Gadoxetate disodium (Gd-EOB-DTPA) contrast-enhanced magnetic resonance imaging for differentiation between benign and malignant splenic lesions in dogs

Malignant splenic lesions in dogs are common, with hemangiosarcoma diagnosed most frequently, and there have been no consistent clinicopathologic, gross, or imaging characteristics identified that differentiate malignant from benign splenic lesions. Histopathology is required for definitive diagnosis, and given the poor long-term prognosis of malignant splenic lesions, a noninvasive tool to aid in diagnosis would be valuable. This prospective cohort study utilized gadoxetate disodium, a liver-specific contrast agent (Gd-EOB-DPTA; Eovist), to identify the general lesion and pre- and postcontrast signal characteristics of benign and malignant splenic and hepatic lesions in dogs with naturally occurring disease. Twenty-five dogs were enrolled, Eovist-enhanced MRI was performed, and dogs were taken to surgery for splenectomy and other organ biopsy. All histopathology and MRI studies were evaluated by a single pathologist and a single radiologist, respectively. The associations between the tumor type and numerous variables defined on MRI were evaluated using Fisher's exact tests, and the significance was identified at a P-value of .05. Malignant splenic masses were identified in 11/25 (44%) dogs, and 5/11 malignancies represented hemangiosarcoma. The presence of abdominal effusion (P = .017) and the presence of hepatic nodules on MRI (P = .009) were associated with splenic malignancy. There were no benign T2 hyperintense and no malignant T2 hypointense lesions (P = .021). Utilization of the T2 W MRI sequence may aid in the identification of malignant splenic lesions, particularly when accompanied by abdominal effusion and hepatic lesions.

Critical Advances for Democratizing Ultrasound Diagnostics in Human and Veterinary Medicine

The democratization of ultrasound imaging refers to the process of making ultrasound technology more accessible. Traditionally, ultrasound imaging has been predominately used in specialized medical facilities by trained professionals. Advancements in technology and changes in the health-care landscape have inspired efforts to broaden the availability of ultrasound imaging to various settings such as remote and resource-limited areas. In this review, we highlight several key factors that have contributed to the ongoing democratization of ultrasound imaging, including portable and handheld devices, recent advancements in technology, and training and education. Examples of diagnostic point-of-care ultrasound (POCUS) imaging used in emergency and critical care, gastroenterology, musculoskeletal applications, and other practices are provided for both human and veterinary medicine. Open challenges and the future of POCUS imaging are presented, including the emerging role of artificial intelligence in technology development.

Pathological Characterization and Risk Factors of Splenic Nodular Lesions in Dogs (Canis lupus familiaris)

In dogs, the spleen is a secondary lymphoid organ that can be affected by both neoplastic and non-neoplastic nodules. In general, few studies relate histopathological diagnosis to tumor size and the number of nodules in spleen biopsies. Some of these studies are inconclusive regarding the difference between neoplastic and non-neoplastic lesions and have small sample sizes or do not consider all splenic lesions. This study aimed to characterize splenic masses and determine risk factors for spleen tumors in dogs. A total of 507 histological reports corresponding to the diagnosis of splenic lesions in dogs from a private laboratory of animal pathology in the Metropolitan Region, Chile, were used. Data were analyzed by descriptive statistics and multiple logistic regression. The most frequent neoplastic and non-neoplastic diagnoses were hemangiosarcoma and hyperplasia, respectively. Most of the cases occurred in male (265 cases, 52.3%), senior (421 cases, 83%), and purebred individuals (342 cases, 67.5%). The most affected breeds were the Cocker Spaniel, German Shepherd, and Labrador Retriever. The most frequent lesion was a single nodule. The variables that exhibited a greater risk for the presentation of splenic neoplasia were male sex (odds ratio (OR) = 16.21; 95% confidence interval (CI) 1.741-150.879; p = 0.014), the presence of two or more splenic nodules (OR = 3.94; 95% CI 2.168-7.177; p < 0.001), an increase in nodule size greater than 2 cm (OR for quartiles 2, 3 and 4 of 2.2; 95% CI 1.036-4.941; p = 0.041, 2.9; 95% CI 1.331-6.576; p = 0.008, and 3.6; 95% CI 1.562-8.499; p = 0.003, respectively), and increasing age (OR = 1.23; 95% CI 1.048-1.436; p = 0.011). On the other hand, males exhibited a lower risk as age increases (OR = 0.76; 95% CI 0.615-0.928; p = 0.008). In conclusion, this study identified that males, multinodular presentation, nodule size, and age are risk factors for the occurrence of splenic neoplasia in dogs, knowledge that will contribute to the diagnostic management of dogs with spleen lesions.

Evaluation of the validity of the double two-thirds rule for diagnosing hemangiosarcoma in dogs with nontraumatic hemoperitoneum due to a ruptured splenic mass: a systematic review

OBJECTIVE

To evaluate the validity of the double two-thirds rule for a diagnosis of splenic hemangiosarcoma in dogs with nontraumatic hemoperitoneum due to a ruptured splenic mass.

SAMPLE

Systematic literature review.

PROCEDURES

3 databases (PubMed, CAB abstracts, and World of Science) were searched in November 2020. Articles were included if data on dogs with nontraumatic hemoperitoneum due to a splenic mass were included and subsequent pathologic diagnosis could be determined.

RESULTS

In total, 2,390 unique articles were identified, with 66 articles meeting the criteria for full-text review and 14 articles included for analysis. A total of 1,150 dogs were evaluated, with 73.0% (840/1,150) of dogs being diagnosed with a malignant splenic lesion and 27.0% (310/1,150) being diagnosed with a benign splenic lesion. Of the malignancies, 87.3% (733/840) were hemangiosarcoma. Levels of evidence were low, and bias was high as most included studies were retrospective case series.

CLINICAL RELEVANCE

The double two-thirds rule should be refined when evaluating dogs with nontraumatic hemoperitoneum from a ruptured splenic mass, with more dogs being diagnosed with a malignancy and hemangiosarcoma specifically than the double two-thirds rule indicates. These findings may be useful in an emergency setting to guide owners on potential diagnoses for dogs with nontraumatic hemoperitoneum due to a ruptured splenic mass. However, there remains a portion of these dogs with benign conditions and nonhemangiosarcoma malignancies that may have a good long-term prognosis compared to dogs with hemangiosarcoma. Studies with higher levels of evidence, lower risks of bias, and large case numbers are needed in the literature.

Applications of Contrast-Enhanced Ultrasound in Splenic Studies of Dogs and Cats

Simple Summary

Contrast-enhanced ultrasound (CEUS) is a noninvasive imaging technique that has become a reliable tool for identifying and monitoring lesions in both human and animals. In the last decade, its use in veterinary diagnostic imaging has gained increasing importance, and it can be reliable in everyday clinical practice. However, there is a lack of reviews describing existing CEUS results in the study of splenic lesions, which is of particular importance in dogs and cats. This information is important for validating its efficacy, to facilitate decision making related to sampling procedures and diagnosis, or even as a means to select CEUS as an alternative diagnostic tool in specific cases. Our goal was to review the existing studies of CEUS applications for splenic ultrasound studies in cats and dogs, present these results in a systematic manner, and combine this information into practical guidelines that can be used to help diagnosis and interpretation in both clinical cases and research.

Abstract

Contrast-enhanced ultrasound (CEUS) is an emerging technology in veterinary medicine involving the administration of intravenous contrast agents, and it is increasingly recognized for its high potential as a diagnostic imaging tool for small animals. This exam is easy and quick to perform, safe and reliable, and allows for the differentiation of lesions. It permits the identification of lesions that may require more invasive procedures, from those that can be safely dismissed to those that can be followed-up with ultrasound imaging. Although it has been extensively reviewed for use in human medicine, there is an overall lack of information about the application of this technique for cats and dogs, particularly in splenic studies, which can be particularly important for small animals. The present review describes and summarizes the CEUS applications used for splenic analysis in cats and dogs, providing a basic overview of CEUS technology with examples of common and uncommon features of focal splenic lesions. It also systematically gathers the results obtained for benign and malignant splenic lesions described in the literature, whilst providing guidelines for their interpretation. Furthermore, it presents the advantages of using CEUS for splenic analysis in cats and dogs and the main factors that may influence the quality of the imaging and the accuracy of the diagnosis. This type of knowledge can be used to provide a framework to help veterinarians make informed decisions regarding the use of this emerging technique for splenic lesions, guiding their interpretation of CEUS findings in the splenic ultrasounds of cats and dogs.

Accuracy of B-mode ultrasound and ARFI elastography in predicting malignancy of canine splenic lesions

The objective was to evaluate the accuracy of B-mode ultrasonography and ARFI elastography in detecting malignancy in canine splenic lesions. Thirty-seven spleens with abnormalities (16 benign and 21 malignant) from dogs of different breeds and ages were evaluated. Echogenicity, echotexture, organ length and height were evaluated using B-mode. By ARFI elastography, tissue stiffness was evaluated qualitatively (elastogram) and quantitatively (measuring the shear wave velocity-SWV). Lesions were classified as diffuse, focal or multifocal (cranial, medial or caudal portion) and comparisons of the SWV between the injured and non-injured areas were performed. In the B-mode, no features were associated to malignancy (P > 0.05). In the elastogram, 35 spleens were non-deformable and 2 deformable, having no association with malignancy. The greater SWV was observed in malignant lesions (3.4 ± 0.6 m/s), followed by areas free from alterations (2.1 ± 0.3 m/s) and benign lesions (1.7 ± 0.5 m/s), with difference between groups (P < 0.0001). It was found that a SWV > 2.6 m/s indicates malignancy of canine splenic lesions (sensitivity of 95%, specificity of 100%, PPV of 100%, NPV of 94% and accuracy of 97%), concluding that ARFI elastography is a promising technique for differentiating malignancy in these lesions.

Diagnostic value of the ultrasonographic description of a splenic mass or nodule as cavitated in 106 dogs with nontraumatic hemoabdomen

OBJECTIVE

To assess the diagnostic value of the ultrasonographic description of a splenic mass or nodule as cavitated in dogs with nontraumatic hemoabdomen.

ANIMALS

106 dogs with a nontraumatic hemoabdomen that underwent abdominal ultrasonography and splenectomy with histologic examination of splenic lesions between 2005 and 2018.

PROCEDURES

Medical records were reviewed for abdominal ultrasonographic and histologic findings. Diagnostic performance of ultrasonographic description of a splenic mass or nodule as cavitated as evidence of hemangiosarcoma or any malignancy was evaluated.

RESULTS

Ultrasonographic description of splenic lesions as cavitated had poor diagnostic utility in predicting presence of hemangiosarcoma or malignancy. Sensitivity and specificity of this test were 41.9% (95% CI, 30.5% to 54.3%) and 51.2% (95% CI, 36.8% to 65.4%), respectively, for detecting hemangiosarcoma, with positive and negative predictive values of 55.3% (95% CI, 41.2% to 68.6%) and 37.9% (95% CI, 26.6% to 50.8%), respectively. Results were similar for detecting malignancy. Cavitated lesions outside of the spleen were too rare for statistical analysis to be of value.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that relying on ultrasonographic description of cavitation to diagnose splenic lesions as malignant in dogs with nontraumatic hemoabdomen is unfounded. Other preoperative diagnostic tests may be more valuable in determining short- and long-term prognoses.

Impact of region-of-interest size and location on quantitative contrast-enhanced ultrasound of canine splenic perfusion

Background

During contrast enhanced ultrasound (CEUS), the features of the regions of interest (ROI) can affect the value of the perfusion-related parameters obtained from a time intensity curve (TIC). In veterinary medicine, conflicting have been reported on the influence of ROI size and location on renal CEUS. There are some disagreeing evidences regarding the optimal method for selecting ROI in quantitative analysis of renal perfusion using CEUS.

The aim of this study was to evaluate the effect of the size and location of ROIs in the spleen of conscious dogs on perfusion variables determined using sulphur hexafluoride contrast-enhanced ultrasounds.

Results

A prospective observational study on 15 client-owned mixed-breed adult dogs was performed using a system equipped with contrast-tuned imaging technology. Qualitative and quantitative assessments of the spleen enhancement pattern were carried out. Three square ROIs (0.05 cm²) were manually drawn in a row and spaced 1 mm apart, placing adjacent ROIs at three different depths. Three medium rectangular ROIs (0.3 cm²) include the 3 smallest ROIs in each row, indicated by the letters A, B and C, and a single large square ROI (1 cm²) was drawn containing all previous ROIs. Software analysis of time-intensity curves generated within each ROI allowed us to calculate the perfusion-related parameters: peak enhancement, time to peak, regional blood flow, mean transit time and regional blood volume.

The coefficient of variation for all blood-related parameters was always lower in the larger ROI than in the other smaller ROIs. ROI A and B, positioned proximally and medially, levels respectively, showed similar coefficients of variation to the largest ROI. The analysis of variance model exhibited a significant effect of location and size of the ROIs in the quantitative analysis of canine spleen perfusion, with a reduction of perfusion-related parameters in the distal ROI.

Conclusions

The recommendation for a quantitative CEUS examination of a dog’s spleen is to analyze splenic perfusion by drawing a sufficiently large ROI proximal to the ultrasound beam on the splenic parenchyma. This may be of clinical relevance in the diagnosis of splenic diseases.

Development and validation of a multivariable model and online decision-support calculator to aid in preoperative discrimination of benign from malignant splenic masses in dogs

OBJECTIVE

To develop a multivariable model and online decision-support calculator to aid in preoperative discrimination of benign from malignant splenic masses in dogs.

ANIMALS

522 dogs that underwent splenectomy because of splenic masses.

PROCEDURES

A multivariable model was developed with preoperative clinical data obtained retrospectively from the records of 422 dogs that underwent splenectomy. Inclusion criteria were the availability of complete abdominal ultrasonographic examination images and splenic histologic slides or histology reports for review. Variables considered potentially predictive of splenic malignancy were analyzed. A receiver operating characteristic curve was created for the final multivariable model, and area under the curve was calculated. The model was externally validated with data from 100 dogs that underwent splenectomy subsequent to model development and was used to create an online calculator to estimate probability of splenic malignancy in individual dogs.

RESULTS

The final multivariable model contained 8 clinical variables used to estimate splenic malignancy probability: serum total protein concentration, presence (vs absence) of ≥ 2 nRBCs/100 WBCs, ultrasonographically assessed splenic mass diameter, number of liver nodules (0, 1, or ≥ 2), presence (vs absence) of multiple splenic masses or nodules, moderate to marked splenic mass inhomogeneity, moderate to marked abdominal effusion, and mesenteric, omental, or peritoneal nodules. Areas under the receiver operating characteristic curves for the development and validation populations were 0.80 and 0.78, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

The online calculator (T-STAT.net or T-STAT.org) developed in this study can be used as an aid to estimate the probability of malignancy in dogs with splenic masses and has potential to facilitate owners' decisions regarding splenectomy.

Partial Gastrectomy at the Time of Splenectomy in Two Dogs With Splenic Neoplasia and Gastric Involvement

Splenic malignancies are reported in 30%-76% of dogs presenting with splenic masses, and splenectomy is the cornerstone in their management. However, long term prognosis is guarded due to the high rates of distant metastases reported both for HSA and nonangiogenic nonlymphomatous sarcomas. Metastases from splenic tumors usually occur to regional lymph nodes, liver, omentum, and lungs. These case series aim to describe 2 cases of splenic neoplasia with gastric involvement and report the surgical technique and outcomes associated with the condition. Two mixed-breed dogs were referred for a splenic mass and underwent explorative celiotomy. In both cases, the splenic mass was firmly attached to the gastric wall, and splenectomy with concurrent partial gastrectomy was thus performed. In case 1, liver lobectomy due to a hepatic mass was also performed. In case 2, the regional nodes were also excised due to lymphoadenomegaly. Both dogs recovered uneventfully from surgery and were discharged from the hospital at 72 and 96 hours. Histopathological examination was costent with splenic undifferentiated sarcoma and hepatic adenocarcinoma in one dog. The other dog had a diagnosis of malignant fibrous histiocytoma with nodal metastases. Neoplastic invasion of the stomach was histologically confirmed in both dogs. Adjuvant chemotherapy was refused, and both dogs were euthanized due to tumor progression at 71 and 58 days, respectively. According to our results, splenectomy with concurrent gastrectomy is feasible in dogs with splenic tumours involving the gastric wall. However, long term prognosis is poor, as previously reported for metastatic splenic sarcomas.

Contrast-enhanced ultrasound features of hepatocellular carcinoma in dogs

Background

This study aimed to describe the contrast-enhanced ultrasound (CEUS) features of canine hepatocellular carcinoma (HCC) in relation to cellular differentiation and lesion size.

Methods

Sixty dogs with a cytological diagnosis of HCC and that underwent a CEUS examination were retrospectively selected. The wash-in and wash-out patterns of contrast enhancement, along with the time to wash-in and the time to wash-out, of each lesion were recorded. A dimensional cut-off value of 3 cm was adopted for classification.

Results

Cellular differentiation had a significant influence on both wash-in (chi-squared=16.99; P<0.001) and wash-out (chi-squared=10.9; P=0.004) patterns of contrast enhancement. Lesion size had a lower, but still significant, influence on both wash-in (chi-squared=12.7; P=0.005) and wash-out (chi-squared=7.42; P=0.024) patterns. A homogeneous hyperenhancement in the arterial phase followed by homogeneous wash-out were suggestive of a well-differentiated HCC. The cellular differentiation of lesions with inhomogeneous hyperenhancement or hypoenhancement/no enhancement as well as an inhomogeneous wash-out or no wash-out could not be inferred.

Conclusions

No significant difference in the time to wash-in and the time to wash-out in relation to cellular differentiation or lesion size was evident. CEUS has the potential to improve efficiency in the diagnosis of HCCs in dogs.

Use of contrast-enhanced ultrasound for assessment of nodular lymphoid hyperplasia (NLH) in canine spleen

Background

Nodular lymphoid hyperplasia (NLH) is one of the most common non-neoplastic splenic lesions in dogs, especially in old ones, showing a splenic enlargement. More recent studies have been focused on Contrast Enhanced Ultrasonography (CEUS) analysis of the spleen for establishing normal perfusion patterns and blood pool phase peculiarities of focal lesions.

The aim of the study was to evaluate the qualitative and quantitative CEUS analysis of the canine splenic NLH, characterizing the CEUS pattern of this pathology on 20 clinical cases.

Results

A prospective, observational study was performed using a system equipped with contrast-tuned imaging technology. Mechanical Index was set from 0.08 to 0.11; the contrast medium was a second generation contrast medium composed of sulphur hexafluoride encapsulated of a shell of phospholipids (SonoVue®). Qualitative and quantitative assessment of the enhancement pattern of splenic NLH were performed.

Cytology and histology identified 20 splenic NLH. All of the benign hyperplastic lesions assessed were isoechoic with a homogeneous pattern than the surrounding normal spleen, during the wash-in phase (10–20 s) of the CEUS exam. Before finishing the wash-in phase, 20–45 s from the contrast medium inoculation, 19/20 benign nodules became markedly hypoechoic to the adjacent spleen. Sensitivity of hypoechoic pattern for NLH was 95%.

Conclusions

These findings should prove useful in the evaluation of focal splenic masses in dogs. Since enhancement and perfusion patterns of NLH seem to coincide with some neoplastic lesions of the spleen previously reported, in clinical practice attention must be paid to the final diagnosis of canine splenic lesions using only the CEUS exam.

Evaluation of Nodular Splenic Lesions in 370 Small-Breed Dogs (<15 kg)

Three hundred seventy small-breed dogs (<15 kg) undergoing splenectomy for the presence of nodular splenic lesions were evaluated in a retrospective study to assess associations with breeds, malignancy, hemoperitoneum, and median survival time compared with previous studies. Data analyzed included signalment, histopathologic diagnosis, presence or absence of hemoperitoneum, breed associations, and survival times. In the current study, 44% (163/370) of dogs had nonneoplastic splenic lesions and 56% (207/370) had neoplastic lesions. Hemangiosarcoma was present in 27% (100/370) of splenic lesions. Hemoperitoneum was present in 31% (115/370) of dogs, and of this population, 66% (76/115) had malignant splenic lesions. The most common breeds were miniature schnauzers, dachshunds, and beagles, with beagles exhibiting a positive association with malignancy. The presence of hemoperitoneum was associated with malignancy. Distribution for nodular splenic lesions, correlation of hemoperitoneum to malignancy, and median survival time were similar to previous reports in large-breed dogs. Small-breed dogs who present with hemoperitoneum are 2.6 times more likely to have a diagnosis of a malignant splenic lesion. The most common small-breed dogs with nodular splenic lesions were miniature schnauzers, dachshunds, and beagles. Beagles and small-breed terriers were more likely to have malignant splenic lesions, and small-breed terriers were more likely to present with hemoperitoneum.

Presurgical assessment of splenic tumors in dogs: a retrospective study of 57 cases (2012-2017)

The purpose of this study was to evaluate the clinical and imaging characteristics of canine splenic tumors and to establish guidelines for the presurgical assessment of splenic tumors in dogs. Fifty-seven dogs that underwent total splenectomy for the treatment of splenic tumors were evaluated by examining medical records, hematologic results, diagnostic imaging results, and histopathologic results. The maximum lesion size from ultrasonography was significantly different between malignant and benign tumors (p = 0.002). There was a correlation between tumor margination and type of splenic tumors (p = 0.045). Precontrast lesion attenuation on computed tomography was significantly different between splenic malignant and benign tumors (p = 0.001). The mean ± SD precontrast lesion attenuation of malignant tumors was 40.3 ± 5.9 Hounsfield units (HU), and for benign tumors, it was 52.8 ± 6.8 HU. In conclusion, some variables of the imaging examination could be used to distinguish the type of splenic tumor. Based on the study results, using a diagnostic flowchart would be effective in increasing the survival rate of patients with splenic malignant tumors. In addition, fine needle aspiration or magnetic resonance imaging prior to surgical exploration and histopathologic examination may be useful in achieving a more accurate diagnosis.

Histopathologic characteristics of biopsies from dogs undergoing surgery with concurrent gross splenic and hepatic masses: 125 cases (2012-2016)

Objective

To investigate the histopathologic characteristics of concurrent splenic and liver masses in dogs undergoing splenectomy and liver mass biopsy/resection. Medical records of 125 client-owned dogs found to have splenic mass or masses and a liver mass or masses during surgery were examined. Signalment (age, sex, breed), body weight, and results of histopathology were recorded for all dogs.

Results

Twenty-seven percent (34/125) of the dogs in this study had no evidence of malignancy in either the liver or the spleen. Sixty of 125 dogs (48.0%) had malignancy in the spleen and liver, and 56 (56/60, 93.3%) of those dogs had the same malignancy in both organs. Signalment was similar to that in other reports of splenic pathology. In this clinical population of dogs, 27% of dogs with concurrent gross splenic and liver masses discovered intraoperatively had benign lesions in both locations and therefore had a favorable prognosis.

Electronic supplementary material

The online version of this article (10.1186/s13104-018-3220-1) contains supplementary material, which is available to authorized users.

Triple-phase helical computed tomography in dogs with solid splenic masses

We investigated the utility of triple-phase helical computed tomography (CT) in differentiating between benign and malignant splenic masses in dogs. Forty-two dogs with primary splenic masses underwent triple-phase helical CT scanning (before administration of contrast, and in the arterial phase, portal venous phase, and delayed phase) prior to splenectomy. Tissue specimens were sent for pathological diagnosis; these included hematomas (n=14), nodular hyperplasias (n=12), hemangiosarcomas (n=11), and undifferentiated sarcomas (n=5). The CT findings were compared with the histological findings. Nodular hyperplasia significantly displayed a homogeneous normal enhancement pattern in all phases. Hemangiosarcoma displayed 2 significant contrast-enhancement patterns, including a homogeneous pattern of poor enhancement in all phases, and a heterogeneous remarkable enhancement pattern in the arterial and portal venous phases. Hematoma and undifferentiated sarcoma displayed a heterogeneous normal enhancement pattern in all phases. The contrast-enhanced volumetric ratios of hematoma tended to be greater than those of undifferentiated sarcoma. Our study demonstrated that the characteristic findings on triple-phase helical CT could be useful for the preoperative differentiation of hematoma, nodular hyperplasia, hemangiosarcoma, and undifferentiated sarcoma in dogs. Triple-phase helical CT may be a useful diagnostic tool in dogs with splenic masses.

Effects of size and location of regions of interest examined by use of contrast-enhanced ultrasonography on renal perfusion variables of dogs

OBJECTIVE To determine effects of the size and location of regions of interest (ROIs) in the renal cortex of unsedated dogs on renal perfusion variables determined by use of contrast-enhanced ultrasonography (CEUS). ANIMALS 12 client-owned adult (1.5 to 2 years old) Labrador Retrievers (8 males and 4 females; mean ± SD body weight, 27 ± 1.6 kg). PROCEDURES Each dog received 2 bolus injections of sulfur hexafluoride during CEUS. Three small oval ROIs (area of each ROI, 0.11 cm(2)) located in a row with a distance of 1 mm between adjacent ROIs and 1 large oval ROI (area, 1 cm(2)) that encompassed the 3 smaller ROIs were manually drawn in the renal cortex. The ROIs were located at a depth of 1.5 to 2.0 cm in the near field of the renal cortex. Software analysis of time-intensity curves within each ROI was used to identify peak enhancement, time to peak enhancement, regional blood flow, and mean transit time. RESULTS The location and size of the ROIs of unsedated dogs did not cause significant differences in the mean values of the renal perfusion variables. CONCLUSIONS AND CLINICAL RELEVANCE The development of CEUS has provided a unique means for visually examining and quantifying tissue perfusion. Results of this study indicated that it was possible to use small or large ROIs during renal CEUS to evaluate renal perfusion in dogs.

Diagnostic Imaging of the Hepatobiliary System: An Update

Recent advances in diagnostic imaging of the hepatobiliary system include MRI, computed tomography (CT), contrast-enhanced ultrasound, and ultrasound elastography. With the advent of multislice CT scanners, sedated examinations in veterinary patients are feasible, increasing the utility of this imaging modality. CT and MRI provide additional information for dogs and cats with hepatobiliary diseases due to lack of superimposition of structures, operator dependence, and through intravenous contrast administration. Advanced ultrasound methods can offer complementary information to standard ultrasound imaging. These newer imaging modalities assist clinicians by aiding diagnosis, prognostication, and surgical planning.

Hepatobiliary Neoplasia

Older companion animals may be uncommonly affected with hepatobiliary neoplasia. If clinical signs are shown they are often nonspecific. Animals may have increased liver enzyme activities detected on serum biochemistry. Ultrasound imaging can help to characterize liver lesions and guide sampling with fine needle aspiration. Treatment for massive liver tumor morphology involves liver lobectomy. Prognosis depends on the tumor morphology, type, and stage, but can be good for cats and dogs with massive hepatocellular tumors, with animals experiencing prolonged survival and low recurrence rates.

Survival time of dogs with splenic hemangiosarcoma treated by splenectomy with or without adjuvant chemotherapy: 208 cases (2001-2012)

OBJECTIVE

To determine survival time for dogs with splenic hemangiosarcoma treated with splenectomy alone, identify potential prognostic factors, and evaluate the efficacy of adjuvant chemotherapy.

DESIGN

Retrospective case series.

ANIMALS

208 dogs.

PROCEDURES

Medical records were reviewed, long-term follow-up information was obtained, and survival data were analyzed statistically.

RESULTS

154 dogs were treated with surgery alone, and 54 were treated with surgery and chemotherapy. Twenty-eight dogs received conventional chemotherapy, 13 received cyclophosphamide-based metronomic chemotherapy, and 13 received both conventional and metronomic chemotherapy. Median survival time of dogs treated with splenectomy alone was 1.6 months. Clinical stage was the only prognostic factor significantly associated with survival time. When the entire follow-up period was considered, there was no significant difference in survival time between dogs treated with surgery alone and dogs treated with surgery and chemotherapy. However, during the first 4 months of follow-up, after adjusting for the effects of clinical stage, survival time was significantly prolonged among dogs receiving any type of chemotherapy (hazard ratio, 0.6) and among dogs receiving both conventional and metronomic chemotherapy (hazard ratio, 0.4).

CONCLUSIONS AND CLINICAL RELEVANCE

Clinical stage was strongly associated with prognosis for dogs with splenic hemangiosarcoma. Chemotherapy was effective in prolonging survival time during the early portion of the follow-up period. Combinations of doxorubicin-based conventional protocols and cyclophosphamide-based metronomic protocols appeared to be more effective than either type of chemotherapy alone, but prolongations in survival time resulting from current protocols were modest.

Use of Contrast-Enhanced Ultrasound in the Differential Diagnosis of Adrenal Tumors in Dogs

We evaluated the diagnostic accuracy of the contrast-enhanced ultrasonography (CEUS), using a second-generation microbubble contrast agent, in differentiating the different types of adrenal mass lesions in 24 dogs. At B-mode ultrasound, 9 lesions involved the right adrenal gland, 14 the left, and 1 was bilateral. Each dog received a bolus of the contrast agent into the cephalic vein, immediately followed by a 5-mL saline flush. The first contrast enhancement of each adrenal lesion was evaluated qualitatively to assess the degree of enhancement and its distribution during the wash-in and wash-out phases, as well as the presence of non-vascularized areas and specific vascular patterns. Pathological diagnoses were determined in all dogs by histopathology or by cytology. Combining enhancement degree and vascularity resulted in the best predictive model, allowing CEUS to differentiate adrenocortical adenoma (n=10), adenocarcinoma (n=7), and pheochromocytoma (n=7) with an accuracy of 91.7% (P &lt; 0.001). Combining enhancement degree and vascularity, CEUS can discriminate malignant versus benign adrenal lesions with a sensitivity of 100.0%, a specificity of 80.0%, and an accuracy of 91.7% (P &lt; 0.001). In conclusion, results of this study confirm that CEUS is useful for differentiating between the different types of adrenal tumors in dogs.

EFFECT OF SEDATION ON CONTRAST-ENHANCED ULTRASONOGRAPHY OF THE SPLEEN IN HEALTHY DOGS

Contrast-enhanced ultrasound of the spleen enables the dynamic assessment of the perfusion of this organ, however, both subjective and quantitative evaluation can be strongly influenced by sedative agent administration. The purpose of this prospective, experimental study was to test effects of two sedative agents on splenic perfusion during contrast-enhanced ultrasound of the spleen in a sample of healthy dogs. Contrast-enhanced ultrasound of the spleen was repeated in six healthy Beagles following a cross-over study design comparing three protocols: awake, butorphanol 0.2 mg/Kg intramuscular (IM), and dexmedetomidine 500 μg/m(2) IM. After intravenous injection of a phospholipid stabilized sulfur hexafluoride microbubble solution (SonoVue®, Bracco Imaging, Milano, Italy), the enhancement intensity and perfusion pattern of the splenic parenchyma were assessed and perfusion parameters were calculated. Normal spleen was slightly heterogeneous in the early phase, but the parenchyma was homogeneous at a later phase. Sedation with butorphanol did not modify perfusion of the spleen. Dexmedetomidine significantly reduced splenic enhancement, providing diffuse parenchymal hypoechogenicity during the entire examination. Measured parameters were significantly modified, with increased arrival time (AT; (< 0.0001) and time to peak (TTP; P < 0.0001), and decreased peak intensity (PI; P = 0.0108), wash-in (P = 0.0014), and area under the curve (AUC; P = 0.0421). Findings supported the use of butorphanol and contraindicated the use of dexmedetomidine as sedatives for splenic contrast ultrasound procedures in dogs. Short-term and diffuse heterogeneity of the spleen in the early venous phase was determined to be a normal finding.

ASSOCIATIONS BETWEEN DUAL-PHASE COMPUTED TOMOGRAPHY FEATURES AND HISTOPATHOLOGIC DIAGNOSES IN 52 DOGS WITH HEPATIC OR SPLENIC MASSES

Ability to noninvasively differentiate malignant from nonmalignant abdominal masses would aid clinical decision making. The aim of this retrospective, cross-sectional study was to identify features in dual-phase computed tomographic (CT) studies that could be used to distinguish malignant from nonmalignant hepatic and splenic masses in dogs. Medical records were searched for dogs that had an abdominal dual-phase CT examination, a hepatic or splenic mass, and subsequent histopathologic diagnosis. Computed tomographic images for all included dogs were acquired prior to and <30 s (early phase) and >60 s (delayed phase) after intravenous contrast administration. Fifty-two dogs with 55 masses were studied: 24 hepatic, including 14 (58%) malignant and 10 (42%) non-malignant; 31 splenic, including 18 (58%) malignant and 13 (42%) nonmalignant. There was substantial overlap in the pre- and postcontrast CT features of malignant and nonmalignant hepatic and splenic masses. Regardless of histologic diagnosis, hepatic masses most frequently showed marked, generalized enhancement in early phase images that persisted in the delayed phase. Splenic hemangiosarcoma and nodular hyperplastic lesions most frequently showed marked, generalized enhancement in early phase images that persisted in delayed images whereas most splenic hematomas had slight enhancement in early phase images. All splenic hematomas and 77% of the hemangiosarcomas had contrast accumulation compatible with active hemorrhage. There were no other significant differences in quantitative or categorical CT data between malignant and nonmalignant hepatic or splenic masses. Dual-phase CT of dogs with hepatic or splenic masses provides limited specific diagnostic information.

MicroRNA-214 and MicroRNA-126 Are Potential Biomarkers for Malignant Endothelial Proliferative Diseases

Malignant endothelial proliferative diseases including human angiosarcoma (AS) and canine hemangiosarcoma (HSA) are serious diseases with a grave prognosis. Establishing liquid biopsy-based biomarkers for screening has definite clinical utility; however, plasma miRNAs up- or down-regulated in these sarcomas have been unclear. For identifying possible diagnostic plasma miRNAs for these sarcomas, we investigated whether plasma miR-214 and miR-126, which miRNAs play important roles in angiogenesis and tumorigenesis, were elevated in malignant endothelial proliferative diseases. For this investigation, human angiosarcoma and canine hemangiosarcoma cell lines and clinical plasma samples of canine hemangiosarcoma were examined by performing miRNA qRT-PCR. We report here that human angiosarcoma and canine hemangiosarcoma cell lines over-secreted miR-214 and miR-126 via microvesicles; in addition, their levels in the plasma samples from canines with hemangiosarcoma were increased. Moreover, the surgical resection of primary tumors decreased the levels of plasma miR-214 and miR-126. Our findings suggest that these malignant endothelial proliferative diseases over-secreted miR-214 and miR-126, thus suggesting that these miRNAs have potential as diagnostic biomarkers for malignant endothelial proliferative diseases in canine and possible in human angiosarcoma.

The use of contrast-enhanced ultrasonography for the detection of active renal hemorrhage in a dog with spontaneous kidney rupture resulting in hemoperitoneum

OBJECTIVE

To describe the use of contrast-enhanced ultrasonography (CEUS) for the detection of active renal hemorrhage in a dog with spontaneous kidney rupture resulting in hemoperitoneum.

CASE SUMMARY

A 9-month-old, sexually intact male Boxer dog presented for acute collapse, abdominal pain, and tachycardia. Physical examination findings were consistent with hypovolemia and acute abdomen. B-mode ultrasonography revealed peritoneal effusion and a right kidney mass. Subsequently, a CEUS study was performed on the right kidney, which demonstrated active hemorrhage from that kidney resulting in both hemoretroperitoneum and hemoperitoneum. At exploratory surgery, ultrasonographic findings were confirmed and a right nephrectomy was performed. Histopathology demonstrated severe parenchymal alterations along with the presence of nematode larvae. Fecal and urine testing for the presence of parasitic ova were negative. Identification of the larvae was inconclusive. At 30 days postoperatively, repeat B-mode ultrasound and clinicopathologic testing was unremarkable. The dog was alive at 1 year postsurgery with no ill effects.

NEW OR UNIQUE INFORMATION PROVIDED

To the authors' knowledge, this is the first report of CEUS for the detection of active hemorrhage from a kidney resulting in hemoretroperitoneum and hemoperitoneum in a dog. Although rare, the finding of nematode larvae within the renal parenchyma may have been the cause of kidney rupture. Importantly, surgical removal of the kidney was curative. Benign processes causing kidney rupture such as parasitic infestation should be considered in the working diagnosis as related to geographical location.

Diagnosis of a large splenic tumor in a dog: computed tomography versus magnetic resonance imaging

This study demonstrated magnetic resonance imaging (MRI) and computed tomography for large-sized splenic hemangiosarcoma. Radiography and ultrasonography revealed the presence of a large-sized soft-tissue mass in the cranial abdomen. Computed tomography showed hypoattenuating mass. The mass was located in contact with liver, spleen and stomach, and the origin of the mass remained ambiguous. The mass was T2-hyperintense and T1-hypointense with mild contrast enhancement. MRI allowed a differentiation between large-sized tumor and neighboring normal structure, and the mass was consequently identified as arising from spleen. These results suggested that MRI might be a useful tool to visualize large-sized splenic tumors and improve the accuracy of diagnosis.

An Overview of Small Animal Veterinary Sonography

This article is an overview of the field of small animal veterinary sonography, including its history, examples of utilization, and a brief review of the small animal abdominal sonographic examination that includes images of normal examples and typical pathology.

Safety of contrast-enhanced ultrasonography in dogs and cats: 488 cases (2002-2011)

OBJECTIVE

To determine the incidence of adverse events within 24 hours after contrast-enhanced ultrasonography (CEUS) in dogs and cats and compare the risk of death within 24 hours after imaging for animals that underwent ultrasonography with and without injection of a contrast agent.

DESIGN

Retrospective case-control study.

ANIMALS

750 animals (411 case dogs, 238 control dogs, 77 case cats, and 24 control cats).

PROCEDURES

At 11 institutions, medical records were reviewed of dogs and cats that had CEUS performed (cases) as were medical records of dogs and cats with clinical signs similar to those of case animals that had ultrasonography performed without injection of a contrast agent (controls). Information regarding signalment; preexisting disease; type, dose, and administration route of contrast agent used; immediate (within 1 hour after CEUS) and delayed (> 1 and ≤ 24 hours after CEUS) adverse events; and occurrence and cause of death (when available) was extracted from each medical record. Risk of death within 24 hours after ultrasonography was compared between case and control animals.

RESULTS

Of the 411 case dogs, 3 had immediate adverse events (vomiting or syncope) and 1 had a delayed adverse event (vomiting). No adverse events were recorded for case cats. Twenty-three of 357 (6.4%) clinically ill case animals and 14 of 262 (5.3%) clinically ill control animals died within 24 hours after ultrasonography; risk of death did not differ between cases and controls.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that CEUS was safe in dogs and cats.

Qualitative and quantitative contrast enhanced ultrasonography of the pancreas using bolus injection and continuous infusion methods in normal dogs

Quantitative contrast enhanced ultrasound is a major breakthrough for ultrasound imaging in recent years. However, contrast enhancement of the pancreas is brief with bolus injection. To assess if continuous infusion of Sonazoid^® can prolong the duration of pancreatic enhancement over bolus injections, eight adult dogs received bolus injection and continuous infusion of Sonazoid^® on separate days. Contrast enhanced ultrasound of the pancreatic parenchyma and proximal descending duodenum was performed, and time intensity curves reflecting tissue perfusions were generated. Perfusion parameters- time to initial upslope, peak time, time to wash-out and peak intensity were calculated and evaluated. Fast wash-in to intense peak, followed by rapid wash-out was observed for time intensity curves of bolus injection. With continuous infusion, contrast wash-in to peak intensity was gradual, followed by long plateau and slow wash-out. Median contrast enhancement durations of the pancreas and duodenum were significantly prolonged by continuous infusion from 11 sec (range, 10 to 23 sec) and 16 sec (range, 3 to 43 sec) at bolus injection to 205 sec (range, 170 to 264 sec, P<0.01) and 193 sec (range, 169 to 216 sec, P<0.05), respectively. Median peak intensity of the pancreas was 100.9 MPV (range, 80.2 to 124.3 MPV) at bolus injection and 77.6 MPV (range, 58.2 to 99.5 MPV, P<0.05) at continuous infusion. Prolonged continuous imaging is afforded by continuous infusion of contrast agent. Peak intensity of the pancreas was slightly diminished in continuous infusion, but offered adequate imaging subjectively.

Comparison between survey radiography, B-mode ultrasonography, contrast-enhanced ultrasonography and contrast-enhanced multi-detector computed tomography findings in dogs with acute abdominal signs

Contrast-enhanced multi-detector computed tomography (CE-MDCT) is used routinely in evaluating human patients with acute abdominal symptoms. Contrast-enhanced ultrasound (CEUS) continues to be in its infancy as it relates to evaluation of the acute abdomen. The purpose of this study was to compare survey radiography, B-mode ultrasound, CEUS, and CE-MDCT findings in canine patients presenting with acute abdominal signs; with a focus on the ability to differentiate surgical from non-surgical conditions. Nineteen dogs were prospectively enrolled. Inclusion required a clinical diagnosis of acute abdominal signs and confirmed surgical or non-surgical causes for the clinical signs. Agreement for the majority of recorded imaging features was at least moderate. There was poor agreement in the identification of pneumoperitoneum and in the comparison of pancreatic lesion dimensions for B-mode vs. CEUS. The CT feature of fat stranding was detected in cases including, but not limited to, gastric neoplasia with perforation, pancreatitis, and small intestinal foreign body. Ultrasound underestimated the size and number of specific lesions when compared with CE-MDCT. Contrast-enhanced ultrasound was successful in detecting bowel and pancreatic perfusion deficits that CE-MDCT failed to identify. Accuracy for differentiation of surgical vs. non-surgical conditions was high for all modalities; 100%, 94%, and 94% for CE-MDCT, ultrasonography and survey radiography respectively. Findings indicated that CE-MDCT is an accurate screening test for differentiating surgical from non-surgical acute abdominal conditions in dogs. Focused CEUS following CE-MDCT or B-mode ultrasonography may be beneficial for identifying potentially significant hypoperfused lesions.

Use of quantitative contrast-enhanced ultrasonography to detect diffuse renal changes in Beagles with iatrogenic hypercortisolism

OBJECTIVE

To determine the feasibility of quantitative contrast-enhanced ultrasonography (CEUS) for detection of changes in renal blood flow in dogs before and after hydrocortisone administration.

ANIMALS

11 Beagles.

PROCEDURE

Dogs were randomly assigned to 2 treatment groups: oral administration of hydrocortisone (9.6 mg/kg; n = 6) or a placebo (5; control group) twice a day for 4 months, after which the dose was tapered until treatment cessation at 6 months. Before treatment began and at 1, 4, and 6 months after, CEUS of the left kidney was performed by IV injection of ultrasonography microbubbles. Images were digitized, and time-intensity curves were generated from regions of interest in the renal cortex and medulla. Changes in blood flow were determined as measured via contrast agent (baseline [background] intensity, peak intensity, area under the curve, arrival time of contrast agent, time-to-peak intensity, and speed of contrast agent transport).

RESULTS

Significant increases in peak intensity, compared with that in control dogs, were observed in the renal cortex and medulla of hydrocortisone-treated dogs 1 and 4 months after treatment began. Baseline intensity changed similarly. A significant increase from control values was also apparent in area under the curve for the renal cortex 4 months after hydrocortisone treatment began and in the renal medulla 1 and 4 months after treatment began. A significant time effect with typical time course was observed, corresponding with the period during which hydrocortisone was administered. No difference was evident in the other variables between treated and control dogs.

CONCLUSIONS AND CLINICAL RELEVANCE

Quantitative CEUS allowed detection of differences in certain markers of renal blood flow between dogs treated orally with and without hydrocortisone. Additional studies are needed to investigate the usefulness of quantitative CEUS in the diagnosis of diffuse renal lesions.

Imaging diagnosis-cholangiocellular adenoma: contrast-enhanced ultrasonographic findings of a benign tumor mimicking malignant neoplasia in a dog

A 9-year-old Giant Schnauzer was referred for polyuria and polydipsia. On abdominal ultrasound, a hyperechoic mass with low color Doppler signal was detected in the medial right hepatic lobe. Contrast-enhanced ultrasound (CEUS) demonstrated increased enhancement of the mass during the arterial phase, and contrast washout during portal and late phases with decreased enhancement relative to the liver. These findings were consistent with primary liver malignancy or liver metastasis. A final diagnosis of cholangiocellular adenoma was made based on histopathology. To our knowledge, this is the first description of a benign hepatic neoplasm exhibiting malignant CEUS characteristics in a dog.

Mass-to-splenic volume ratio and splenic weight as a percentage of body weight in dogs with malignant and benign splenic masses: 65 cases (2007-2008)

OBJECTIVE

To determine whether mass-to-splenic volume ratio or splenic weight as a percentage of body weight was significantly different between dogs with benign versus malignant splenic masses.

DESIGN

Retrospective case series.

ANIMALS

65 dogs that underwent splenectomy.

PROCEDURES

Medical records of dogs examined between October 2007 and June 2008 because of a splenic mass were reviewed. Information obtained included dog age, breed, and weight; whether hemoperitoneum was present; splenic weight and dimensions (length, width, and height) at the time of splenectomy; dimensions (length, width, and height) of the splenic mass; and histologic diagnosis. Information on survival time was recorded when available.

RESULTS

30 (46%) dogs had hemangiosarcoma, 10 (15%) had other types of malignant masses, and 25 (39%) had benign masses. Dogs with benign splenic masses had a significantly higher mean mass-to-splenic volume ratio and higher mean splenic weight as a percentage of body weight than did dogs with hemangiosarcoma.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that mass-to-splenic volume ratio and splenic weight as a percentage of body weight may be useful in differentiating between hemangiosarcoma and benign lesions in dogs with splenic masses.

Elevated serum thymidine kinase activity in canine splenic hemangiosarcoma*

Thymidine kinase 1 (TK1) is a soluble biomarker associated with DNA synthesis. This prospective study evaluated serum TK1 activity in dogs presenting with hemoabdomen and a splenic mass. An ELISA using azidothymidine as a substrate was used to evaluate TK1 activity. Sixty-two dogs with hemoabdomen and 15 normal controls were studied. Serum TK1 activity was significantly higher in dogs with hemangiosarcoma (HSA) than in normal dogs (mean ± SEM = 17.0 ± 5.0 and 2.01 ± 0.6, respectively), but not dogs with benign disease (mean ± SEM = 10.0 ± 3.3). Using a cut-off of 6.55 U/L, TK activity demonstrated a sensitivity of 0.52, specificity of 0.93, positive predictive value of 0.94 and negative predictive value of 0.48 for distinguishing HSA versus normal. When interval thresholds of <1.55 and >7.95 U/L were used together, diagnostic utility was increased. Serum TK1 evaluation may help to discriminate between benign disease and HSA in dogs with hemoabdomen and a splenic mass.

Quantitative contrast-enhanced ultrasonographic analysis of perfusion in the kidneys, liver, pancreas, small intestine, and mesenteric lymph nodes in healthy cats

OBJECTIVE

To evaluate perfusion of abdominal organs in healthy cats by use of contrast-enhanced ultrasonography.

ANIMALS

10 young healthy anesthetized cats.

PROCEDURES

Contrast-enhanced ultrasonography of the liver, left kidney, pancreas, small intestine, and mesenteric lymph nodes was performed on anesthetized cats.

RESULTS

Typical perfusion patterns were found for each of the studied organs. Differences in perfusion among organs were associated with specific physiologic features. The liver was enhanced gradually and had a more heterogeneous perfusion pattern because of its dual blood supply and close proximity to the diaphragm, compared with other organs. An obvious and significant difference in perfusion was detected between the renal cortex and medulla. No significant differences in perfusion were detected among the pancreas, small intestine, and mesenteric lymph nodes.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that contrast-enhanced ultrasonography can be used in cats to estimate organ perfusion as in other species. Observed differences in perfusion variables can be mostly explained by physiologic differences in vascularity.

Effect of anaesthesia on contrast-enhanced ultrasound of the feline spleen

The spleens of 18 healthy cats were imaged using contrast-enhanced ultrasound (CEUS) to evaluate splenic perfusion and to compare perfusion patterns in awake and anaesthetised cats. Two groups of cats were imaged; the first (Group 1) consisted of 10 young, anaesthetised cats and the second (Group 2) comprised eight young to middle aged cats that were initially imaged when awake and later following anaesthesia. A two-phase enhancement of the spleen was observed both in awake and in anaesthetised cats. The time to first appearance of the contrast was significantly faster in awake (3.9±0.6s) than anaesthetised (4.8±1.0s) cats in Group 2 (P=0.031). A marked heterogeneous perfusion pattern was more prevalent in the anaesthetised (50%) compared to the awake (12.5%) animals in Group 2. The spleen was heterogeneous for approximately 30s in all groups. The results indicated that CEUS suspected focal perfusion defects of the spleen, especially during general anaesthesia, should be evaluated with caution and only after the initial heterogeneity has disappeared.

Contrast harmonic ultrasonographic appearance of focal space-occupying renal lesions

To describe the contrast-enhanced ultrasonographic appearance of various focal, space-occupying renal lesions and determine its value in their detection and characterization. Following baseline B-mode sonography of 15 dogs and one cat with renal space-occupying lesion(s), contrast-enhanced sonography was performed. The resulting images were evaluated qualitatively using conspicuity and number of lesions, and enhancement patterns were assessed during early arterial and late corticomedullary phases. Renal lesions were malignant in the cat (renal cell carcinoma) and 10 dogs (four renal cell carcinoma, two histiocytic sarcoma, one B-cell lymphoma, two hemangiosarcoma metastasis, one ch emodectoma metastasis) and benign in five dogs (two abscesses, one traumatic hematoma, one idiopathic hematoma, one hemorrhagic/necrotic nodule). Substantial overlap was present regarding the baseline sonographic features of benign vs. malignant lesions. With contrast-enhanced sonography, all renal cell carcinomas were characterized by large tortuous arteries, sometimes enhancing slightly earlier than vessels in the surrounding normal kidney. During the late corticomedullary phase, renal cell carcinomas had intense homo- or heterogeneous, iso- or slightly hypoechoic enhancement, which decreased progressively. Compared with renal cell carcinoma, histiocytic sarcoma and lymphoma had smaller and less obvious arteries, and an earlier loss of enhancement during the late phase. All hemangiosarcoma metastases appeared as nonenhancing nodules during the early arterial and late corticomedullary phases of enhancement, and additional lesions were detected. Histiocytic sarcoma and benign lesions had increased conspicuity with baseline sonography. The descriptions provided herein will be valuable as more work is done to establish the role of contrast-enhanced sonography in the assessment of renal lesions.