Hand-held Gamma Probe Research Articles

Abstract 2575: GD2 targeted dual-labeled intraoperative molecular imaging probe for neuroblastoma

Abstract Neuroblastoma (NB) is the most common pediatric extracranial solid tumor, with a 5-year survival rate under 50% for those with high-risk disease. Complete surgical resection is essential for these patients and is associated with improved outcomes. However, NB resection presents significant technical challenges due to encasement of vital structures that must be preserved, as well as remote deposits of disease. The current approach to find and safely resect tumor depends on the surgeon’s eyes and hands alone. Fluorescence tracers allow enhanced tumor visualization, but most are not molecularly targeted which leads to poor tumor to background signal. Further, fluorescent signal does not penetrate more than a few millimeters, a limitation that can be overcome by inclusion of a radiotracer. We, therefore, generated and evaluated a dual radio and fluorescent antibody-based probe targeting the GD2 tumor antigen to improve the identification of NB with widely available intraoperative handheld instruments. We generated an intraoperative probe (111In-αGD2-IRDye800CW) with retained affinity and stability. In vivo- Nu/j mice were injected with SK-N-BE(2) NB cells. After tumors grew for five weeks, mice were given tail vein injections of the probe. Gamma and optical biodistribution studies were performed to determine the specificity of binding and tumor to background signal four- and six-days post probe injection. Probe uptake was compared to an isotype. Gross dissections and surgeries aimed at improving completeness of resection were performed using a handheld fluorescent camera (SPY-PHI) and a gamma probe (Neoprobe). The handheld gamma probe detected xenografts with great sensitivity (average in vivo 818 cps of In111 in tumor region versus 34.8 cps in the tail). The fluorescent imaging showed high specific binding to the tumor region. Gamma biodistribution results indicated high accumulation within tumor (13.5 %ID/g) with lower accumulation in blood (3.49 %ID/g) and muscle (0.45 %ID/g). Uptake of the probe greatly exceeded isotype control antibody on days 4 and 6 post-agent injection, for both gamma and optical biodistributions. Initial tumor resection using 111In-DTPA-aGD2-IRDye800CW in an NB bearing mouse identified residual disease left behind when resection was performed using white light alone; the residual disease was then removed, guided by fluorescence imaging. Our dual-labeled probe demonstrated antigen specificity and allowed for the sensitive detection and visualization of NB in vivo with widely available intraoperative tools. This targeted probe could provide a means to improve surgical NB resection, by enabling localization of the all regions of tumor using radio-guidance, followed by clear definition of tumor margins with fluorescent signal, to maximize preservation of vital tissues. Ultimately, we believe this approach can improve safety, extent of NB resection, and patient outcomes. Citation Format: ReidAnn E. Sever, Lauren Taylor Rosenblum, Kayla C. Stanley, Dominic M. Menendez, W Barry Edwards, Marcus M. Malek, Gary Kohanbash. GD2 targeted dual-labeled intraoperative molecular imaging probe for neuroblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2575.

Accuracy of sentinel node mapping in Marjolin ulcer: Comparison of three different injection techniques

BackgroundMarjolin ulcer is a specific type of squamous cell cancer that can benefit from the use of lymphoscintigraphy.The purpose of this study was to evaluate 3 different injection techniques for sentinel node biopsy in patients with Marjolin ulcer. MethodsForty-eight patients with Marjolin ulcer (27 male and 21 female) ranging in age from 24 to 85 years were included in our study. Intratumoral (IT), peritumoral (PT) and periscar (PS) tissue injections of radiotracer were done in 9, 10, and 29 patients respectively. Injections were done 2–4 h before surgery. Lymphoscintigraphy was done for mapping the lymphatic drainage. During surgery, lymphatic mapping and sentinel node biopsy was performed using a handheld gamma probe. After harvesting sentinel nodes, regional lymph node dissection was done. ResultSentinel node detection rate was higher in the PS group as compared to the IT and PT groups (89.6% vs. 50% and 22.2%) respectively. False negative rate was 0%. Pathologically involved sentinel nodes were detected in 16% of the included patients of our study which led to management change. None of the patients with pathologically non-involved sentinel nodes developed regional lymph node recurrence. ConclusionLymphatic mapping and sentinel node biopsy is feasible in Marjolin ulcer with high detection rate and low false negative cases which by detection of regional lymph node involvement can potentially change the management of patients. Injection site may be an important factor influencing the success of the procedure and injection of the mapping material in the peri-scar normal skin proximal to the lesion is the best technique.

Reliability and outcomes of lymph nodes biopsy in cT1-cT2 N0 supraglottic laryngeal squamous cell carcinoma.

In oral and oropharyngeal squamous cell carcinoma (SCC), sentinel node biopsy (SNB) was described as a reliable and reproductive alternative to elective neck dissection for the staging of clinical N0 T1-T2 patients. The SNB technique in supraglottic laryngeal SCC was successfully described in small series. The aim of this study is to analyze retrospectively the results of SNB technique in supraglottic SCC in CHU Godinne, to determine if the technique is reliable and may be proposed in a future multicentral prospective trial. The study involved a retrospective analysis of 39 patients who underwent surgery between 2003 and 2019 at CHU Godinne. All patients presented with clinical N0 neck status. The SNB procedure included general anesthesia, 99-technetium colloid peritumoral injection, and lymphoscintigraphy. The hand-held gamma probe was utilized for SNB after tumoral resection during the same operating session. Out of 39 patients, 36 underwent SNB as the sole staging tool, while 3 patients received SNB in combination with elective neck dissection. Primary outcome was the 2-years neck recurrence-free survival (RFS). Secondary outcomes were the 2- and 5-years disease-specific survival (DSS). Additionally, sensitivity and negative predictive value (NPV) of the SNB technique were analyzed. Sentinel nodes were successfully identified in all 39 patients. An average of 4 nodes excised per patient. Positives SN were detected in 23% (9 in 39) cases, leading to subsequent selective neck dissection. Two cases of neck recurrence were observed, both considered as false negatives, occurring after an average of 3.5 months. Th median follow-up period was 48 months with a 2-year RFS of 95%. Sensitivity and NPV of the SNB technique were found to be 82% and 94%, respectively. Two and five years DSS were 84% and 71.7%, respectively. The results suggest that SNB in T1-T2 supraglottic SCC is a feasible and reliable technique for managing the neck in N0 early-stage patients. However, to establish its oncological equivalence with selective node dissection, further prospective and comparative studies are warranted. The findings of this study underscore the importance of ongoing research in refining and validating the role of SNB in the management of supraglottic SCC, potentially paving the way for more widespread adoption in clinical practice.

The Sentinel Node and Occult Lesion Localization (SNOLL) Technique Using a Single Radiopharmaceutical in Non-palpable Breast Lesions.

In order to perform a full surgical resection on non-palpable breast lesions, a current method necessitates correct intraoperative localization. Additionally, because it is an important prognostic factor for these patients, the examination of the lymph node status is crucial. The aim of this study was to evaluate the efficiency of the sentinel node and occult lesion localization (SNOLL) technique in localizing nonpalpable breast lesions together with sentinel lymph node (SLN) using a single radiotracer, that is, nanocolloid particles of human serum albumin (NC) labeled with technetium-99m (99mTc). 39 patients were included, each having a single non-palpable breast lesion and clinically no evidence of axillary disease. Patients received 99mTc- NC intratumorally on the same day as surgery under the guidance of ultrasound. Planar and single-photon emission computed tomography/computed tomography lymphoscintigraphy were performed to localize the breast lesion and the SLN. The occult breast lesion and SLN were both localized using a hand-held gamma-probe, which was also utilized to determine the optimal access pathway for surgery. In order to ensure a radical treatment in a single surgical session and reduce the amount of normal tissue that would need to be removed, the surgical field was checked with the gamma probe after the specimen was removed to confirm the lack of residual sources of considerable radioactivity. Breast lesions were successfully localized and removed in all patients. Pathological findings revealed breast carcinoma in 11/39 patients (28%) and benign lesions in 28 (72%). Axillary SLNs were detected in 31/39 (79.5%) patients. The metastatic involvement of SLN was only seen in two cases. While the identification rate of the SNOLL technique performed with an intratumoral injection of 99mTc-NC as the sole radiotracer in non-palpable breast lesions was great, it was not fully satisfactory in SLNs.

SENTINEL LYMPH NODE BIOPSY IN THE MANAGEMENT OF PATIENTS WITH MALIGNANT MELANOMA

Objectives: To evaluate the efficacy of sentinel lymph node biopsy in the treatment of malignant melanoma. Materials and Methods: Thirty-two melanoma patients without distant or clinical lymph node metastasis underwent preoperative lymphoscintigraphy using Tc99m and a handheld gamma probe to identify sentinel lymph nodes for biopsy. In cases with detected sentinel lymph node metastasis, the patient may require total complete lymph node dissection, combined with optional systemic therapy. Follow-up was performed to evaluate the efficacy of this procedure. Results: In 32 melanoma patients, the most common site of primary tumors was the extremity, accounting for 90.6%, with a mean Breslow index (thickness of the primary tumor) of 1.84 mm. The incidence of microscopic lymph node metastasis was 34.4%. For cases with no detected sentinel lymph node metastasis, 100% of patients had a stable condition, and no recurrence or metastasis was detected. In 11 cases with occult nodal metastasis: 2 deaths, 4 patients were treated with chemotherapy, and 5 cases without chemotherapy. The mean duration of hospitalization for the group with sentinel lymph node metastasis was greater than that of the group without sentinel lymph node metastasis, 25.1 ± 3.1 days and 13.5 ± 1.3 days, respectively. Conclusion: Our results suggest that sentinel lymph node biopsy is a less invasive technique for melanoma patients with no clinically detectable lymph node and distant metastases. This procedure has shown initial outcomes, but it is necessary to conduct a study with a larger sample size and a longer follow-up time, as well as comparing it with a control group for accurate evaluation. Received 23 June 2023Revised 22 September 2023Accepted 27 November 2023

Radio-Guided Occult Lesion Localization With 99m Tc for the Localization of Nonpalpable Melanoma and Soft Tissue Sarcoma Lesions: A Feasibility Study.

Localization techniques are needed to facilitate resection of nonpalpable lesions. In this study, the feasibility of radio-guided occult lesion localization (ROLL) with 99m Tc is investigated for the localization of nonpalpable, small, suspicious, or proven melanoma or soft tissue sarcoma lesions at various locations throughout the body. Patients with nonpalpable, suspicious, or proven melanoma or soft tissue sarcoma lesions were selected for this study. Within 24 hours before surgery, a median dose of 33.92 MBq 99m Tc-labeled human albumin particles ( 99m Tc-NA or 99m Tc-MAA) was injected in the lesion under ultrasound guidance. A hand-held gamma probe was used to detect the radioactive signal and guidance during surgery. In this study, 20 patients with a total of 25 lesions were included and analyzed. The median size of the lesions was 1.8 cm (interquartile range [IQR], 1.8-4.0 cm), of which 44% were intramuscular located and 36% were subcutaneous, and 20% consisted of suspicious lymph nodes, mostly in the lower extremity. At median 4 hours (IQR, 3-6 hours) postinjection, 99m Tc ROLL showed a 100% intraoperative identification rate with proper signal identification with the gamma probe in all patients. With a median surgery time of 76 minutes (IQR, 45-157 minutes), all targeted lesions could be resected without 99m Tc-related complications, resulting in 88% microscopically margin-negative resection. No reoperations were needed for the same lesion. The 99m Tc ROLL procedure is feasible for the localization and excision of small, nonpalpable melanoma and soft tissue sarcoma lesions at various locations in the body.

Sentinel lymph node mapping: current applications and future perspectives in thyroid carcinoma.

Sentinel lymph node (SLN) mapping is a standard, minimally-invasive diagnostic method in the surgical treatment of many solid tumors, as for example melanoma and breast cancer, for detecting the presence of regional nodal metastases. A negative SLN accurately indicates the absence of metastases in the other regional lymph nodes (LN), thus avoiding unnecessary lymph nodal dissection. Papillary thyroid carcinoma (PTC) is the most common type of thyroid carcinoma (TC) with cervical LN metastases at diagnosis in 20-90%, and nodal involvement correlates with local persistence/recurrence. The SLN in PTC is an intraoperative method for staging preoperative N0 patients and for detecting metastatic LNs "in and outside" the cervical LN central compartment; it represents an alternative method to prophylactic central neck node dissection. In this review we summarize different methods and results of the use of SLN in TC. The SLN identification techniques currently used include the selective vital-dye (VD) method, 99mTc-nanocolloid planar lymphoscintigraphy with intraoperative use of a hand-held gamma probe (LS), the combination LS + VD, and the combination LS and preoperative SPECT-CT (LS + SPECT/CT). The application of the SLN procedure in TC has been described in many studies, however, the techniques are heterogeneous, and the role of SLN in TC, with indications, results, advantages and limits, is still debated.

Radioguided Occult Lesion Localization Technique for Biopsy of Nonpalpable Subcutaneous Lesions in Suspected Metastatic Melanoma.

In patients with a history of melanoma, the risk of recurrence depends on the stage at diagnosis. Patients who present with more advanced disease are more likely to experience recurrence; patients with less advanced disease at presentation have slower progression and lower likelihood of recurrence. The aim of this study was to evaluate the use of a minimally invasive and targeted technique as a diagnostic and therapeutic tool for the excision of nonpalpable lesions suspected to be melanoma metastases. The authors evaluated 21 patients with stage IIB, IIC, or III melanoma and subcutaneous nonpalpable lesions with a high risk of malignancy on positron emission tomography/computed tomography scan during oncologic follow-up. To guide biopsy, the authors used the radioguided occult lesion localization technique, using intralesional injection of technetium-99m albumin macroaggregates the day before surgery. During surgery, a handheld gamma probe was used to locate the lesions. Surgical localization of radiolabeled lesions was achieved in all cases. Relapsed melanoma was histologically confirmed in 13 patients. This technique proved to be a simple, safe, and effective method to detect and biopsy nonpalpable or difficult-to-locate lesions in suspected metastatic melanoma. The main advantage was disease restaging (eg, from stage II to III), allowing patients to access adjuvant therapies not approved as early-stage melanoma treatment. Therapeutic, IV.

Real-time Fluorescent ICG and 99m-Tc Nanocolloid Tracer Navigation in Bilateral Sentinel Lymph Node Mapping of Vulvar Cancer

The effectiveness of sentinel lymph node (SLN) biopsy has been validated by two prospective trials, GROINS VI and GOG 1731-2. According to ESGO guideline in patients with unifocal tumors with a diameter of <4 cm, in the absence of suspected inguinal lymph nodes, SLN biopsy is recommended. The use of a radioactive tracer is mandatory.2 Using Indocyanine green (ICG) increase the detection of the vulvar sentinel node from 89.7 to 100%3. Aim of this video is to share our experience about the feasibility, safety and usefulness of the surgical identification of SLN in vulvar cancer using real-time fluorescent indocyanine green with 99m-technetium nanocolloid. Stepwise demonstration of the technique with narrated video footage. Tertiary level hospital "IRCCS Istituto Nazionale dei Tumori", Milano, Italy. A 50-year-old woman was diagnosed with vulvar cancer on biopsy of 1.5 cm size vulvar lesion under the clitoris area and referred to our Operative Unit. F-18 fluorodeoxyglucose positron-emission tomography-computed tomography (PET) showed no extra-vulvar disease. The patient was scheduled for radical vulvectomy and bilateral inguinal sentinel lymph-node biopsy (SLN). In this video the surgical procedure involved double location of SLN, first with the 99m-technetium detector followed by ICG identification. We used an ICG dilution of 2.5 mg/mL in sterile water and injected 4 mL around the tumor 5-10 min before visualization. First a handheld gamma probe used to identify the location of the SLN(s) with 99m-technetium. The fluorescence imaging was performed by the quest imaging system (FLUOPTICS©, Middenmeer, The Netherlands) that combine autofluorescence and fluorescence perfusion imaging. Second, we carried out the SLN biopsy using a dark mood procedure to identify the IGC tracer. The fluorescence imaging enables the detection of these markers through some millimeters of tissue and ICG has the advantage that is visible through the skin4. This video shows a successful combined 99m-technetium and ICG fluorescence image-guided bilateral SLN biopsy in a vulvar cancer patient using a near-infrared (NIR) optical imaging system (FLUOPTICS©). ICG for SLN mapping appears to be safe in women with vulvar cancer with a satisfactory detection rate. This may help in retaining surgical radicality while minimizing operative complications.

Role of Sentinel Lymph Node Drainage Mapping for Localization of Contralateral Lymph Node Metastasis in Locally Advanced Oral Squamous Cell Carcinoma - A Prospective Pilot Study.

Sentinel lymph node biopsy (SLNB) has become the standard of care for nodal staging in early-stage oral squamous cell carcinoma (OSCC) as an alternative to elective neck dissection. However, the role of sentinel lymph node (SLN) and lymphatic drainage mapping with image-guided surgery has not been studied in locally advanced OSCC. Therefore, this study was undertaken to evaluate the role of lymphatic drainage mapping in the identification of contralateral cervical lymph node metastasis in locally advanced OSCC (Stage III-IVb). We have prospectively analyzed treatment-naïve patients of locally advanced, lateralized OSCC (n = 20). All patients underwent SLN imaging using peritumoral injection 0.5-1.0 mCi of 99 mTc-Sulfur colloid (Filtered) and intraoperative identification of contralateral neck nodes using a handheld gamma probe (Crystal Photonics). A total of 20 patients (18 males and 2 females) with a median age of 52.5 (33-70 years) were included. Ipsilateral SLN was localized in 18 (90%) patients. Bilateral cervical nodes were visualized only in 7 (35%) patients on lymphoscintigraphy (LSG). Out of the seven patients, 5 patients underwent bilateral neck dissection and 2 patients had unilateral neck dissection with LSG-guided exploration of contralateral cervical node and intraoperative frozen section examination. Six out of these seven patients had one or other risk factor for contralateral metastasis (patients had either primary in the tongue, involvement of floor of mouth, or tumor thickness >3.75 mm). On postoperative HPE, only 1/20 (5%) patient showed metastasis in the contralateral cervical lymph node. Correct identification of metastatic disease in contralateral neck directly influences clinical management, as it can reduce contralateral neck failure rate and limit the morbidity associated with unnecessary contralateral neck dissection, and it is also crucial in radiotherapy planning in locally advanced OSCC. In the current study, lymphatic drainage mapping showed a metastatic rate of 5% in the contralateral neck nodes in locally advanced, lateralized OSCC. However, the role of SLNB and lymphatic drainage mapping in this subgroup of OSCC needs to be studied in larger population to validate these findings.

Abstract B042: Sentinel lymph node detection in breast cancer: Comparison of blue dye and filtered Technetium 99m sulphur colloid radiotracer injection

Abstract Aim: This prospective study was performed to compare the identification rate, sensitivity and specificity of blue dye and filtered Technetium 99m labelled sulphur colloid (Tc99m SC), individually and in combination for the detection of sentinel lymph nodes in clinically node negative early-stage breast cancer. Materials and methods: Thirty-two women with biopsy-proven breast cancer (cT1N0M0-T2N0M0) were included in this prospective study over a period of 18 months (2019-2020). Four peri-areolar intradermal injections of filtered Tc99m SC were administered 2-3 hours before surgery. Sequential dynamic anterior images of the chest were acquired on a gamma camera, followed by anterior and anterior oblique static images and hybrid single photon emission computed tomography / computed tomography (SPECT/CT) of the affected breast and ipsilateral axilla. Pre-operatively, the sites of detected sentinel lymph nodes (SLNs) were marked on the skin surface using a hand-held gamma probe. SLNs were then identified intra-operatively after peri-tumoral methylene blue injection (blue nodes) and with the gamma probe (hot nodes). These SLNs were removed and sent for frozen section histopathology separately, labelled as hot only, blue only and hot and blue. All patients underwent axillary lymph node dissection (ALND). The final histopathology of all lymph nodes excised during ALND and SLN biopsy were analysed. Identification rate, sensitivity and specificity of both the methods for SLN detection individually and in combination were compared. Results: SLN data of 32 female patients aged 54.7±10.6 years with cT1N0M0-T2N0M0 was analysed. In 87.5% of patients (n=28) the same lymph node was identified by blue dye and filtered Tc99m SC and discordance was seen in 12.5% (n=3) patients. No SLN was detected by any method in one patient. Identification rate of filtered Tc99m SC alone, blue dye alone and combination techniques was 96.9% (n=31), 93.8% (n=30) and 96.9% (n=31) respectively. Of total 593 dissected lymph nodes including 78 SLNs (average 2.4±1.7 per patient), metastasis was found in 198 lymph nodes (12/32 patients). The sensitivity and specificity of the procedure considering only filtered Tc99m SC, blue dye alone and combination of the two tracers was found to be 83.3% (95% CI of 51.6-97.9) and 100% (95% CI of 82.4-100), 75% (95% CI of 42.8- 94.5) and 100% (95% CI of 81.5 -100) and 83.3% (95% CI of 51.6-97.9) and 100% (95% CI of 82.4-100) respectively. Conclusion: SLNB with filtered Tc99m SC using the intra operative gamma probe has better identification rate and sensitivity than blue dye in detecting SLN, while preoperative SPECT/CT helped the surgeon to locate the SLN during surgery. Blue dye has a complementary role in identifying the SLN due to ease of visualisation while operating. Citation Format: Anish Bhattacharya, Yamini Mathur, Ishita Laroiya, Amanjeet Bal, Sarika Sharma, Bhagwant R. Mittal. Sentinel lymph node detection in breast cancer: Comparison of blue dye and filtered Technetium 99m sulphur colloid radiotracer injection [abstract]. In: Proceedings of the AACR Special Conference: Cancer Metastasis; 2022 Nov 14-17; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_2):Abstract nr B042.

Tilmanocept as a novel tracer for lymphatic mapping and sentinel lymph node biopsy in melanoma and oral cancer.

Sentinel lymph node biopsy (SLNB) has been pivotal for pathological assessment of nodal status in cutaneous melanoma (CM) and oral cavity squamous cell carcinoma (OCSCC) thus crucial for staging. An ideal agent for lymphatic mapping should have a standardized preparation, appropriate accumulation in first-echelon nodes and no side effects. Tilmanocept, a CD206-receptor targeted novel radiotracer fulfils these properties. This study investigated Tilmanocept for lymphoscintigraphy and intraoperative identification of sentinel lymph nodes (SLN) in CM and OCSCC. This prospective cross sectional study examined patients who presented to Crown Princess Mary Cancer Centre, Westmead Hospital, Sydney. Patients had biopsy proven tumours with clinically and radiologically negative regional lymph nodes. Tilmanocept guided lymphoscintigraphy was followed by intraoperative SLNs identification via handheld gamma probe. Primary endpoints were detection and retrieval rate of SLNs while secondary endpoints included pathological status of SLNs. Thirty-five patients were included (26 with CM and 9 with OCSCC) with the most common primary tumour site for CM on the extremities (33.3%). Lymphoscintigraphy with Tilmanocept identified at least 1 SLN (sensitivity 100%) in all patients. SLNs were retrieved in all of patients intraoperatively (100% retrieval rate) with positive nodes found in 20% of patients. Tilmanocept also demonstrated 100% tissue specificity, with lymph nodal tissue confirmed histologically, with no false positives. Tilmanocept is a reliable radiotracer for assessing the nodal status in patients with CM and OCSCC. Our group is the first to evaluate the use of Tilmanocept in the Australian setting, adding to the limited studies worldwide.

Phantom study of SPECT/CT augmented reality for intraoperative localization of sentinel lymph nodes in head and neck melanoma

ObjectiveTo show that augmented reality (AR) visualization of single-photon emission computed tomography (SPECT)/computed tomography (CT) data in 3D can be used to accurately localize targets in the head and neck region. Materials and methodsEight head and neck styrofoam phantoms were painted with a mixture of radioactive solution (Tc-99m) detectable with a handheld gamma probe and fluorescent ink visible only under ultraviolet (UV) light to create 10–20 simulated lymph nodes on their surface. After obtaining SPECT/CT images of these phantoms, virtual renderings of the nodes were generated from the SPECT/CT data and displayed using a commercially available AR headset. For each of three physician evaluators, the time required to localize lymph node targets was recorded (1) using the gamma probe alone and (2) using the gamma probe while wearing the AR headset. In addition, the surface localization accuracy when using the AR headset was evaluated by measuring the misalignment between the locations visually marked by the evaluators and the ground truth locations identified using UV stimulation of the ink at the site of the nodes. ResultsFor all three evaluators, using the AR headset significantly reduced the time to detect targets (P = 0.012, respectively) compared to using the gamma probe alone. The average misalignment between the location marked by the evaluators and the ground truth location was 8.6 mm. ConclusionAR visualization of SPECT/CT data in 3D allows for accurate localization of targets in the head and neck region, and may reduce the localization time of targets.

Sentinel lymph node mapping in post chemotherapy nonseminoma testicular cancer patients undergoing retroperitoneal lymph node dissection: A series of nine cases.

Objective(s):Testicular germ cell cancers are the most common solid malignancy among young men at the age ranging between 14 and 35 years. In this study, we evaluated the feasibility of sentinel lymph node mapping using intraoperative injection of radiotracer in nonseminomatous testicular cancer patients with history of orchiectomy who were candidate for retroperitoneal lymph node dissection (RPLND) in post-chemotherapy setting.Methods:Nine consecutive cases were included in the study. Technetium-99m-labelled phytate was injected in two divided doses in the stump of the spermatic cord, through transabdominal approach. A hand-held gamma probe was used for radio-guided retroperitoneal sentinel lymph node detection intraoperatively and confirming the location of the sentinel lymph nodes.Results: Detection rate and the false negative rate were estimated as the main indices. The detection rate was 6/9 (66%) and the false negative rate was 0/2 (0%). Location of the dissected sentinel lymph nodes were interaortocaval (2 patients), internal iliac (1 patient), external iliac (1 patient), common iliac (2 patients), and paraaortic (1 patient).Conclusion:Sentinel lymph node mapping technique seems to be feasible and promising in post chemotherapy non-seminoma testis cancer patients who are candidate for RPLND; however, further larger studies are needed to increase and standardize the detection rate.

Feasibility of Radio-Guided Surgery for Neuroendocrine Tumours Using 99mTc-HYNIC TOC

Introduction and aim: Intra-operative localization of small functioning pancreatic neuroendocrine tumours and liver metastases can be challenging. We here demonstrate the feasibility, technical protocol, utility and safety aspect of intra-operative tumour localization in using 99mTc-HYNIC-TOC. Materials and methods: 6 patients diagnosed with GEP-NET with or without liver secondaries were included in this study (5 males, 1 female). 3 patients had primary NET of the pancreas of which 2 patients had in additional liver metastases, 1 patient had distal ileal NET with loco-regional nodes and liver metastases, 1 patient had primary nodal gastrinoma with no evidence of any pre-operative lesions in duodenum/pancreas, 1 patient had bilobar liver secondaries from metastatic rectal NET. All patients were injected with 925-1110 MBq of 99mTc-HYNIC-TOC IV and surgery was done after 18-20 hours later on day 2. Intra-operative tumour localization was done using a hand-held high sensitivity gamma probe. Results: Total 23 lesions were localised intra-operatively and confirmed on histopathological as NET. Of these, were 10 in the liver, 3 in pancreas, 9 in nodes and 1 in the distal ileum. Of these 23 lesions, 19 were localized pre-operatively on imaging and by non-aided visualization by surgeon and 4 lesions (17%) were exclusively seen on intra-op localization using probe. These included 2 nodes and 2 liver lesions, all of which measured less than 1cm. Conclusion: Radio-guided surgery gastro-entero-pancreatic neuroendocrine tumours using indigenous 99mTc-HYNIC-TOC is safe and feasible in clinical setting and promises to improve precision of intra-operative localization of lesions in liver and pancreas.

A photoacoustic finder fully integrated with a solid-state dye laser and transparent ultrasound transducer

The standard-of-care for evaluating lymph node status in breast cancers and melanoma metastasis is sentinel lymph node (SLN) assessment performed with a handheld gamma probe and radioisotopes. However, this method inevitably exposes patients and physicians to radiation, and the special facilities required limit its accessibility. Here, we demonstrate a non-ionizing, cost-effective, handheld photoacoustic finder (PAF) fully integrated with a solid-state dye laser and transparent ultrasound transducer (TUT). The solid-state dye laser handpiece is coaxially aligned with the spherically focused TUT. The integrated finder readily detected photoacoustic signals from a tube filled with methylene blue (MB) beneath a 22 mm thick layer of chicken tissue. In live animals, we also photoacoustically detected both SLNs injected with MB and subcutaneously injected melanomas. We believe that our radiation-free and inexpensive PAF can play a vital role in SLN assessment.

Sentinel lymph node biopsy in upper tract urothelial cancers: an experience with intraoperative radiotracer injection.

The feasibility of the sentinel node mapping in upper tract urothelial cancers (UTUC) was evaluated, using a radiotracer as the mapping material. To identify the sentinel lymph nodes, 37 MBq of [99mTc] phytate was injected in five patients with the renal pelvis or ureter cancer, who were candidates for ureterectomy and lymphadenectomy. The radiotracer was injected in a peritumoral fashion following the surgical exposure of the tumour. The sentinel lymph nodes were detected using a handheld gamma probe. By intraoperatively injecting the radiotracer immediately after surgical exposure of the tumour, at least one sentinel lymph node could be detected in each patient, and the detection rate was 100%. The location of sentinel nodes was in the paracaval, renal hill, retro-aortic, para-aortic, common iliac, and external iliac areas, which was dependent on the tumour location. No false-negative case was identified. Sentinel node mapping is feasible in UTUC. Injection technique (intra-vesical approach vs peri-tumoral injection after exposure of the tumour) and location of the tumour (proximal vs distal) may affect the technique's feasibility.

156P The effectiveness of intraoperative administration of both radioactive isotope and blue dye without pre-surgery gamma imaging in comparison with the conventional technique for sentinel node biopsy

Our departmental audit revealed some problems associated with the conventional technique of SLNB such as scheduling issues for OT, co-ordination issues and time lost in the process. Our analysis showed us that the sentinel node was always in axilla, appeared soon after injection, the injection was painful, and the location of the node did not influence the incision. We sat with our nuclear medicine colleagues and evolved a strategy to overcome these problems: Do away with the imaging under gamma camera; shift injection venue to the operating room, thus avoiding a lot of co-ordination and scheduling issues; avoid pain by injecting isotope after induction of general anaesthesia and; train persons to inject the radioactive material. This study is looking at 200 patients of SLN biopsy done by the conventional technique compared to the next 200 patients done with the dual technique. Intraoperative dual SLN mapping consisted of subareolar injection of technetium 99m- labelled filtered sulphur colloid (15-37 MBq) and 2 ml of 1% iso sulfan blue dye just after anaesthetic induction. The conventional technique consisted of subareolar injection of radioactive colloid in Nuclear medicine followed by SPECT imaging and subareolar injection of blue dye intraoperatively. In both cases the SLN was detected using gamma probe and blue colour. SLN’s identified during these procedures were classified as “blue-hot” nodes, “hot-only” nodes, or “blue-only” nodes. Table: 156PConventional techniqueDual techniqueP valueTotal patients202238Sentinel node detected196 (97%)232 (97.47%)0.773Hot and blue159 (81.12%)204 (87.9%)0.054Hot only36 (18.36%)25 (10.7%)0.027 (significant)Blue only1 (0.51%)3 (1.29%)0.399SLN +VE, Other nodes -VE32240.070Only non SLN +VE620.096SLN +VE, NON SLN +12150.875 Open table in a new tab SLN detection rate of dual technique was equivalent to conventional technique. Thereby, even in the absence of Nuclear medicine facility within the hospital, the SLNB can still be performed by procuring the radioactive colloid from a source at a distant site in the same town or city and using the hand-held gamma probe without affecting sensitivity or detection rates.

Is the retropharyngeal lymph node the first echelon node for carcinoma tonsil? Prospective evaluation and literature review.

Tonsil cancer being predominantly treated by non-surgical means, there is a paucity of data on lymph nodal drainage pathways and histo-pathologically confirmed metastatic rates. This study assesses the retropharyngeal lymph node (RPLN) in N0 squamous cell carcinoma tonsil as a possible first echelon node and a site for occult metastasis. Prospective study involving treatment naïve N0 carcinoma tonsil treated by primary surgery and adjuvant treatment from June 2017 to March 2019. In-vivo lymph nodal drainage patterns were assessed by sentinel node mapping by preoperative SPECT-CT and intra-operative hand-held Gamma probe. All patients had a subsequent Level I-III/IV sampling neck dissection supplemented with RPLN dissection. Histological evaluation of sentinel nodes and RPLN involved step-serial sectioning and pan-cytokeratin immunohistochemistry. A comprehensive literature review was performed with keywords "retropharyngeal lymph node", "oropharynx", "tonsil", "squamous cell carcinoma" to determine the incidence of RPLN positivity in previously published series. Sentinel node was successfully identified by SPECT-CT in all 17 patients (ipsilateral level 2a-13/17, 2b-1/17, 3-1/17; bilateral 2a-1/17; isolated contralateral retropharyngeal node-1/17). 8/17 had occult neck metastasis. In no patient was an ipsilateral RPLN identified as the sentinel node. Histological sampling did not indicate metastatic tumor in the RPLN in any patient (0/17). A systematic literature review further confirmed that RPLN metastasis in oropharyngeal cancer is noted only in the presence of pN + disease at other neck levels, and isolated RPLN metastasis is extremely rare (1.2%). The ipsilateral RPLN is not identified either as the first echelon node or as a site of occult metastatic disease in N0 tonsil cancer. CTRI/2019/06/019551.

Identification of Sentinel Lymph Node in Breast Cancer with three Tracers (Radiocolloid, Methylene blue, and Indocyanine Green). (Case Report)

BACKGROUND: Sentinel lymph node (SNL) biopsy in breast cancer for the determination of axillary status is standard procedures in surgical treatment of early-stage breast cancer. The identification of the SNL is usually performed by radiocolloid injection or/and injection of methylene blue due. The use of indocyanine green (ICG) dye, which is fluorescent dye, which movement in breast and axillar pit, can be followed with special cameras which detect near infrared specatar of light.&#x0D; CASE REPORT: In this paper, we present case report of patient with breast cancer, where we perform SNL detection with three methods: Use of radiocolloid which we trace with static gamma camera, and intraoperatively with hand held gamma probe, methylene blue dye which movement we followed by eye contact and using indocyanine green which movement was followed by specially constructed multispectral camera, which can detect near-infrared fluorescence that is emitted by ICG and methyline blue, respectively.&#x0D; CONCLUSION: Fluorescent imaging with ICG is a sensitive, valuable, and safe method for SNL biopsy. Finding new agents that would identify the SNL, especially if they are not radioactive would be an important step in wider application of this method.