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.

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.

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.

Use of indirect computed tomography lymphangiography to determine metastatic status of sentinel lymph nodes in dogs with a pre-operative diagnosis of melanoma or mast cell tumour.

Canine melanomas and mast cell tumours (MCTs) frequently metastasize to lymph nodes, worsening prognosis compared with dogs without metastasis. Sentinel lymph node (SLN) evaluation is more specific than evaluation of the lymph node closest to the tumour, which may not be the draining lymph node. Computed tomography lymphangiography (CTL) allows for SLN identification and one study of canine mammary tumours found that CTL was able to assist in determination of the metastatic status of inguinal SLNs prior to extirpation and histopathology. The objective of the present study was to evaluate CTL for use in determining metastasis to the SLN in dogs with a pre-operative diagnosis of melanoma or MCT in various locations by correlating CTL findings with histopathology. The hypothesis was that CTL would not be able to determine the metastatic status of lymph nodes, based on author experience. Dogs were prospectively enrolled and underwent CTL and subsequent SLN extirpation. Histopathology results for the primary tumour, SLN, and additional extirpated lymph nodes were recorded. Fifteen dogs were enrolled and 21 SLN were evaluated. The SLN enhancement pattern (heterogeneous, homogenous or peripheral) was not associated with metastasis, nor was the attenuation value at 1 minute, 5 minutes, or the change in attenuation value. No correlation was found between CTL findings and metastatic status of SLNs. Based on these results, CTL alone cannot be used to diagnose SLN metastasis. Extirpation of the SLN with histopathology is recommended to diagnose lymph node metastasis in dogs with melanoma and MCT.

Anatomic and volumetric characterization of the cisterna chyli using CT lymphangiography and computer-assisted design software in dogs with idiopathic chylothorax.

The objectives of this retrospective, observational study were to characterize the anatomical features of the cisterna chyli (CC) in a cohort of dogs diagnosed with idiopathic chylothorax that underwent CT lymphangiography (CTLa), and to evaluate the feasibility of computer-assisted design (CAD) software to quantify volumetric measurements of the CC. Twenty-three client-owned dogs with idiopathic chylothorax were included. Additionally, CTLa was performed in three canine cadavers to assess the ability of CAD software to accurately acquire volumetric measurements. Injection sites, attenuation values, anatomic location, dimensions, and aortic diameter to CC ratio (Ao:CC) were recorded. Video records of video-assisted thoracic surgery (VATS) thoracic duct ligation (TDL) were reviewed in eight out of 23 dogs to compare operative and CTLa findings. The CC was dorsal and right-sided in 18 out of 23 dogs, located between L1 and L4 in 21 dogs, and extended as far cranially as T11 in two dogs. The median measurements for length, height, and width were 150.0, 5.5, and 13.3 mm, respectively. Median total volume was 1.82 mL. Median volumes to the right and left of the aorta were 1.46 and 0.49 mL, respectively (P = .014). Median total CC volume to body weight ratio (CC:bw) was 0.07 mL/kg. The presence of an intrathoracic CC was observed intraoperatively in six out of eight cases that underwent VATS TDL. Findings supported the use of CTLa and CAD as feasible methods for characterizing the CC in dogs diagnosed with chylothorax. These methods may facilitate interventional planning involving the CC such as embolization.

The development of an indirect computed tomography lymphography protocol for sentinel lymph node detection in head and neck cancer and comparison to other sentinel lymph node mapping techniques.

Identification of metastatic disease critically impacts the care and prognosis of patients with neoplasia. Multiple techniques exist for identifying the sentinel or first lymph node(s) that receive draining tumour lymph. Identification of the sentinel lymph node enables accurate tissue sampling for determination of lymphatic metastasis. The aims of this study were to develop a computed tomography (CT) protocol for identifying the sentinel lymph node in dogs with tumours of the head and neck. In addition, indirect CT lymphography was compared to lymphoscintigraphy and vital dye injection to determine which technique more reliably identified the sentinel lymph node. CT indirect lymphography using intratumoral injection of iodinated contrast identified draining lymphatic vessels in eight of 18 dogs and identified the sentinel lymph node in five of 18 dogs. CT indirect lymphography employing four-quadrant peritumoral injection of iodinated contrast identified draining lymphatic vessels in 18 of 20 dogs and identified the sentinel lymph node in 11 of 20 dogs. Vital dye injection and lymphoscintigraphy identified the sentinel lymph node in 17 of 18 and 20 of 20 dogs, respectively. Identified sentinel lymph nodes were either ipsilateral or bilateral to the primary tumour. Both CT techniques were found to be safe and simple. Peritumoral injection has the greatest promise for the detection of sentinel lymph nodes in various head and neck cancers using CT, while lymphoscintigraphy had the greatest success of the compared techniques.

Computed tomographic lymphangiography of the thoracic duct by subcutaneous iohexol injection into the metatarsal region.

OBJECTIVE: To evaluate the efficacy of subcutaneous iohexol injection into the metatarsal region for thoracic duct lymphangiography in dogs and to determine the minimum effective dose. STUDY DESIGN: Experimental study and clinical report. ANIMALS: Five healthy beagle dogs and one dog with chylothorax. METHODS: For the experimental study, iohexol was injected subcutaneously into the metatarsal region of five dogs at three doses (0.5, 0.75, and 1 mL/kg), and the injection sites were massaged gently. Computed tomography (CT) was performed 1, 3, 5, 7, 10, 15, and 20 minutes after iohexol injection. Subjective quality was assessed, and Hounsfield unit values were measured at several regions of interest (T1, T4, T8, T13, and L3). In the dog with chylothorax, iohexol (1.0 mL/kg) was injected into the right metatarsal region prior to CT. RESULTS: The thoracic duct was visualized and enhanced by contrast in all dogs after injection of 0.75 and 1.0 mL/kg of iohexol, and in two dogs after injection of 0.5 mL/kg at 3, 5, and 7 minutes. The thoracic duct was gradually attenuated with increasing doses of iohexol. In the dog with chylothorax, the entire thoracic duct was well enhanced and dilated, and tortuous cranial mediastinal lymphatics were detected. CONCLUSION: The thoracic duct was visualized when at least 0.75 mL/kg of iohexol was injected subcutaneously into the metatarsal region of dogs. CLINICAL SIGNIFICANCE: Subcutaneous injection of iohexol into the metatarsal region offers a simple alternative to conventional thoracic duct lymphangiography.

Efficacy of en bloc thoracic duct ligation in combination with pericardiectomy by video-assisted thoracoscopic surgery for canine idiopathic chylothorax.

OBJECTIVE: To compare the outcomes of pericardiectomy performed with conventional clipping thoracic duct ligation (C-TDL) to those with en bloc thoracic duct ligation (EB-TDL) using video-assisted thoracoscopic surgery (VATS) for canine idiopathic chylothorax. STUDY DESIGN: Retrospective consecutive case series. ANIMALS: Thirteen client-owned dogs with idiopathic chylothorax. METHODS: Medical records of dogs treated with pericardiectomy in combination with TDL by VATS without intraoperative contrast were reviewed. Five and seven dogs underwent C-TDL and EB-TDL, respectively, and 11 dogs were evaluated by preoperative and 7- to 10-days-postoperative computed tomography-lymphography (CTLG). No clinical symptoms with absent or minimal pleural effusion was defined as clinical improvement. Long-term remission (LTR) was defined as rapid resolution of pleural effusion and no recurrence for more than 1 year. Anesthesia time, operation time, the duration of hospitalization, and time until pleural effusion resolution were compared. RESULTS: Clinical improvement was achieved in 91.7% of the cases (C-TDL, 4/5; EB-TDL, 7/7), excluding one case of intraoperative death. The LTR rate was significantly higher with EB-TDL (6/7 [85.7%]) than with C-TDL (1/5 [20%]). Anesthesia time, operation time, and time until pleural effusion resolution were significantly better with EB-TDL than with C-TDL. The rates of thoracic ducts visualization by postoperative CTLG were 100% (5/5) with C-TDL and 42.9% (3/7) with EB-TDL. CONCLUSION: En bloc TDL was an effective treatment for canine idiopathic chylothorax in this patient population. It compared favorably to C-TDL, although missed branches at the time of surgery may explain the difference between C-TDL and EB-TDL in this small population of cases. CLINICAL SIGNIFICANCE: En bloc TDL by VATS was an effective minimally invasive treatment for canine idiopathic chylothorax. Computed tomography-lymphography can be used for surgical planning and postoperative evaluation.