Dual-phase CT Angiography of the Normal Canine Portal and Hepatic Vasculature

A dual-phase computed tomography (CT) angiographic technique was developed to image the hepatic and portal vascular systems using a nonselective peripheral injection of contrast medium. The arterial phase of the dual-phase scan imaged the hepatic arteries and veins, and the portal phase imaged the portal vein as well as its tributaries and branches. There were three steps involved in acquiring the dual-phase scan: a survey helical scan for orientation, a dynamic scan for timing, and finally the dual-phase helical scan. Five normal dogs were imaged using a helical scan technique. The timing of the arterial and portal phases of the scan was calculated using time vs. attenuation graphs generated from a dynamic scan. The median time of appearance of contrast medium in the cranial abdominal aorta was 8.6 s and the median time of appearance of contrast medium in the hepatic artery occurred 0.4 s later. The median time of peak enhancement in the cranial abdominal aorta was 12.0 s. The median time of appearance of contrast medium in the portal vein was 14.6 s and median time of peak enhancement was 33.0 s. The dual-phase scans provided excellent vascular opacification. The hepatic arteries, hepatic veins, cranial and caudal mesenteric veins, splenic vein, gastroduodenal vein, and portal vein branches were all consistently well defined. Dual-phase CT angiography is a minimally invasive technique which provides an excellent three-dimensional representation of portal and hepatic vascular anatomy.     

Computed Tomography of the Normal Bovine Tarsus

The objective of this study was to provide a detailed multiplanar computed tomographic (CT) anatomic reference for the bovine tarsus. The tarsal regions from twelve healthy adult cow cadavers were scanned in both soft and bone windows via a 16‐slice multidetector CT scanner. Tarsi were frozen at ?20^o C and sectioned to 10‐mm‐thick slices in transverse, dorsal and sagittal planes respecting the imaging protocol. The frozen sections were cleaned and then photographed. Anatomic structures were identified, labelled and compared with the corresponding CT images. The sagittal plane was indispensable for evaluation of bone contours, the dorsal plane was valuable in examination of the collateral ligaments, and both were beneficial for assessment of the tarsal joint articulations. CT images allowed excellent delineation between the cortex and medulla of bones, and the trabecular structure was clearly depicted. The tarsal soft tissues showed variable shades of grey, and the synovial fluid was the lowest attenuated structure. This study provided full assessment of the clinically relevant anatomic structures of the bovine tarsal joint. This technique may be of value when results from other diagnostic imaging techniques are indecisive. Images presented in this study should serve as a basic CT reference and assist in the interpretation of various bovine tarsal pathology.     

Computed Tomography and Cross‐sectional Anatomy of the Normal Dromedary Camel Tarsus (One Humped Camel)

The purpose of this study was to provide a detailed computed tomographic (CT) anatomic reference for the dromedary camel tarsus. Six cadaver pelvic limbs, obtained from three clinically and radiographically sound dromedary camels, were scanned in both soft tissue and bone windows starting from the calcaneal tuber towards the proximal metatarsus. Limbs were frozen at ?20°C and sectioned transversely via an electric bone saw. The CT images were evaluated and correlated with their corresponding cryosections. The resulting images provided detailed anatomic features for bones, joints and soft tissue components of the tarsus and are intended to serve as a basic reference for the CT scanning of the dromedary camel tarsal pathology.     

Computed Tomographic Angiography under Sedation in the Diagnosis of Suspected Canine Pancreatitis: A Pilot Study

Background

Computed tomography (CT) is highly accurate for diagnosing pancreatitis in humans. The diagnosis of pancreatitis in dogs is based on clinical signs, laboratory findings, and ultrasonographic (US) changes. There are, however, inherent limitations in relying on laboratory and ultrasound findings for the clinical diagnosis of pancreatitis in dogs.

Hypothesis/Objectives

We hypothesized that CT angiography would be a rapid and reliable method to confirm pancreatitis in dogs compared to ultrasonography. The aim was to describe the CT characteristics and compare them to ultrasound findings and correlate the CT appearance to the severity of the patients'' clinical course.

Animals

A prospective pilot case series; 10 dogs with pancreatitis were enrolled if the history, clinical signs, laboratory, and ultrasonographic findings were indicative of pancreatitis.

Methods

A 3‐phase angiographic CT was performed under sedation. Afterward, each dog had US‐guided aspirates of the pancreas collected and blood drawn for cPLi assay. Images were evaluated for portion of visible pancreas, pancreatic size and margin, pancreatic parenchyma, presence of peripancreatic changes and contrast enhancement pattern. The results were compared with outcome.

Results

An enlarged, homogeneously to heterogeneously attenuating and contrast‐enhancing pancreas with ill‐defined borders was identified in all dogs. CT identified more features characterizing pancreatic abnormalities compared to US. Thrombi were found in 3/10 dogs. Three dogs with heterogeneous contrast enhancement had an overall poorer outcome than those with homogenous enhancement.

Conclusions and Clinical Importance

CT angiography under sedation was used in dogs to confirm clinically suspected pancreatitis and identified clinically relevant and potentially prognostic features of pancreatitis in dogs.     

Use of Contrast‐Enhanced Ultrasonography in Chronic Pathologic Canine Testes

Contrast‐enhanced ultrasound with sulphur hexafluoride microbubbles was performed in seven healthy dogs without a history of reproductive pathology and with histologically confirmed normal testes and in 42 dogs with chronic scrotal anomalies. All dogs underwent orchiectomy and histological examination. Enhancement patterns and perfusion parameters (peak intensity and regional blood flow) of testes of healthy dogs and testes with chronic lesions were compared. Fourteen non‐pathologic and 60 pathologic testes were considered. Forty testes were neoplastic (24 interstitial cell tumours, 9 seminomas, 7 Sertoli cell tumours), 20 were non‐neoplastic (16 testicular degenerations, 2 chronic orchitis, 1 testicular atrophy, 1 interstitial cell hyperplasia). In healthy dogs, the contrast medium flow had a rapid homogeneous wash‐in and wash‐out, with a short peak phase. With contrast ultrasound, testes that were inhomogeneous with a hyperenhancing pattern were associated with neoplasia (sensitivity: 87.5%, specificity: 100%). Lesions with persistent inner vessels and a hypo‐to‐isoechoic background were significantly associated with seminomas (sensitivity: 77.8%, specificity: 100%). Testes with non‐neoplastic lesions were characterized by a scant/moderate homogeneous enhancement. Perfusion parameters were higher in neoplastic lesions. Contrast ultrasound was a feasible diagnostic tool in the assessment of testicular lesions, with hyperenhancement being an important feature in the diagnosis of malignancy.     

Computed Tomography and Magnetic Resonance Anatomy of the Normal Orbit and Eye of the Horse

Traumatic and infectious diseases of the eye and orbit can occur in horses. For diagnosis and monitoring of such diseases, medical imaging is useful including computed tomography (CT) and magnetic resonance imaging (MRI). The aim of the current study was to describe CT and MRI anatomy of the equine orbit and ocular globe. The heads from four adult horses were scanned with a 6‐slice Emotion 6 CT (Siemens, Erlangen), and a 3.0 Tesla Siemens Verio 6 MRI using T1 and T2‐weighted sequences. To validate CT and MR reference images, these were compared with anatomical models and gross anatomical sections. The bony limits of the orbital cavity, the relationship of the orbit with sinuses and foramina of the skull were well identified by CT. MRI was useful to observe soft tissues and was able to identify adnexae of the ocular globe (eyelids, periorbital fat, extraocular muscles, lacrymal and tarsal glands). Although MRI was able to identify all components of the eye (including the posterior chamber), it could not differentiate sclera from choroid and retina. The only nerve identified was the optic nerve. Vessels were not seen in this series of cadaver heads. This study showed that CT and MRI are useful techniques to image the equine orbit and eye that can have clinical applications.     

Computed Tomographic Angiography of the Pancreas in Cats with Chronic Diabetes Mellitus Compared to Normal Cats

Background

Diabetes mellitus (DM) is a common endocrinopathy in cats. No known diagnostic test or patient characteristic at the time of diagnosis can predict likely disease course, unlike in people in whom computed tomographic angiography (CTA) is used. No published data exist regarding the CTA appearance of the pancreas in cats with DM, and thus, it is unknown what if any CTA variables should be further assessed for associations with pancreatic endocrine function.

Hypothesis/Objectives

A significant difference in pancreatic attenuation, volume, and size will be identified between normal cats and those with chronic DM on CTA.

Animals

Ten healthy control cats and 15 cats with naturally occurring DM present for >12 months.

Methods

Prospective cross‐sectional study comparing pancreatic attenuation, enhancement pattern, size, volume, pancreatic volume‐to‐body weight ratio (V:BW), pancreatic arterial: portal phase ratio (A:P), time‐to‐arterial enhancement, and time‐to‐peak portal enhancement on CTA between sedated healthy control cats and those with chronic DM.

Results

The pancreas in cats with chronic DM was significantly larger, had higher volume, higher V:BW, and shorter time‐to‐peak portal enhancement on CTA when compared to normal cats.

Conclusions and Clinical Importance

Peak portal enhancement time, pancreatic size, pancreatic volume, and V:BW can be used to differentiate normal sedated cats from those with chronic DM by CTA. These variables warrant further investigation to identify possible associations with endocrine function.     

Low‐Field Magnetic Resonance Imaging and Multislice Computed Tomography for the Detection of Cervical Syringomyelia in Dogs

Background

Syringomyelia (SM) is defined as the presence of fluid‐containing cavities within the parenchyma of the spinal cord. Sagittal magnetic resonance (MR) images have been described as the preferred technique for visualizing SM in dogs and humans.

Objective

To investigate whether computed tomography (CT) can be used to diagnose SM.

Animals

Thirty‐two client‐owned dogs referred for investigation of the cervical spine on magnetic resonance imaging (MRI) and CT.

Methods

Two reviewers retrospectively analyzed sagittal and transverse T1‐weighted spin echo (T1WSE) MR images and CT images from each dog for the presence of SM and, if SM was present, the width (mm, syrinx width [SW]) was measured. The results were analyzed statistically.

Results

For the presence of SM there was a moderate interobserver agreement for MR (81%, κ = 0.54) and almost perfect agreement for CT (94%, κ = 0.87). There was a moderate intramodality agreement for both observers (observer 1 81%, κ = 0.59; observer 2 81%, κ = 0.57). For measurement of SW the repeatability was the best on the midsagittal T1WSE images (95% repeatability coefficient <0.52 mm) and the reproducibility was the best on midsagittal images in both modalities (95% limits of agreement −0.55–0.45; P = 0.002).

Conclusion and Clinical Importance

Both techniques can be used to detect SM. Midsagittal MR and CT images are best used for measuring SW. Computed tomography can be used as a diagnostic tool for SM when MRI is not available, but CT cannot replace MRI as the standard screening technique for the detection of SM in Cavalier King Charles Spaniel for breeding purposes.     

Anatomy of the Thorax Structures in a Newborn Dromedary Camel by Computed Tomography

The anatomical and clinical studies of computed tomography (CT) in Camelidae are scarce. The use of CT in large animal medicine is currently limited by the logistic problems of acquiring computed tomographic images. Several CT studies exist on adult llamas, but not in camels. Accurate interpretation of the planimetric CT normal anatomy is necessary for the study and evaluation of pathological tissues. The purpose of our work was to evaluate the thorax of the newborn camel and related structures by means of CT images and macroscopic sections. One newborn camel of one week was used. It was euthanized for medical reasons unrelated to disease of the thorax. CT images were obtained and detailed anatomy of the thorax was acquired. Different CT windows, soft‐tissue and pulmonary windows, were applied in order to obtain detailed attenuation shades of the thoracic structures. The camel was frozen and sectioned using an electric saw, and we obtained high quality images of the thorax compared with CT images. Clinically relevant anatomic structures of the thorax cavity were identified and labelled in the corresponding CT and gross‐section photographs. The information presented in this paper should serve as an initial reference to evaluate CT images of the newborn camel thorax.