Computed tomographic findings in canine and feline heart base tumors (25 cases)

Tumors located at the heart base are rare in dogs and cats and aortic body tumors (chemodectoma/paraganglioma), hemangiosarcoma, ectopic thyroid carcinoma, lymphoma, and other uncommon neoplasia can be found at that location. The objective of this retrospective case series was to describe the CT characteristics of canine and feline heart base tumors. CT studies of 21 dogs and four cats with histologically or cytologically confirmed heart base tumors were reviewed for size, location, shape, margination, contrast enhancement, adjacent neovascularization, invasion, mass effect, cavitary effusions, and metastasis. Neuroendocrine tumors (15 aortic body tumors, three ectopic thyroid carcinoma, and three nonspecific neuroendocrine) were more commonly observed than hemangiosarcoma (4) and were frequently located between the cranial vena cava and aortic arch (12/21; 57%) and or dorsal to the pulmonary trunk bifurcation/pulmonary arteries (10/21; 48%). Hemangiosarcoma was more commonly found cranioventral to the aortic arch and cranial to the right auricular appendage (3/4; 75%). Mediastinal and peritumoral neovascularization was associated with 16/21 (76%) neuroendocrine tumors but none of the hemangiosarcoma. Median postcontrast attenuation in Hounsfield units (HU) was higher in neuroendocrine (110 HU) than in hemangiosarcoma (51 HU). Pericardial effusion was frequently observed with hemangiosarcoma (3/4; 75%) and infrequently in neuroendocrine (3/21; 14%). In four cases (all neuroendocrine), concurrent cranial mediastinal masses were present. CT provides useful information regarding the characteristics of heart base tumors, indicating differences between the appearance of neuroendocrine tumors and hemangiosarcoma. However, no differences were found between aortic body tumors and ectopic thyroid carcinoma.

Evaluation of the normal gastrointestinal tract in cats using dual-phase computed tomography

OBJECTIVES

In cats, although ultrasonography remains the preferred modality to evaluate the gastrointestinal tract, computed tomographic (CT) examination of the abdomen is commonly performed. However, a normal description of the gastrointestinal tract is lacking. This study describes the conspicuity and contrast enhancement pattern of the normal gastrointestinal tract in cats using dual-phase CT.

MATERIALS AND METHODS

Pre- and dual-phase postcontrast (early scan at 30 seconds and late scan mean at 84 seconds) abdominal CT exams of 39 cats without history, clinical signs or diagnosis of gastrointestinal disease were reviewed. The gastrointestinal tract was examined for conspicuity and enhancement pattern using commercially available viewing software (Osirix, v.6.5.2), and diameters of 16 gastrointestinal segments were recorded and compared with published radiographic and ultrasonographic reference values.

RESULTS

Of the 624 gastrointestinal segments, 530 (84.9%) were identified on precontrast studies and 545 (87.3%) segments on postcontrast studies. Of the gastrointestinal wall segments, 257 (41.2%) were identified on precontrast studies and 314 (50.3%) on postcontrast studies. Gastrointestinal segment diameters correlated well with published normal values, whereas wall thickness measurements usually were smaller compared with sonographic normal values. Early mucosal surface enhancement was frequently seen in the gastric cardia and fundus and ileocolic junction, and a mainly transmural wall enhancement in other gastrointestinal segments.

CLINICAL SIGNIFICANCE

Dual-phase CT allows for the identification of gastrointestinal tract segments and walls in cats. Contrast enhancement improves conspicuity and demonstrates wall layering in the cardia, fundus and ileocolic junction.

Tumours involving the retrobulbar space in cats: 37 cases

OBJECTIVES

The aim of this multicentre retrospective study was to describe the clinical presentation, imaging findings, diagnosis and outcomes of cats with retrobulbar neoplasia.

METHODS

A total of 37 cats that were diagnosed with retrobulbar neoplasia and underwent advanced imaging were recruited from searches of the clinical records of two referral hospitals. All cats had neoplasia confirmed via cytology or histopathology. Data relating to the signalment, presentation, results of investigations, treatment and outcome were recorded. A review of imaging studies was performed where possible.

RESULTS

In total, 23 cases (62%) were presented with respiratory signs. Exophthalmos was the most common ophthalmological examination finding, present in 18 cases (49%). Thirty-two cases (86%) had secondary extension of neoplasia to the retrobulbar space (most commonly from the nasal cavities), present in 20 cases (54%), of which 12 were lymphoma. In cases where contrast was administered, 28/35 (80%) had contrast-enhancing masses. Orbital extension was detected in 21 cases (57%), exophthalmos in 22 (59%), globe deformation in 12 (32%) and local lymphadenomegaly in 22 (61%). In total, 36 (97%) retrobulbar tumours were malignant. Thoracic imaging, where it was performed, was concerning for metastasis in 8/25 cases (31%), with abdominal imaging suggestive of metastasis in 5/12 (42%). The most common diagnosis was lymphoma with 19 cases (51%), with nasal lymphoma representing 12 of these, followed by carcinoma in 10 (27%). The median survival time, for cases where death was recorded, was 85 days (range 1-263 days).

CONCLUSIONS AND RELEVANCE

To the authors' knowledge, this is the largest study of neoplasia affecting the feline retrobulbar space. Retrobulbar tumours in cats are overwhelmingly malignant, and commonly due to secondary extension of tumours originating elsewhere. Lymphoma, particularly arising from the nasal cavities, was the most common cause. Cats presenting with signs suggestive of retrobulbar disease should be assessed for disease affecting any of the structures of the head.

A Retrospective Study of Clinical and Histopathological Features of 81 Cases of Canine Apocrine Gland Adenocarcinoma of the Anal Sac: Independent Clinical and Histopathological Risk Factors Associated with Outcome

Canine apocrine gland anal sac adenocarcinoma (AGASAC) is a malignant tumour with variable clinical progression. The objective of this study was to use robust multivariate models, based on models employed in human medical oncology, to establish clinical and histopathological risk factors of poor survival. Clinical data and imaging of 81 cases with AGASAC were reviewed. Tissue was available for histological review and immunohistochemistry in 49 cases. Tumour and lymph node size were determined using the response evaluation criteria in the solid tumours system (RECIST). Modelling revealed tumour size over 2 cm, lymph node size grouped in three tiers by the two thresholds 1.6 cm and 5 cm, surgical management, and radiotherapy were independent clinical variables associated with survival, irrespective of tumour stage. Tumour size over 1.3 cm and presence of distant metastasis were independent clinical variables associated with the first progression-free interval. The presence of the histopathological variables of tumour necrosis, a solid histological pattern, and vascular invasion in the primary tumour were independent risk factors of poor survival. Based upon these independent risk factors, scoring algorithms to predict survival in AGASAC patients are presented.

Canine intrahepatic portosystemic shunt insertion into the systemic circulation is commonly through primary hepatic veins as assessed with CT angiography

Congenital intrahepatic portosystemic shunts (IHPSS) in dogs are traditionally classified as right, left, or central divisional. There are few descriptive studies regarding the variation of IHPSS within these categories. This multicenter, analytical, cross-sectional study aimed to describe a large series of dogs with CT angiography (CTA) of IHPSS, hypothesizing that there would be variation to the existing classification. Ninety CTA studies were assessed for IHPSS type, insertion, and the relationship of the insertion to the primary hepatic veins. Ninety-two percent of IHPSS inserted into a primary hepatic vein (HV) or phrenic vein, 8% inserted directly into the ventral aspect of the intrahepatic caudal vena cava. The most common IHPSS type was a single right divisional (44%), including those inserting via the right lateral HV or the caudate HV. Left divisional IHPSS (33%) inserted into the left HV or left phrenic vein. Central divisional IHPSS (13%) inserted into the quadrate HV, central HV, dorsal right medial HV, or directly into the ventral aspect of the intrahepatic caudal vena cava. Multiple sites of insertion were seen in 9% of dogs. Within left, central, and right divisional types, further subclassifications can therefore commonly be defined based on the hepatic veins with which the shunting vessel communicates. Relating IHPSS morphology to the receiving primary HV could make IHPSS categorization more consistent and may influence the type and method of IHPSS attenuation recommended.

Survey of surgical specialists' content preferences in radiology reports for extrahepatic portosystemic shunts

The aim of this prospective, survey study was to assess the opinions of specialist surgeons as to the preferred content, nomenclature, and classification of extrahepatic portosystemic shunts for inclusion in radiology reports. A link to an online survey was sent by email to members of the European College of Veterinary Surgeons and the Association of Veterinary Soft Tissue Surgeons, and was made available on the American College of Veterinary Surgeons web forum and Facebook page. There were 93 respondents (survey sent to over 2500 email addresses and made available in two online locations). Most respondents agreed that they both review the images themselves (87/92, 95%) and read the radiology report (82/92, 89%) prior to surgery. Most respondents believed that the radiology report should contain a detailed anatomic description of the insertion (83/92, 90%), origin (54/91, 59%), and course (70/92, 76%) of the shunt, as well as a measure of the diameter of the shunting vessel at its insertion (54/92, 59%). Most respondents (70/90, 78%) disagreed that a brief description of shunt type, such as portocaval or portophrenic, was sufficient. Respondents were undecided regarding the use of an alphanumeric classification system (36/92, 39% agree; 32/92, 35% disagree). There was agreement that details of the presence or absence of urolithiasis (91/93, 98%), renomegaly (54/93, 58%), and peritoneal fluid (72/92, 78%) should be included in the report. The results of this study will help to guide reporting radiologists in providing descriptions of extrahepatic portosystemic shunts that include information most preferred by the recipient surgeons.

Comparative evaluation of a novel, moderately hypofractionated radiation protocol in 56 dogs with symptomatic intracranial neoplasia

Background: Use of strongly hypofractionated radiation treatments in dogs with intracranial neoplasia did not improve outcomes and yielded increased rates of toxicosis.

Objectives: To evaluate safety and efficacy of a new, moderately hypofractionated radiation protocol of 10 × 4 Gy compared to a standard protocol.

Animals: Convenience sample of 56 client‐owned dogs with primary symptomatic brain tumors.

Methods: Retrospective observational study. Twenty‐six dogs were assigned to the control standard protocol of 20 × 2.5 Gy (group A) and 30 dogs to the new protocol of 10 × 4 Gy (group B), assigned on owners' informed consent. Statistical analysis was conducted under the “as treated” regime, using Kaplan‐Meier and Cox‐regression analysis. Treatment was delivered with technically advanced image‐guided radiation therapy. The 2 treatment groups were compared in terms of outcome and signs of toxicosis.

Results: Overall progression‐free interval (PFI) and overall survival (OS) time were favorable, with 663 (95%CI: 497;828) and 637 (95%CI: 403;870) days, respectively. We found no significant difference between the two groups: PFI for dogs in group A vs B was 608 (95%CI: 437;779) days and mean (median not reached) 863 (95%CI: 644;1083) days, respectively (P = .89), and OS for dogs in group A vs B 610 (95%CI: 404;816) and mean (median not reached) 796 (95%CI: 586;1007) days (P = .83).

Conclusion and Clinical Importance: In conclusion, 10 × 4 Gy is a safe and efficient protocol for treatment of primary intracranial neoplasia and future dose escalation can be considered.

Comparison of medical and/or surgical management of 23 cats with intracranial empyema or abscessation

Objectives

Feline intracranial abscessation or empyema is infrequently reported in the veterinary literature. To date, the largest study is based on a population of 19 cats with otogenic infection. The aim of this study was to review a larger population of cats with intracranial empyema from multiple aetiologies and document their signalment, imaging findings, treatment protocols (including medical and/or surgical management) and to compare outcomes.

Methods

Cases presenting to a single referral centre over a 10 year period with compatible history, neurological signs and imaging findings consistent with intracranial abscessation and empyema were reviewed retrospectively.

Results

Twenty-three cats met the inclusion criteria. Advanced imaging (CT and/or MRI) was performed in 22/23 cats; one case was diagnosed via ultrasound. Ten cases underwent medical and surgical management combined, 10 underwent solely medical management and three were euthanased at the time of diagnosis. Short-term outcome showed that 90% of surgically managed and 80% of medically managed cats were alive at 48 h post-diagnosis. Long-term survival showed that surgically managed cases and medically managed cases had a median survival time of 730 days (range 1–3802 days) and 183 days (range 1–1216 days), respectively. No statistical significance in short- or long-term survival ( P >0.05) was found between medically and surgically managed groups.

Conclusions and relevance

Feline intracranial abscessation and empyema are uncommon conditions that have historically been treated with combined surgical and medical management. This study documents that, in some cases, intracranial abscessation and empyema can also be successfully treated with medical management alone.

Treatment of mandibular osteomyelitis in two red-necked wallabies (Macropus rufogriseus) by means of intensive long-term parenteral drug administration and serial computed tomographic monitoring

CASE DESCRIPTION 2 female red-necked wallabies (Macropus rufogriseus) were evaluated because of sudden-onset mandibular swelling, ptyalism, and hyporexia. CLINICAL FINDINGS Physical examination revealed a mandibular swelling with a fluctuant center in both wallabies. Hematologic analysis revealed leukocytosis with a mature neutrophilia and monocytosis in one wallaby (case 1) and a slight neutrophilia, hyperglobulinemia, and high serum alanine aminotransferase activity in the other (case 2). Cytologic examination of the swelling revealed a uniform population of gram-negative rods in case 1 and neutrophilic inflammation in case 2. Radiography revealed a soft tissue mandibular swelling with osteolucency around mandibular incisor roots in both wallabies. Computed tomography revealed changes consistent with chronic active mandibular osteomyelitis and reactive bone formation, but also sequestra formation not appreciable via radiography. TREATMENT AND OUTCOME Long-term antimicrobial treatment was initiated with clindamycin (17 to 21 mg/kg [7.7 to 9.5 mg/lb], IV, q 12 h for 40 to 55 days) and high-dose benzathine penicillin G (80,000 U/kg [36,364 U/lb], SC, q 12 h for 150 days). Serial CT was performed to evaluate response to treatment and resolution of disease. A CT scan 18 months after the initial evaluation revealed complete resolution of osteomyelitis and sequestra. CLINICAL RELEVANCE Advanced imaging and long-term treatment and management were integral to the successful outcome for these wallabies, given that the osseous changes visible on CT images were not visible on standard radiographs, guiding therapeutic decision-making. This report provides new therapeutic and diagnostic monitoring information to assist clinicians with similar cases.

MRI and clinical characteristics of suspected cerebrovascular accident in nine cats

Objectives

Cerebrovascular accidents (CVAs) are infrequently reported in cats. To date, clinical characteristics, including lesion localisation and MRI findings, have only been reported in two cats. The aim of the current study is to document MRI findings in cats presenting with CVAs over an 11 year period. Cases were reviewed according to initial clinical presentation, subsequent physical and neurological findings, predisposing systemic disease and short- and long-term (when available) outcome with a view to identifying any typical pattern in disease occurrence.

Methods

Patient records of cats presenting to a single referral centre from January 2005 to September 2016 with acute onset, non-progressive (after 24 h) intracranial signs compatible with a CVA and where an MRI was performed within 72 h were retrospectively reviewed.

Results

Nine cats met the inclusion criteria. All cats had ischaemic CVAs (presumptively diagnosed in eight cats and confirmed in one cat following post-mortem examination). No cases of haemorrhagic CVAs were identified. Four cats presented with territorial infarcts that were confined to the territory of the rostral or caudal cerebellar arteries (n = 4). Lacunar infarcts were identified in five cats in the location of the cerebrum (n = 1), the thalamus/midbrain (n = 2) and the medulla oblongata (n = 2). Concurrent systemic disease was identified in most (n = 8/9). In the present study short-term prognosis was favourable and 8/9 cats survived to 48 h following admission.

Conclusions and relevance

CVAs in cats occur in the same vascular territories as in dogs and have similar MRI features. This study notes that the presenting cats had a high likelihood of concurrent disease (8/9 cases) but had a favourable short-term prognosis, if neither the clinical presentation nor concurrent disease were severe.

Comparison of clinical signs and outcomes between dogs with presumptive ischemic myelopathy and dogs with acute noncompressive nucleus pulposus extrusion

OBJECTIVE To compare clinical signs and outcomes between dogs with presumptive ischemic myelopathy and dogs with presumptive acute noncompressive nucleus pulposus extrusion (ANNPE). DESIGN Retrospective study. ANIMALS 51 dogs with ischemic myelopathy and 42 dogs with ANNPE examined at 1 referral hospital. PROCEDURES Medical records and MRI sequences were reviewed for dogs with a presumptive antemortem diagnosis of ischemic myelopathy or ANNPE. Information regarding signalment, clinical signs at initial examination, and short-term outcome was retrospectively retrieved from patient records. Long-term outcome information was obtained by telephone communication with referring or primary-care veterinarians and owners. RESULTS Compared with the hospital population, English Staffordshire Bull Terriers and Border Collies were overrepresented in the ischemic myelopathy and ANNPE groups, respectively. Dogs with ANNPE were significantly older at disease onset and were more likely to have a history of vocalization at onset of clinical signs, have spinal hyperesthesia during initial examination, have a lesion at C1-C5 spinal cord segments, and be ambulatory at hospital discharge, compared with dogs with ischemic myelopathy. Dogs with ischemic myelopathy were more likely to have a lesion at L4-S3 spinal cord segments and have long-term fecal incontinence, compared with dogs with ANNPE. However, long-term quality of life and outcome did not differ between dogs with ischemic myelopathy and dogs with ANNPE. CONCLUSIONS AND CLINICAL RELEVANCE Results revealed differences in clinical signs at initial examination between dogs with ischemic myelopathy and dogs with ANNPE that may aid clinicians in differentiating the 2 conditions.

Radiographic anatomy of juvenile bovine limbs

Juvenile bovine patients who present with clinical signs of lameness are commonly evaluated using radiographic techniques both within a hospital setting and in a farm environment. The radiographic development of the juvenile bovine skeleton is currently poorly documented. In this study, the limbs of four heifer calves were sequentially radiographed to assess development of the juvenile bovine appendicular skeleton in the first 12 months of life. Images were acquired at three weeks, three months, six months, nine months and one year of age. The normal radiographic anatomy of the fore limbs and hindlimbs and the changes over the first 12 months are described. The majority of physes remain open throughout this period, with the exception of the proximal physes of the proximal and middle phalanges, the proximal radial physis, and the proximal humeral physis which close radiographically between 9 months and 12 months of age, and fusion of the fourth and central tarsal bones occurs between 9 months and 12 months of age. The results of this study may aid in differentiating normal and abnormal anatomy in the juvenile bovine limb.

Use of dual-phase contrast computed tomography for evaluation of the normal canine male genital tract

OBJECTIVES

To evaluate the use of dual-phase contrast-enhanced computed tomography for the depiction of the features of the male genital tract, highlighting differences between entire and neutered dogs.

METHODS

Computed tomography exams of 23 entire and 23 neutered male dogs with no history of urogenital disease were included in this retrospective study, with exams acquired pre-, 30 and 98·9 ±27·4 seconds after intravenous contrast administration. The genital structures were subjectively evaluated for visibility, contrast enhancement and enhancement pattern and differences between entire and neutered dogs were described. Objective measurements of attenuation and size of the prostatic tissue were acquired.

RESULTS

The root, body and glans of the penis could be evaluated in all dogs and appeared larger in entire dogs, though objective measurements could not be reliably made because these structures are small and curved. There was contrast enhancement of the cavernous structures, most reliably in the bulb and corpus spongiosum and most frequently in entire dogs in the delayed post-contrast phase. In entire dogs, the small testicular vessels most commonly had a vermiform shape in the early post-contrast phase, and a homogeneous appearance in the delayed phase. Sternal recumbency with the coxofemoral joints extended improved visibility of the genital structures.

CLINICAL SIGNIFICANCE

Dual-phase contrast-enhanced computed tomography is useful for depiction of the structures of the male genital tract, with the early phase especially highlighting the vascular and the delayed phase the cavernous structures.

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.

Comparison of the Diagnostic Image Quality of the Canine Maxillary Dentoalveolar Structures Obtained by Cone Beam Computed Tomography and 64-Multidetector Row Computed Tomography

The objective of this blinded study was to validate the use of cone beam computed tomography (C) for imaging of the canine maxillary dentoalveolar structures by comparing its diagnostic image quality with that of 64-multidetector row CT Sagittal slices of a tooth-bearing segment of the maxilla of a commercially purchased dog skull embedded in methylmethacrylate were obtained along a line parallel with the dental arch using a commercial histology diamond saw. The slice of tooth-bearing bone that best depicted the dentoalveolar structures was chosen and photographed. The maxillary segment was imaged with cone beam CT and 64-multidetector row CT. Four blinded evaluators compared the cone beam CT and 64-multidetector row CT images and image quality was scored as it related to the anatomy of dentoalveolar structures. Trabecular bone, enamel, dentin, pulp cavity, periodontal ligament space, and lamina dura were scored In addition, a score depicting the evaluators overall impression of the image was recorded. Images acquired with cone beam CT were found to be significantly superior in image quality to images acquired with 64-multidetector row CT overall, and in all scored categories. In our study setting cone beam CT was found to be a valid and clinically superior imaging modality for the canine maxillary dentoalveolar structures when compared to 64-multidetector row CT.

INTER- AND INTRAOBSERVER AGREEMENT FOR DIAGNOSING PRESUMPTIVE ISCHEMIC MYELOPATHY AND ACUTE NONCOMPRESSIVE NUCLEUS PULPOSUS EXTRUSION IN DOGS USING MAGNETIC RESONANCE IMAGING

Ischemic myelopathy (IM) and acute noncompressive nucleus pulposus extrusion (ANNPE) are common spinal emergencies in dogs with similar clinical presentations. Magnetic resonance imaging (MRI) criteria for a presumptive antemortem diagnosis have been reported, however inter- and intraobserver agreement for use of these criteria has not been established. The aim of this retrospective, descriptive, cross-sectional study was to describe inter- and intraobserver agreement for using previously published MRI criteria to diagnose presumptive IM and ANNPE in a sample dogs. Dogs with a presumptive diagnosis of IM or ANNPE and available MRI scan data were retrieved from medical record archives during the period of 2009 and 2013. A total of 127 dogs were identified. From this sample, MRI scans for 60 dogs were randomly selected and duplicated for intraobserver analysis, giving a total of 187 anonymized studies that were presented to two blinded assessors (one board-certified veterinary neurologist, one board-certified veterinary radiologist). Assessors were asked to diagnose lesions as IM or ANNPE based on previously published MRI characteristics. Interobserver agreement in diagnosing IM or ANNPE was moderate (Kappa = 0.56) and intraobserver agreement was moderate to good (Assessor 1 Kappa = 0.79, Assessor 2 Kappa = 0.47). Agreement was strongest for detecting presence of lesions overlying a vertebral body (94% of lesions that were diagnosed as IM) or overlying an intervertebral disk (85% of lesions that were diagnosed as ANNPE). Findings indicated that use of previously published MRI criteria yields moderate inter- and moderate to good intraobserver agreement for a presumptive diagnosis of IM or ANNPE in dogs.

QUANTITATIVE PLANAR AND VOLUMETRIC CARDIAC MEASUREMENTS USING 64 MDCT AND 3T MRI VS. STANDARD 2D AND M-MODE ECHOCARDIOGRAPHY: DOES ANESTHETIC PROTOCOL MATTER?

Cross-sectional imaging of the heart utilizing computed tomography and magnetic resonance imaging (MRI) has been shown to be superior for the evaluation of cardiac morphology and systolic function in humans compared to echocardiography. The purpose of this prospective study was to test the effects of two different anesthetic protocols on cardiac measurements in 10 healthy beagle dogs using 64-multidetector row computed tomographic angiography (64-MDCTA), 3T magnetic resonance (MRI) and standard awake echocardiography. Both anesthetic protocols used propofol for induction and isoflourane for anesthetic maintenance. In addition, protocol A used midazolam/fentanyl and protocol B used dexmedetomedine as premedication and constant rate infusion during the procedure. Significant elevations in systolic and mean blood pressure were present when using protocol B. There was overall good agreement between the variables of cardiac size and systolic function generated from the MDCTA and MRI exams and no significant difference was found when comparing the variables acquired using either anesthetic protocol within each modality. Systolic function variables generated using 64-MDCTA and 3T MRI were only able to predict the left ventricular end diastolic volume as measured during awake echocardiogram when using protocol B and 64-MDCTA. For all other systolic function variables, prediction of awake echocardiographic results was not possible (P = 1). Planar variables acquired using MDCTA or MRI did not allow prediction of the corresponding measurements generated using echocardiography in the awake patients (P = 1). Future studies are needed to validate this approach in a more varied population and clinically affected dogs.

Effects of two different anesthetic protocols on cardiac flow measured by two dimensional phase contrast magnetic resonance imaging

Companion animals are routinely anesthetized or heavily sedated for cardiac MRI studies, however effects of varying anesthetic protocols on cardiac function measurements are incompletely understood. The purpose of this prospective study was to compare effects of two anesthetic protocols (Protocol A: Midazolam, fentanyl; Protocol B: Dexmedetomidine) on quantitative and qualitative blood flow values measured through the aortic, pulmonic, mitral, and tricuspid valves using two-dimensional phase contrast magnetic resonance imaging (2D PC MRI) in healthy dogs. Mean flow per heartbeat values through the pulmonary artery (Qp) and aorta (Qs) were compared to right and left ventricular stroke volumes (RVSV, LVSV) measured using a reference standard of 2D Cine balanced steady-state free precession MRI. Pulmonary to systemic flow ratio (Qp/Qs) was also calculated. Differences in flow and Qp/Qs values generated using 2D PC MRI did not differ between the two anesthetic protocols (P = 1). Mean differences between Qp and RVSV were 3.82 ml/beat (95% limits of agreement: 3.62, -11.26) and 1.9 ml/beat (-7.86, 11.66) for anesthesia protocols A and B, respectively. Mean differences between Qs and LVSV were 1.65 ml/beat (-5.04, 8.34) and 0.03 ml/beat (-4.65, 4.72) for anesthesia protocols A and B, respectively. Mild tricuspid or mitral reflux was seen in 2/10 dogs using 2D PC MRI. No aortic or pulmonic insufficiency was observed. Findings from the current study indicated that these two anesthetic protocols yield similar functional measures of cardiac blood flow using 2D PC MRI in healthy dogs. Future studies in clinically affected patients are needed.

Otogenic meningoencephalomyelitis due toCryptococcus gattii(VGII) infection in a cat from Western Australia

Case summary

A 7-year-old spayed domestic longhair cat from Perth, Western Australia, presented with left-sided head tilt, dysphonia, head shaking, inappetence and weight loss. A polypoid lesion had previously been removed from the external ear canal. Otitis media with extension into the external ear canal was suspected and investigated using video-otoscopy and computed tomography examination. Invasive disease with extension from the middle ear to the base of the skull, and intracranial extension into the caudal fossa and cranial cervical vertebral canal was detected. Cytology of external ear canal exudate showed capsulated budding yeasts and Cryptococcus gattii VGII was cultured. Treatment with amphotericin B infusions and oral fluconazole was prescribed, with nutritional support via oesophagostomy tube. The cat clinically recovered 12 months after treatment commenced.

Relevance and novel information

This case report describes the successful medical treatment of otogenic meningoencephalomyelitis due to C gattii (VGII) infection in a cat.

Assessment of respiration-induced displacement of canine abdominal organs in dorsal and ventral recumbency using multislice computed tomography

Respiratory-induced organ displacement during image acquisition can produce motion artifacts and variation in spatial localization of an organ in diagnostic computed tomography (CT) examinations. The purpose of this prospective study was to quantify respiratory-induced abdominal organ displacement in dorsal and ventral recumbency using five normal dogs. All dogs underwent CT examinations using 64 multidetector row CT (64-MDCT). A "3-dimensional (3D) apneic CT exam" of the abdomen was acquired followed by a "4-dimensional (4D) ventilated CT exam." The liver, pancreas, both kidneys, both medial iliac lymph nodes, and urinary bladder were delineated on the 3D-apneic examination and the organ outlines were compared to the maximum alteration in organ position in the 4D-ventilated examination. Displacement was measured in dorsal-to-ventral (DV), right-to-left (RL), and cranial-to-caudal (CC) directions. Respiratory-induced displacement of canine abdominal organs was not predictable and showed large variability in the three directions evaluated. For most canine abdominal organs, dorsal recumbency provided overall the least amount of displacement among all directions evaluated except for liver and urinary bladder. For liver, a large variability was found for all directions and a statistically significant difference was found only in the RL direction with ventral recumbency exhibiting less displacement (P = 0.0099). For the urinary bladder, ventral recumbency also provided less displacement but this was statistically significant only in the RL direction (P < 0.0001). Findings from this study indicated that dorsal recumbency may be preferred for minimizing respiratory motion artifacts in whole abdomen studies, but ventral recumbency may be preferred for liver and urinary bladder studies when respiration cannot be controlled.

Effects of two different anesthetic protocols on 64-MDCT coronary angiography in dogs

Heart rate is a major factor influencing diagnostic image quality in computed tomographic coronary artery angiography (MDCT-CA), with an ideal heart rate of 60-65 beats/min in humans. The purpose of this prospective study was to compare effects of two different clinically applicable anesthetic protocols on cardiovascular parameters and 64-MDCT-CA quality in 10 healthy dogs. Scan protocols and bolus volumes were standardized. Image evaluations were performed in random order by a board-certified veterinary radiologist who was unaware of anesthetic protocols used. Heart rate during image acquisition did not differ between protocols (P = 1), with 80.6 ± 7.5 bpm for protocol A and 79.2 ± 14.2 bpm for protocol B. Mean blood pressure was significantly higher (P > 0.05) using protocol B (protocol A 62.9 ± 9.1 vs. protocol B 72.4 ± 15.9 mmHg). The R-R intervals allowing for best depiction of individual coronary artery segments were found in the end diastolic period and varied between the 70% and 95% interval. Diagnostic quality was rated excellent, good, and moderate in the majority of the segments evaluated, with higher scores given for more proximal segments and lower for more distal segments, respectively. Blur was the most commonly observed artifact and mainly affected the distal segments. No significant differences were identified between the two protocols for optimal reconstruction interval, diagnostic quality and measured length individual segments, or proximal diameter of the coronary arteries (P = 1). Findings indicated that, when used with a standardized bolus volume, both of these anesthetic protocols yielded diagnostic quality coronary 64-MDCT-CA exams in healthy dogs.

Diagnosis and surgical treatment of a malignant trichoepithelioma of the ear canal in a pet rabbit (Oryctolagus cuniculus)

CASE DESCRIPTION

A 10-year-old spayed female Holland Lop-mix pet rabbit (Oryctolagus cuniculus) was evaluated because of purulent-hemorrhagic discharge from the right ear canal and a suspected mass within that ear canal.

CLINICAL FINDINGS

Results of contrast-enhanced CT, video otoscopy, and histologic examination of endoscopic tissue biopsy samples indicated severe otitis media and externa and a benign trichoepithelioma of the right ear canal.

TREATMENT AND OUTCOME

Total ear canal ablation and lateral bulla osteotomy were performed. Histologic examination of a surgical biopsy sample of the mass indicated malignant trichoepithelioma. Tumor recurrence was detected 22 weeks after surgery. The rabbit was euthanized 33 weeks after surgery because of the large size of the recurrent tumor and declining quality of life. Necropsy findings indicated a malignant trichoepithelioma with local and lymphatic invasion into the right mandibular lymph node.

CLINICAL RELEVANCE

This was the first report of the clinical diagnosis, surgical treatment, and outcome for a domestic rabbit with a diagnosis of a malignant trichoepithelioma of the ear canal and associated otitis media and externa. Neoplasia should be included as a differential diagnosis for pet rabbits with otitis externa and media. Although such tumors are typically benign, trichoepitheliomas in rabbits can be malignant. Computed tomography and histologic examination of tissue samples were useful diagnostic techniques, but histologic examination of an endoscopic biopsy sample did not allow identification of malignant characteristics of the trichoepithelioma.

Advanced multimodality imaging of an anomalous vessel between the ascending aorta and main pulmonary artery in a dog

A 1-year-old male German shorthaired pointer was referred for evaluation of tachypnea and hemoptysis. A grade VI/VI left basilar continuous murmur was ausculted. Multimodality imaging consisting of thoracic radiographs, transthoracic and transesophageal echocardiography, fluoroscopy-guided selective angiography, computed tomography angiogram (CTA) and magnetic resonance angiogram (MRA), was performed on this patient. The defect included a left-to-right shunting anomalous vessel between the ascending aorta and main pulmonary artery, along with a dissecting aneurysm of the main and right pulmonary artery. An MRA post-processing technique (PC VIPR) was used to allow for high resolution angiographic images and further assessment of the patient's hemodynamics prior to surgical correction. This case report describes the clinical course of a canine patient with a rare form of congenital cardiac disease, and the multiple imaging modalities that were used to aid in diagnosis and treatment.

Simultaneous MRI of lung structure and perfusion in a single breathhold

PURPOSE

To develop and demonstrate a breathheld 3D radial ultrashort echo time (UTE) acquisition to visualize co-registered lung perfusion and vascular structure.

MATERIALS AND METHODS

Nine healthy dogs were scanned twice at 3 Tesla (T). Contrast-enhanced pulmonary perfusion scans were acquired with a temporally interleaved three-dimensional (3D) radial UTE (TE = 0.08 ms) sequence in a breathhold (1 s time frames over a 33 s breathhold). The 3D breathheld volume was reconstructed into time-resolved perfusion datasets, and a composite vascular structure dataset. For structural comparison, a 5 min respiratory-gated 3D radial UTE scan was acquired. Data were analyzed by quantitative metrics and radiologist scoring.

RESULTS

Appropriate time-course of contrast was seen in all subjects. Right ventricle to aorta transit times were 7.4 ± 2.0 s. Relative lung enhancement was a factor of 8.4 ± 1.5. Radiologist scoring showed similarly excellent visualization of the pulmonary arteries to the subsegmental level in breathheld (94% of cases) and respiratory-gated (100% of cases) acquisitions (P = 0.33) despite the aggressive under sampling in the breathheld scan. Similarly, differentiation of lung tissue and airways was achieved by both acquisition methods.

CONCLUSION

A time-resolved 3D radial UTE sequence for simultaneous imaging of pulmonary perfusion and co-registered vascular structure is feasible.

Computed tomographic features of basihyoid ectopic thyroid carcinoma in dogs

Eight dogs with a firm, nonpainful swelling in the ventral laryngeal region and with a final diagnosis of ectopic thyroid carcinoma were investigated by Computed Tomography (CT) at six different institutions. Computed Tomography findings were reviewed, focusing on lesion volume, shape, margins, relationship with surrounding structures and adjacent vessels, attenuation characteristics, and presence of metastases. Ectopic thyroid carcinomas were seen as oval-to-bilobed masses centered on the basihyoid bone with associated bone lysis, highly vascularized capsules with central poorly contrast enhancing areas. In all cases there was laryngeal wall infiltration, in two dogs invasion of the laryngeal lumen and in one case invasion of the ventral muscular and subcutaneous plane. Metastases were found in retropharyngeal lymph nodes (three cases) and in the lung (two cases). Ectopic thyroid carcinoma should be considered in the differential diagnosis when a mass in the basihyoid region is present. Described CT features may be typical for ectopic thyroid neoplasia and could be used to help decide the therapeutic plan.

Visceral smooth muscle α-actin deficiency associated with chronic intestinal pseudo-obstruction in a Bengal cat (Felis catus x Prionailurus bengalensis)

An adult Bengal cat (Felis catus × Prionailurus bengalensis) with a prolonged history of partial anorexia, regurgitation, and weight loss and a clinical, radiographic, and ultrasonographic diagnosis of persistent megaesophagus and gastrointestinal ileus was submitted for necropsy. The intestinal tract was diffusely distended by gas and fluid with appreciable loss of muscle tone and an absence of luminal obstruction, consistent with the clinical history of chronic intestinal pseudo-obstruction. Histologically, the autonomic nervous system was intact, but the smooth muscle within the gastrointestinal wall exhibited a marked basophilia that was most pronounced in the jejunum. Immunohistochemistry for neurofilament, synaptophysin, CD117, and desmin demonstrated that the number of myenteric ganglia, number of interstitial cells, and leiomyocyte desmin content were similar when compared with the unaffected age- and species-matched control. Immunohistochemistry for smooth muscle α-actin demonstrated a striking loss of immunoreactivity, predominantly in the circular layer of the jejunum, that corresponded with the tinctorial change in leiomyocytes. Transmission electron microscopy revealed loss of myofibrils, loss of organelle polarity, and significantly larger central mitochondria (megamitochondria) in affected leiomyocytes, as well as nonspecific degenerative changes. Although the presence of a primary leiomyopathy and a causal relationship could not be confirmed in this case, leiomyopathies are considered a cause of chronic intestinal pseudo-obstruction in human medicine, and loss of smooth muscle α-actin immunoreactivity is one recognized marker for intestinal dysmotility.

Imaging diagnosis-pulmonary-tracheobronchial prolapse in a new Caledonian giant gecko (Rhacodactylus leachianus)

A 3-year-old male New Caledonian giant gecko, or Leach's gecko (Rhacodactylus leachianus) presented with acute lethargy and coelomic distention. Findings from survey radiographs and an upper gastrointestinal tract contrast study were consistent with severe aerophagia, a collapsed left lung, and hyperinflation of the right lung due to suspected bronchial obstruction. The gecko was treated with conservative medical management, but was found dead 5 days after presentation. Necropsy findings showed intussusception of the proximal left lung into the left mainstem bronchus and trachea.

Osteosarcoma of the maxilla with concurrent osteoma in a southern sea otter (Enhydra lutris nereis)

Southern sea otters (Enhydra lutris nereis) are threatened marine mammals that belong to the family Mustelidae and are native to the coast of Central California. Neoplasia is reported infrequently in sea otters. An adult female free-ranging southern sea otter was found alive at Pebble Beach, Monterey County, California, on January 1st, 1994 and died soon after capture. The carcass was submitted to the US Geological Survey - National Wildlife Health Center for necropsy examination. Grossly, a mass with rubbery texture was firmly attached to the left maxillary region of the skull and the nasopharynx was occluded by soft neoplastic tissue. Post-mortem skull radiographs showed an oval, smoothly marginated mineralized opaque mass centered on the left maxilla, extending from the canine tooth to caudal to the molar and replacing portions of the zygomatic arch and palatine and temporal bones. The majority of the mass protruded laterally from the maxilla and was characterized by central homogeneous mineral opacity. Microscopically, the mass was characterized by fully differentiated lamellar non-osteonal bone that expanded beyond the margins of the adjacent normal osteonal bone. Sections of the nasopharyngeal mass were comprised of moderately pleomorphic cells with bony stroma. Gross, microscopical and radiological findings were compatible with maxillary osteosarcoma with concurrent osteoma.

Pulmonary angiography with 64-multidetector-row computed tomography in normal dogs

Pulmonary angiography using 64-multidetector-row computed tomography (MDCT) was used to evaluate pulmonary artery anatomy, and determine the sensitivity of pulmonary artery segment visualization in four Beagle dogs using images reconstructed to 0.625 mm and retro-reconstructed to 1.25 and 2.5 mm slice thickness. Morphologically, characteristic features included a focal narrowing in the right cranial pulmonary artery in all dogs, which should not be mistaken as stenosis. While the right cranial pulmonary artery divided into two equally sized branches that were tracked into the periphery of the lung lobe in all dogs, only a single left cranial (cranial portion) lobar artery was present. Compared with 1.25 and 2.5 mm retro-reconstructions, 0.625 mm reconstructions allowed for detection of significantly (P≤0.05) more pulmonary artery segments and sharper depiction of vessel margins. Clinical applications such as prevalence and significance of diameter changes, and detection of pulmonary arterial thrombembolism on lobar and sublobar level, using pulmonary angiography with 64-MDCT applying 0.625 mm reconstruction slice thickness remain to be established.