Metastatic diagnosis of canine sternal lymph nodes using computed tomography characteristics: A retrospective cross-sectional study

Lymphotropic nanoparticle magnetic resonance imaging for diagnosing metastatic lymph nodes in dogs with malignant head and neck tumours

Lymphotropic nanoparticle magnetic resonance imaging (LNMRI) utilises ultrasmall paramagnetic iron nanoparticles (USPIOs) for imaging of metastatic lymph nodes in patients afflicted with cancer. LNMRI has been shown to be a highly effective and accurate way to diagnose metastasis in humans but has not been commonly reported on in veterinary medicine. USPIOs are phagocytised by macrophages and then localised to lymph nodes where they create a susceptibility artefact on gradient echo MRI sequences. In this study dogs (n = 24) with naturally occurring head and neck tumours were imaged with LNMRI then had mandibular and retropharyngeal lymph nodes extirpated for histological analysis. Subjective and objective analysis of the LNMRI images was performed and imaging results compared to histology as the gold standard. A total of 149 lymph nodes were included in this study. The overall sensitivity, specificity and accuracy was 64%, 94.4% and 89.3% respectively. However, if dogs with mast cell tumours were excluded from analysis the sensitivity, specificity and accuracy rose to 85.7%, 95.7% and 94.6%. LNMRI is potentially an accurate way to determine the presence of lymph node metastasis in dogs with some types of head and neck tumours. However, LNMRI has only moderate accuracy in dogs with oral or mucocutaneous mast cell tumours in this region.

Sternal lymphadenopathy in dogs with malignancy in different localizations: A CT retrospective study of 60 cases

Sternal lymph nodes (SLNs) drain a multitude of regions in dogs, including the pectoral and shoulder region, the thoracic wall and mammary glands, the mediastinum, thymus, diaphragm, and the ventral abdominal wall and peritoneal cavity. Neoplastic conditions of these regions can lead to sternal lymphadenopathy. The aim of this study was to assess the most frequent localizations of the primary neoplasia and the most frequent tumor types in dogs with sternal lymphadenopathy. Computed tomographic (CT) characteristics of SLNs in dogs with confirmed neoplasia were also described. For this single-center retrospective descriptive study, dogs with sternal lymphadenopathy and cytological or histological diagnosis of neoplasia were included. Sixty dogs fulfilled the inclusion criteria: 30 (50%) with thoracic neoplasia, 19 (32%) with abdominal neoplasia, 6 (10%) with neoplasia of the front limbs and 5 (8%) with generalized neoplasia. Based on the cytological/histological diagnosis of the primary neoplasia, 31/60 (52%) dogs presented with a sarcoma, 15/60 (25%) with carcinoma, and 14/60 (23%) with round cell tumor. The presence of heterogeneous contrast enhancement was more frequent in dogs with sarcoma, while the concomitant presence of other abnormal lymph nodes was more frequent in dogs with round cell neoplasia. Tumors of different types and in different location can result in sternal lymphadenopathy in dogs. The most frequent in this study were thoracic and abdominal neoplasia, followed by neoplasia of the shoulder region. Sarcoma was the most common tumor type detected in this study, and the main CT characteristic of the SLNs in case of sarcoma was heterogeneous contrast enhancement.

Canine anal sac gland carcinoma with regional lymph node metastases treated with sacculectomy and lymphadenectomy: Outcome and possible prognostic factors

The staging system commonly used in canine anal sac gland carcinoma (ASGC) is a revised Tumour-Node-Metastasis (TNM) system published in 2007. This staging system consists in four stages and, for dogs with nodal metastases, the size of the metastatic lymph node (mLN) defines the N stage. However, we hypothesise that (1) the mLN size has no prognostic significance when the mLN can be excised, (2) a high number of mLNs is associated with poorer prognosis and (3) the measurement of the mLN on imaging is not reproducible. To investigate these hypotheses, medical records and diagnostic images of dogs with ASGC and mLN, treated with sacculectomy and lymphadenectomy, with or without chemotherapy, were reviewed. Interobserver variability for mLN measurement was assessed. Prognostic factors including mLN size and number were investigated. Time to documented progression (TDP) and disease-specific survival (DSS) were evaluated. Progression-free interval (PFI) was analysed with interval-censored data analysis. Fifty-seven dogs were included. The median PFI, TDP and DSS were 110 (95%CI 61.5-185.5), 196 (95%CI 162-283) and 340 days (95%CI 321-471), respectively. For measurement of the largest mLN, interobserver agreement was excellent but limits of agreement reached 39.7%. Neither the size of the largest mLN nor the use of adjuvant chemotherapy were associated with outcome. The number of mLNs was associated with outcome and having more than four mLNs was associated with shorter PFI (p < .001), TDP (p = .004) and DSS (p < .001). While mLN size measurement was not consistently reproducible and did not influence outcome in our cohort, number of mLNs did. Further studies are required for development of a revised staging system.

Contrast enhanced computed tomography assessment of superficial inguinal lymph node metastasis in canine mammary gland tumors

Mammary gland neoplasms are predominant in dogs. However, sentinel lymph node (SLN) status assessment criteria have not been established for these cases. In this retrospective, secondary analysis, diagnostic case control study, CT images of 65 superficial inguinal SLNs were obtained before and 1, 3, 5, and 10 min after intravenous administration of contrast agent (iopamidol 370 mgI/mL). The presence and degree of postcontrast enhancement were assessed, by means of the median absolute density value and the maximum absolute density value at any time point in the center and in the periphery of each SLN measured in Hounsfield units (HU), before and after contrast agent administration. These values were compared with histopathological findings postsurgical excision. Receiver operating characteristic analysis was conducted. The absolute density values ranged widely at each time point and within each group of nodes (negative, positive, control group). At all time points, the median density value in the center and in the periphery was significantly higher in metastatic than in non-metastatic SLNs (P ≤ .014). Among the parameters tested, the median absolute density value measured in the periphery of the SLN 3 min after injection showed the highest sensitivity, specificity, and accuracy (AUC) (87.5%, 82.1%, and 92.1% respectively), with a cutoff value of 50.9 HU. The maximum absolute density value at any time point in the center and periphery of the SLNs was also significantly higher in metastatic SLNs compared to non-metastatic (P ≤ .001). With a cutoff value of 59.5 HU, the maximum absolute density value in the periphery of the SLN displayed high sensitivity and specificity (87.5% and 89.3%, respectively). The results of this study support the hypothesis that contrast enhanced CT imaging may aid in the assessment of SLN metastasis in dogs with mammary gland neoplasms.

Prognostic value of sternal lymphadenopathy on malignancy and survival in dogs undergoing splenectomy

The purpose of this retrospective cohort study was to determine prevalence of sternal lymphadenopathy in a population of dogs undergoing splenectomy, and to evaluate if the prevalence was associated with splenic malignancy. In addition, the study investigated if survival in dogs diagnosed with hemangiosarcoma (HSA) differed between those with or without sternal lymphadenopathy at the time of surgery. Digital radiographs and medical records for dogs who underwent splenectomy from 2013 to 2016 where retrospectively reviewed. One hundred ninety-five dogs underwent splenectomy during the study period. The overall prevalence of sternal lymphadenopathy was 12.8%. The prevalence of sternal lymphadenopathy in dogs with hemangiosarcoma was 16.2% (12/74), other malignancy was 15.8% (3/19), and with a benign process 9.8% (10/102). There was no significant association between sternal lymphadenopathy with hemoperitoneum (p = .20) or between sternal lymphadenopathy and presence of neoplasia (p = .37). There was no significant difference in survival probability in all dogs with or without sternal lymphadenopathy (p = .073). However, sternal lymphadenopathy was associated with lower survival in 74 dogs with HSA (p = .036) and 19 with other splenic malignancies (p = .039). The presence of sternal lymphadenopathy should not be considered a negative prognostic indicator if present in dogs presenting with a hemoperitoneum. Although the presence of sternal lymphadenopathy at the time of initial presentation was not significantly associated with survival time in all dogs with splenic disease, it may have predictive value related to survival of dogs with splenic malignancy.

Computed tomography measurements of presumptively normal canine sternal lymph nodes

Background

There is a lack of information regarding the CT appearance of sternal lymph nodes in dogs. This retrospective anatomic study was aimed to describe the general appearance of sternal lymph nodes in healthy dogs.

Results

Twenty-seven dogs with no abnormality in blood work, urinalysis and CT images were included in the study. Dogs were divided into three weight groups; ≤10 kg, 10.1 to 30 kg and ≥ 30.1 kg. Multi-planar reconstructions of CT images were made to identify sternal lymph nodes. The number, location, size, density and heterogeneity of sternal lymph nodes were recorded. Density and heterogeneity of lymph nodes were measured on pre- and postcontrast images. Except for one dog, sternal lymph nodes were identified in all the dogs. The mean number of sternal lymph nodes per dog was 2.1 (SD 0.6), and the most frequent localisation was at the level of the second sternebra (23 dogs; 85%). There was a positive correlation between the weight and all the dimensions of sternal lymph nodes. A significant negative correlation was found between the age and dorsoventral dimension of the lymph node. Short-to-long axis ratios were not significantly different between the weight groups. None of the measured dimensions nor the ratio values was significantly different between the medium-sized dogs (10.1 to 30 kg) and the large dogs (≥ 30.1 kg). There was a significant difference between precontrast and postcontrast density and heterogeneity values of sternal lymph nodes.

Conclusions

Based on the results, we recommend using the short-to-long axis ratios for sternal lymph node size evaluation among dogs of different size. Sternal lymph nodes in this study appeared on precontrast examination as heterogeneous, and homogenous on the postcontrast examination.

CT imaging features of canine thymomas

Canine thymomas have been evaluated based on clinical features, treatment options, surgical excision, and outcomes with limited information on specific CT features. The objective of this retrospective, descriptive, cross-sectional study was to describe the CT characteristics of confirmed thymomas and to compare these imaging features to outcome. A total of 22 dogs met the inclusion criteria of histologically confirmed thymomas with concurrent CT imaging. Tumor size varied widely ranging from small and well-circumscribed to large and invasive. Delayed-phase, contrast-enhanced CT studies were best for determining the degree of contrast enhancement in tumors. Of these, 19 of 22 masses had heterogeneous enhancement and three of 22 masses had homogeneous enhancement. Vascular invasion was present in seven of 22 cases. Larger tumors were associated with vascular invasion (height: P = .04; width and volume: P = .02). On precontrast CT, larger tumors (16/21) were heterogeneous and cystic, with smaller tumors (5/21) being more homogeneous (all values P < .05). A larger size was associated with recurrence in fully resected masses (height: P = .03), but not a shorter outcome (P > .3 for all size dimensions). Postoperative complications and incomplete tumor resection were associated with shorter outcome (both values P < .01). Metastasis was confirmed in four cases. There were six cases with lymphadenopathy noted on CT; five of the six cases did not have evidence of metastasis. Larger tumors were more likely to be cystic and associated with vascular invasion.

Survival analysis in dogs with urinary transitional cell carcinoma that underwent whole-body computed tomography at diagnosis

This retrospective study aimed to evaluate factors associated with survival and to compare characteristics between tumour localizations in dogs with urinary transitional cell carcinoma (TCC) that underwent whole-body computed tomography (CT) at diagnosis. Dogs with histologically confirmed TCC that received medical therapy between 2010 and 2017 were included; dogs that underwent surgery or radiotherapy for the primary tumour were excluded. According to the CT findings, primary tumour localization (classified into the Bladder, Urethra and Bladder and Urethra groups), prostate involvement, iliosacral lymphadenomegaly, sternal lymphadenomegaly and metastasis to the bone and lung were evaluated for survival analysis. CT at diagnosis revealed iliosacral lymphadenomegaly, sternal lymphadenomegaly, bone metastasis and lung metastasis in 47.7%, 18.5%, 24.6% and 35.4% of the 65 included dogs, respectively. The overall median survival time was 196 days. On multivariable analysis, TCC localization (hazard ratio [HR], 1.90; P = .037), bone metastasis (HR, 2.76; P = .013) and sternal lymphadenomegaly (HR, 3.56; P = .004) were significantly associated with survival. Compared to the Bladder group (n = 16), the Urethra group (n = 26) had higher metastasis rates to the bone (6.3% vs 42.3%; P = .045) and lung (6.3% vs 46.2%; P = .022). The survival time was shorter in the Urethra group than in the Bladder group (121.5 vs 420 days; P < .001), and it was similar only in female dogs (247 vs 420 days; P = .031). These findings suggest that whole-body CT could be valuable for predicting the prognosis in urinary TCC.