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

Use of New Ultrasonography Methods for Detecting Neoplasms in Dogs and Cats: A Review

The aim of this literature review was to present the novel imaging modalities elastography and contrast-enhanced ultrasonography. We provided an overview of the concepts and applications of each technique for the investigation of neoplastic and metastatic tumors in dogs and cats. Studies on elastography are based on the elasticity and deformation of the evaluated tissue. The information obtained from the different types of elastography can aid in the detection and differentiation of malignant and benign structures. Descriptions of elastography studies in several organs and tissue in veterinary medicine reported that, in general, malignant tumors tend to be more rigid and, therefore, less deformable than benign lesions or in comparison to the healthy parenchyma. Contrast-enhanced ultrasonography is based on the intravenous injection of contrast media constituted by microbubbles. This imaging modality can be performed in nonsedated animals and provides information on the tissue perfusion, allowing the investigation of macro- and micro-circulation. Studies on different organs and tissues were performed in dogs and cats and revealed a tendency of malignant tumors to present faster transit of the contrast media (time to wash-in, peak and wash-out). These advanced techniques can be associated with other imaging modalities, aiding important information to the well-established exams of B-mode and Doppler ultrasonography. They can be used as screening tests, potentially representing an alternative to the invasive sampling methods required for cytological and histopathological analysis.

Adrenocortical hypoperfusion detected by contrast-enhanced ultrasound in a dog with trilostane-induced hypoadrenocorticism

A 12-year-old neutered male Chihuahua dog was diagnosed with pituitary-dependent hypercortisolism and treated with trilostane. Eighty-nine days later, the dog showed lethargy accompanied by hyponatraemia and hyperkalaemia. Hypoadrenocorticism due to trilostane was suspected, but the result of the adrenocorticotropic hormone stimulation test was not conclusive. Contrast-enhanced ultrasound showed loss of adrenocortical blood flow in both adrenal glands, indicating adrenocortical hypoperfusion and isolated hypoadrenocorticism. Treatment with fludrocortisone acetate improved the condition and electrolyte abnormalities. Thirteen months later, the dog showed alopecia, and an adrenocorticotropic hormone stimulation test revealed increased cortisol concentration, indicating hypercortisolism recurrence. The dog died due to progressive deterioration 22 months after the initial presentation. Post-mortem examination revealed focally extensive necrosis with marked calcification in the parenchyma of the adrenal glands and regeneration of the cells in the zona fasciculata with severe fibrosis. Adrenocortical hypoperfusion detected by contrast-enhanced ultrasound can support the diagnosis of adrenal necrosis and hypoadrenocorticism.

Contrast-enhanced ultrasound features of adrenal lesions in dogs

BACKGROUND

The contrast-enhanced ultrasound (CEUS) features of adrenal lesions are poorly reported in veterinary literature.

METHODS

Qualitative and quantitative B-mode ultrasound and CEUS features of 186 benign (adenoma) and malignant (adenocarcinoma and pheochromocytoma) adrenal lesions were evaluated.

RESULTS

Adenocarcinomas (n = 72) and pheochromocytomas (n = 32) had mixed echogenicity with B-mode, and a non-homogeneous aspect with a diffused or peripheral enhancement pattern, hypoperfused areas, intralesional microcirculation and non-homogeneous wash-out with CEUS. Adenomas (n = 82) had mixed echogenicity, isoechogenicity or hypoechogenicity with B-mode, and a homogeneous or non-homogeneous aspect with a diffused enhancement pattern, hypoperfused areas, intralesional microcirculation and homogeneous wash-out with CEUS. With CEUS, a non-homogeneous aspect and the presence of hypoperfused areas and intralesional microcirculation can be used to distinguish between malignant (adenocarcinoma and pheochromocytoma) and benign (adenoma) adrenal lesions.

LIMITATIONS

Lesions were characterised only by means of cytology.

CONCLUSIONS

CEUS examination is a valuable tool for distinction between benign and malignant adrenal lesions and can potentially differentiate pheochromocytomas from adenocarcinomas and adenomas. However, cytology and histology are necessary to obtain the final diagnosis.

Correlation of minimally invasive imaging techniques to assess intestinal mucosal perfusion with established markers of chronic inflammatory enteropathy in dogs

Background

Minimally invasive diagnostic imaging techniques to detect intestinal inflammation in dogs are lacking. Contrast‐enhanced ultrasound (CEUS) and endoscopic narrow band imaging‐like endoscopy (Storz Professional Image Enhancement System [SPIES]) might allow quantification of intestinal mucosal perfusion and microvessel density in chronic inflammatory enteropathy (CIE) of dogs.

Hypothesis/Objectives

Markers of mucosal perfusion as determined by CEUS and SPIES endoscopy are potentially useful diagnostic markers to help characterize CIE and correlate with histological inflammation type and severity.

Animals

Thirty client‐owned dogs diagnosed with CIE at a referral hospital were prospectively enrolled.

Materials and Methods

Data from CEUS, SPIES, and white light (WL) endoscopy were correlated with World Small Animal Veterinary Association (WSAVA) endoscopy and histology scores and vessel density as determined by immunohistochemistry for von Willebrand factor (vWF). Automated linear modeling was used to determine predictors of endoscopic and histologic severity.

Results

Duodenal histology correlated with SPIES data (area percentage value, rho = 0.424, P = .04). White light endoscopy parameters correlated with SPIES parameters in the duodenum. Colonic histology correlated positively with CEUS, whereas colonic CEUS parameters correlated inversely with vWF expression. Several duodenal parameters combined predicted duodenal histology scores to a level of 73.4%. For the colon, 2 parameters contributed more than others to 73.1%.

Conclusion and Clinical Importance

Minimally invasive CEUS and SPIES appear feasible to assess intestinal perfusion in CIE. Use of SPIES endoscopy may be promising for assessing small intestinal inflammation, whereas CEUS could be used to assess colonic perfusion and inflammation. Both techniques need to be investigated further for their clinical utility.

Utility of contrast-enhanced ultrasound in differential diagnosis of adrenal tumors in dogs

This prospective case study aimed to clarify the clinical significance of contrast-enhanced ultrasound (CEUS) for the differential diagnosis of canine adrenal tumors. Forty-three client-owned dogs with adrenal tumors were included. All dogs underwent CEUS, which was evaluated qualitatively and quantitatively. The peak signal intensity (PI), time to peak signal intensity (TPI), mean transit time (MTT), upslope, and downslope were calculated for each time-intensity curve. The histopathological diagnosis of each resected mass was compared with the CEUS findings and parameters. Enhancement distribution, vascularity, tortuous nourishing vessels, enhancement pattern, and late-phase enhancement did not differ significantly between adrenal cortical adenoma (CA), adenocarcinoma (CAC), and pheochromocytoma (PHEO) in qualitative assessment. In PHEO, the TPI was significantly more rapid compared with that in CA (P=0.0287) and CAC (P=0.0404). The MTT in PHEO was significantly shorter than that in CA (P=0.0016) and CAC (P=0.0003). Upslope in PHEO was larger than that in CAC (P=0.0406). Downslope in PHEO was significantly larger than that in CA (P=0.0048) and CAC (P=0.0018). A receiver operating characteristic curve analysis demonstrated that the area under the MTT curve yielded 0.91 for distinguishing PHEO from adrenocortical tumors in dogs; an MTT cut-off value less than 6,225 msec yielded a sensitivity of 69%, specificity of 94%, and likelihood ratio of 12.46. CEUS appears to be clinically applicable for the differential diagnosis between cortical and medullary origins of primary adrenal tumors in dogs.

Use of Contrast-Enhanced Ultrasonography for the Characterization of Tumor Thrombi in Seven Dogs

Simple Summary

Some neoplasia—such as adrenal and thyroid glands tumors—have been associated with “tumor thrombi” both in humans and dogs. The detection and characterization of these venous tumor thrombi is important for both surgical planning and prognosis. In human medicine, contrast-enhanced ultrasonography (CEUS) is considered an accurate diagnostic technique for differentiating malignant from benign portal vein thrombosis in hepatocellular carcinomas. Data regarding the characteristics of tumor thrombi in dogs are currently lacking. Therefore, the aim of this study was to assess the feasibility of CEUS for the characterization of malignant venous thrombosis in dogs. On the basis of our results, CEUS appeared to be useful in the detection of malignant intravascular invasion; contrast uptake of the thrombus was present in all cases. In addition, CEUS may clearly detect newly formed vessels within the thrombus, and arterial-phase enhancement and washout in the venous phase were the main features in malignant thrombosis in our dogs. As CEUS is an easy to perform, noninvasive technique, its application in the detection of malignant thrombosis in dogs may be used to improve the diagnosis in oncological canine patients.

Abstract

Tumors of adrenal and thyroid glands have been associated with vascular invasions—so-called tumor thrombi, both in humans and dogs. The detection and characterization of venous thrombi is an important diagnostic step in patients with primary tumors for both surgical planning and prognosis. The aim of this study was to describe the use of contrast-enhanced ultrasonography (CEUS) for the characterization of tumor thrombi. Dogs with tumor thrombus who underwent bi-dimensional ultrasound (B-mode US) and CEUS were included. Seven dogs were enrolled in this retrospective case series. On B-mode US, all thrombi were visualized, and vascular distension and thrombus-tumor continuity were seen in three and two cases, respectively. On color Doppler examination, all thrombi were identified, seemed non-occlusive and only two presented vascularity. On CEUS, arterial-phase enhancement and washout in the venous phase were observed in all cases. Non-enhancing areas were identified in the tumor thrombi most likely representing non-vascularized tissue that could potentially be embolized in the lungs after fragmentation of the tumor thrombi. On the basis of these preliminary study, CEUS appeared to be useful for the characterization of malignant intravascular invasion.

Safety of percutaneous ultrasound-guided fine-needle aspiration of adrenal lesions in dogs: Perception of the procedure by radiologists and presentation of 50 cases

Background

Percutaneous ultrasound (US)‐guided fine‐needle aspiration (FNA) of adrenal gland lesions is controversial in veterinary medicine.

Objective

To evaluate the frequency and radiologists' perception of the risk of the procedure as well as determining the incidence of complications.

Methods

Retrospective study. A first survey was submitted by e‐mail to all board‐certified radiologists of the American College of Veterinary Radiology (ACVR) and European College of Veterinary Diagnostic Imaging (ECVDI). A second survey was sent to radiologists who declared having performed the procedure at least once in their career (observational cross‐sectional case study).

Results

The first survey was sent to 977 diplomates and answered by 138. Of 138 diplomates, 40 currently performed the procedure and 98 did not; 44 of the 98 gave the hypertensive crisis risk in pheochromocytoma as a reason. To the second survey, 12 of 65 responded positively; 50 dogs with 58 lesions were recruited, including 23 pheochromocytomas. Complications were reported in 4 of 50 dogs; 3 hemorrhages (1 mild and 1 moderate) and 1 death from acute respiratory distress syndrome (possibly related to laryngeal paralysis). No hypertensive crisis was reported. There was no relationship between the method of FNA/type of needle used and occurrence of complications. Based on the recollection of these 65 radiologists, who performed approximately 200 FNA of adrenal lesions, a death rate of approximately 1% was estimated.

Conclusions and Clinical Importance

Percutaneous US‐guided FNA of adrenal lesions can be considered a minimally risky procedure, despite the negative perception by radiologists.

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.

Contrast-enhanced ultrasonography features of hepatobiliary neoplasms in cats

BACKGROUND

Contrast-enhanced ultrasonography (CEUS) features of primary hepatobiliary neoplasms have been reported in dogs but no information is available in cats.

METHODS

Qualitative and quantitative features of bile duct adenomas (BDAs, n=20), bile duct carcinomas (BDCs, n=16), and hepatocellular carcinomas (HCCs, n=8) are described in 44 cats.

RESULTS

There was an overlap in CEUS qualitative features between different histotypes, both in wash-in and wash-out phases. Distinction between different neoplasms based only on the CEUS qualitative features was not possible. At peak of enhancement, the BDAs, BDCs and HCCs showed a large range of echogenicities, from hypoenhancement to hyperenhancement, in comparison to the liver parenchyma. Eight of 20 BDAs showed inhomogeneous hyperenhancement during wash-in, which is a feature reported as typical of malignant lesions in dogs. BDC had a significantly faster wash-in compared with both BDA and HCC but the diagnostic accuracy of all the included quantitative variables was only moderate. No significant differences in the wash-out quantitative features of BDA and BDC were evident.

CONCLUSION

There is poor evidence that CEUS may be used to distinguish between different primary hepatobiliary neoplasms in cats.

Contrast-enhanced ultrasonography of maternal and fetal blood flows in pregnant bitches

We evaluated the potential usefulness of CEUS to assess fetal-maternal circulation during pregnancy in dogs. Nine bitches were examined at 23, 30, and 45 days of gestation using an ultrasound machine (LOGIQ E9) and SonoVue^® contrast media as echo-signal enhancer. Qualitative and quantitative evaluation of contrast enhancement patterns of uterine artery and utero/placental vessels were performed on recorded images. Independently of the gestational periods, the qualitative evaluation showed the initial wash-in phase from the first appearance of the uterine artery to the rapid distribution in embryonic vesicles or placenta to the progressive washout, whilst there was no enhancement of either embryos or fetuses in any bitch. Independent of gestational age, parameters derived from quantitative analysis of time intensity-curves of contrast enhancement (peak intensity, time to peak, rise time, washout) did not vary between proximal placenta, distal placenta, and uterine artery. With the progression of gestation, AUC values did not change in both proximal and distal placenta, but in the uterine artery it was lower (P ≤ 0.05) at day 30 than at day 23 (464.8 ± 16.1 vs.596.4 ± 28.1, respectively). In conclusion, CEUS appears to safely permit evaluation of the maternal and fetal vessels in the first two third of gestation, without any clinically relevant adverse effects. Further studies in a larger number of bitches in different stages of pregnancy are needed to establish standard parameters for normal pregnancies that can be used to detect abnormalities of pregnancy.