ASSESSMENT OF SENTINEL LYMPH NODE METASTASIS IN CANINE MAMMARY GLAND TUMORS USING COMPUTED TOMOGRAPHIC INDIRECT LYMPHOGRAPHY

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.     

The Lymph Drainage Pattern of the Mammary Glands in the Cat: A Lymphographic and Computerized Tomography Lymphographic Study

Seventy-three clinically normal, lactating cats were used to investigate the lymph drainage of 73 mammary glands. In 50 cats of the first group, the number of lymphatic vessels emerging from the examined mammary gland, their course and the lymph nodes into which they are drained were studied by indirect lymphography (IL) after intramammary injection of an oily contrast medium. In 23 cats of the second group, the lymph drainage of the mammary glands was studied by computerized tomography indirect lymphography (CT-IL) after intramammary injection of a water soluble contrast medium. The following day, the lymph drainage of the mammary gland examined by CT-IL was studied by IL, as it was described in the first group, for comparison purposes. The main conclusions drawn after this study were as follows: lymph drains from the first and second mammary glands with one or rarely two or three lymphatic vessels to the accessory axillary lymph nodes. Lymph drains from the third mammary gland with one or two and rarely three lymphatic vessels usually to the accessory inguinal lymph nodes or to the accessory axillary lymph nodes. In some cases, it drains to both lymph nodes simultaneously or it may rarely drain only to the medial iliac lymph nodes. The fourth mammary gland with one or two and rarely three lymphatic vessels usually drains to the accessory inguinal lymph nodes. It may rarely drain only to the medial iliac lymph nodes. Mammary lymphatic vessels that cross the midline and lymphatic connection between the mammary glands were not demonstrated. No differences in the mammary lymph drainage pattern between IL and CT-IL were found.     

99mTc-labeled dextran for mammary lymphoscintigraphy in dogs

Lymphoscintigraphy is the technique of choice for sentinel lymph node detection in women with early breast cancer, but there is limited information evaluating the value of this technique in animals. We investigated mammary lymphatic drainage in 25 young female mongrel dogs by intramammary injection of 18.5 MBq of 99mTc-dextran (70,000 Da). Lymph node anatomical referencing was obtained using an external marker, bone scintigraphy, or scintiscanning the body contour. Cranial and caudal thoracic mammary glands drained into the cranial sternal lymph node and axillary lymph center. The cranial thoracic mammary gland also drained into the superficial cervical lymph node in two of five animals. The cranial abdominal gland was drained by the axillary lymph center. The caudal abdominal mammary gland was drained by the superficial inguinal lymph node in all animals and simultaneously by medial iliac lymph nodes in four of five animals. In one dog, this mammary gland was also drained by the mediastinal and the superficial cervical lymph nodes. The inguinal mammary gland was drained by superficial inguinal lymph nodes and simultaneously via the medial iliac lymph node in one animal. Lymphatic communications between lymph nodes were identified in 11 of 25 (44%) animals. 99mTc-dextran mammary lymphoscintigraphy was easy and rapid to perform and may provide valuable information for further studies.     

The lymph drainage of the neoplastic mammary glands in the bitch: a lymphographic study

The purpose of this investigation was to study the lymph drainage of the neoplastic mammary glands in the bitch using indirect lymphography. The main conclusions drawn from the study of 41 natural cases were as follows: the first or cranial thoracic and second or caudal thoracic neoplastic mammary glands usually drain into the ipsilateral axillary lymph nodes and rarely into the ipsilateral axillary and sternal lymph nodes, simultaneously. The third or cranial abdominal neoplastic mammary gland usually drains into the ipsilateral axillary and superficial inguinal lymph nodes simultaneously, but sometimes only cranially into the ipsilateral axillary lymph nodes. Rarely, it drains only caudally into the ipsilateral superficial inguinal and medial iliac lymph nodes, simultaneously. The fourth or caudal abdominal neoplastic mammary gland usually drains only caudally into the ipsilateral superficial inguinal lymph nodes. Rarely, it drains into the ipsilateral axillary and superficial inguinal lymph nodes simultaneously. The fifth or inguinal neoplastic mammary gland usually drains into the ipsilateral superficial inguinal lymph nodes but rarely, does it also drain into the ipsilateral popliteal lymph node and into a lymphatic plexus at the medial aspect of the ipsilateral thigh. Lymphatic connections between the neoplastic and adjacent normal mammary glands were demonstrated in only one case. The lymph drainage pattern of the neoplastic mammary glands is slightly different to that described in normal glands using the same radiographic method.     

Computed Tomographic Lymphography of the Thoracic Duct by Mesenteric Lymph Node Injection

Objective— To document a novel technique to image the thoracic duct and its tributaries by contrast enhanced computed tomography (CT) lymphography.
Study Design— Clinical report.
Animals— Dogs (n=6) idiopathic chylothorax.
Methods— Ultrasonography was used to guide percutaneous injection of intestinal lymph nodes with nonionic iodinated contrast medium for preoperative CT lymphography of the thoracic duct in 6 dogs with chylothorax. Thoracic CT images were acquired immediately after contrast medium injection. All dogs had subtotal pericardectomy and thoracic duct ligation. Postoperative thoracic duct lymphography was performed in 3 dogs. Superficial cervical lymph node lymphography was performed in 2 dogs to determine cervical lymphatic contribution to thoracic effusions.
Results— Preoperative thoracic duct lymphography using this technique was successful in delineating the cisterna chyli, thoracic duct, and associated lymphatic vessels in all dogs. Immediate postoperative lymphography performed in 2 dogs revealed successful duct ligation in 1 dog and persistent lymphatic leakage in the other. A 1-month postoperative thoracic duct lymphogram performed in 1 dog revealed unsuccessful ligation or recannulation of 1 of 3 redundant vessels seen preoperatively.
Conclusion— Percutaneous CT lymphography results in excellent detection of the thoracic duct and abnormal thoracic duct drainage patterns both pre- and postoperatively. The contribution of superficial cervical lymph node drainage to reoccurrence of effusions can be evaluated.
Clinical Relevance— Percutaneous CT lymphography using ultrasound-guided contrast medium injection should be considered as an alternative to conventional open abdominal approaches to radiographic or CT lymphography.     

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

Locoregional lymph nodes are routinely examined in order to define the spatial extent of neoplastic disease. As draining patterns of certain tumor types can be divergent from expected anatomical distribution, it is critical to sample the lymph nodes truly representing the draining area. The aim of this bicenter prospective pilot study was to describe the technique of computed tomographic (CT)‐lymphography for primary draining lymph node mapping in tumor staging in dogs. Forty‐five dogs with macro‐ or microscopic tumors in specified localizations were evaluated. Depending on body weight, 0.8–2 ml contrast agent (iohexol) was injected into four quadrants around the tumor, and CT‐images were obtained at 1, 3, 6, 9, and 12 minutes post‐injection. Attenuation of chosen regions of interest (Hounsfield units (HU)) and patterns of enhancement were assessed for 284 lymph nodes in the precontrast study with median HUs of 31.1 (Interquartile range (IQR) = 18.4) and for 275 in the intravenous postcontrast study with 104.3 HU (IQR = 31.2) (paired Wilcoxon test, P < 0.001). In the CT‐lymphography study, 45 primary draining lymph nodes with a significantly higher median HU value of 348.5 (IQR = 591.4) (one‐sample t‐test, P < 0.001) were identified. Primary draining lymph nodes were found to be clearly visible after 1–3 minutes after local injection, often concurrent with a good visibility of the lymphatic vessel system. The herein described technique of peritumorally injected CT‐contrast agent followed by subsequent CT‐lymphography for primary draining lymph node mapping works well in a majority of cases in all investigated sites and warrants further validation for different tumor entities.     

FEASIBILITY OF CONTRAST‐ENHANCED ULTRASOUND‐GUIDED BIOPSY OF SENTINEL LYMPH NODES IN DOGS

Our goal was to develop and validate a technique to identify the sentinel lymph nodes of the mammary glands of healthy dogs with contrast‐enhanced ultrasound, and evaluate the feasibility of obtaining representative samples of a sentinel lymph node under ultrasound guidance using a new biopsy device. Three healthy intact female adult hounds were anesthetized and each received an injection of octafluoropropane‐filled lipid microspheres and a separate subcutaneous injection of methylene blue dye around a mammary gland. Ultrasound was then used to follow the contrast agent through the lymphatic channel to the sentinel lymph node. Lymph node biopsy was performed under ultrasound guidance, followed by an excisional biopsy of the lymph nodes and a regional mastectomy procedure. Excised tissues were submitted for histopathologic examination and evaluated as to whether they were representative of the node. The ultrasound contrast agent was easily visualized with ultrasound leading up to the sentinel lymph nodes. Eight normal lymph nodes (two inguinal, one axillary in two dogs; two inguinal in one dog) were identified and biopsied. Lymphoid tissue was obtained from all biopsy specimens. Samples from four of eight lymph nodes contained both cortical and medullary lymphoid tissue. Contrast‐enhanced ultrasound can be successfully used to image and guide minimally invasive biopsy of the normal sentinel lymph nodes draining the mammary glands in healthy dogs. Further work is needed to evaluate whether this technique may be applicable in patients with breast cancer or other conditions warranting evaluation of sentinel lymph nodes in animals.     

Sentinel lymph node mapping in canine mast cell tumours using a preoperative radiographic indirect lymphography: Technique description and results in 138 cases

Several sentinel lymph node (SLN) mapping techniques, to detect nodal metastasis in canine tumours have been investigated in the last 10 years in veterinary oncology. The purpose of this prospective study was to describe a reliable, quick, and inexpensive technique for SLN mapping in canine patients affected by cutaneous and subcutaneous mast cell tumours (MCT). Eighty dogs were enrolled in this study for a total of 138 cytologically diagnosed MCTs. Sentinel lymph node mapping was performed by injecting iomeprole peritumorally followed by serial radiographs at 1, 3, 6 and 9-min post injection. A total of 168 SLNs were detected, 90% at first radiograph, 1 min after the peritumoral iomeprole injection, while in the rest of the cases SLN was identified at 3 min. Sentinel lymph nodes detected by the preoperative radiographic indirect lymphography with iomeprole (PRILI) differed from regional lymph nodes in 57% of cases. The PRILI technique detected simultaneously multiple SLNs in the 26% of cases and multiple lymph centers in the 31% of MCTs. To allow the surgical identification of the SLNs, a peritumoral injection of methylene blue was performed at the time of surgery. This study reports a widely available technique for SLN mapping using digital radiographs in combination with a water-soluble medium, representing a cost-effective alternative to other SLN mapping procedures. Based on our results, this technique can be effective for SLNs mapping in dogs with MCTs but further comparative studies are needed to assess its reliability and efficacy in different tumours.     

The topography of the lymph vessels of mammary glands in female cats

Malignant tumours of the mammary gland in the female cat metastasize, especially through the lymphatic system. However, the anatomical knowledge of this system in cats is not sufficient to develop a reasoned model for the extirpation of these glands in the case of malignant tumours. A study of the topography of the collector vessels in 50 female cats was conducted by indirect injection in vivo of India ink inside the mammary parenchyma. All the lymph nodes were controlled by microscopic examination and lymph vessels were examined after clearing. The success rate of the colouration of the lymph vessels was 76.4%. Clearing showed several principal routes of drainage, different for each gland. Contrary to the presentation observed in the bitch, no evidence existed in any of the 65 cases of lymphatic plexuses connecting the two mammary glands of each row in the female cat. The result of this study is in favour of the development of a new model for the surgical extirpation of mammary tumours in cats.     

The Lymph Drainage of the Mammary Glands in the Bitch: a Lymphographic Study. Part II: the 3rd Mammary Gland

The objective of this investigation was to study the lymph drainage of the 3rd mammary gland in the bitch using indirect lymphography. The main conclusions drawn after the study of 62 normal lactating mongrel bitches were as follows: lymph usually drains from the third gland to the axillary and superficial inguinal nodes simultaneously, but in some cases it drains only cranially to the axillary nodes. It may, rarely, drain only caudally to the superficial inguinal nodes. A lymphatic connection between the mammary glands could not be demonstrated. It was demonstrated that there is a connection between the superficial inguinal lymph nodes on either side. It is suggested that lymphatic connection between the axillary and sternal nodes and the axillary nodes of both sides should be possible in some cases. Lymphatics of the mammary glands that cross the midline were not demonstrated. No relationship between the number of lymph nodes and the body size of the dog could be demonstrated.     

The Lymph Drainage of the Mammary Glands in the Bitch: a Lymphographic Study. Part I: The 1st, 2nd, 4th and 5th Mammary Glands

The objective of this paper was to study the lymph drainage of the 1st, 2nd, 4th and 5th mammary glands in the bitch using indirect lymphography. The main conclusions drawn after the study of 67 normal lactating mongrel bitches were as follows: lymph drains from the first gland, usually to the axillary nodes, and, in few cases, to the axillary and superficial cervical nodes simultaneously. The second gland drains to the axillary nodes. The fourth gland usually drains to the superficial inguinal nodes, but it may, rarely, drain to the superficial inguinal and medial iliac nodes simultaneously. The fifth gland drains to the superficial inguinal nodes. Lymphatic connection between the mammary glands could not be demonstrated. Furthermore, it was confirmed that lymph can pass from one gland to another, through their common regional lymph nodes, by retrograde flow. It was demonstrated that there is a connection between the superficial inguinal lymph nodes from either side. It is suggested that lymphatic connection between the axillary and sternal nodes and between the axillary and bronchial nodes should be possible in some cases. Lymphatics of the mammary glands that cross the midline were not demonstrated.     

泌乳周期中外源物质对大鼠乳腺内肥大细胞数量的影响及乳腺组织内组胺含量的研究

选择泌乳期和静止期大鼠，经乳腺局部（乳导管）或外周（跖部皮下）注射辣根过氧化物酶（HRP）后，应用改良甲苯胺蓝染色法（MTB）对乳腺及其引流（鼠蹊部）和非引流（腘）淋巴结内的肥大细胞数量变化进行了研究，用荧光测定改良法检测了乳腺组织中组胺含量。结果显示，对照组乳腺及引流和非引流淋巴结内的肥大细胞数量均为静止期显著多于泌乳期（P〈0．01），乳腺中组胺含量也呈相同的变化趋势。在泌乳期从不同部位引人HRP后，乳腺及乳腺引流淋巴结内肥大细胞数量明显增多，与对照组相比差异极显著（P〈0．01）；而乳腺非引流淋巴结内肥大细胞数量则略有减少，与对照组相比差异不显著（P〉0．05）。在静止期从不同部位引人HRP后，乳腺及乳腺非引流淋巴结内肥大细胞数均减少，而乳腺引流淋巴结内的肥大细胞数则随引人部位不同而有差别：乳腺引人时增加，而外周引入时减少。本研究结果表明肥大细胞数量随生理周期的改变而增减的趋势与乳腺的发育、乳腺局部免疫状态及内分泌调节都有关系，而且不同泌乳阶段乳腺内肥大细胞对异物的易感性也存在差异。     

Indirect computed tomography lymphangiography with aqueous contrast for evaluation of sentinel lymph nodes in dogs with tumors of the head

Sentinel lymph node evaluation is widely used in human medicine to evaluate the first lymph node(s) to which a tumor drains. Sentinel lymph node biopsy allows avoidance of extensive lymphadenectomies in cases where the sentinel lymph node is negative for metastasis, thereby reducing patient morbidity. It has been shown that regional lymph nodes are not always the sentinel lymph node, thus identification and sampling of sentinel lymph nodes allows for more accurate staging, which is critical for treatment and prognostication in dogs with cancer. The objective of this prospective, pilot study was to determine if indirect computed tomography (CT) lymphangiography with aqueous contrast agent would successfully allow identification of sentinel lymph nodes in dogs with masses on the head. Eighteen dogs underwent CT lymphangiography. The sentinel lymph node was successfully identified within 3 min of contrast injection in 16 dogs (89%). Compression of lymphatic vessels from endotracheal tube ties and/or the patient's own body weight delayed or prevented identification of sentinel lymph nodes in two dogs (11%). Computed tomography lymphangiography with aqueous contrast can be used successfully to rapidly identify sentinel lymph nodes in dogs with masses on the head.     

CT thoracic duct lymphography in cats by popliteal lymph node iohexol injection

Three different doses (1.0, 1.5, and 2.0 ml) of iohexol (300 mgl/ml) were injected percutaneously into the popliteal lymph node of eight adult cats under ultrasound guidance. Serial transverse CT images of five regions of interest (L3, T13, T8, T4, and T1 level) were performed at 2-min intervals, and the attenuation in Hounsfield Units (HU) of the lymphatic vessels was measured for determination of the optimal dose of iohexol and CT scan parameters. The optimal dose was 1.5 ml and helical CT acquisition is recommended to be performed as soon as possible after iohexol injection. In helical scans, the thoracic duct was characterized by variable branch numbers that formed a single trunk and entered the venous system at variable levels. CT lymphography using this protocol was performed in a cat with chylothorax. The thoracic duct was tortuous and focally dilated, and leakage of contrast medium was observed. Percutaneous CT lymphography using ultrasound-guided administration of iohexol into the popliteal lymph node appears reliable for delineation of the thoracic duct in cats.     

Frequency of an accessory popliteal efferent lymphatic pathway in dogs

Staging and therapeutic planning for dogs with malignant disease in the popliteal lymph node are based on the expected patterns of lymphatic drainage from the lymph node. The medial iliac lymph nodes are known to receive efferent lymph from the popliteal lymph node; however, an accessory popliteal efferent pathway with direct connection to the sacral lymph nodes has also been less frequently reported. The primary objective of this prospective, anatomic study was to describe the frequency of various patterns of lymphatic drainage of the popliteal lymph node. With informed client consent, 50 adult dogs with no known disease of the lymphatic system underwent computed tomographic lymphography after ultrasound‐guided, percutaneous injection of 350 mg/ml iohexol into a popliteal lymph node. In all 50 dogs, the popliteal lymph node drained directly to the ipsilateral medial iliac lymph node through multiple lymphatic vessels that coursed along the medial thigh. In 26% (13/50) of dogs, efferent vessels also drained from the popliteal lymph node directly to the internal iliac and/or sacral lymph nodes, coursing laterally through the gluteal region and passing over the dorsal aspect of the pelvis. Lymphatic connections between the right and left medial iliac and right and left internal iliac lymph nodes were found. Based on our findings, the internal iliac and sacral lymph nodes should be considered when staging or planning therapy for dogs with malignant disease in the popliteal lymph node.     

COMPARATIVE POPLITEAL AND MESENTERIC COMPUTED TOMOGRAPHY LYMPHANGIOGRAPHY OF THE CANINE THORACIC DUCT

Thoracic duct computed tomography (CT) lymphangiograms were performed on seven clinically normal dogs. The appearance of the thoracic duct system was compared following administration of contrast medium through a mesenteric lymphatic vessel vs. ultrasound guided percutaneous injection into a popliteal lymph node using helical and sequential CT acquisition modes. The number of visible thoracic duct branches and the largest thoracic duct branch cross‐sectional area and mean Hounsfield units (HU) were determined from thoracic vertebra 9 to lumbar vertebra 1. Procedural time and patient discomfort were also assessed. Popliteal administration produced a successful thoracic duct lymphangiogram in eight of 11 dogs (73%) after two attempts, while mesenteric administration was successful in eight of 10 dogs (80%) after a single attempt. Popliteal lymphography required 46% of the time and was associated with less patient discomfort than mesenteric lymphangiography. The number of thoracic duct branches seen was not significantly different for either administration technique (P=0.256) or CT acquisition mode (P=0.417). However, the cross‐sectional area and mean HU of the largest thoracic duct branch were greater with mesenteric administration (P<0.001), and helical image acquisition (P<0.001). The thoracic duct branch number, size, and location were highly variable between dogs. Percutaneous popliteal lymphography appears to be an acceptable alternative to mesenteric lymphangiography for the detection of thoracic duct branches in the dog when using either helical or sequential CT acquisition modes.     

ULTRASOUND‐GUIDED MESENTERIC LYMPH NODE IOHEXOL INJECTION FOR THORACIC DUCT COMPUTED TOMOGRAPHIC LYMPHOGRAPHY IN CATS

Computed tomographic (CT) lymphography was performed in cats using percutaneous ultrasound‐guided injection of contrast medium into a mesenteric lymph node. The thoracic duct and its branches were clearly delineated in CT images of seven cats studied. The thoracic duct was characterized by anatomic variation and appeared as single or multiple branches. The thoracic duct and the cisterna chyli were identified along the ventral or left ventral aspect of the vertebrae from the level of the cranial lumbar to the caudal cervical vertebrae. The thoracic duct was identified in the central caudal mediastinum, deviated to the left in the cranial mediastinum, and finally moved toward the venous system. Small volumes of extranodal contrast medium leakage were identified in all cats. After injection, the mesenteric lymph nodes were cytologically normal. Ultrasound‐guided CT lymphography via percutaneous mesenteric lymph node injection appears safe and effective in cats.     

Lymphatic Drainage on Healthy and Neoplasic Mammary Glands in Female Dogs: Can it Really be Altered?

The purpose of this research was to study the mammary lymphatic drainage under a macroscopic and mesoscopic view, comparing the vascular pattern of healthy and neoplasic mammary glands injected with drawing ink alcoholic and fluorescein solutions, in 46 mongrel female dogs. The results pointed out that the thoracic gland is drained by the axillary lymph centre, but in mammary neoplasia either superficial cervical or ventral thoracic lymph centres can be involved. Cranial and caudal abdominal glands may be drained by the axillary, inguinofemoral and popliteal lymph centres. However, the popliteal drainage is specific for the healthy caudal abdominal mammary gland. The inguinal gland can be drained by both inguinofemoral and popliteal lymph centres in both neoplasic and healthy conditions. Regarding the mammary lymphatic communications, this research demonstrated that neoplasic glands present more types of anastomosis (40.9%), than healthy glands (33.33%), and an increase in contralateral anastomosis (50%) compared with healthy ones (33%). Given the data, the mammary neoplasia can change the lymphatic drainage pattern in terms of lymph centres and vascular arborization, thus forming new drainage channels and recruiting a larger number of lymph nodes. Lastly, some comments were made about the severity of a specific neoplasic mammary gland and conditions to be considered before making a decision in terms of the most adequate operative procedure, and suggestions for further investigations.     

Use of indirect lymphography to identify sentinel lymph node in dogs: a pilot study in 30 tumours

This study reports the clinical value of sentinel lymph node (SLN) mapping with indirect lymphography (IL) using iodized oil (IO) as a marker injected preoperatively around the site of the primary tumour and radiography or tomodensitometry for imaging. Surgical extirpation of the node was performed following peritumoural injection of methylene blue (MB). Twenty nine dogs affected by 30 palpable solid tumours were prospectively studied. SLNs were identified by IL in 96.6% of the IL studies. IL followed by MB studies were performed in 25 dogs (26 studies). In these studies, agreement between IL and MB was observed in 84.6%. One dog had a minor complication following IO injection. This protocol represents an attractive alternative to scintigraphy for SLN mapping. This less technically demanding protocol may provide a wider access to SLN identification for application in veterinary oncology.