodes. The sentinel node is not necessarily the hottest or the most nearby node, although this is often the case. Lymphoscintigraphy has been an essential component for preoperative sentinel node identification. With the new generation of multimodality gamma cameras, SPECT/CT has been incorporated into the sentinel node procedure. The resulting SPECT/CT fused images depict sentinel nodes in an anatomical landscape providing a helpful roadmap for surgeons. Therefore, it is necessary to define the role of SPECT/CT in relation to the classical planar lymphoscintigraphy for the identification of sentinel nodes. To understand the combined use of lymphoscintigraphy and SPECT/CT, the criteria for sentinel node identification on preoperative images must be specified. The authors, based on their experience in this field, present tentative criteria to identify lymph nodes as sentinel nodes both in planar and SPECT/CT images and classify them into different categories. The use of these scintigraphic categories to characterize radioactive lymph nodes is also helpful for surgical decision making.

[Use of intraoperative lymphoscintigraphy in doubtful cases of sentinel node detection]

Lymphoscintigraphy is a widely accepted method used to detect selectively the sentinel node in malignant melanoma. This is the case report of a patient who was operated on for an inguinal melanoma and who was referred to the Nuclear Medicine Section for preoperative lymphoscintigraphy. There were technical problems for sentinel node detection due to the proximity of injection points. We aimed to know the possibility to perform an intraoperative lymphoscintigraphy as a valid and useful technique in cases as this one.

Incidence of internal mammary node metastases after a sentinel lymph node technique in breast cancer and its implication in the radiotherapy plan

PURPOSE

To analyze the frequency in determining pathologically proven metastatic involvement of internal mammary nodes (IMN) after sentinel lymph node (SLN) technique in breast cancer and to evaluate the implications for radiotherapy (RT) management of patients.

METHODS AND MATERIALS

Two hundred and twenty-five patients who underwent lymphatic mapping for early breast cancer treated with breast-conserving surgery and radiation (80%) or mastectomy (20%) were evaluated. There were two phases in the study: the validation phase (105 patients, 52 T1, 53 T2 < or = 4 cm), and the application phase (120 patients, 70 T1, 50 T2 < or = 2.5 cm). In the validation, if a drainage pathway to the IMN was identified, no biopsy was performed in this phase. In the application, if the study showed metastases in the IMNs, biopsy was performed. When histologically proven IMN metastases were detected, RT was included on the IMN chain planned with a 3D treatment system using conformal techniques. At the beginning of the study the injection site was subdermal and subsequently, the injection site was changed to peritumoral and intratumoral to search for IMN.

RESULTS

In 31 patients of 225 (14%) hot spots were observed in the internal mammary chain (11.5% and 17.2% in the validation and application phases, respectively). In the validation phase, in 11 cases (11.5%) IMN drainage was observed, and in the application phase, in 20 cases (17.2%). Sampling of the internal mammary basin based on lymphoscintigraphy results was successful in 69% of the cases (14 of 20) and revealed metastatic involvement in 14% (2 of 14). This represents incidence of only 1.7% (2 of 116) in early breast cancer patients with SLN study in the application phase. In both cases the axillary SLN was also positive. Both patients with metastatic involvement of the IMN area received RT on the IMN chain next to the remaining breast after conservative surgery.

CONCLUSIONS

We can conclude that 14% of the patients with intraoperative drainage into the IMN surgical examination of the lymph nodes had pathologically positive metastases. The percentage in pathologically proven metastatic involvement of IMN after the SLN technique in early breast cancer is low, but it is not negligible. Moreover, it is expected to increase since the international recommendations have established a 3-cm cutoff for practicing the SLN technique. Although the real value of IMN irradiation in early breast cancer is not known, including this chain in postoperative radiotherapy is not recommended unless pathologically proven IMNs have been produced by the SLN technique. To avoid overdosage or underdosage in the joint between the medial tangential and IMN fields, an individualized 3D dosimetry study is mandatory to enhance dose distribution and reduce the heart volume to lessen side effects.

Localización del ganglio centinela en cáncer de mama. Inyección periareolar del radiocoloide

Traditional lymphadenectomy is being replaced by sentinel node biopsy in initial management of early stage breast cancer. The aim of this study was to validate the technique in our center, where we perform preoperative lymphoscintigraphy and intraoperative detection of sentinel node, after periareolar radiotracer and peritumoral blue dye injection. Sixty patients, breast cancer stages I and II, were included. Lymphatic mapping was performed the day before surgery, after the administration of 74 MBq 99mTc sulfur colloid in periareolar subdermal tissue. Surgical detection of sentinel node through gamma probe was followed by intraoperative and occasionally delayed biopsies. Finally, full axillary node dissection was completed. Lymphoscintigraphy identified sentinel node in 78% of the patients (47/60): 43 in axilla, 4 in internal mammary chain. Probe guided axillary detection was achieved in 88% (53/60): in every patient with axillar migration in scan, in 9/13 without imaged drainage and in 1/4 with internal mammary chain migration. Sensitivity of blue dye technique was 75% (45/60), the concordance between both procedures being high. Considering both, the overall success rate of surgical detection was 90% (54/60); if we exclude those patients who showed exclusive extraaxillar drainage, the success rate reaches 95%. Malignancy was found in 24% of sentinel nodes removed (13/54); it being the only metastatic axillary node in 4/13. No false negative sentinel nodes were found. Therefore, negative predictive value and accuracy were 100%. These results allow us to validate the technique in our center.

Utilidad de la detección del ganglio centinela en el tratamiento y la estadificación del carcinoma de cérvix uterino inicial

OBJECTIVE

The aim of this study was to evaluate the usefulness of intraoperative sentinel node (SN) detection in patients with initial cervix cancer.

PATIENTS AND METHODS

Lymphoscintigraphy and intraoperative SN detection was performed in 17 patients with initial cervix cancer who we going to have a radical laparoscopic hysterectomy and pelvic lymphadenectomy. Conization was performed in 4/17. The day before surgery, an injection of 111 MBq 99mtechnetium nanocolloid around the primary tumour and a subsequent lymphoscintigraphy were carried out. Blue dye was injected at the same location intraoperatively. A laparoscopic gamma probe was used to identify SNs.

RESULTS

SNs were successfully localized using a combination of radiocolloid and blue dye in 16/17 patients (detection rate 94 %). The detection rate only using blue dye technique decreases to 71 % (12/17) and it reaches an 82 % (14/17) if we avoid the blue dye injection. In 3 cases, there was no migration in lymphoscintigraphy and in one of the three SN could not be detected. Thirty-three SNs were identified (1.9 nodes/patient). The most frequent location was left external iliac nodal group (13 nodes: 39 %). SNs were identified in regions that are not included in usual lymphadenectomy: right parametrium (2 sentinel nodes, one of them in the retrouterine region), and interiliac (2 SNs). In all four patients with previous conization SNs were identified (detection rate 100 %).

CONCLUSIONS

The rate of SN detection combining lymphoscintigraphy with gamma probe and blue dye is 82 %. The use of blue dye allows increasing this rate to 94 % in those cases which migration was not seen or when the SN is placed near the injection site. The SN technique offers the possibility to find SNs in regions not included in usual lymphadenectomy.