Lymphaticovenous anastomosis of the caudal thoracic duct to the azygous vein: A feline cadaver study.

OBJECTIVE: The aim of this study was to describe a technique for anastomosis of the thoracic duct (TD) to the azygos vein (AV) using a microvascular anastomotic coupler (MAC) device in feline cadavers. Our hypothesis was that a TD-AV lymphaticovenous anastomosis would be feasible in feline cadavers. STUDY DESIGN: Cadaveric study. ANIMALS: Eight domestic shorthair feline cadavers. METHODS: A left paracostal laparotomy and 9th or 10th intercostal thoracotomy was performed. Contrast media was injected into a mesenteric lymph node and lymphography was used to identify the TD and its branches. The TD and AV were isolated, ligated, and divided with the aid of a surgical microscope. The TD and AV were anastomosed end-to-end using a 1.5 or 2.0 mm MAC. Intraoperative patency was assessed by manipulation of chyle and venous blood across the anastomosis. Mesenteric lymphography was repeated to confirm postoperative anastomotic patency. RESULTS: The TD was identified via lymphography in seven of eight cats. The anastomosis was successful and patency was confirmed via intraoperative assessment and postoperative lymphography in all cats. The median (range) duration for the dissection and anastomosis portions of the procedure was 122 (80-150) min. CONCLUSION: End-to-end anastomosis of the TD to the AV using a MAC was feasible in the feline cadaver without major intraoperative technical challenges. CLINICAL SIGNIFICANCE: Anastomosis of the TD and AV may have application as an alternative treatment for idiopathic chylothorax in cats. By directly connecting the abdominal lymphatics to the central venous system, the stimulus for collateral vessel development around the site of TD ligation may be minimized, which may prevent leakage of chyle through the more cranial lymphatics.

Ultrasonographic and CT-scan findings of splenic active chylous effusion and postlymphangiography enhancement in a cat with chylothorax associated with splenic angiosarcoma.

A 12-year-old domestic shorthair cat was presented with relapsing noncardiogenic chylothorax. CT-lymphangiography of the thorax confirmed bilateral pleural effusion without evidence of an underlying intra-thoracic origin. Abdominal CT-lymphangiography revealed a 2.6 cm diameter splenic mass surrounded by chylous effusion actively collecting during ultrasonographic assessment. Following splenectomy, histopathological analysis revealed that the splenic mass exhibited characteristics indicative of splenic angiosarcoma. This case report highlights the utility of advanced thoracic and abdominal imaging, notably CT-lymphangiography, in the diagnostic evaluation of chylothorax in cats. The identification of a splenic mass encased in chylous effusion should prompt a proactive case management strategy.

Advances in the Treatment of Chylothorax.

Idiopathic chylothorax is a challenging clinical condition historically associated with poor resolution rates following surgical intervention. Recent advances in imaging and surgical techniques have revolutionized the treatment of this disease process. Computed tomographic lymphangiography has facilitated improved surgical planning and postoperative assessment, while intraoperative use of near-infrared fluorescence imaging aids in highly accurate intraoperative thoracic duct identification. Utilizing these advancements, minimally invasive surgical techniques have been successfully developed and have been associated with considerable improvements in surgical outcomes.

CT features of cutaneous and subcutaneous canine mast cell tumors and utility of conventional and indirect lymphography to detect clinically unknown mast cell tumors and to map the sentinel lymph nodes.

Computed tomography is frequently used to stage canine mast cell tumors (MCTs). The aims of this prospective, observational study were to describe the CT features of MCTs, to evaluate the performance of CT in detecting additional or incidental MCTs, to distinguish between cutaneous (cMCT) or subcutaneous (scMCT) MCTs, and to identify one or multiple sentinel lymph nodes (SLNs) by indirect CT lymphography (ICTL). Seventy-two dogs affected by 111 MCTs were included. The recorded parameters were: shape, size, attenuation (Hounsfield units [HU]), location (cutaneous or subcutaneous), and presence of fat stranding. The SLNs were compared with the regional lymph nodes and supplementary MCTs were registered. Mast cell tumors mostly appeared with well-defined margins (89%), round/oval shape (71%), homogeneous enhancement (90%) with a mean postcontrast density of 62.0 ± 23.4 HU and associated with fat stranding (43%). Cutaneous mast cell tumors were more frequently round (P = .003), whereas scMCTs were oval (P = .011) with a larger mean maximal diameter (2.91 ± 1.57 cm vs 1.46 ± 1.28 cm, P = .002) and more feeding vessels (77% vs 39% P = .044). Compared with histopathology, CT accuracy in differentiating cMCTs and sMCTs was 57%, with an interobserver agreement of 88% (three reviewers). Indirect CT lymphography showed the SLN in 82 of 85 (97%) cases, 32% of them not corresponding to the regional node. CT showed additional or incidental MCTs in 23 of 72 (32%) dogs. In conclusion, the common CT appearance of canine cMCTs and scMCTs is reported with some statistical differences between the two categories. CT is useful in identifying clinically undetected MCTs and SLNs, although it shows low accuracy in distinguishing between cMCT and scMCT.

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.

Contrast-enhanced and indirect computed tomography lymphangiography accurately identifies the cervical lymphocenter at risk for metastasis in pet dogs with spontaneously occurring oral neoplasia.

For dogs with oral tumors, cervical lymph node (LN) metastasis alters treatment and prognosis. It is therefore prudent to make an accurate determination of the clinical presence (cN+ neck) or absence (cN0 neck) of metastasis prior to treatment. Currently, surgical LN extirpation with histopathology is the gold standard for a diagnosis of metastasis. Yet, recommendations to perform elective neck dissection (END) for staging are rare due to morbidity. Sentinel lymph node (SLN) mapping with indirect computed tomography lymphangiography (ICTL) followed by targeted biopsy (SLNB) is an alternative option to END. In this prospective study, SLN mapping followed by bilateral END of all mandibular LNs (MLNs) and medial retropharyngeal LNs (MRLNs) was performed in 39 dogs with spontaneously occurring oral neoplasia. A SLN was identified by ICTL in 38 (97%) dogs. Lymphatic drainage patterns were variable although most often the SLN was identified as a single ipsilateral MLN. In the 13 dogs (33%) with histopathologically confirmed LN metastasis, ICTL correctly identified the draining lymphocentrum in all (100%). Metastasis was confined to the SLN in 11 dogs (85%); 2 dogs (15%) had metastasis beyond the SLN ipsilaterally. Contrast enhanced CT features had good accuracy in predicting metastasis, with short axis measurements less than 10.5 mm most predictive. ICTL imaging features alone were unable to predict metastasis. Cytologic or histopathologic SLN sampling is recommended prior to treatment to inform clinical decision-making. This is the largest study to show potential clinical utility of minimally invasive ICTL for cervical LN evaluation in canine oral tumors.

Indirect lymphography for sentinel lymph node detection in dogs with mast cell tumors.

Objective: The objective of this report is to describe the technique and diagnostic utility of indirect lymphography (IL) using water-soluble contrast for sentinel lymph node (SLN) mapping in dogs with mast cell tumors. Animals: Fifty-three dogs with 59 mast cell tumors were included. Procedure: Medical records were retrieved for dogs with a cytological diagnosis of mast cell tumor which also had IL performed for lymph node mapping. Dogs were excluded when surgery had been performed before presentation. Images were reviewed by a Board-certified radiologist for uptake of contrast within the sentinel lymph node. Results: Lymphography studies from 34 tumors (57.6%) were diagnostic (clearly identifiable lymphatics and sentinel lymph node). Lymphography studies from 12 tumors (20.3%) were partially diagnostic (identifiable lymphatics, but sentinel lymph node not highlighted). Lymphography studies from 13 tumors (22%) were non-diagnostic. Indirect lymphography studies were interpreted as either diagnostic or partially diagnostic in 77.9% of tumors. Conclusion: The results indicate that IL is a simple, available technique to allow for identification of a sentinel lymph node in dogs with mast cell tumors. Clinical relevance: Indirect lymphography is a simple and widely accessible technique for SLN mapping in dogs with mast cell tumors, particularly for the general practice environment.

Lymphographie indirecte pour la détection des ganglions lymphatiques sentinelles chez les chiens atteints de tumeurs mastocytaires. Objectif: L'objectif de ce rapport est de décrire la technique et l'utilité diagnostique de la lymphographie indirecte (IL) utilisant un contraste soluble dans l'eau pour la cartographie des ganglions lymphatiques sentinelles (SLN) chez les chiens atteints de tumeurs mastocytaires. Animaux: Cinquante-trois chiens avec 59 tumeurs mastocytaires ont été inclus. Procédure: Les dossiers médicaux ont été récupérés pour des chiens avec un diagnostic cytologique de tumeur mastocytaire qui ont également subi une IL pour la cartographie des ganglions lymphatiques. Les chiens ont été exclus lorsque la chirurgie avait été pratiquée avant la présentation. Les images ont été examinées par un radiologue certifié (ACVR) pour la prise de contraste dans le ganglion lymphatique sentinelle. Résultats: Les études de lymphographie de 34 tumeurs (57,6 %) étaient diagnostiques (lymphatiques clairement identifiables et ganglion sentinelle). Les études de lymphographie de 12 tumeurs (20,3 %) étaient partiellement diagnostiques (lymphatiques identifiables, mais ganglion sentinelle non mis en évidence). Les études de lymphographie de 13 tumeurs (22 %) étaient non diagnostiques. Les études de lymphographie indirecte ont été interprétées comme diagnostiques ou partiellement diagnostiques dans 77,9 % des tumeurs. Conclusion: Les résultats indiquent que l'IL est une technique simple et disponible pour permettre l'identification d'un ganglion lymphatique sentinelle chez les chiens atteints de tumeurs mastocytaires. Pertinence clinique: La lymphographie indirecte est une technique simple et largement accessible pour la cartographie du SLN chez les chiens atteints de tumeurs mastocytaires, en particulier dans le milieu de la pratique générale.(Traduit par Dr Serge Messier).

Sentinel lymph node mapping with computed tomography lymphography for mast cell tumours and a comparison between regional and sentinel lymph node histological status: Sixty-two cases.

It is known that the regional lymph node (RLN) may not correspond to the sentinel lymph node (SLN) (the first lymph node draining the tumour), and many diagnostic techniques have recently been aimed at its detection. Although lymphoscintigraphy is the gold standard in both human and veterinary medicine for SLN mapping, it is relatively unavailable in veterinary medicine due to costs and difficult management of the radiotracer. This prospective study evaluated, as a first aim, the feasibility and sensitivity of the computed tomography lymphography (CTL) in detecting the SLN in 62 mast cell tumours (MCTs). The second aim was to evaluate the accuracy of the CTL in identifying the most representative lymph node of the patient's lymphatic status; the histological status of the SNL was compared with that of the RLN, to see in how many cases the patient's stage would have changed according to the RLN. When the RLN turned out to be also the SLN it was decided to excise, as a control LN, the one localised in the neighbourhood of the MCT (neighbouring lymph node; NLN). The detection rate was 90%, with failure of SLN identification in six cases. In 18 (32%) of 56 MCTs with a diagnostic CTL, the SLN did not correspond to the RLN. Forty-five MCTs were surgically removed, together with their corresponding SLN and RLN/NLN. Since the clinical stage of the patient would have changed in only 7% of cases, CTL is a reliable method of detecting the SLN and, for staging purposes, there is no need to remove other LNs.

Computed tomographic lymphangiography following percutaneous intrahepatic injection of iopamidol in cats.

OBJECTIVE: To determine if computed tomographic lymphangiography (CTL) after ultrasound-guided percutaneous injection of intrahepatic iopamidol (Isovue 370) in healthy cats would safely and effectively lead to opacification of the hepatic lymphatics, cisterna chyli, and thoracic ducts (TDs). STUDY DESIGN: A prospective pilot study design with randomization of the sides of the liver injected. SAMPLE POPULATION: 6 purpose-bred cats. PROCEDURES: Cats were anesthetized and based on random assignment, and the left or right liver was injected with iodinated contrast material. CTL images were taken at 5, 10, and 15 minutes postinjection to determine the quality of opacification of the cisterna chyli and TDs. RESULTS: Eleven hepatic injections from 6 cats were available for review. One CT file was corrupted and unusable. Seven out of 11 hepatic contrast injections yielded a diagnostic study. Five out of 11 were graded as excellent, 0/11 were graded as good, and 2/11 were graded as fair. Opacification of the cisterna chyli and TDs was absent in 4/11 studies. Three out of 6 cats had mild to moderate increases in hepatocellular enzymes when assayed 3 months postprocedure. The hepatic lymphatics, cisterna chyli, and TDs were opacified in all studies deemed diagnostic. CLINICAL RELEVANCE: Intrahepatic contrast injection offers a novel portal for thoracic duct lymphangiography that documents the hepatic contribution to the mesenteric lymphatics, cisterna chyli, and thoracic duct. The procedure may be helpful in the preoperative diagnostic evaluation of cats with chylothorax.

Comparison of indirect computed tomographic lymphography and near-infrared fluorescence sentinel lymph node mapping for integumentary canine mast cell tumors.

OBJECTIVE: To compare the independent and combined use of indirect computed tomographic lymphography (ICTL) and near-infrared fluorescence (NIRF) for sentinel lymph node (SLN) mapping in dogs with integumentary mast cell tumors (MCT) and report the metastatic LN rate. STUDY DESIGN: Prospective clinical study. ANIMALS: Twenty client-owned dogs. METHODS: Dogs underwent preoperative ICTL, then intraoperative NIRF SLN mapping and excision of the anatomic lymph node (ALN) and/or SLN, and primary MCT. Technique agreement was complete if the same SLN was detected, and partial if the same SLN was detected along with additional SLN. No agreement occurred if the techniques detected different or no SLN. MCT were graded using two- and three-tier schemes, and LN were graded from HN0-3; HN2-3 were considered metastatic. RESULTS: Complete, partial, and no agreement between ICTL and NIRF was seen in 8/20 (40%), 8/20 (40%), and 4/20 (20%) dogs, respectively. Detection of ICTL-SLN and NIRF-SLN failed in 1/20 (5%) and 4/20 (20%), respectively. Tumors were grade II/low-grade in 19/20 (95%) and grade III/high-grade in 1/20 (5%) dogs. Nineteen out of 20 (95%) dogs had HN2-3 LN. CONCLUSIONS: Technique agreement of at least one SLN was seen in 16/20 (80%) dogs. Although most MCT were classified as intermediate to low grade, LN metastases were commonly detected. CLINICAL SIGNIFICANCE: Combining ICTL and NIRF for MCT SLN mapping yields high SLN detection rates. Lymph node metastasis may be more common than previously reported for intermediate to low grade MCT.

Prospective evaluation of lymphatic embolization as part of the treatment in dogs with presumptive idiopathic chylothorax.

OBJECTIVE: To describe the embolization technique and short-term clinical outcome in dogs undergoing lymphatic embolization (LE) as part of treatment for presumptive idiopathic chylothorax (IC). Additionally, to document findings in computed tomography lymphangiography (CTLa) following embolization. STUDY DESIGN: Prospective case series. ANIMALS: Eight client-owned dogs. METHODS: Dogs underwent CTLa followed by thoracic duct ligation (TDL), pericardiectomy (PC) and LE. A mixture of 3:1 lipiodol: n-butyl cyanoacrylate embolic solution was injected through a catheterized mesenteric lymphatic vessel via limited abdominal approach using intraoperative fluoroscopy. CTLa was scheduled for 12 weeks postoperatively, and long-term follow-up was obtained via telephone contact. RESULTS: LE was technically successful in six of the eight dogs; and clinically successful in five of the six dogs. In the unsuccessful dog, a diagnosis of lymphangiosarcoma was determined, and the owners elected for euthanasia. Five dogs who underwent successful LE underwent CTLa at 12 weeks. Complete resolution of pleural effusion occurred in three dogs and scant pleural effusion in two dogs. A robust lymphatic embolus preventing antegrade continuation of radiocontrast was documented in all five dogs. Five of the six dogs that underwent LE, were alive and clinically normal at 358-960 days postoperatively. CONCLUSIONS: LE is a feasible part of treatment for dogs with IC. Additionally, a robust lymphatic embolus and lack of radiocontrast flow past the embolus was documented at 12 weeks following surgery. CLINICAL SIGNIFICANCE: LE has the potential to reduce surgical failure by reducing efferent lymphatic chyle flow, occluding missed lymphatic branches and preventing the development of collateral branches.

Computed tomography lymphangiography via intrametatarsal pad injection is feasible in cats with chylothorax.

OBJECTIVE: To evaluate the feasibility of CT lymphangiography via intrametatarsal pad injection in cats with chylothorax. ANIMALS: 7 client-owned cats. PROCEDURES: This was a multicenter, retrospective, descriptive study. Medical records and imaging data from 4 veterinary hospitals were reviewed to identify cats with chylothorax that had undergone intrametatarsal pad injection via CT lymphangiography. In total, 7 client-owned cats were included in the study. Signalment, history, image findings, and follow-up data were recorded. Descriptive statistics were used to analyze the success rate of thoracic duct (TD) enhancement and describe relevant clinical findings. RESULTS: Enhancement of TDs was successful in 6 of the 7 cats within 5 to 15 minutes after initiating intrametatarsal pad injection under general anesthesia. Successful migration of contrast medium into the lymphatic vessels cranial to the popliteal lymph nodes was observed in all cats within 5 minutes after injection. The recommended dose of contrast medium to achieve TD enhancement was 1 mL/kg (0.5 mL/kg/pad; concentration, 350 mg of iodine/kg). Only 1 cat had mild swelling of the paws after the procedure, and it recovered quickly without pain medication; no cats experienced lameness. Similar to dogs and unlike in previously published reports, 72% of TD branches were located in the right hemithorax. CLINICAL RELEVANCE: CT lymphangiography via intrametatarsal pad injection is a feasible and safe procedure for cats with chylothorax. This technique provides detailed information regarding the unique TD anatomy and cisterna chyli location. It also contributes to surgical planning.

Effect of contrast agent viscosity and massage on success of computed tomography lymphangiography with aqueous contrast for sentinel lymph node identification in healthy dogs.

Sentinel lymph node (SLN) evaluation is important for accurate cancer staging. Computed tomography (CT) lymphangiography with aqueous contrast is a feasible technique for SLN identification in dogs. Although most studies report success rates around 90%, success rates as low as 60% have been reported. One reason for low success rates may be the difference in viscosity of the various agents used in comparison to normal lymph viscosity. The objective of this study was to evaluate contrast agents of differing viscosities for use in CT lymphangiography for SLN identification and to determine the influence of massage on contrast flow rates. The hypothesis was that lower viscosity agents would have a higher success rate and faster time to identification of the SLN than higher viscosity agents and that massage would increase contrast flow rates. Dogs were anaesthetised and CT lymphangiography was performed with four contrast agents of differing viscosities in a randomized crossover design. Injections were made on the dorsal pes bilaterally on two study days and the popliteal lymph nodes were evaluated for contrast uptake. There was no significant difference in success of SLN identification or time to SLN identification among the four agents. Massage of the injection site increased rate of contrast flow through the lymphatics. No specific recommendation for one contrast agent over another can be made with these results. Massage is recommended to improve lymphatic flow when performing CT lymphangiography with aqueous contrast in dogs.

Canine idiopathic chylothorax: Anatomic characterization of the pre- and postoperative thoracic duct using computed tomography lymphography.

Surgical treatment has improved the prognosis of canine idiopathic chylothorax, although a recurrence of the disease occurs occasionally after the procedure. An improved understanding of possible causes for this recurrence would be helpful for prognosis and treatment planning in affected patients. In this retrospective case series study, we described the detailed pre- and postoperative computed tomographic lymphography (CTLG) imaging characteristics for a group of dogs with surgically confirmed idiopathic chylothorax. Preoperative CTLG was performed in 12 of 14 dogs diagnosed with idiopathic chylothorax. Thoracic ducts were present on the right side in 10 dogs, left side in one dog, and bilaterally in one dog. All the 14 dogs received a combination therapy of pericardiectomy and thoracic duct ligation (TDL) by video-assisted thoracoscopic surgery. One week after surgery, a postoperative CTLG was performed, and the thoracic ducts were apparent in seven of 14 dogs. Three dogs had an unchanged course of the thoracic duct, which could have resulted from a missed duct. Four dogs were identified as having a bypass formation: the oblique duct originated at the ligation site and connected to the duct on the other side. Our findings indicated that one of the possible causes for postoperative recurrence of chylothorax in dogs could be "invisible or sleeping" fine ducts that are collapsed and not visible in preoperative CTLG scans. After TDL causes a change in the pressure of lymphatic flow, these fine thoracic ducts may become apparent using postoperative CTLG.

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.

Lymphatic drainage from the head and neck is variable with significant crossover, therefore sentinel lymph node (SLN) mapping can help ensure the appropriate lymph node(s) are sampled. To improve sensitivity, SLN mapping utilizing multiple modalities and a combination of preoperative computed tomography lymphography (CTL) and intraoperative near infrared fluorescence imaging (NIRF) with indocyanine green (ICG) +/- methylene blue (MB) dye has been suggested. The aim of this study was to describe a method for intraoperative ICG lymphography and determine agreement for SLN detection using preoperative CTL and intraoperative ICG NIRF + MB lymphography (IOL) in dogs with oral tumours. Fourteen client-owned dogs were included. All dogs had preoperative CTL with iodinated contrast and intraoperative IOL with an exoscope. Lymph nodes with CTL contrast-enhancement, blue staining or fluorescence were considered sentinel. The overall SLN identification rate was 100% when CTL and IOL were combined. A total of 57 SLNs were identified. Indocyanine green NIRF identified a greater proportion of SLNs (91%; 52/57) compared with MB (50.8%; 29/57) and CTL (42.1%; 24/57). Eighteen SLNs were identified by all three modalities with a fair level of agreement using Fleiss kappa. These findings suggest a combination of preoperative CTL with intraoperative SLN mapping techniques may greatly improve the ability to accurately detect the SLN in dogs with oral tumours.

Lymphaticovenous anastomosis of the caudal thoracic duct to an intercostal vein: A canine cadaver study.

OBJECTIVE: To describe a technique for anastomosis of the thoracic duct (TD) to the 11th or 12th intercostal vein (ICV) using a microvascular anastomotic coupler (MAC) in the dog. STUDY DESIGN: Cadaveric study. ANIMALS: Eight beagles. METHODS: A right paracostal laparotomy and 10th intercostal thoracotomy were performed in each dog. Mesenteric contrast lymphography was used to identify the TD and its branches on fluoroscopy. The TD and adjacent 11th or 12th ICV were isolated, double ligated, and divided using a surgical microscope. The caudal TD and proximal ICV were anastomosed in an end-to-end fashion using a 1.5 mm or 2 mm MAC. Mesenteric lymphography was repeated to document patency of the anastomosis. RESULTS: The TD was identified via lymphography in all dogs; five dogs had a single duct, and three dogs had additional branches. The anastomosis was successful in all eight dogs, and flow into the azygos vein without leakage was confirmed via lymphography. CONCLUSION: End-to-end anastomosis of the TD to an ICV using a MAC was technically feasible in the canine cadaver. CLINICAL SIGNIFICANCE: Lymphaticovenous anastomosis combined with TD ligation may have application as a treatment for idiopathic chylothorax. By maintaining the flow of chyle from the abdominal lymphatics to the systemic circulation, this procedure may reduce the stimulus for collateral circulation and persistent flow to the cranial mediastinal lymphatics.

Morphology of the cisterna chyli in nine dogs with idiopathic chylothorax and in six healthy dogs assessed by computed tomographic lymphangiography.

OBJECTIVE: To describe the morphology of the lymphatics in the region of the cisterna chyli in healthy dogs and in dogs with idiopathic chylothorax by using computed tomographic lymphangiography. STUDY DESIGN: Retrospective study. ANIMALS: Nine dogs with idiopathic chylothorax and six healthy dogs. METHODS: Computed tomographic lymphangiograms were reviewed to evaluate the number of cisterna chyli branches, total cross-sectional area of the branches normalized to the cross-sectional area of the aorta, number of branches with cross-sectional area greater than 25% of the aorta cross-sectional area, and ratio of the total perimeter to the total cross-sectional area of the branches. Data (mean ± SD) were compared between unaffected dogs and dogs with idiopathic chylothorax. RESULTS: The cisterna chyli included more branches in dogs with chylothorax (4.30 ± 1.57) than in unaffected dogs (1.67 ± 0.56, P = .02), occupying a relative perimeter approximately double that in unaffected dogs (P < .001). The relative cross-sectional area of the cisterna chyli was approximately twofold smaller in affected (0.73 ± 0.35) than in unaffected (1.63 ± 0.91, P = .02) dogs. The fraction of dogs with branches greater than 25% of the cross-sectional area of the aorta tended to be larger in unaffected dogs (P = .07). Most larger branches were located dorsal or to the right of the aorta. CONCLUSION: The cisterna chyli of dogs with idiopathic chylothorax contained smaller and more numerous branches compared with that of unaffected dogs. CLINICAL SIGNIFICANCE: Altered cisterna chyli morphology may impact the surgical approach for cisterna chyli ablation in dogs with idiopathic chylothorax.

Identification of intra-abdominal lymphatics in canine carcasses by laparoscopic fluorescence lymphography with intradermal and intrapopliteal ICG administration.

OBJECTIVE: To evaluate the feasibility of laparoscopic fluorescence lymphography (LFL) using indocyanine green (ICG) via intradermal (ID) or intrapopliteal (IPP) administration in an ex vivo canine model. METHODS: Six thawed adult male dog carcasses were placed in the Trendelenburg position after placing three surgical ports in triangulation. ICG (0.5 mg/ml; 0.05 mg/kg) was administered to five of the carcasses (one carcass was a pilot) via ID in the left torso and IPP (right position, by surgical access) to stain the lymphatic pathway and medial iliac lymph node (MILN). Fluorescence quality, staining time, structures stained, and lymph node histopathology were assessed. Thoracic duct staining was also evaluated. RESULTS: ID administration showed staining of parts of the lymphatic pathway of the iliosacral lymph center in all cases using a single dose of ICG, with left MILN visualization in four carcasses. IPP administration showed staining of the right MILN in all cases, using a single dose in four carcasses. ICG reached the thoracic duct in one case. The two administration routes showed similar results in terms of required ICG volume, staining time, and visualization quality, although IPP was more effective in staining the MILN. CONCLUSIONS: This study confirms the feasibility of staining the iliosacral lymph center (mainly the MILNs) by LFL in thawed dog carcasses via ID or IPP administration of ICG. However, the IPP route showed greater effectiveness in staining the MILN.

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

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.

Computed tomographic lymphangiography via intra-metatarsal pad injection is feasible in dogs with chylothorax.

Lymphangiography can be useful for preoperative planning in chylothorax. Conventional ultrasound-guided intranodal injection can be difficult in some cases and is dependent upon operator skill. Alternative methods have been proposed to simplify the procedure, but their feasibility has not been sufficiently evaluated in clinical cases. The primary purpose of this multicenter, retrospective, descriptive study was to assess the feasibility and describe the clinical findings of CT lymphangiography by intrametatarsal pad injection in dogs with naturally occurring chylothorax. Twenty dogs were analyzed, and enhancement of thoracic ducts (TDs) was successful in 18 (90%) dogs within 5-14 min after initiating the injection, while successful enhancement of the lymphatic vessels cranial to the popliteal lymph nodes was seen in all dogs within 5 min after injection. The dose with good success to achieve TD enhancement was 1 mL/kg (concentration 350 mg I/kg). Only two dogs had mild discomfort after recovery from general anesthesia. Computed tomography lymphangiography by intrametatarsal pad injection is a feasible, easy, and safe procedure, which could provide adequate TD and cisterna chyli enhancement, identify TD number and cisterna chyli location and structure, and contribute to surgical planning.