Assessment of Sentinel Lymph Node Metastasis in Canine Mammary Gland Tumors Using Computed Tomographic Indirect Lymphography

Abstract

In the staging process of the breast cancer, demonstrating metastasis of the sentinel lymph node (SLN) has an important prognostic value, in both humans and animals. The aim of this prospective case-control study was to determine the diagnostic value of computed tomographic indirect lymphography (CT-LG) for detecting SLN metastasis in dogs with mammary cancer. Thirty-three female dogs with tumors in the abdominal and inguinal mammary glands were prospectively selected and subjected to CT-LG, 1 and 5 min after injection of 1 ml of contrast agent (iopamidol) in the subareolar tissue of the neoplastic and the contralateral normal mammary glands. The pattern of postcontrast opacification, degree of postcontrast enhancement, and size and shape were assessed in 65 SLNs in total and were correlated with histopathological findings. The absence of opacification or heterogeneous opacification 1 min after contrast medium injection showed the highest sensitivity, specificity, and accuracy (93%, 100%, and 98.4%, respectively). In images taken 1 min after injection, an absolute density value lower than 444 Hounsfield units (HU) in the center of the SLN also provided significant sensitivity and specificity (93.8% and 75%, respectively). The size and shape of the SLN (maximum and minimum diameter, maximum/minimum diameter ratio, maximum diameter/height of fifth thoracic vertebral body ratio) showed the lowest sensitivity and specificity. Results of this study support the hypothesis that CT-LG could help in the assessment of SLN metastasis in cases of mammary gland tumors in dogs.

Computed tomographic‐lymphography as a complementary technique for lymph node staging in dogs with malignant tumors of various sites

“…Furthermore, the procedure is described to be a multidisciplinary approach and accuracy largely depends on the expertise of the specialists performing the procedure . The simpler technique of CT‐lymphography was briefly used in dog mammary tissue as a preliminary pilot study in order to establish CT‐lymphography for breast cancer in women and its prognostic value could recently be shown to detect metastasis in dogs with mammary tumors . Our aim herein was to properly establish and describe the method of CT‐lymphography for different sites in the dog and we were able to show that the technique works well in the explored tumors and sites.…”

“…[15][16][17][18][19][20] Normal dogs were initially used as a model to test the feasibility of mammary CT-lymphography for breast cancer in humans with good success and this technique has recently been shown to have a diagnostic value in the detection of metastasis in dogs with mammary tumors. 21,22 However, little attention has been paid to this nonradioactive, simple, and fast technique for tumor staging of different anatomical sites in dogs.…”

The impact of extirpation of non‐palpable/normal‐sized regional lymph nodes on staging of canine cutaneous mast cell tumours: A multicentric retrospective study

“…Notably, some authors have recently explored the utility of some diagnostic and surgical procedures in an attempt to remove regional or sentinel LNs that were not clinically suspected for metastasis in cMCTs and other canine malignancies in order to obtain an early detection. 15,[17][18][19][20] Due to inconsistency in LN sampling inside the enrolled population, selection of different inclusion criteria for the study population (eg, high-risk cMCT or Patnaik grade II cMCT only) and different sampling methods (cytology vs histology) within and among studies, the exact rate of metastatic nodal involvement in canine cMCT is difficult to state based on the current literature. 3,11,[14][15][16][21][22][23] In a recent paper, the reported rate of nodal metastasis for canine cMCT at first presentation confirmed by means of cytology was 18.1% 23 ; this rate increased to 61% in the study by Baginski et al that included 90 dogs with grade II MCTs, of which 55 had an enlarged RLN.…”

Ventral cervical versus bilateral lateral approach for extirpation of mandibular and medial retropharyngeal lymph nodes in dogs

“…Because of the aberrant lymphatic drainage seen in dogs with metastatic oral tumors, sentinel lymph node mapping aids in identifying which lymph node to biopsy or remove to avoid unnecessary dissection and associated morbidity. Current preoperative sentinel lymph node mapping techniques that have been described include a 4‐quadrant lipiodol injection (2‐4 mL over 105 minutes) followed by radiographs 24 hours postinjection, contrast assisted ultrasound with peritumoral injection of 99m Tc‐sulfur colloid, or preoperative 4‐quadrant iopamidol injection (1 mL in 4 quadrants over 2 minutes) followed by a diagnostic computed tomography 1‐15 minutes after injection . Intraoperative sentinel lymph node mapping techniques include a 4‐quadrant methylene blue injection (0.5‐1 mL) 10‐15 minutes prior to surgical incision.…”

“…Current preoperative sentinel lymph node mapping techniques that have been described include a 4-quadrant lipiodol injection (2-4 mL over 105 minutes) followed by radiographs 24 hours postinjection, 19 contrast assisted ultrasound with peritumoral injection of 99m Tc-sulfur colloid, 6,20 or preoperative 4quadrant iopamidol injection (1 mL in 4 quadrants over 2 minutes) followed by a diagnostic computed tomography 1-15 minutes after injection. 21 Intraoperative sentinel lymph node mapping techniques include a 4-quadrant methylene blue injection (0.5-1 mL) 10-15 minutes prior to surgical incision. Unfortunately, there is a lack of knowledge regarding correlation between the identified sentinel lymph node and the true metastatic lymph node in small animal patients, so more work must be performed in this area.…”