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.

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.

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.

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.

Evaluation of left ventricular function with cardiac magnetic resonance imaging and echocardiography after administration of dobutamine and esmolol in healthy beagle dogs.

Unlike echocardiography, cardiac magnetic resonance imaging (cardiac MRI) results in a near-exact assessment of cardiac structures and function. However, most veterinary studies have focused on dogs with normal cardiac function. We hypothesized that there would be significant differences in cardiac measurements between cardiac MRI and echocardiography when left ventricular (LV) function was abnormal. This study was undertaken to compare measurements of LV function produced by cardiac MRI and echocardiography in dogs whose LV function was altered by pharmacological agents. This study was conducted with six healthy beagle dogs. We increased left ventricular contractility by administration of dobutamine; we decreased cardiac contractility with esmolol. Stroke volume measurements were made by using both cardiac MRI and echocardiography under seven different conditions with general anesthesia: control, three doses of esmolol (100, 200, and 500 µg/kg/min), and three doses of dobutamine (10, 20, and 50 µg/kg/min). Experiments involving each condition were conducted at least 1 week apart. When LV contractility was normal, ejection fraction (EF) and stroke volume (SV), as measured by echocardiography and cardiac MRI, were not significantly different. However, when contractility was changed by pharmacological agents, EF and SV were overestimated by echocardiography, compared to MRI. Evaluation of cardiac function in patients treated with pharmacological agents should be conducted carefully because EF and SV measured by echocardiography can be overestimated, compared with EF and SV obtained by cardiac MRI.

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.

Three-dimensional volumetric magnetic resonance imaging (MRI) analysis of the soft palate and nasopharynx in brachycephalic and non-brachycephalic dog breeds.

The purpose of this study was to use magnetic resonance imaging (MRI) to compare the volumes and three-dimensional configurations of the soft palate and nasopharynx in non-brachycephalic and brachycephalic dogs with different body weights, and infer which factors influence nasopharyngeal volume. This was a retrospective observational study. The brain MRI medical records of all dogs referred to the Veterinary Medical Center, Chungbuk National University, between 2013 and 2016, for evaluation of intracranial disease were reviewed. There was a significant difference in the two-dimensional parameters including soft palate length/skull length ratio (P<0.01) and maximum soft palate thickness (P<0.01), and three-dimensional parameters which included soft palate volume (P<0.01), nasopharyngeal volume (P<0.01), soft palate/total upper airway volume ratio (P<0.01), and nasopharyngeal volume/total upper airway volume ratio (P<0.01), between brachycephalic and non-brachycephalic dog breeds. Nasopharyngeal volume correlated positively with the maximum soft palate thickness and body weight in all breeds. The three-dimensional morphologic grades of soft palate were significantly different between the two groups. In brachycephalic breeds, Grade 3 was observed in 33% of cases but was absent in non-brachycephalic breeds, where Grade 1 was present in 85% of the cases. We can conclude that three-dimensional morphology and upper airway volume are significantly different between brachycephalic and non-brachycephalic breeds, and body weight and maximum soft palate thickness are the key factors associated with a decreased nasopharyngeal volume.

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.

Serum cholecystokinin concentrations in dogs with naturally acquired pituitary-dependent hyperadrenocorticism.

OBJECTIVE To determine serum cholecystokinin (CCK) concentrations in dogs with pituitary-dependent hyperadrenocorticism (PDH) and to evaluate associations among CCK concentration, PDH, and gallbladder mucocele (GBM). ANIMALS 14 client-owned dogs with PDH and 14 healthy dogs. PROCEDURES Dogs were separated into 4 groups: healthy dogs without gallbladder sludge (group A; n = 7), healthy dogs with gallbladder sludge (group B; 7), dogs with PDH and gallbladder sludge (group C; 8), and dogs with PDH and GBM (group D; 6). Serum CCK concentrations were then measured before and 1, 2, and 4 hours after consumption of a high-fat meal. Concentrations in dogs with PDH were also measured before and after trilostane treatment. Results were compared among groups and assessment points. RESULTS Preprandial serum CCK concentrations in group C were significantly lower than those in groups A, B, and D, but no significant differences in postprandial CCK concentrations were identified among the groups 1, 2, or 4 hours after the meal. With respect to trilostane treatment of dogs with PDH, no significant differences were identified between pre- and post-trilostane serum CCK concentrations in group C or D. Median CCK concentration after trilostane treatment was higher in group D than in group C, but this difference was not significant. CONCLUSIONS AND CLINICAL RELEVANCE The outcomes in this study did not support the hypothesis that a low circulating CCK concentration affects the development of GBM in dogs with PDH.

Correlation between caudal pulmonary artery diameter to body surface area ratio and echocardiography-estimated systolic pulmonary arterial pressure in dogs.

Caudal pulmonary artery diameter (CPAD) to body surface area (BSA) ratios were measured in ventrodorsal thoracic radiographs to assess the correlation between CPAD to BSA ratios and systolic pulmonary arterial pressure (PAP) in dogs. Thoracic radiographs of 44 dogs with systolic pulmonary arterial hypertension (PAH) and 55 normal dogs were evaluated. Systolic PAP was estimated by Doppler echocardiography. CPADs were measured at their largest point at the level of tracheal bifurcation on ventrodorsal radiographs. Both right and left CPAD to BSA ratios were significantly higher in the PAH group than in the normal group (p < 0.0001). Linear regression analysis showed positive associations between PAP and right and left CPAD to BSA ratio (right, p = 0.0230; left, p = 0.0012). The receiver operating characteristic curve analysis revealed that the CPAD to BSA ratio had moderate diagnostic accuracy for detecting PAH. The operating point, sensitivity, specificity, and area under the curve were 28.35, 81.40%, 81.82%, and 0.870; respectively, for the right side and 26.92, 80.00%, 66.67%, and 0.822, respectively, for the left. The significant correlation of CPAD to BSA ratio with echocardiography-estimated systolic PAP supports its use in identifying PAH on survey thoracic radiographs in dogs.

Quantitative CT assessment of bone mineral density in dogs with hyperadrenocorticism.

Canine hyperadrenocorticism (HAC) is one of the most common causes of general osteopenia. In this study, quantitative computed tomography (QCT) was used to compare the bone mineral densities (BMD) between 39 normal dogs and 8 dogs with HAC (6 pituitary-dependent hyperadrenocorticism [PDH]; pituitary dependent hyperadrenocorticism, 2 adrenal hyperadrenocorticism [ADH]; adrenal dependent hyperadrenocorticism) diagnosed through hormonal assay. A computed tomogaraphy scan of the 12th thoracic to 7th lumbar vertebra was performed and the region of interest was drawn in each trabecular and cortical bone. Mean Hounsfield unit values were converted to equivalent BMD with bone-density phantom by linear regression analysis. The converted mean trabecular BMDs were significantly lower than those of normal dogs. ADH dogs showed significantly lower BMDs at cortical bone than normal dogs. Mean trabecular BMDs of dogs with PDH using QCT were significantly lower than those of normal dogs, and both mean trabecular and cortical BMDs in dogs with ADH were significantly lower than those of normal dogs. Taken together, these findings indicate that QCT is useful to assess BMD in dogs with HAC.

Assessment of trabecular bone mineral density using quantitative computed tomography in normal cats.

The aim of this study was to assess age-related changes and anatomic variation in trabecular bone mineral density (tBMD) using quantitative computed tomography (QCT) in normal cats. Seventeen normal cats were included in this study and divided into the following 3 age groups:<6 months (n=4), 2-5 years (n=10) and >6 years (n=3). A computed tomographic scan of each vertebra from the 12th thoracic to the 7th lumbar spine and the pelvis was performed with a bone-density phantom (50, 100 and 150 mg/cm(3), calcium hydroxyapatite, CIRS phantom(®)). On the central transverse section, the elliptical region of interest (ROI) was drawn to measure the mean Hounsfield unit (HU) value. Those values were converted to equivalent tBMD (mg/cm(3)) by use of the bone-density phantom and linear regression analysis (r(2) >0.95). The mean tBMD value of the thoracic vertebrae (369.4 ± 31.8 mg/cm(3)) was significantly higher than that of the lumbar vertebrae (285 ± 58.1 mg/cm(3)). The maximum tBMD occurred at the T12, T13 and L1 levels in all age groups. There was a statistically significant difference in the mean tBMD value among the 3 age groups at the T12 (P<0.001), T13 (P<0.001) and L4 levels (P=0.013), respectively. The present study suggests that age-related changes and anatomic variation in tBMD values should be considered when assessing tBMD using QCT in cats with bone disorders.

Assessment of glomerular filtration rate with dynamic computed tomography in normal Beagle dogs.

The objective of our study was to determine individual and global glomerular filtration rates (GFRs) using dynamic renal computed tomography (CT) in Beagle dogs. Twenty-four healthy Beagle dogs were included in the experiment. Anesthesia was induced in all dogs by using propofol and isoflurane prior to CT examination. A single slice of the kidney was sequentially scanned after a bolus intravenous injection of contrast material (iohexol, 1 mL/kg, 300 mgI/mL). Time attenuation curves were created and contrast clearance per unit volume was calculated using a Patlak plot analysis. The CT-GFR was then determined based on the conversion of contrast clearance per unit volume to contrast clearance per body weight. At the renal hilum, CT-GFR values per unit renal volume (mL/min/mL) of the right and left kidneys were 0.69 ± 0.04 and 0.57 ± 0.05, respectively. No significant differences were found between the weight-adjusted CT-GFRs in either kidney at the same renal hilum (p = 0.747). The average global GFR was 4.21 ± 0.25 mL/min/kg and the whole kidney GFR was 33.43 ± 9.20 mL/min. CT-GFR techniques could be a practical way to separately measure GFR in each kidney for clinical and research purposes.

Evaluation of glomerular filtration rate by use of dynamic computed tomography and Patlak analysis in clinically normal cats.

OBJECTIVE: To obtain quantitative variables of the abdominal aorta and both kidneys on the basis of time-attenuation curves (TACs) and to measure glomerular filtration rate (GFR) for each kidney and the global GFR in clinically normal cats by use of dynamic computed tomography (CT) and Patlak analysis. ANIMALS: 9 healthy cats. PROCEDURES: All the cats were anesthetized with propofol. Anesthesia was maintained by administration of isoflurane, and CT examination was performed in the anesthetized cats. The TACs and renal volume were measured by use of the baseline precontrast and single-slice dynamic scans. The CT-GFR of each kidney and the global CT-GFRs were calculated via Patlak plot analysis. RESULTS: CT-GFR results from 7 cats were valid. Peak aortic enhancement was detected between 9.0 and 14.0 seconds after iohexol injection, and the initial peak time of renal parenchymal enhancement was 15 to 24 seconds after iohexol injection. Mean ± SD global GFR was 2.06 ± 0.62 mL/min/kg. Mean ± SD CT-GFR of the right and left kidneys was 0.97 ± 0.32 mL/min/kg and 1.05 ± 0.31 mL/min/kg, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: The CT-GFR method can be rapidly and conveniently performed in clinically normal cats. This combined structural-functional approach provided physiologic and morphological information on the kidneys of cats.

Computed tomographic evaluation of abdominal fat in minipigs.

Computed tomography (CT) exams were conducted to determine the distribution of abdominal fat identified based on the CT number measured in Hounsfield Units (HU) and to measure the volume of the abdominal visceral and subcutaneous fat in minipigs. The relationship between the CT-based fat volumes of several vertebral levels and the entire abdomen and anthropometric data including the sagittal abdominal diameter and waist circumference were evaluated. Moreover, the total fat volumes at the T11, T13, L3, and L5 levels were compared with the total fat volume of the entire abdomen to define the landmark of abdominal fat distribution. Using a single-detector CT, six 6-month-old male minipigs were scanned under general anesthesia. Three radiologists then assessed the HU value of visceral and subcutaneous abdominal fat by drawing the region of interest manually at the T11, T13, L1, L3, and L5 levels. The CT number and abdominal fat determined in this way by the three radiologists was found to be correlated (intra-class coefficient = 0.9). The overall HU ranges for the visceral and subcutaneous fat depots were -147.47 to -83.46 and -131.62 to -90.97, respectively. The total fat volume of the entire abdomen was highly correlated with the volume of abdominal fat at the T13 level (r = 0.97, p < 0.0001). These findings demonstrate that the volume of abdominal adipose tissue measured at the T13 level using CT is a strong and reliable predictor of total abdominal adipose volume.

Evaluation of triphasic helical computed tomography of the kidneys in clinically normal dogs.

OBJECTIVE: To determine computed tomography (CT) delay times by use of a sequential scan and identify the normal enhancement pattern in each phase of a triphasic CT scan of the kidneys in dogs. ANIMALS: 14 healthy Beagles. PROCEDURES: A sequential CT scan was used for investigating delay time, and a triphasic helical CT scan was used for identifying the normal enhancement pattern and determining Hounsfield unit values in the kidneys of dogs. RESULTS: In the cine scan (single-slice dynamic scan), the optimal delay times were 10 seconds in the corticomedullary phase and 44 seconds in the nephrographic phase, after contrast medium injection. By use of triphasic CT images, Hounsfield unit values were acquired in each phase. CONCLUSIONS AND CLINICAL RELEVANCE: Triphasic CT of the kidneys in clinically normal dogs was established by acquisition of delay times in a cine scan and may become an important imaging modality in the diagnosis of renal diseases and in treatment planning in dogs.

Evaluation of the effects of thiopental, propofol, and etomidate on glomerular filtration rate measured by the use of dynamic computed tomography in dogs.

OBJECTIVE: To evaluate the effects of thiopental, propofol, and etomidate on glomerular filtration rate (GFR) measured by the use of dynamic computed tomography in dogs. ANIMALS: 17 healthy Beagles. PROCEDURES: Dogs were randomly assigned to receive 2 mg of etomidate/kg (n = 5), 6 mg of propofol/kg (7), or 15 mg of thiopental/kg (5) during induction of anesthesia; anesthesia was subsequently maintained by isoflurane evaporated in 100% oxygen. A 1 mL/kg dosage of a 300 mg/mL solution of iohexol was administered at a rate of 3 mL/s during GFR measurement. Regions of interest of the right kidney were manually drawn to exclude vessels and fatty tissues and highlight the abdominal portion of the aorta. Iohexol clearance per unit volume of the kidney was calculated by use of Patlak plot analysis. RESULTS: Mean ± SD weight-adjusted GFR of the right kidney after induction of anesthesia with thiopental, propofol, and etomidate was 2.04 ± 0.36 mL/min/kg, 2.06 ± 0.29 mL/min/kg, and 2.14 ± 0.43 mL/min/kg, respectively. However, no significant differences in weight-adjusted GFR were detected among the treatment groups. CONCLUSIONS AND CLINICAL RELEVANCE: Results obtained for the measurement of GFR in anesthetized dogs after anesthetic induction with etomidate, propofol, or thiopental and maintenance with isoflurane did not differ significantly. Therefore, etomidate, propofol, or thiopental can be used in anesthesia-induction protocols that involve the use of isoflurane for maintenance of anesthesia without adversely affecting GFR measurements obtained by the use of dynamic computed tomography in dogs.

Undifferentiated pleomorphic sarcoma (malignant fibrous histiocytoma) of the head in a dog.

A six year-old intact female miniature poodle was presented with a soft mass of the forehead region. Computed tomography identified generalized frontal bone loss and a large extracranial mass, which had a low attenuation area of hemorrhagic necrosis with septation and enhancement of solid components. In magnetic resonance imaging, the mass was isointense in T1-weighted images except its fluid parts and hyperintense in T2-weighted images with lobulated by low-signal septa. Surgery was performed to remove the mass, and histopathologic examination revealed that the mass was consistent with undifferentiated pleomorphic sarcoma (malignant fibrous histiocytoma). The dog died from the rapidly recurrent mass and severe pulmonary metastasis.