64-Slice ECG-gated computed tomographic angiography for assessment of coronary arteries in brachycephalic dogs with pulmonary stenosis

BACKGROUND

Brachycephalic dogs with pulmonary stenosis are known to have a higher incidence of concurrent coronary artery abnormalities than non-brachycephalic breeds, which increases risk when performing balloon valvuloplasty. The use of ECG-gated CT angiography has been reported for the evaluation of coronary arteries in normal dogs and dogs with pulmonary stenosis. The purpose of this study was to report findings of coronary artery origination and morphology of main branches using ECG-gated CT angiography in brachycephalic dogs with pulmonary stenosis.

METHODS

An ECG-gated CT angiographic protocol was used to image coronary artery anatomy in nine brachycephalic dogs with pulmonary stenosis. Images were assessed for quality as well as coronary artery morphology by one veterinary radiologist, one veterinary cardiologist and one veterinary radiology resident.

RESULTS

All nine dogs had good to excellent image quality. Coronary artery anomalies were identified in three of nine dogs: one R2A anomaly, one L2A anomaly and one L2C anomaly. Two dogs were assessed to be poor balloon valvuloplasty candidates based on CT angiographic images.

LIMITATION

Coronary artery morphology was not confirmed via postmortem examination in all patients.

CONCLUSION

ECG-gated CT angiography is a minimally invasive imaging modality capable of diagnosing various coronary artery anomalies in brachycephalic dogs with pulmonary stenosis and aiding in the determination of patient candidacy for balloon valvuloplasty.

Comparison of two-dimensional imaging to three-dimensional modeling of intrahepatic portosystemic shunts using computed tomography angiography

Computed tomography angiography (CTA) is used for the diagnosis of intrahepatic portosystemic shunts (IHPSS). When planning for transcatheter intervention, caudal vena cava (CVC) measurements are typically obtained from two-dimensional (2D) imaging to aid in stent selection. We hypothesized that clinically applicable three-dimensional (3D) IHPSS models can be generated, and CVC measurements will not differ between 2D images and 3D models. Computed tomography angiography datasets from client-owned dogs with IHPSS at the University of Georgia Veterinary Teaching Hospital from 2016 to 2022 were analyzed. Materialise Mimics 25.0 and 3-matic 17.0 were used for 3D modeling. Caudal vena cava diameters were measured in 2D dorsal and transverse planes 20 mm cranial and caudal from the shunt ostium and were compared with CVC diameters from 3D models. Length was measured in the 2D dorsal plane between midpoints of each diameter and compared to the 3D model length. Data are presented as mean (SD), and intraclass correlation coefficients were performed. Three-dimensional models were generated for 32 IHPSS (15 right-, 12 left-, and five central-divisional). Two-dimensional dorsal and transverse area-associated diameter measurements were 16.7 mm (5.6) and 15.5 mm (4.2) cranial; 14.9 mm (4.2) and 14.3 mm (3.7) caudal. Three-dimensional area-associated diameter measurements were 15.3 mm (4.4) cranial and 14.0 mm (3.6) caudal. The 2D length was 61.5 mm (7.1) compared with 3D 59.9 mm (7.2). Intraclass correlation coefficients comparing 2D and 3D diameters were all >0.80, indicating very good agreement, with good agreement (>0.60) for length. Clinically applicable 3D IHPSS models can be generated using engineering software. Measurements from 3D models are consistent with 2D planar imaging. Both 2D CTA and 3D virtual models can be utilized for preprocedural planning, depending on clinician preference.

Optimizing contrast protocol for bone-subtraction CT angiography of intracranial arteries in normal dogs using 160-slice CT

BACKGROUND

Bone-subtraction computed tomography angiography (CTA) (BSCTA) is a new technique designed to overcome the limitation of three-dimensional CTA, where the vessels surrounded by bone and calcification can be obscured. An optimal contrast CT protocol for intracranial artery visualization with BSCTA has yet to be established in dogs.

OBJECTIVES

The purpose of this study was to determine the optimal contrast protocol of CTA for visualizing intracranial artery using an automatic bone-subtraction technique in dogs.

METHODS

Brain CTA was performed four times for each of nine healthy beagle dogs to cover all the contrast protocols: two different contrast iodine concentrations (300 and 370 mgI/mL) and two different contrast media injection rates (2 and 4 mL/s). Bone removal post-processing was performed automatically by subtracting the non-enhanced CT data from the contrast CT data using a dedicated workstation. The bone-subtracted intracranial vessels were analysed for quantitative and qualitative evaluation.

RESULTS

Quantitative evaluation showed significantly higher CT attenuation values for the group with a 370 mgI/mL iodine content at a rate of 4 mL/s than the two groups with a 300 mgI/mL iodine content at the rates of 2 and 4 mL/s (p < 0.001). Qualitative assessment revealed significantly higher mean scores for the 370 mgI/mL groups than the 300 mgI/mL groups and significantly higher mean scores for the 4 mL/s groups than the 2 mL/s groups (p < 0.05).

CONCLUSIONS

The optimal contrast protocol for BSCTA suggests that high iodine material concentration and high injection rate should be used for strong arterial attenuation and great visualization of the intracranial arterial structure in dogs.

Percutaneous shunt vessel embolisation with Amplatzer vascular plugs II and IV in the treatment of dogs with splenophrenic shunts: four cases (2019-2022)

OBJECTIVES

To describe the treatment of four dogs with splenophrenic shunts using percutaneous shunting vessel embolisation with Amplatzer vascular plugs II and IV and provide information on their clinical outcomes.

MATERIALS AND METHODS

Dogs with splenophrenic shunts treated at a veterinary hospital from January 2019 to December 2022 were identified through a medical record search.

RESULTS

Six dogs with splenophrenic shunts were identified. Two dogs were excluded because they were treated with laparoscopic surgery. Four underwent percutaneous shunting vessel embolization with Amplatzer vascular plugs and were included in the case series. A sheath was placed in the left external jugular vein and a balloon catheter was advanced to the shunting vessel under fluoroscopy. Portal vein pressure was confirmed to be within an acceptable range during temporary balloon occlusion. Based on preoperative CT angiography and intraoperative contrast examination, Amplatzer vascular plugs II were selected for two dogs and IV were selected for two dogs. Under fluoroscopy, the plug was deployed into the shunting vessel, and angiography confirmed occlusion. In all cases, the increase in portal pressure after temporary occlusion was within the acceptable range, and complete occlusion of blood flow was possible with a single plug. There were no major procedure-related complications. No dogs developed post-ligation seizures or signs of portal hypertension. In addition, improvements in ammonia values were observed in all cases.

CLINICAL SIGNIFICANCE

Percutaneous splenophrenic shunt embolisation using Amplatzer vascular plugs II and IV is technically feasible in dogs, and assessed by intra-procedure angiography, a single plug completely obstructed blood flow in all dogs. Based on the literature search, this is the first report describing Amplatzer vascular plugs for the treatment of splenophrenic shunts.

Computed tomography angiography aids in predicting resectability of isolated liver tumors in dogs

OBJECTIVE

To assess the accuracy of CT angiography (CTA) in predicting resectability, degree of surgical difficulty, and individual factors that may impact resectability of isolated hepatic masses in dogs.

ANIMALS

Prospective study of 20 dogs with 21 isolated hepatic masses.

PROCEDURES

All CTAs and surgeries were performed between June 16, 2013, and November 30, 2016, at The Animal Medical Center in New York. Preoperative CTA images were evaluated by a board-certified surgeon (n = 2). A preoperative assessment was completed, documenting several predetermined factors aimed at predicting resectability of each mass and the degree of surgical difficulty. Resectability was divided into gross resectability and complete histologic excision. Following surgery, the surgeon completed a postoperative assessment documenting the intraoperative findings. Independently, a blinded board-certified radiologist analyzed the images and completed an identical preoperative assessment.

RESULTS

The radiologist was more accurate in lesion localization compared to the surgeon (P = .023). Seventeen (17/21) masses were grossly resectable in surgery. Two additional (2/21) masses that were deemed grossly resectable were incompletely excised on histopathologic analysis. Both the surgeon and radiologist were accurate in their prediction of gross resectability and complete excision. Major vascular involvement, multilobar involvement, and right-sided laterality negatively affected resectability. The surgeon was significantly more accurate in predicting the degree of surgical difficulty (κ = 0.50) when compared to the radiologist (κ = 0.38).

CLINICAL RELEVANCE

Preoperative CTA of isolated hepatic masses is useful in prediction of surgical difficulty and resectability, as well as identifying several factors that impact resectability.

Comparison of bone subtraction CT angiography with standard CT angiography for evaluating circle of Willis in normal dogs

BACKGROUND

Bone subtraction computed tomography angiography (BSCTA) is a useful alternative technique for improving visualization of vessels surrounded by skull bone. However, no studies have compared computed tomography angiography (CTA) and BSCTA for improving the visibility of canine cerebral blood vessels.

OBJECTIVES

To evaluate the potential benefit of BSCTA for better delineation of brain arteries of the circle of Willis (CoW) in dogs by comparing BSCTA with non-subtraction computed tomography angiography (NSCTA).

METHODS

Brain CTA was performed for nine healthy beagle dogs using a bolus tracking method with saline flushing. A total dose of 600 mgI/kg of contrast agent with an iodine content of 370 mgI/mL was injected at a rate of 4 ml/s. Bone removal was achieved automatically by subtracting non-enhanced computed tomography (CT) data from contrast CT data. Five main intracranial arteries of the CoW were analyzed and graded on a scale of five for qualitative evaluation.

RESULTS

Scores of basilar artery, middle cerebral artery, and rostral cerebral artery in the BSCTA group were significantly higher than those in the NSCTA group (p = 0.001, p = 0.020, and p < 0.0001, respectively). Scores of rostral cerebellar artery (RcA) and caudal cerebral artery (CCA) did not differ significantly between the two groups. However, scores of RcA and CCA in the BSCTA group were higher than those in the NSCTA group.

CONCLUSIONS

BSCTA improved visualization of intracranial arteries of the CoW with close contact to bone. Thus, it should be recommended as a routine scan method in dogs suspected of having brain vessel disease.

Suspected contrast-induced nephropathy in three sequential patients undergoing computed tomography angiography and transarterial embolization for nonresectable neoplasia

CASE DESCRIPTION

During the same week, 3 sequential patients (a 10-year-old 8.7-kg spayed female poodle cross [dog 1], 13-year-old 2.6-kg spayed female domestic longhair cat, and 13-year-old 9.0-kg castrated male mixed-breed dog [dog 2]) underwent CT-angiography (day 0) and transarterial embolization (day 1) for nonresectable hepatocellular carcinoma (n = 2) or prostatic carcinoma (1).

CLINICAL FINDINGS

Contrast-induced nephropathy (CIN) was suspected in all animals on the basis of higher serum creatinine concentrations after contrast medium administration (exposure), compared with baseline concentrations before exposure, consistent with CIN definitions. The total dose of contrast medium was < 3 mL/kg for each exposure. For all 3 patients, creatinine concentration peaked at a median of 3 days (range, 2 to 3 days) after the first exposure (day 0), and the median absolute and relative increases in creatinine concentration after exposure (vs baseline concentrations before exposure) were 2.9 mg/dL (range, 2.2 to 3.7 mg/dL) and 410% (range, 260 to 720%), respectively.

TREATMENT AND OUTCOME

The patients received individually tailored supportive care for acute kidney injury. Serum creatinine concentrations began to improve at a median of 4 days (range, 3 to 4 days) and returned to within reference limits at a median of 7 days (range, 3 to 13 days) following initial exposure.

CLINICAL RELEVANCE

CIN should be considered as a potential complication following IV administration of contrast medium. Short-term outcome following CIN can be excellent with supportive care.

Novel coronary artery anomaly in a French bulldog with pulmonary stenosis

A 9-month-old French Bulldog with pulmonary stenosis (PS) underwent transthoracic echocardiography (TTE) and electrocardiogram-gated coronary computed tomography angiography (ECG-CCTA) for presurgical planning of pulmonary balloon valvuloplasty (PBV). Transthoracic echocardiography revealed severe PS and identified two distinct coronary ostia (left and right). Electrocardiogram-gated coronary computed tomography angiography showed a circumpulmonary course of the interventricular paraconal coronary artery, which abnormally originated from the right coronary artery. Based on this case report, the echocardiographic identification of two coronary ostia does not rule out a coronary artery anomaly with circumpulmonary course (as previously hypothesized), and coronary computed tomography angiography may be recommended for presurgical planning of PBV in French Bulldogs.

Effects of kernel and window setting combinations on assessments of small and complicated vasculature in computed tomography angiographic images of dogs with and without tumors

OBJECTIVE

To evaluate the effect of kernel and window settings on the assessment of small and complicated vasculature in CT angiographic (CTA) images of kidneys, jejunum with mesentery, and tumors in dogs.

ANIMALS

20 healthy dogs and 20 dogs with tumors.

PROCEDURES

Images from CTA performed previously in dogs were reconstructed with 3 different combinations of kernel and window settings (soft kernel with soft tissue window, soft kernel with bone window, and sharp kernel with bone window), and reconstructed images of the left kidney and the jejunum with the mesentery in healthy dogs and tumors in affected dogs were evaluated by reviewers blinded to the settings.

RESULTS

For images of kidney and jejunum with mesentery, reviewers' scores for the conspicuity of vascularity in the arterial phase and the differentiation of the organs from the adjacent structures were significantly higher when viewed in bone window (vs soft tissue window) regardless of kernel setting. For images of head and gastrointestinal tumors, reviewers' scores for differentiation of intratumoral vasculature were higher when viewed in sharp kernel with bone window versus other setting combinations. However, the conspicuity of gastrointestinal, hepatic, or splenic tumoral vessels from the adjacent structures had higher reviewer scores for images in soft kernel with soft tissue window, compared with other setting combinations.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that reconstruction of CTA images with sharp kernel combined with bone window settings might have clinical utility in evaluating and planning treatments for dogs with various tumors; however, additional research is warranted to further identify effects of various kernel and window setting combinations on assessments of small and complicated vasculature in larger and more diverse populations of dogs with and without tumors.

Effects of airway pressure on contrast enhancement and diameter of the pulmonary artery in healthy dogs as determined by use of computed tomography angiography

OBJECTIVE

To evaluate effects of airway pressure on contrast enhancement and diameter of the pulmonary artery and determine the optimal airway pressure for pulmonary CT angiography in dogs.

ANIMALS

8 healthy Beagles.

PROCEDURES

Thoracic CT was performed at end-expiration (0 cm H₂O) and 2 positive-pressure end-inspirations (10 and 20 cm H₂O). Attenuation curves of enhancement for the sinus of the pulmonary trunk artery were obtained by use of a bolus technique. Contrast medium (300 mg of I/kg) was administered IV, and CT imaging began at the time of peak enhancement. At each pressure, time to peak enhancement, ratio of blood flow from the caudal vena cava to the right side of the heart (K_CdVC), and enhancement characteristics and diameter changes of the pulmonary artery were evaluated.

RESULTS

All dogs had a significant delay for time to peak enhancement in the sinus of the pulmonary trunk artery as airway pressure increased. The K_CdVC progressively increased as airway pressure increased, and there was low contrast enhancement and increased pulmonary artery filling defects at 20 cm H₂O. All pulmonary arteries had marked increases in diameter as pressure increased. Arterial distensibility in the gravity-dependent cranial lung region was greater than that in the gravity-independent caudal lung region at the 2 positive-pressure end-inspirations.

CONCLUSIONS AND CLINICAL RELEVANCE

Airway pressure affected time to peak enhancement, K_CdVC, contrast enhancement, and pulmonary artery diameter. Results suggested that 10 cm H₂O could be an optimal pressure for evaluation of the pulmonary artery of dogs by use of CT angiography. (Am J Vet Res 2019;80;756-763).

Postmortem imaging in goats using computed tomography with air as a negative contrast agent

PURPOSE

Evaluation of the usefulness of air as a negative contrast medium of blood vessels in goats in post mortem computed tomography (PMCT) and establishing the protocol with appropriate doses and timing of the contrast medium administration.

METHODS

Thirty three goats were euthanized 10 to 300 min before the study. First, in 3 goats air was administered into the left or right common carotid artery at dose of 60, 100 and 120 ml/kg, and after each dose PMCT was performed in lateral recumbency. As the latter dose proved to visualize blood vessels best, following 30 goats were examined in the same manner but only with the use of air dose of 120 ml/kg. The quality of CT scans was evaluated independently by two board-certified radiologists.

RESULTS

In all studied animals the vascular system filled with air was clearly visualized on CT scans. In most of goats this amount of air revealed vessels smaller than 4 mm in diameter.

CONCLUSIONS

PMCT with air as a negative contrast agent may be an alternative technique used in post-mortem angiography.

Transcatheter embolization of systemic-to-pulmonary artery fistulas in a dog using embolization coils and silk suture

A 4-month-old intact female Cavalier King Charles spaniel presented for evaluation of a left, basilar continuous murmur. Transthoracic echocardiography suggested anomalous vessels around the main pulmonary artery, and computed tomography angiography revealed two systemic-to-pulmonary artery fistulas. Transcatheter embolization of these fistulas was achieved with a combination of embolization coils and silk suture threads delivered through a microcatheter.

Evaluation of hepatic tumor portal perfusion using mesenteric angiography: A pilot study in 5 dogs

BACKGROUND

Mesenteric angiography is a sensitive method for visualizing portal perfusion in the dog.

OBJECTIVES

To evaluate hepatic portal perfusion in dogs with incompletely resectable hepatic tumors using mesenteric angiography.

ANIMALS

Five client-owned dogs with incompletely resectable hepatic tumors evaluated with mesenteric angiography.

METHODS

Retrospective case series. Electronic medical records at the Animal Medical Center were analyzed to identify dogs that underwent mesenteric portography to determine blood flow to nonresectable hepatic tumors and subsequently determine ideal routes for transarterial embolization, vascular stent placement, or both. The images obtained from mesenteric angiography were analyzed and compared to those obtained from computed tomography angiography.

RESULTS

Portography was accomplished using direct mesenteric venography in 3 dogs with hepatocellular carcinoma (HCC), cranial mesenteric arteriography in 1 dog with hepatic adenoma or well-differentiated HCC, and via splenic arteriovenous fistula in 1 dog with diffuse hepatic hemangiosarcoma metastases. Mean pixel densities in areas of hepatic tumor growth identified statistically significant decreases in portal blood flow (P = .02) compared to normal hepatic parenchyma.

CONCLUSIONS AND CLINICAL IMPORTANCE

Initial findings indicate that the blood supply to large and metastatic hepatic tumors in dogs may correlate with that in humans, such that the majority of the tumor blood supply arises from the hepatic artery and not the portal vein. Differences in blood supply between normal hepatic parenchyma and hepatic tumors might be exploited by developing selective tumor therapies such as arterial embolization or chemoembolization that largely spare normal liver tissue. Further investigation is warranted.

Morphometric evaluation of the portal vein by means of abdominal computed tomographic angiography in dogs free of vascular anomalies

OBJECTIVE To determine the mean diameter of the main portal vein (PV) in healthy dogs by use of CT angiography, identify any associations between PV diameter and certain dog characteristics, and validate a clinically valuable ratio for quantifying the size of the PV. ANIMALS 100 dogs with no hepatic, cardiac, or vascular anomalies that underwent abdominal CT angiography. PROCEDURES Diameters of the main PV, abdominal aorta (Ao), and caudal vena cava (CVC) were measured by 2 observers at a defined location on postcontrast CT angiographic images in axial, sagittal, and transverse planes. Dog characteristics were evaluated for associations with PV diameter, and a PV:Ao diameter ratio was calculated. Intraclass correlations were calculated to assess intra- and interobserver agreement in vessel diameter measurements. RESULTS Mean diameter values were 7.9 mm (range, 4.1 to 14.8 mm) for the PV, 8.9 mm (range, 3.7 to 13.7 mm) for the Ao, and 11.4 mm (range, 4.4 to 22.5 mm) for the CVC. The PV:Ao diameter ratio was 0.91 mm. The PV diameter was significantly associated with dog body weight but not with dog age, sex, or neuter status. Intra- and interobserver reliabilities for measurements of all 3 vessels were considered excellent (intraclass correlation coefficients > 0.85). CONCLUSIONS AND CLINICAL RELEVANCE Findings indicated that the PV:Ao diameter ratio was a repeatable measurement that may be useful for evaluating the size of the portal vasculature in dogs and possibly for distinguishing healthy PVs from abnormal PVs in dogs with hepatic vascular anomalies.

Clinical, echocardiographic and advanced imaging characteristics of 13 dogs with systemic-to-pulmonary arteriovenous fistulas

OBJECTIVES

The objective is to describe the clinical, radiographic, echocardiographic and angiographic findings in dogs with systemic-to-pulmonary arteriovenous fistula (SPAVF).

ANIMALS

Thirteen medical records of client-owned dogs with a diagnosis of SPAVF were reviewed/analysed.

METHODS

This is a retrospective study of case records. Thoracic radiography, transthoracic echocardiography (TTE), transesophageal echocardiography (TEE), three-dimensional TEE, intracardiac echocardiography, fluoroscopy-guided or computed tomography (CT) angiography were carried out.

RESULTS

Based on the TTE, SPAVF was identified in seven of the included dogs. In eight cases, TEE and angiography were both performed and confirmed the diagnosis. Computed tomography angiography was performed in three dogs. A case was diagnosed by TEE alone, another one by three-dimensional TEE and the latter by intracardiac echocardiography.

CONCLUSIONS

Transthoracic echocardiography identified seven cases of SPAVF, while definitive diagnosis in the remaining dogs required selective angiography or computed tomography angiography.

Micro-arteriovenous malformation causing spontaneous metacarpal pad hemorrhage in a dog

A 5-year-old neutered male Labrador retriever dog with a 3-year history of intermittent hemorrhage from the right metacarpal pad was evaluated. A small region of hyperattenuation of the metacarpal pad was evident on computed tomographic angiography. Excisional biopsy of the location of the purported hemorrhage revealed a micro-arteriovenous malformation on histologic examination.