Sentinel lymph node detection differs when comparing lymphoscintigraphy to lymphography using water soluble iodinated contrast medium and digital radiography in dogs

Abstract

Sentinel lymph node (SLN) mapping by various means has become standard of care in certain types of human cancers and is receiving more attention in veterinary oncology. Current SLN mapping techniques can be costly and often require advanced imaging equipment. The objective of this prospective, method comparison study was to compare an SLN mapping protocol of lymphoscintigraphy to lymphography using water soluble iodinated contrast medium (WIC) and digital radiography for identification of an SLN. Lymphoscintigraphy and lymphography were performed on eight healthy purpose-bred dogs using technetium-99m sulfur colloid and WIC injected into the subcutaneous tissues in a four-quadrant technique around a predefined area of skin on the brachium. Images were obtained using a gamma camera and digital radiography at different time points post-injection. Image sequences were evaluated by one of two American College of Veterinary Radiology board-certified veterinary radiologists. Data obtained were compared between methods using descriptive statistics. An SLN was identified in all dogs with lymphoscintigraphy and seven of eight dogs with lymphography. Agreement between results of the lymphoscintigraphy and lymphography studies was a complete match in three dogs, a partial match in four dogs, and no match in one dog. The SLN detected differed based on the imaging modality used.

Near‐infrared fluorescent image‐guided lymph node dissection compared with locoregional lymphadenectomies in dogs with mast cell tumours

“…We, therefore, consider it a very promising approach, but a validation in subsequent prospective controlled studies will be needed. Assessment of true-positive and false-negative SLNs would additionally require a complete lymph basin resection and a comparison of the metastatic status of all lymph nodes for validation (Hlusko et al 2020a). This was not uniformly done in all cases of this series and will also have to be addressed in subsequent studies.…”

The Role of Sentinel Node Mapping and Lymphadenectomies in Veterinary Surgical Oncology

“…In a similar study comparing CT lymphography, methylene blue, and lymphoscintigraphy, a comparably low success rate of 55% was described for CT lymphography [59]. Lastly, Rossi et al published a large study on 45 dogs with several solid malignancies and were able to detect at least 1 SLN after a maximum of 3 min in 60% of dogs [37]. Recently, four veterinary studies proved the successful implementation of CT lymphography in clinical canine patients with mammary tumors [42], anal gland sac cancer [40], tumors of the head [39], and tumors at various sites [41].…”

“…contrast-enhanced ultrasound (CEUS) [32], single-photon emission computed tomography (SPECT) [33], positron emission tomography (PET) [34], pre-and intraoperative lymphoscintigraphy, and the injection of blue dyes for direct visualization or fluorescent dyes for near-infrared (NIR) fluorescent imaging [35]. Corresponding evaluations of indirect radiographic [36][37][38] and CT lymphography [39][40][41][42], lymphoscintigraphy [15,20,24,[43][44][45][46][47], CEUS [25,48], methylene blue staining [20,24,47], and NIR-lymphography [14,47,[49][50][51] are also available for dogs and, most recently, also for cats [26,52].…”

“…However, relatively low detection rates, compared with other SLN mapping techniques, have been reported, in addition to discrepancies in suspected SLNs. Hlusko et al compared indirect lymphography to the current gold standard, lymphoscintigraphy, in eight healthy dogs, and found discrepancies in five of the eight dogs [37]. This presents a major limitation and should be considered before applying these techniques.…”

Determining agreement between preoperative computed tomography lymphography and indocyanine green near infrared fluorescence intraoperative imaging for sentinel lymph node mapping in dogs with oral tumours

“…SLN mapping is standard of care in human medicine for breast cancer, melanoma, and head and neck cancers 14‐16 . Various SLN mapping techniques have been described in human and veterinary medicine including blue dyes, 17‐20 lymphoscintigraphy, 11,18,20‐22 indirect radiographic lymphography, 23,24 indirect computed tomographic lymphography (CTL), 4,5,25‐30 and near infrared fluorescence imaging (NIRF) 31‐34 . A combined pre and intraoperative approach to SLN mapping has been suggested to optimize the accuracy for SLN detection 5,29 .…”