[68Ga]Ga-tilmanocept PET/CT lymphoscintigraphy: a novel technique for sentinel lymph node imaging

Surgical radioguidance with beta-emitting radionuclides; challenges and possibilities: A position paper by the EANM

Radioguidance that makes use of β-emitting radionuclides is gaining in popularity and could have potential to strengthen the range of existing radioguidance techniques. While there is a strong tendency to develop new PET radiotracers, due to favorable imaging characteristics and the success of theranostics research, there are practical challenges that need to be overcome when considering use of β-emitters for surgical radioguidance. In this position paper, the EANM identifies the possibilities and challenges that relate to the successful implementation of β-emitters in surgical guidance, covering aspects related to instrumentation, radiation protection, and modes of implementation.

Practice points for lymphoedema care in low- and middle- income countries developed by nominal group technique

BACKGROUND

Lymphoedema is a common, distressing, and debilitating condition affecting more than 200 million people globally. There is a small body of evidence to guide lymphoedema care which underpins several lymphoedema clinical practice guidelines developed for high-income countries (HIC). Some of these recommendations are unlikely to be feasible in low-resource settings.

AIM

To develop practice points for healthcare workers that optimise lymphoedema care in low- and middle-income countries (LMIC).

METHODS

A nominal group technique (NGT) was undertaken to gain consensus on which content from HIC guidelines was important and feasible to include in practice points for LMIC, and other important advice or recommendations. Participants included experts, clinicians, and volunteers involved in lymphoedema care in LMIC. The NGT followed five key stages: silent 'ideas' generation, round-robin rationale, clarification, refinement and verification. The first, fourth and fifth stages were completed via email, and the second and third during a video meeting in order to generate a series of consensus based prevention, assessment, diagnosis, and management of lymphoedema in LMIC practice points.

RESULTS

Of sixteen participants invited, ten members completed stage 1 of the NGT (ideas generation), of whom six contributed to stages 2 (round-robin) and 3 (clarification). All those who completed stage 1 also completed stages 4 (refinement) and 5 (verification). Practice points unanimously agreed on included Complex Decongestive Therapy (CDT) and good skin care, with management to be determined by lymphoedema stage. For podoconiosis-endemic areas, the use of socks and shoes was identified as very important in the prevention of non-filarial lymphoedema and other lymphoedema-causing conditions. Participants indicated that diagnosing lymphoedema using the lymphoscintigraphy and Indocyanine green (ICG) fluorescent lymphography was not possible due to unavailability and cost in LMIC. Surgical procedures for lymphoedema management were unanimously eliminated due to the unavailability of technology, limited workforce, and expensive cost in LMIC.

CONCLUSION

The consensus-based practice points generated by this project provide healthcare workers with guidance on caring for people with lymphoedema in LMIC. Further development of workforce capacity is needed.

Feasibility and Safety of Tailored Lymphadenectomy Using Sentinel Node-Navigated Surgery in Patients with High-Risk T1 Esophageal Adenocarcinoma

BACKGROUND

Selective lymphadenectomy using sentinel node-navigated surgery (SNNS) might offer a less invasive alternative to esophagectomy in patients with high-risk T1 esophageal adenocarcinoma (EAC). The aim of this study was to evaluate the feasibility and safety of a new treatment strategy, consisting of radical endoscopic resection of the tumor followed by SNNS.

METHODS

In this multicenter pilot study, ten patients with a radically resected high-risk pT1cN0 EAC underwent SNNS. A hybrid tracer of technetium-99m nanocolloid and indocyanine green was injected endoscopically around the resection scar the day before surgery, followed by preoperative imaging. During surgery, sentinel nodes (SNs) were identified using a thoracolaparoscopic gammaprobe and fluorescence-based detection, and subsequently resected. Endpoints were surgical morbidity and number of detected and resected (tumor-positive) SNs.

RESULTS

Localization and dissection of SNs was feasible in all ten patients (median 3 SNs per patient, range 1-6). The concordance between preoperative imaging and intraoperative detection was high. In one patient (10%), dissection was considered incomplete after two SNs were not identified intraoperatively. Additional peritumoral SNs were resected in four patients (40%) after fluorescence-based detection. In two patients (20%), a (micro)metastasis was found in one of the resected SNs. One patient experienced neuropathic thoracic pain related to surgery, while none of the patients developed functional gastroesophageal disorders.

CONCLUSIONS

SNNS appears to be a feasible and safe instrument to tailor lymphadenectomy in patients with high-risk T1 EAC. Future research with long-term follow-up is warranted to determine whether this esophageal preserving strategy is justified for high-risk T1 EAC.

Sentinel lymph node detection in thyroid carcinoma using 68Ga-tilmanocept PET/CT: a proof-of-concept study protocol

Sentinel lymph node biopsy (SLNB) is a diagnostic staging procedure. The procedure aims to identify the first draining lymph node(s), which are most likely to contain metastases. SLNB is applied in various cancers, but not currently in thyroid carcinoma. However, treatment strategies are changing, making SLNB clinically relevant. SLNB may lead to more accurate staging, prevent unnecessary treatment and help achieve earlier curation. 68Ga-tilmanocept PET/computed tomography (CT) can better localize sentinel lymph nodes (SLNs) near the primary tumor than planar scintigraphy and single-photon emission computed tomography (SPECT)/CT. This paper describes the rationale and design of a study investigating SLNB using 68Ga-tilmanocept PET/CT and indocyanine-green-99mTc-nanocolloid in ten differentiated and medullary thyroid carcinoma patients. Localization and number of SLNs, pathology result, optimal scan protocol, surgical time and surgeon's experience are examined. Clinical Trial Registration: 2021-002470-42 (EudraCT).

Optical Coherence Tomography Angiography and Attenuation Imaging for Label-Free Observation of Functional Changes in the Intestine after Sympathectomy: A Pilot Study

We present in this study optical coherence tomography angiography (OCTA) and OCT attenuation imaging (OCTAI) for in vivo non-destructive visualization of intramural blood and lymphatic vessels of the intestine wall. Rabbit small intestine in the norm and after thoracolumbar sympathectomy served as the object of the intraoperative study. Compared to OCTA real-time imaging, OCTAI takes several minutes and can be termed as “nearly real time”. OCTAI signal processing was modified to take into account the signal-to-noise ratio and the final thickness of the intestine wall. The results showed that, after sympathectomy, changes in functioning of intramural blood and lymphatic vessels were observed with a high statistical significance. The occurrence of trauma-induced constriction of the blood and lymphatic vessels led to an especially pronounced decrease in the length of small-caliber (<30 µm) blood vessels (p < 10−5), as well as in the volumetric density of lymphatic vessels (on average by ~50%) compared to their initial state. Remarkably, OCTA/OCTAI modalities provide the unique ability for “nearly-instant detection” of changes in functional status of the tissues, long before they become visible on histology. The proposed approach can be used in further experiments to clarify the mechanisms of changes in intestinal blood and lymph flows in response to trauma of the nervous system. Furthermore, potentially it can be used intraoperatively in patients requiring express diagnosis of the state of intramural blood and lymph circulation.

Unilateral versus bilateral nodal irradiation: Current evidence in the treatment of squamous cell carcinoma of the head and neck

Cancers of the head and neck region often present with nodal involvement. There is a long-standing convention within the community of head and neck radiation oncology to irradiate both sides of the neck electively in almost all cases to include both macroscopic and microscopic disease extension (so called elective nodal volume). International guidelines for the selection and delineation of the elective lymph nodes were published in the early 2000s and were updated recently. However, diagnostic imaging techniques have improved the accuracy and reliability of nodal staging and as a result, small metastases that used to remain undetected and were thus in the past included in the elective nodal volume, will now be included in high-dose volumes. Furthermore, the elective nodal areas are situated close to the parotid glands, the submandibular glands and the swallowing muscles. Therefore, irradiation of a smaller, more selected volume of the elective nodes could reduce treatment-related toxicity. Several researchers consider the current bilateral elective neck irradiation strategies an overtreatment and show growing interest in a unilateral nodal irradiation in selected patients. The aim of this article is to give an overview of the current evidence about the indications and benefits of unilateral nodal irradiation and the use of SPECT/CT-guided nodal irradiation in squamous cell carcinomas of the head and neck.

Contemporary update of SPECT tracers and novelties in radioguided surgery: a perspective based on urology

Recent technical advances and implementation of novel radiotracers have further increased the potential of radioguided surgery for a broad variety of malignancies. Indeed, the possibilities for future applications of novel radiotracers in diverse oncological strategies has become more promising than ever. This literature review aims to provide a contemporary update on a selected group of radiotracers and evaluates the usability of radioguided surgery and sentinel node procedures, focusing on most promising advances. For example, the impact of targeted radiotracers on prostate specific membrane antigen (PSMA), CD206 receptor-targeted agents (^99mTc-tilmanocept), and hybrid tracers adding fluorescence to radioguidance (ICG-^99mTc-nanocolloid) as well as targeting hypoxia-induced carbonic anhydrase IX (CAIX) will be covered. Furthermore, future outlooks on the implementation of gold nanoparticles (AuNP's), but also technical advances in improved radiotracer detection by hybrid gamma devices will be discussed.