Diagnostic Imaging of the Hepatobiliary System: An Update

Surgical Management Of Feline Biliary Tract Disease: Decision-making and techniques

PRACTICAL RELEVANCE

Diseases of the hepatobiliary system are not uncommon in first-opinion practice. The anatomy of the feline hepatobiliary tract differs from that of dogs and may predispose cats to inflammatory hepatobiliary disease. Case management can be challenging, and the prognosis is variable and dependent on the underlying disease process.

CLINICAL CHALLENGES

Biliary tract disease in the cat has non-specific clinical signs that overlap with those of diseases of other body systems. Diagnostic tests of the hepatobiliary system are widely available, but interpretation of results can be challenging. Deciding on medical or surgical management can also be challenging; for example, various degrees of cholestasis may be seen with different diseases and disease severities, and will influence the decision to manage the patient medically or surgically. Surgery is indicated in cases of bile peritonitis, severe cholestasis, focal neoplasia or disease that is refractory to medical management. Intensive perioperative and postoperative management, with 24 h hospitalisation facilities, is essential.

AUDIENCE

This review article is written for the small animal general/primary care practitioner, with an emphasis on decision-making in the surgical management of feline hepatobiliary disease.

EVIDENCE BASE

Evidence available in the published literature is reviewed and presented, and the inherent limitations are discussed.

Creation of Three-Dimensional Anatomical Vascular and Biliary Models for the Study of the Feline Liver (Felis silvestris catus L.): A Comparative CT, Volume Rendering (Vr), Cast and 3D Printing Study

In this study, six adult feline cadavers were examined using CTA, 3D printing, and casts injected with epoxy. The aorta, the portal vein, and the gallbladder of 3 feline cadavers were separately injected with a 50% mixture of colored vulcanized latex and hydrated barium sulfate as contrast medium to analyze by CT the arterial, venous and biliary systems. The other three cadavers were injected with a mixture of epoxy resin in the aorta, gallbladder and hepatic veins, separately. After the corrosion and washing process, hepatic vascular and biliary casts were obtained. The images obtained by CT showed the vascular and biliary system using a soft tissue window. For the identification of vascular and biliary structures, the 3D prints together with the 3D reconstructions were analyzed, and the results were compared with the casts obtained with epoxy resin. Each of the arterial, venous and biliary branches associated with each of the liver lobes were identified with the help of the printings. In conclusion, the creation of 3D prototypes of nonpathological feline hepatic parenchyma can be used in the veterinary clinic as a basis for the detection of pathological problems in addition to obtaining future pathological hepatic 3D models.

CT features of divisional bile ducts in healthy Labrador Retrievers

Computed tomography (CT) is increasingly being used for the study of gallbladder and bile duct diseases. The first step in interpreting CT findings is understanding the cross-sectional anatomy of the structures involved, but there are no published studies describing the CT features of the divisional bile ducts. In dogs, anatomic studies report two common patterns including three or four divisional bile ducts. The aim of this retrospective, descriptive, anatomical study was to describe the size and pattern of the visible divisional bile ducts, based on their location and extension, using contrast-enhanced CT in a group of Labrador Retrievers without evidence of hepatobiliary diseases. The correlation between the biliary duct number and dimensions, and the visceral fat area percentage (VFA%) was also evaluated. The right lateral divisional duct (RLD) was visualized in four of 40 dogs, the left lateral divisional duct (LLD) in nine of 40 dogs, and in 17 of 40 dogs, both were simultaneously visualized. In 10 of 40 dogs, the RLD and LLD were not highlighted. When visible, the RLD has a median diameter of 0.23 cm and a median length of 0.82 cm. The LLD has a median diameter of 0.23 cm and a median length of 2.72 cm. The median diameter of the common bile duct before and after the insertion of divisional bile ducts was 0.23 and 0.25 cm, respectively. No correlation with the VFA% was found. At least one of the divisional bile ducts could be visualized using contrast-enhanced CT in the majority of sampled dogs (75%) .

Association of plasma metabolites and diagnostic imaging findings with hepatic lipidosis in bearded dragons (Pogona vitticeps) and effects of gemfibrozil therapy

OBJECTIVES

To evaluate the association between plasma metabolites, biochemical analytes, diagnostic imaging findings, and the histologic diagnosis of hepatic lipidosis in bearded dragons. To assess the effects of gemfibrozil therapy on hepatic lipid accumulation and associated diagnostic tests.

ANIMALS

Fourteen bearded dragons (Pogona vitticeps) with varying severity of hepatic lipid accumulation (with and without hepatic lipidosis) were included.

PROCEDURES

Animals underwent coelomic ultrasound, computed tomography (CT) scans, and coelioscopic hepatic biopsies. Clinical pathology tests included lipidologic tests, hepatic biomarkers, and mass spectrometry-based metabolomics. Animals were medicated with gemfibrozil 6mg/kg orally once a day for 2 months in a randomized blinded clinical trial prior to repeating previous diagnostic testing.

RESULTS

Hounsfield units on CT were negatively associated with increased hepatic vacuolation, while ultrasound and gross evaluation of the liver were not reliable. Beta-hydroxybutyric-acid (BHBA) concentrations were significantly associated with hepatic lipidosis. Metabolomics and lipidomics data found BHBA and succinic acid to be potential biomarkers for diagnosing hepatic lipidosis in bearded dragons. Succinic acid concentrations were significantly lower in the gemfibrozil treatment group. There was a tendency for improvement in the biomarkers and reduced hepatic fat in bearded dragons with hepatic lipidosis when treated with gemfibrozil, though the improvement was not statistically significant.

CONCLUSIONS

These findings provide information on the antemortem assessment of hepatic lipidosis in bearded dragons and paves the way for further research in diagnosis and treatment of this disease.

Diagnostic value of endoscopic retrograde cholangiopancreatography and therapeutic value of endoscopic sphincterotomy in dogs with suspected hepatobiliary disorders

Background

Conventional diagnostic methods have some limitations in diagnosing specific causes of canine hepatobiliary disorders. In the evaluation of the hepatobiliary system in dogs, ultrasonography (US) is the first imaging method of choice. Nonetheless, endoscopic retrograde cholangiopancreatography (ERCP) has also been proven to be a practicable technique for evaluating canine hepatobiliary (endoscopic retrograde cholangiography, ERC) and pancreatic duct (endoscopic retrograde pancreatography, ERP) disorders, providing additional therapeutic options by sphincterotomy (EST). To date, the efficacy and safety of diagnostic and therapeutic ERCP has not been evaluated in veterinary medicine literature. The present study sought to report complications and outcomes of dogs undergoing ERCP and EST, and to assess the usefulness of diagnostic ERCP by comparing the findings of US, ERCP and histopathological findings in liver and pancreas.

Results

This retrospective case series comprises data collected from 15 dogs that underwent successful ERC/ERCP. Nine dogs underwent EST following ERC. US and ERC were best in agreement when assessing the common bile duct. In case of disagreement between the modalities, the ERC findings of the ductal structures were in line with the available pathology findings more often than the US findings, whereas the opposite was noted for the gallbladder. The technical success rates were 88.2% for ERC, 66.7% for ERP, and 81.8% for EST, with no major complications during or immediately after the procedure. Immediate bile flow after EST was recorded in 7/9 dogs but only four showed coinciding clinical and laboratory improvement and four dogs were euthanized within 1-6 days after EST.

Conclusions

US remains a valuable initial diagnostic imaging method for hepatobiliary disorders and allows good assessment of the gallbladder. ERC can serve as a complementary procedure for diagnostic assessment of the hepatobiliary duct disorders. However, in order to improve the outcomes of EST, careful selection of patients for the procedure would require more advanced diagnostic imaging of the hepatobiliary area.

Remote-controlled cholangiography injection device: first clinical study in China

BACKGROUND

X-ray cholangiography is of great value in the imaging of biliary tract diseases; however, occupational radiation exposure is unavoidable. Moreover, clinicians must manually inject the contrast dye, which may result in a relatively high incidence of adverse reactions due to unstable injection pressure. Thus, there is a need to develop a novel remote-controlled cholangiography injection device.

METHODS

Patients with external biliary drainage requiring cholangiography were included. A remote-controlled injection device was developed with three major components: an injection pump, a pressure sensor, and a wireless remote-control panel. Image quality, adverse reactions, and radiation dose were evaluated.

RESULTS

Different kinds of X-ray cholangiography were successfully and smoothly performed using this remote-controlled injection device in all patients. The incidence of adverse reactions in the device group was significantly lower than that in the manual group (4.17% vs. 13.9%, P = 0.001), and increasing the injection pressure increased the incidence of adverse reactions. In addition, the device helped operators avoid ionizing radiation completely.

CONCLUSIONS

With good control of injection pressure (within 10 kPa), the remote-controlled cholangiography injection device could replace the need for the doctor to inject contrast agent with good security and effectivity. It is expected to be submitted for clinical application.

Computed tomography features for differentiating malignant and benign focal liver lesions in dogs: A meta-analysis

Computed tomography (CT) is often performed to complement ultrasound following detection of focal liver lesions (FLL). There is no consensus in the literature regarding the CT features that might be helpful in the distinction between benign and malignant FLL. The aim of this meta-analysis was to identify, based on the available literature, the qualitative and quantitative CT features able to distinguish between benign and malignant FLL. Studies on the diagnostic accuracy of CT in characterising FLL were searched in MEDLINE, Web of Science, and Scopus databases. Pooled sensitivity, pooled specificity, diagnostic odds ratio (DOR), receiver operator curve (ROC) area, were calculated for qualitative features. DOR were used to determine which qualitative features were most informative to detect malignancy; quantitative features were selected/identified based on standardised mean difference (SMD). Well-defined margins, presence of a capsule, abnormal lymph nodes, and heterogeneity in the arterial, portal and delayed phase were classified as informative qualitative CT features. The pooled sensitivity ranged from 0.630 (abnormal lymph nodes) to 0.786 (well-defined margins), while pooled specificity ranged from 0.643 (well-defined margins) to 0.816 (heterogeneous in delayed phase). Maximum dimensions, ellipsoid volume, attenuation of the liver in the pre-contrast phase, and attenuation of the liver in the arterial, portal, and delayed phase were found to be informative quantitative CT features. Larger maximum dimensions and volume (positive SMD), and lower attenuation values (negative SMD) were more associated with malignancy. This meta-analysis provides the evidence base for the interpreting CT imaging in the characterization of FLL.

Challenging diagnostic work-up of a massive fluid-filled structure in the cranial abdomen of a cat

A 9-year-old female, neutered European shorthair cat was presented with acute vomiting, obvious jaundice and painful enlargement of the abdomen. Icteric skin and mucous membranes in addition to severe bilirubinaemia (mainly direct bilirubin) and a large increase in liver enzyme activities were the main findings at the initial examination. Radio- and ultrasonographic evaluation revealed a massive fluid-filled structure caudal to the liver displacing abdominal organs, in particular the stomach. As this structure with a diameter of 8-10 cm occupied considerable space in the cranioventral abdomen, a detailed ultrasonographic examination of the liver and the gallbladder, and determination of the structure's association with a particular abdominal organ was initially impossible. Via ultrasound-assisted puncture under general anaesthesia 300 ml of an almost clear fluid could be aspirated. Cytological examination revealed a cyst content-like fluid with cell detritus.Further ultrasonographic and computed tomographic diagnostics followed by abdominal laparotomy finally enabled diagnosis of a cystic dilatation of the entire common bile duct and accumulation of white bile. Histopathological examination after euthanasia (requested by the owner) identified lymphoplasmacytic cholangitis and necrosis of the duodenal papilla. The massive dilatation of the common bile duct complicated its definite diagnosis by diagnostic imaging methods. It was most likely caused by a longer-standing obstruction of the bile flow by lymphoplasmacytic cholangitis with necrosis and granulation tissue formation in the area of the duodenal papilla. An interesting but initially misleading feature was the presence of white bile. The etiology of this extremely rare condition remains obscure but in the described case a manifestation of impaired hepatocyte function secondary to biliary stasis is suspected to be the cause.

Diagnostic utility of abdominal ultrasonography for evaluation of dogs with nontraumatic hemoabdomen: 94 cases (2014-2017)

OBJECTIVE

To evaluate the utility of abdominal ultrasonography (AUS) to detect grossly evident masses in dogs with nontraumatic hemoabdomen.

ANIMALS

94 client-owned dogs.

PROCEDURES

Electronic medical records from 2014 to 2017 were searched to identify dogs with nontraumatic hemoabdomen that had an AUS performed by a radiologist and subsequently underwent gross evaluation by surgery or necropsy. Ultrasonography, surgery, and histology reports were reviewed, and descriptive statistics were performed. Sensitivity of ultrasonography to detect grossly identifiable masses was calculated.

RESULTS

Differences were identified between AUS and surgical or necropsy findings for 51 of 94 (54%) dogs. Splenic masses were most commonly identified as the cause of hemoabdomen. Sensitivity of AUS was 87.4%, 37.3%, and 31.3% for masses in the spleen, liver, and mesentery, respectively. Five dogs had more lesions identified with AUS than were found on gross evaluation; 0 of 6 dogs with peritoneal diffuse nodular metastasis had lesions detected by AUS.

CONCLUSIONS AND CLINICAL RELEVANCE

In this sample of dogs, the utility of AUS to detect grossly identifiable lesions in dogs with nontraumatic hemoabdomen was limited, with the highest and lowest sensitivity found for splenic masses and diffuse nodular metastasis, respectively.

Observational Study on Lameness Recovery in 10 Dogs Affected by Iliopsoas Injury and Submitted to a Physiotherapeutic Approach

Simple Summary

Acute trauma of the iliopsoas muscle is often observed in sports and very active dogs. Nevertheless, the diagnosis is not always correctly addressed and can be underestimated during a clinical visit because it is generally secondary to other orthopedic and neurological issues. However, a correct diagnosis can lead to complete recovery of lameness in dogs who submit to physiotherapy. This paper has investigated, in a preliminary observational study, the recovery time for dogs affected by primary iliopsoas lesions and their return to normal activity.

Abstract

This preliminary study has investigated the outcome of physiotherapy in 10 dogs affected by a primary lesion of the iliopsoas muscle and the potential effects of sex, age, and breed on recovery. Ten dogs with primary injury of the iliopsoas muscle were retrospectively included in this study. Dogs were submitted to a rehabilitation program, characterized by a multimodal approach, including physical therapies and modalities. After recovery, patients were submitted to a further support period of rehabilitation to promote muscle strengthening and limit injury recurrence during their return to normal functional and sports activity. Border collies were highly represented. The recovery of lameness occurred after a mean of 22.6 ± 14.7 (median 18) days with a median number of five sessions. None of the examined variables affected the recovery time, except for the border collie breed, which showed a significantly faster recovery time; however, there was no difference between the breeds with regard to the number of sessions. Multimodal rehabilitation therapy may promote lameness recovery of mild-to-moderate iliopsoas lesions within 3 weeks. This preliminary study reports a clinical approach and recovery of primary iliopsoas lesions, findings that can provide clinicians with useful prognostic information for dogs involved in sports activities.

The Effects of Content Delivery Methods on Ultrasound Knobology and Image Quality Recognition Training in First-Year Veterinary Students

As new technologies are incorporated into the practice of veterinary medicine, it is imperative we utilize the most effective and impactful content delivery methods. Ultrasound technology has become more affordable and compact for veterinary hospitals, leading to easier incorporation into practice. This study compares three methods of delivering ultrasound knobology content to first-year veterinary students at Texas A&M University College of Veterinary Medicine and Biomedical Sciences. In a prospective study, first-year veterinary students were randomly selected to receive one of three content delivery methods: self-directed active learning (SDL), in-person instructor demonstration, or online module instruction. Knowledge acquisition was assessed using a 10-question quiz for short-term understanding followed by a 10-question quiz after a 6-week period to assess long-term knowledge retention. Student demographics were analyzed using the Chi-square test. Quiz scores were analyzed between groups using Kruskal-Wallis tests followed by Dunn's post-tests for multiple comparisons. Values of p ≤ .05 were considered significant. On the short-term and retention quiz questions, students participating in SDL scored significantly higher (10 [5-10]) than those receiving in-person instructor demonstration (9 [3-10] p = .01 and 8 [2-10] p = .0004, respectively) or the online module instruction training (Group C) (6 [1-10] p < 0.0001 and 8 [4-10] p < .001, respectively). Based on quiz scores, veterinary students exhibited better ultrasound knobology and image quality recognition proficiency immediately and at 6-weeks following SDL when compared with other content delivery methods. Self-directed learning methods are recommended when teaching ultrasonography to veterinary students.

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.

Use of contrast-enhanced ultrasonography for the detection of a feline insulinoma

Case summary

A 14-year-old cat was presented with a 2-week history of ataxia, seizure-like episodes, vomiting and weight loss. Serum biochemistry revealed severe hypoglycaemia, associated with low serum fructosamine and high insulin concentrations. On abdominal ultrasound, a focal hypoechoic well-defined mass in the left limb of the pancreas was identified and the presence of an additional smaller nodule was suspected. Contrast-enhanced ultrasonography (CEUS) confirmed the presence of both lesions and revealed a third, even smaller nodule. Partial pancreatectomy was performed. Histopathology and immunohistochemistry confirmed the presence of a multifocal insulinoma. Six months later, the cat presented with tenesmus and obstipation. A colorectal adenocarcinoma was diagnosed with histopathology after partial excision of a colorectal mass. The cat was euthanased a month later owing to recurrent episodes of severe obstipation.

Relevance and novel information

This is the first clinical description of the use of CEUS in the diagnosis of feline insulinoma. Furthermore, the available scientific literature on feline insulinoma was reviewed.

Hepatic computed tomography and cholangiography by use of gadoxetic acid in healthy cats

OBJECTIVE

To evaluate 3 doses of gadoxetic acid (Gd-EOB-DPTA) for hepatic CT and cholangiography in cats and to determine optimal timing for hepatobiliary image acquisition and evaluation of the contrast-enhanced hepatobiliary anatomy.

ANIMALS

6 healthy cats.

PROCEDURES

Cats were anesthetized; sequential CT scans were performed 0, 5, 25, 45, 65, and 85 minutes after IV administration of Gd-EOB-DTPA at low (0.0125 mmol/kg), medium (0.1 mmol/kg), and high (0.3 mmol/kg) doses. Hepatobiliary enhancement for each dose was objectively assessed over time and by use of a subjective semiquantitative visual assessment score.

RESULTS

No contrast-related adverse effects were detected. Each increase in dose of contrast medium resulted in a significant increase in HU across the hepatobiliary system. The liver had a significantly higher number of HU at 45 minutes, with homogenous enhancement at all doses of contrast medium. Contrast-enhanced cystic and bile duct HU were significantly higher and maximal at 65 minutes. Contrast-enhanced gallbladder HU did not plateau by 85 minutes. At a high dose of contrast medium, 12 of 60 (20%) biliary tract scores indicated no enhancement, 34 (57%) indicated poor enhancement, and 14 (23%) indicated moderate enhancement. No cat had excellent enhancement of the biliary tract at any dose.

CONCLUSIONS AND CLINICAL RELEVANCE

Gd-EOB-DTPA-enhanced hepatic CT and cholangiography in cats were safely performed and provided good hepatic enhancement but poor to moderate enhancement of the biliary tract. This technique may be useful for assessing the liver parenchyma in cats, but its value for assessing the biliary tract is questionable.