Contrast‐enhanced ultrasound for sentinel lymph node mapping in the routine staging of canine mast cell tumours: A feasibility study

Quentin Fournier,Samantha Woods,Tiziana Liuti,Spela Bavcar,Alexandra Malbon,Paola Cazzini,Florence Thierry,Maurizio Longo,Jocelyn Bisson

doi:10.1111/vco.12647

Quentin Fournier, Samantha Woods + Show 7 more

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https://doi.org/10.1111/vco.12647

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Abstract

Canine mast cell tumours (MCTs) typically spread to lymph nodes (LNs) before reaching distant sites, and LN assessment is an important part of MCT staging. Sentinel LN (SLN) mapping techniques to identify draining LNs are being developed and could improve the accuracy of MCT staging. The primary objective of this feasibility study was to determine the safety and effectiveness of contrast-enhanced ultrasound (CEUS) to identify SLNs. Secondary objectives were to determine if the SLNs identified by CEUS coincided with the regional LN predicted by the anatomical lymphosomes, if previous MCT excision altered CEUS SLN findings, and if CEUS could identify MCT nodal metastases. Between June 2017 and March 2019, 59 dogs with 62 MCTs were enrolled. No adverse events related to CEUS were reported. CEUS detected at least 1 SLN in 59/62 MCTs (95.2%, 95% CI: 86.5-99.0%). In only 32/59 (54.2%) MCTs, clinicians would have correctly predicted the SLN(s) identified by CEUS. Among the 35 MCTs that had histological examination of the SLN(s), the prevalence of metastasis was 60% (95% CI: 42.1-76.1%). Additional staging procedures did not reveal any metastases in dogs with histologically non-metastatic SLNs. Integration of CEUS SLN mapping into the routine staging of MCTs is promising, but future studies are required to refine this procedure and to investigate if it would translate into a clinical benefit.

Highlights

Secondary objectives were to determine if the Sentinel lymph node (SLN) identified by contrast-enhanced ultrasound (CEUS) coincided with the regional lymph node (LN) predicted by the anatomical lymphosomes, if previous excision of the mast cell tumour (MCT) would alter CEUS SLN findings, and if CEUS uptake patterns could identify MCT nodal metastasis
Fifty-nine dogs with 62 MCTs were enrolled in this study (Table 1) and had CEUS SLN mapping integrated into their routine staging procedures (Figure 1)
Two dogs had two concurrent MCTs in different body areas, microbubble destruction naturally occurred between both examinations by switching back to B-mode and waiting 30 minutes before the second CEUS SLN mapping; one dog developed a second MCT in another body area about a year following his first enrolment

Summary

Introduction

Other SLN mapping techniques have been developed in human oncology, including contrast-enhanced ultrasound (CEUS) or lymphosonography, a non-ionizing and non-invasive technique.[24] The potential of this technique was validated in canine models,[25,26,27,28] prior to application in human patients diagnosed with breast cancer and cutaneous melanoma.[29,30,31,32,33,34] The main advantages are the wide availability of CEUS, low cost, safety and rapid clearance of the contrast,[35] no requirement for general anaesthetic, quick contrast diffusion to the LNs in real-time,[27] the ability to view the fine details of the lymphatics and LNs,[36] and minimal spillover of the contrast to secondary nodes.[28,37] The main disadvantages are the need to select which lymphatic basins to scan, and inter-operator variability This technique seems advantageous for dogs with MCTs as abdominal ultrasound (US) and liver/spleen US-guided FNAC are already often performed for their staging.[3,38,39,40]

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