A correlation of computed tomographic esophageal hiatal cross-sectional surface area between brachycephalic and nonbrachycephalic cats.

In humans and dogs, especially brachycephalics, enlargement of the esophageal hiatus and insufficiency have been correlated with decreased lower esophageal sphincter pressure and increased frequency of gastroesophageal reflux. In cats, it has been suggested that gastroesophageal reflux occurs frequently with upper airway obstruction, including brachycephalics. Therefore, the purpose of the study was to determine whether the esophageal hiatal cross-sectional surface area (EH-CSA) differs between brachycephalic and nonbrachycephalic cats. Clinical records and CT images of cats that underwent thoracic, abdominal, and entire skull CT at multiple centers between January 2015 and September 2022 were retrospectively reviewed. Esophageal hiatal parameters (EH-CSA, EH-long axis diameter, and EH-short axis diameter) and craniometric indices (cranial index, skull index, and facial index) were measured by using multiplanar reconstruction, and the correlation of craniometry with EH-CSA was investigated. Ninety-eight cats (group 1: 42 brachycephalic cats and group 2: 56 nonbrachycephalic cats) were included. Esophageal hiatal cross-sectional surface area in brachycephalic cats was significantly larger than that in nonbrachycephalic cats. The EH-CSA significantly increased with the craniometric indices tending to increase with brachycephalism. The present study contributes to the veterinary literature by providing the EH-CSA as anatomical evidence that could likely correlate to gastroesophageal reflux predisposition in brachycephalic cats.

Can CT texture analysis parameters be used as imaging biomarkers for prediction of malignancy in canine splenic tumors?

Splenic hemangiosarcoma has morphological similarities to benign nodular hyperplasia. Computed tomography (CT) texture analysis can analyze the texture of images that the naive human eye cannot detect. Recently, there have been attempts to incorporate CT texture analysis with artificial intelligence in human medicine. This retrospective, analytical design study aimed to assess the feasibility of CT texture analysis in splenic masses and investigate predictive biomarkers of splenic hemangiosarcoma in dogs. Parameters for dogs with hemangiosarcoma and nodular hyperplasia were compared, and an independent parameter that could differentiate between them was selected. Discriminant analysis was performed to assess the ability to discriminate the two splenic masses and compare the relative importance of the parameters. A total of 23 dogs were sampled, including 16 splenic nodular hyperplasia and seven hemangiosarcoma. In each dog, total 38 radiomic parameters were extracted from first-, second-, and higher-order matrices. Thirteen parameters had significant differences between hemangiosarcoma and nodular hyperplasia. Skewness in the first-order matrix and GLRLM_LGRE and GLZLM_ZLNU in the second, higher-order matrix were determined as independent parameters. A discriminant equation consisting of skewness, GLZLM_LGZE, and GLZLM_ZLNU was derived, and the cross-validation verification result showed an accuracy of 95.7%. Skewness was the most influential parameter for the discrimination of the two masses. The study results supported using CT texture analysis to help differentiate hemangiosarcoma from nodular hyperplasia in dogs. This new diagnostic approach can be used for developing future machine learning-based texture analysis tools.

18F-FDG PET/CT image findings of a dog with adrenocortical carcinoma.

BACKGROUND: In human medicine, 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) has been used to differentiate between benign and malignant adrenal tumors and to identify metastases. However, canine adrenocortical carcinomas identified by 18F-FDG PET/computed tomography (CT) have not been reported. CASE PRESENTATION: A 13-year-old, castrated male, Cocker Spaniel dog with severe systolic hypertension exhibited an adrenal mass approximately 3.6 cm in diameter on ultrasonography. There was no evidence of pulmonary metastasis or vascular invasion on thoracic radiography and abdominal ultrasonography, respectively. 18F-FDG PET/CT was performed to identify the characteristics of the adrenal mass and the state of metastasis. One hour after injection of 5.46 MBq/kg 18F-FDG intravenously, the peripheral region of the adrenal mass visually revealed an increased 18F-FDG uptake, which was higher than that of the liver, and the central region of the mass exhibited necrosis. The maximal standardized uptake value (SUV) of the adrenal mass was 3.24; and relative SUV, calculated by dividing the maximal SUV of the adrenal tumor by the mean SUV of the normal liver, was 5.23. Adrenocortical carcinoma was tentatively diagnosed and surgical adrenalectomy was performed. Histopathologic examination of the resected adrenal mass revealed the characteristics of an adrenocortical carcinoma. After adrenalectomy, systolic blood pressure reduced to below 150 mmHg without any medication. CONCLUSION: This is the first case report of 18F-FDG PET/CT findings in a dog with suspected adrenocortical carcinoma and may provide valuable diagnostic information for adrenocortical carcinoma in dogs.

In Vivo Magnetic Resonance Thermometry for Brain and Body Temperature Variations in Canines under General Anesthesia.

The core body temperature tends to decrease under general anesthesia. Consequently, monitoring the core body temperature during procedures involving general anesthesia is essential to ensure patient safety. In veterinary medicine, rectal temperature is used as an indicator of the core body temperature, owing to the accuracy and convenience of this approach. Some previous studies involving craniotomy reported differences between the brain and core temperatures under general anesthesia. However, noninvasive imaging techniques are required to ascertain this because invasive brain temperature measurements can cause unintended temperature changes by inserting the temperature sensors into the brain or by performing the surgical operations. In this study, we employed in vivo magnetic resonance thermometry to observe the brain temperatures of patients under general anesthesia using the proton resonance frequency shift method. The rectal temperature was also recorded using a fiber optic thermometer during the MR thermometry to compare with the brain temperature changes. When the rectal temperature decreased by 1.4 ± 0.5 °C (mean ± standard deviation), the brain temperature (white matter) decreased by 4.8 ± 0.5 °C. Furthermore, a difference in the temperature reduction of the different types of brain tissue was observed; the reduction in the temperature of white matter exceeded that of gray matter mainly due to the distribution of blood vessels in the gray matter. We also analyzed and interpreted the core temperature changes with the body conditioning scores of subjects to see how the body weight affected the temperature changes.

CT and radiographic evaluation of bronchial collapsibility at forced expiration in asymptomatic brachycephalic dogs.

Bronchial collapse due to bronchomalacia is an important cause of chronic coughing in dogs. Radiographic and CT evidence of bronchial collapse has previously been reported in healthy Beagle dogs under forced expiration. However, published studies in brachycephalic dog breeds that are prone to bronchial collapse are currently lacking. In the present prospective analytical experimental study, CT and radiography were used to measure the bronchial diameter and collapsibility of each pulmonary bronchus during end-expiratory, 5 mL/kg forced-expiratory, and 10 mL/kg forced-expiratory phases in 17 asymptomatic brachycephalic dogs and six healthy Beagle dogs. Bronchial collapsibility was significantly greater during forced expiration, than that at the end of expiration in both groups (P < .001). Bronchial collapsibility measurements of the left lung lobes and the right cranial, middle, and accessory lobes were significantly higher in asymptomatic brachycephalic dogs than those in healthy Beagle dogs, during all expiratory phases (P < .05). The higher bronchial collapsibility of brachycephalic dogs was also supported using CT multiplanar reconstruction images and radiography. In conclusion, radiographic and CT measures of bronchial collapsibility in asymptomatic brachycephalic dogs are higher than measures in healthy Beagle dogs. Therefore, measures of bronchial collapse in brachycephalic dogs should not be evaluated using the same baseline measures as those used for healthy Beagle dogs.

Evaluation of the radiographic liver length/11th thoracic vertebral length ratio as a method for quantifying liver size in cats.

Abdominal radiography is a standard diagnostic test for cats with suspected liver disease, however, absolute measurements of radiographic liver size can be affected by other factors such as positioning, radiographic technique, and obesity. This prospective and retrospective, analytical, cross-sectional study evaluated the liver length/11th thoracic vertebral length (LL/T11) ratio as a method for minimizing these outside effects. In a prospectively recruited sample of 25 clinically healthy cats, measurements of radiographic LL/T11 ratio were compared with CT measurements of liver volume. Effects of radiographic technical factors (body posture, recumbency state, and beam center to LL/T11 ratio) and observer were also tested. In a retrospectively recruited sample of 324 cats with no evidence of liver disease, radiographic measurements of the LL/T11 ratio were performed using right lateral radiographs and compared among signalment groups (age, sex, body weight, and body condition score). There was a strong significant correlation between the LL/T11 ratio and CT liver volume (P < .001), and this ratio was not affected by radiographic technical factors. The reference value of the LL/T11 ratio was 4.22 ± 0.54 and the LL/T11 ratio did not differ among signalment groups. Findings supported the use of the LL/T11 ratio as a novel quantitative index of radiographic liver size in cats. Future studies in clinically affected cats are needed to further validate this method.

Computed tomographic and radiographic bronchial collapse may be a normal characteristic of forced expiration in dogs.

Tracheobronchomalacia has been diagnosed using radiography or bronchoscopy to confirm bronchial changes in luminal diameter during the respiratory cycle. However, studies in healthy humans suggest that some degree of bronchial collapse may be observed during the normal respiratory cycle. In this analytical study, the luminal diameter of the bronchus to each of the six pulmonary lobes and the mean percentage of expiratory collapse from end inspiratory, end expiratory, and two forced expiratory phases (10 and 15 ml/kg) were determined via computed tomography (CT) and radiography in 22 healthy Beagle dogs. The bronchial collapsibility was significantly greater during the forced expiration than the end expiration (P < 0.001); the same results were observed in dorsal and sagittal CT images and radiographs (P < 0.001). Median collapsibility values associated with 15 ml/kg forced expiratory collapse determined via cross-sectional CT images were measured as 16.6-45.5% and differed according to the pulmonary lobe. Median collapsibilities on radiography with 15 ml/kg forced expiration were 57.8% and 62.1% in the right cranial lobe and right caudal lobe, respectively. In conclusion, bronchial diameter may change during the respiratory cycle, and some degree of reduction in bronchial diameter may be an incidental finding in healthy dogs. More rigorous criteria are needed with regards to bronchial collapsibility during normal respiration for the diagnosis of bronchomalacia in order to avoid false-positive diagnoses.

CARDIAC MAGNETIC RESONANCE IMAGING OF PATENT DUCTUS ARTERIOSUS IN THREE DOGS.

Patent ductus arteriosus (PDA) is the most common congenital cardiovascular disorder in dogs and requires an accurate diagnosis for an appropriate treatment. Cardiac MRI (cMRI) has been reported as a method for characterization of canine thoracic vasculature. However, to the authors' knowledge, no published studies describe evaluation of canine PDA through cMRI. Three dogs were selected for this exploratory study. Electrocardiogram gating and breath-hold techniques were performed using a 3T MR scanner. Both black blood imaging and bright blood cine acquisitions were performed. Quantification of stroke volume (SV) and shunting volume were calculated using a stack of short-axis cine images. Additional 4D (three-spatial dimensions plus time)-TRAK (time-resolved MR angiography with keyhole) sequences were conducted in patient 2 to verify other vasculature abnormality. Black blood images clearly depicted the course of the ductus from the descending aorta to the pulmonary artery in all three dogs. Morphological evaluation of PDA classified patients 1 and 2 as Type 2a and patient 3 as Type 1. Patient 2 was confirmed to have a concurrent persistent left cranial vena cava. Left ventricular SV, right ventricular SV, and left-to-right SV ratio were 12.4 ml, 3.36 ml, and 3.704, respectively, in patient 1; 6.85 ml, 1.22 ml, and 5.60 in the patient 2; and 3.67 ml, 2.14 ml, and 1.702 in patient 3. Findings indicated that cMRI is a feasible method for characterizing the morphology of PDA and extracardiac vasculature anomalies in dogs.

High-resolution fluorodeoxyglucose positron emission tomography and magnetic resonance imaging findings of a pituitary microtumor in a dog.

A 16-year-old, castrated, male English cocker spaniel dog was presented due to generalized alopecia. Routine clinical pathology, endocrine and abdominal ultrasonography results were consistent with a diagnosis of pituitary-dependent hyperadrenocorticism. The adenohypophyseal lesion was clearly visualized on both 3 T and 7 T magnetic resonance imaging (MRI) of the pituitary gland. Although biochemical and MRI findings were consistent with a functional pituitary microtumor, a pituitary lesion was not detected using (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET). This report firstly describes the application of high-resolution FDG-PET to a spontaneous pituitary microtumor in a dog.

Computed tomographic heterogeneous enhancement of spleen in healthy cats: comparing with diffuse infiltrative splenic lesions.

Introduction: Contrast-enhanced computed tomography (CT) of the spleen in dogs and cats often displays a heterogeneous enhancement pattern. This study aimed to describe the CT appearances and duration of heterogeneous splenic enhancement in clinically healthy cats and to compare those enhancements with diffuse infiltrative splenic lesions (DISL). Methods: Spleens of 14 healthy cats were imaged using contrast-enhanced CT protocols which were obtained at 10, 25, and 45 s, and then every 40 s thereafter until 245 s had past from the initiation of contrast medium injection. The presence of transient splenic heterogeneity was evaluated. In addition, the relationships of certain variables including age, weight, systolic blood pressure, and splenic volume to the duration and the degree of splenic enhancement were determined. Also, medical records and CT images of five cats with DISL were retrospectively evaluated. Result: Transient heterogeneous enhancement of the spleen was observed in all 14 healthy cats, and the maximum heterogeneity was observed 25 s after the injection. Splenic heterogeneity lasted more than 5 min in nine of 14 cats (64.3%). No statistically significant relationships were seen between the duration and degree of splenic heterogeneity in the images taken 25 s after the injection and variables including weight, age, systolic blood pressure, and splenic volume. Discussion: Compared to the healthy group, early homogeneous splenic enhancement along with generalized splenomegaly was observed in all cats with DISL. Transient splenic heterogeneity is highly common in cats undergoing contrast-enhanced CT even in the generally scanned delayed phases, which can help with the interpretation of CT images of feline spleens. In addition, our results suggest that homogeneous splenic enhancement in post-contrast CT scans along with splenomegaly on CT images could be useful as a diagnostic indicator of DISL in cats.

Case report: Sclerosing encapsulating peritonitis in a cat with disseminated pancreatic adenocarcinoma of presumed ductal origin.

A 9-year-old, neutered male, domestic short-haired cat was referred for recurrent ascites of unknown etiology over a week. Physical examination revealed abdominal distension and ultrasonography revealed a large volume of ascites throughout the abdominal cavity; this was interpreted as modified transudate. The mesentery and abdominal fat were hyperechoic and edematous. Fat tissue was assessed using fine-needle aspiration cytology, and adipocytes, fat-phagocytizing macrophages, and neutrophils were identified. Computed tomography revealed a pancreatic mass connected to the left pancreatic leg. Exploratory laparoscopy confirmed nodular masses and organ adhesions, leading to a tentative diagnosis of sclerosing encapsulating peritonitis. The cat was administered prednisolone, vitamin E, and tamoxifen but died 22 days after the initial therapy. Necropsy revealed a multi-lobulated pancreatic tumor (10 × 10 cm) tightly attached to the stomach and intestine, with a large amount of ascites. The peritoneum, stomach, intestine, and mesentery were covered with numerous disseminated nodules of various sizes (1-5 mm diameter). Microscopically, the tumor consisted of extensive adipose tissue, locally extensive inflammatory infiltrates, fibrous connective tissue, and small invasive proliferative glands. Well-defined small irregular glands composed of single-layered epithelial cells that appear to be of ductal origin were surrounded by an abundant desmoplastic stroma. Neoplastic nodules were widespread in the liver, stomach, peritoneum, mesentery, mesenteric lymph nodes, lungs, and urinary bladder. Immunohistochemistry revealed that the neoplastic glands were positive for pan-cytokeratin, confirming the pancreatic epithelial origin of the tumor. This is the first report of sclerosing encapsulating peritonitis accompanied by aggressive pancreatic adenocarcinoma of presumed ductal origin and extensive metastasis in a cat.

Oesophageal stricture in a cat with true pleuroperitoneal hernia.

A 2-year-old neutered male Bengal cat presented with solid food dysphagia and chronic regurgitation for >5 months. There were no clinical abnormalities on haematological or radiographic examinations. Thoracic radiography revealed a soft tissue opacity mass adjacent to the diaphragm in the caudoventral thorax. Ultrasonography revealed a protruding liver lobe surrounded by a hyperechoic lining from the diaphragm towards the thorax, and a pleuroperitoneal hernia was diagnosed. An endoscopy was performed to examine the cause of regurgitation, and an oesophageal stricture was observed. Endoscopic balloon dilation of the oesophageal stricture was performed, and the regurgitation was resolved immediately. However, regurgitation relapsed 2 months later, and computed tomography was performed to ascertain the cause. Computed tomography revealed oesophageal mural thickening and true pleuroperitoneal hernia with partial liver lobe herniation. A second endoscopy with balloon dilation was performed to treat the relapsing oesophageal stricture, and the clinical signs resolved without the need for herniorrhaphy. Nevertheless, oesophageal stricture could occur due to gastroesophageal reflux related to a pleuroperitoneal hernia; however, a definite link could not be elucidated in this case. This report describes a case of oesophageal stricture and concurrent true pleuroperitoneal hernia in a cat.

GH deficiency in a Dalmatian puppy with megaesophagus.

An 8 wk old female Dalmatian weighing .56 kg presented with growth retardation. The puppy exhibited no abnormalities during physical examination other than significantly reduced growth compared with her littermates. Endocrine results suggested pituitary dwarfism. Two wk later, the puppy returned due to the onset of megaesophagus, but the puppy unfortunately died the following morning. This case report describes the diagnosis of dwarfism in a Dalmatian puppy that was caused by growth hormone (GH) deficiency and describes its early clinical manifestations.

Investigation of canine caudal articular process dysplasia of thoracic vertebrae using computed tomography: Prevalence and characteristics.

Caudal articular process (CAP) dysplasia is a congenital vertebral malformation that results from the failure of ossification center of articular process located in vertebrae, which includes aplasia or hypoplasia. In previous studies, it was reported to be common in small and chondrodystrophic dogs however, investigated in limited breeds. So we aimed to confirm the prevalence and the characteristics of CAP dysplasia in various breeds, and also to investigate the association of CAP dysplasia and spinal cord myelopathy in neurologically abnormal dogs. In this multicenter, retrospective study, the clinical records and thoracic vertebral column computed tomographic (CT) images of 717 dogs between February 2016 and August 2021 were included and 119 dogs which also underwent magnetic resonance imaging (MRI) examination were evaluated. Overall, 337 of 717 dogs (47.0%) had at least one thoracic CAP dysplasia and the prevalence of CAP dysplasia was significantly higher in dogs with a lower body weight (P < 0.0001). A total of 66.4% of toy breeds, 39.0% of small breeds, 20.2% of medium breeds, and 6.0% of large breeds were affected by at least one CAP dysplasia. The most affected vertebra was T4 in toy (48.1%) and small breeds (20.8%), and T5 in medium (20.8%) and large breeds (5.0%). In all groups, prevalence of CAP dysplasia between T1 and T9 was higher than post-diaphragmatic vertebrae (T10-T13). Fifty nine of 119 dogs which underwent both CT and MRI examination had symptoms of spinal cord myelopathy of T3-L3 and twenty-five of 59 dogs (42.3%) had at least one thoracic CAP dysplasia. In that 25 neurologically abnormal dogs, 41 sites of intervertebral disc disease (IVDD) were detected. However, only one dog had both CAP dysplasia and herniated disc at the same level. Also, CAP dysplasia associated non-compressive spinal myelopathy at the same level was found in the other dog. Association CAP dysplasia with spinal myelopathy is speculated but is not confirmed by this study.

Severity of myxomatous mitral valve disease in dogs may be predicted using neutrophil-to-lymphocyte and monocyte-to-lymphocyte ratio.

OBJECTIVE: To investigate the neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR), and platelet-to-lymphocyte ratio (PLR) in dogs with myxomatous mitral valve disease (MMVD). ANIMALS: 106 dogs with MMVD and 22 healthy dogs were included in the study. PROCEDURES: CBC data were obtained retrospectively, and NLR, MLR, and PLR were compared between dogs with MMVD and healthy dogs. The ratios were also analyzed according to MMVD severity. RESULTS: NLR and MLR were significantly higher in dogs with MMVD C and D (NLR of 4.99 [3.69-7.27]; MLR of 0.56 [0.36-0.74]) than in healthy dogs (NLR: 3.05 [1.82-3.37], P < .001; MLR: 0.21 [0.14-0.32], P < .001), MMVD stage B1 (NLR: 3.15 [2.15-3.86], P < .001; MLR: 0.26 [0.20-0.36], P < .001), and MMVD stage B2 dogs (NLR: 3.22 [2.45-3.85], P < .001; MLR: 0.30 [0.19-0.37], P < .001). The area under the receiver operating characteristic curves of the NLR and MLR to distinguish dogs with MMVD C and D from those with MMVD B were 0.84 and 0.89, respectively. The optimal cutoff value for NLR was 4.296 (sensitivity, 68%; specificity, 83.95%), and the MLR value was 0.322 (sensitivity, 96%; specificity, 66.67%). NLR and MLR were significantly decreased after treatment in dogs with congestive heart failure (CHF). CLINICAL RELEVANCE: NLR and MLR can be used as adjunctive indicators of CHF in dogs.

18F-fluorodeoxyglucose positron emission tomography findings of peripheral nerve sheath tumour of the nasal cavity in a dog.

An 8-year-old Miniature Poodle presented with chronic sneezing and unilateral epistaxis. A left-sided intranasal mass was identified on computed tomography. 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) was performed to evaluate the metabolic activity of the mass. The intranasal mass showed mildly increased 18F-FDG uptake. The maximal and mean standardized uptake values (SUVs) of the mass were 3.4 and 2.6, respectively. The maximal SUV of the mass/mean SUV of the normal liver was 2.5. The 7-cm soft, pink mass was easily removed through rhinoscopy, with subsequent dramatic improvement in clinical signs. Histopathological and immunohistochemical analyses determined that the mass was an intermediate-grade malignant peripheral nerve sheath tumour (PNST). This is the first report of 18F-FDG PET findings in a PNST in dogs.

Development of three-dimensional canine hepatic tumor model based on computed tomographic angiography for simulation of transarterial embolization.

Introduction: Transarterial embolization (TAE) is one of the treatment options for liver masses that are not suitable for surgery and they have been applied in veterinary medicine for about 20 years, but surgical resection is considered as the first treatment option, and only a few case reports and articles about TAE in dogs have been published. Although understanding of vascular anatomy for the procedure is important, previous studies lack of the information about hepatic artery anatomy in small and toy-breed dogs. Due to the introduction of 3D print in veterinary medicine, it is now possible to make 3D models for preoperative planning. The purpose of this study is to understand the hepatic arterial vascular structure of various sizes and breeds of dogs, and to develop 3D-printed canine artery models with and without hepatic tumors to simulate TAE procedure. Methods: CT images of a total of 84 dogs with normal hepatic arteries were analyzed, and the mean value and standard deviation of body weight, celiac artery size, and hepatic artery size were 6.47 ± 4.44 kg, 3.28 ± 0.77 mm, and 2.14 ± 0.43 mm, respectively. Results: It was established that type 2-2-1, which has two separate hepatic branches-the right medial and left branch and the right lateral branch that runs to the right lateral lobe and caudate process-is the most prevalent of the hepatic artery branch types, as it was in the previous study. The review of 65 CT images of dogs with hepatic tumors showed that 44.6% (29/65) had multifocal lesions in multiple lobes, for which TAE can be recommended. Discussion: Based on the result, a 3D model of the normal canine hepatic artery and the hepatic tumor was made using one representative case from each group, and despite the models having some limitations in reflecting the exact tactile and velocity of blood vessels, TAE procedure was successfully simulated using both models.

Radiographic Evaluation of Atlas and Axis Anomalies in Toy Breed Dogs With and Without Atlantoaxial Subluxation.

BACKGROUND/AIM: Atlantoaxial subluxation (AAS) is generally a congenital condition that mainly affects toy breed dogs. Previous studies in several toy breed dogs revealed that dogs with AAS had a relatively high proportion of incomplete ossification (IO) of the atlas and dens anomalies compared to dogs without AAS. These anatomical characteristics may be important in surgical decision-making. Thus, the present study evaluated morphological differences in the atlas and axis between Maltese dogs with and without AAS. MATERIALS AND METHODS: The medical records of Maltese dogs with and without AAS from 2015 to 2020 were analyzed. Abnormalities of the atlas and axis were evaluated using computed tomography (CT). RESULTS: A total of 45 dogs were reviewed. Maltese dogs with AAS revealed a higher ratio of IO of the atlas (56%) than non-affected dogs (19%). Dens anomalies were identified in 78% of the dogs with AAS and in 26% of non-affected dogs. The shape of the atlas has been identified as thin, solid compact bone in Maltese dogs. Dogs that revealed IO of the dorsal arch of the atlas showed significantly lower CT values (in Hounsfield units) than dogs without IO. The CT values of the midline of the dorsal arch were significantly lower than those of the outer surrounding region. Dens hypoplasia was defined by measuring the dens-to-axis length ratio according to a previous study. A significantly lower ratio was identified in dogs with AAS than in non-affected dogs. CONCLUSION: The incidence ratio of abnormalities of the atlas and axis in Maltese dogs with AAS was similar to that of previous studies. The dorsal arch of the atlas is composed of thin cortical bone with a vulnerable midline region. As dogs with AAS are more likely to be afflicted with abnormalities in the atlas and axis, considering these morphological features is important when planning the surgical stabilization of AAS.

Evaluation of the Abdominal Aorta and External Iliac Arteries Using Three-Dimensional Time-of-Flight, Three Dimensional Electrocardiograph-Gated Fast Spin-Echo, and Contrast-Enhanced Magnetic Resonance Angiography in Clinically Healthy Cats.

Arterial thromboembolism is associated with high morbidity and mortality rates in cats. Definitive diagnosis requires advanced imaging modalities, such as computed tomography angiography (CTA) and contrast-enhanced (CE) magnetic resonance angiography (MRA). However, CTA involves exposure to a large amount of ionized radiation, and CE-MRA can cause systemic nephrogenic fibrosis. Non-contrast-enhanced (NE) MRA can help accurately diagnose vascular lesions without such limitations. In this study, we evaluated the ability of NE-MRA using three-dimensional electrocardiograph-gated fast spin-echo (3D ECG-FSE) and 3D time-of-flight (3D TOF) imaging to visualize the aorta and external iliac arteries in clinically healthy cats and compared the results with those obtained using CE-MRA. All 11 cats underwent 3D ECG-FSE, 3D TOF, and CE-MRA sequences. Relative signal intensity (rSI) for quantitative image analysis and image quality scores (IQS) for qualitative image analysis were assessed; the rSI values based on the 3D TOF evaluations were significantly lower than those obtained using 3D ECG-FSE (aorta 3D TOF: 0.57 ± 0.06, aorta 3D ECG-FSE: 0.83 ± 0.06, P < 0.001; external iliac arteries 3D TOF: 0.45 ± 0.06, external iliac arteries 3D ECG-FSE:0.80 ± 0.05, P < 0.001) and similar to those obtained using CE-MRA (aorta: 0.58 ± 0.05, external iliac arteries: 0.57 ± 0.03). Moreover, IQS obtained using 3D TOF were significantly higher than those obtained using 3D ECG-FSE (aorta 3D TOF: 3.95 ± 0.15, aorta 3D ECG-FSE: 2.32 ± 0.60, P < 0.001; external iliac arteries 3D ECG-FSE: 3.98 ± 0.08, external iliac arteries 3D ECG-FSE: 2.23 ± 0.56, P < 0.001) and similar to those obtained using CE-MRA (aorta: 3.61 ± 0.41, external iliac arteries: 3.57 ± 0.41). Thus, 3D TOF is more suitable and produces consistent image quality for visualizing the aorta and external iliac arteries in clinically healthy cats and this will be of great help in the diagnosis of FATE.

Case Report: 18F-Fluoro-L-Phenylalanine Positron Emission Tomography Findings and Immunoreactivity for L-Type Amino Acid Transporter 1 in a Dog With Meningioma.

A 12-year-old intact female Miniature Pinscher dog weighing 5.4 kg presented with a history of seizures. On neurological examination, postural reactions were decreased in the left-sided limbs, and menace responses were bilaterally absent. Magnetic resonance imaging (MRI) of the brain was performed, and a solitary amorphous mass (2.7 × 1.9 × 2.2 cm) was observed on the right side of the frontal lobe. Based on the signalment, clinical signs, and MRI findings, a brain tumor was tentatively diagnosed, and meningioma was suspected. The dog was treated with hydroxyurea, prednisolone, and other antiepileptic drugs. One week after the treatment began, postural reactions returned to normal, and the menace response improved. At 119 days after treatment, 18F-fluoro-L-phenylalanine (18F-FDOPA) positron emission tomography (PET) was performed. Marked 18F-FDOPA uptake was observed in the lesion. The mean and maximal standardized uptake values of the lesion were 2.61 and 3.72, respectively, and the tumor-to-normal tissue ratio was 1.95. At 355 days after the initial treatment, a second MRI scan was performed and the tumor size had increased to 3.5 × 2.8 × 2.9 cm. The dog died 443 days after the initial treatment and was definitively diagnosed with grade 1 meningioma by histopathological examination. Immunohistochemical staining for Ki67 and L-type amino acid transporter 1 was positive and negative for p53, respectively. The labeling index of Ki67 was 2.4%. This is the first case to demonstrate 18F-FDOPA PET findings in a clinical case of a dog histologically diagnosed with a meningioma.