Clinical features and MRI characteristics of retinal detachment in dogs and cats.

The aim of this retrospective observational study was to characterize the MRI appearance of retinal detachment (RD) in a sample of dogs and cats. Study inclusion was based on the following medical record criteria: (a) had a diagnosis of RD in at least one eye by either funduscopic examination or ocular ultrasound and had an MRI evaluation including the eyes, or (b) had a diagnosis of RD documented in an MRI report for at least one eye and also had a clinical eye examination. Eighteen patients (12 dogs, 6 cats) and 35 eyes met the inclusion criteria, although four eyes that were clinically examined could not be visualized funduscopically and did not have ocular ultrasound performed (criterion 2). The MRI and clinical diagnosis (via either funduscopy or ultrasound) of RD/no RD was concordant in 27 of 31 eyes (87%). Qualitatively, RD appeared as a variable intensity curvilinear structure located internal and adjacent to the sclera on all sequences and was best delineated on T2W sequences. RDs inconsistently contrast enhanced and, although there was no statistical difference, subjectively appeared more clearly delineated on dorsal and parasagittal images. In conclusion, findings from the current study support using MRI as an ancillary diagnostic test for confirmation or further characterization of RD in dogs and cats.

Ferumoxytol-enhanced magnetic resonance angiography provides comparable vascular conspicuity to CT angiography in dogs with intrahepatic portosystemic shunts.

Computed tomography angiography (CTA) is currently the gold standard imaging modality for anatomically characterizing canine hepatic vascular anomalies; with conventional, gadolinium-enhanced MR angiography being less frequently utilized. However, both imaging modalities are limited by a brief, first pass peak of contrast medium in the vasculature that necessitates precisely timed image acquisition. A long-acting purely intravascular magnetic resonance imaging (MRI) contrast agent, ferumoxytol, offers the potential to reduce complexity of magnetic resonance angiography (MRA) protocol planning by ensuring diagnostic contrast medium concentration in all the vessels that are targeted for imaging. Aims of this prospective, pilot, methods comparison study were to develop an optimized MRA protocol using ferumoxytol in dogs with hepatic vascular anomalies, perform a dose escalation trial to compare image quality with four-dose regimens of ferumoxytol, and compare accuracy of vascular anatomic depiction based on the gold standard of CTA. Six dogs (10.7-36.1 kg) with portosystemic shunts (four intrahepatic left divisional shunts and two intrahepatic right divisional shunts) were recruited for inclusion in the study. A dose-escalation trial was performed to compare image quality at four incremental dose levels of ferumoxytol (1, 2, 3, and 4 mg/kg) and to compare the accuracy of vascular anatomic detection to CTA. Ferumoxytol contrast-enhanced MRA (CE-MRA) at 4 mg/kg provided similar conspicuity of normal and abnormal vasculature compared to CTA with a minimal decrease in spatial resolution. Findings indicated that ferumoxytol holds promise for comprehensive, single breath hold CE-MRA of all abdominal vessels in dogs with portosystemic shunts. Background information provided in this study can be used to support development of other future applications such as intracranial and cardiac MRA, real-time imaging, flow quantification, and potentially sedated MRI imaging.

Pilot study: Application of artificial intelligence for detecting left atrial enlargement on canine thoracic radiographs.

Although deep learning has been explored extensively for computer-aided medical imaging diagnosis in human medicine, very little has been done in veterinary medicine. The goal of this retrospective, pilot project was to apply the deep learning artificial intelligence technique using thoracic radiographs for detection of canine left atrial enlargement and compare results with those of veterinary radiologist interpretations. Seven hundred ninety-two right lateral radiographs from canine patients with thoracic radiographs and contemporaneous echocardiograms were used to train, validate, and test a convolutional neural network algorithm. The accuracy, sensitivity, and specificity for determination of left atrial enlargement were then compared with those of board-certified veterinary radiologists as recorded on radiology reports. The accuracy, sensitivity, and specificity were 82.71%, 68.42%, and 87.09%, respectively, using an accuracy driven variant of the convolutional neural network algorithm and 79.01%, 73.68%, and 80.64%, respectively, using a sensitivity driven variant. By comparison, accuracy, sensitivity, and specificity achieved by board-certified veterinary radiologists was 82.71%, 68.42%, and 87.09%, respectively. Although overall accuracy of the accuracy driven convolutional neural network algorithm and veterinary radiologists was identical, concordance between the two approaches was 85.19%. This study documents proof-of-concept for application of deep learning techniques for computer-aided diagnosis in veterinary medicine.

Retrobulbar vs peribulbar regional anesthesia techniques using bupivacaine in dogs.

OBJECTIVE: To compare the effectiveness of retrobulbar anesthesia (RBA) and peribulbar anesthesia (PBA) in dogs. ANIMAL STUDIED: Six adult mixed-breed dogs (18-24 kg). PROCEDURES: In a randomized, masked, crossover trial with a 10-day washout period, each dog was sedated with intravenously administered dexmedetomidine and administered 0.5% bupivacaine:iopamidol (4:1) as RBA (2 mL via a ventrolateral site) or PBA (5 mL divided equally between ventrolateral and dorsomedial sites). The contralateral eye acted as control. Injectate distribution was evaluated by computed tomography. Following intramuscularly administered atipamezole, corneal and periocular skin sensation, intraocular pressure (IOP), and ocular reflexes, and appearance were evaluated for 24 hours. Comparisons were performed with mixed-effects linear regression (IOP) or the exact Wilcoxon signed rank test (scores). Significance was set at P ≤ .05. RESULTS: Injectate distribution was intraconal in 2/6 RBA- and 4/6 PBA-injected eyes. Eyes undergoing PBA had significantly reduced lateral, ventral, and dorsal periocular skin sensation for 2-3 hours, and significantly reduced corneal sensitivity for 4 hours, relative to control eyes. Chemosis and exophthalmos occurred in 33%-40% of eyes undergoing RBA and 83%-100% eyes undergoing PBA but resolved within 14 hours. Anterior uveitis developed in 2/6 and 1/6 eyes of RBA and PBA, respectively, of them corneal ulcer developed in one eye of each treatment. Both resolved 1-3 days following medical treatment. CONCLUSIONS: Peribulbar injection produced notable anesthesia more reliably than did retrobulbar injection. Both techniques may produce adverse effects, although the uveitis/ulcer could have resulted from the contrast agent used.

DISTAL LIMB SWELLING AND PERIOSTEAL PRODUCTIVE REACTION IN PERIPARTURIENT SICHUAN TAKIN (BUDORCAS TAXICOLOR TIBETANA): FIVE CASES OF PRESUMPTIVE HYPERTROPHIC OSTEOPATHY.

Hypertrophic osteopathy, a syndrome characterized by painful distal limb swelling and proliferative periosteal reaction, primarily involves the metacarpal and metatarsal bones and phalanges. Lesions are often bilaterally symmetric and typically affect all four limbs. Hypertrophic osteopathy is frequently associated with primary intrathoracic disease, though this condition has also been reported secondary to intra-abdominal and intrapelvic disease and associated with pregnancy in both people and horses. Over a 20-yr period, five adult female Sichuan takin (Budorcas taxicolor tibetana), with 13 total pregnancies, were evaluated because of lameness and distal limb swelling. These clinical signs were observed between 2 and 32 days (mean = 19 days) prior to parturition (gestation period in takin approximately 200-240 days) and resolved in all animals following parturition. Lameness and limb swelling resolved between 8 and 168 days (median = 15 days) after parturition. Sixteen radiographic examinations, from four of the individuals, documented proliferative periosteal reaction, primarily of the metacarpal bones, metatarsal bones, and phalanges. The clinical progression, resolution of signs, and radiographic features in these cases are consistent with hypertrophic osteopathy, secondary to pregnancy. This is the first report describing presumptive hypertrophic osteopathy in takin.

Prospective evaluation of outcome of dogs with intrahepatic portosystemic shunts treated via percutaneous transvenous coil embolization.

OBJECTIVE: To report outcome and complications after percutaneous transvenous coil embolization (PTCE) and evaluate the clinical, laboratory, and imaging changes in dogs with intrahepatic portosystemic shunts (IHPSS) pre-PTCE and post-PTCE. STUDY DESIGN: Prospective clinical trial. ANIMALS: Twenty-five dogs (15 dogs in imaging subgroup) with IHPSS. METHODS: Clinical signs, hematologic, and biochemical parameters were recorded before and 3 months after PTCE. All dogs received the same medical treatment and underwent PTCE. In the imaging subgroup, ultrasonography, hepatic portal scintigraphy, and computed tomography-angiography were performed pre-PTCE and post-PTCE. RESULTS: All evaluated bloodwork values improved by at least 50% of their initial value, by 3 months post-PTCE. Liver volume increased after PTCE (P = .001), but remained lower than normal in 11/15 dogs. Hepatic arterial fraction decreased after PTCE (P = .029), consistent with increased portal blood flow to the liver. Twenty-four of 25 dogs were available for reevaluation at 3 months, and all abnormal clinical signs had resolved in 22/24 dogs. CONCLUSION: PTCE appears promising as a treatment for IHPSS, as clinical signs resolved in most cases, bloodwork abnormalities often normalized, and the procedure was performed safely with minimal complications. PTCE increased hepatic portal perfusion and liver volume in most dogs. These promising results justify a future randomized clinical trial comparing PTCE, other attenuation options, and medical management alone.

A comparison of retrobulbar and two peribulbar regional anesthetic techniques in dog cadavers.

OBJECTIVE: To compare injectate distribution and likelihood of regional anesthesia to the orbit following retrobulbar (RB) or peribulbar (PB) injections in dog cadavers. STUDY DESIGN: Randomized, masked study. ANIMALS: Twenty-four dog cadavers (aged 5.5-17 years, 2.0-36.3 kg). METHODS: Orbits underwent one of three injection techniques with bupivacaine 0.5% and iohexol (1:1): ventrolateral RB injection (1-2 mL; 15 orbits), medial canthal PB injection (2-8 mL; PB-1; 16 orbits), or dorsomedial and ventrolateral PB injections (each 1-4 mL; PB-2; 16 orbits). The likelihood of successful regional anesthesia was estimated based on computed tomographic images scored for injectate volume of distribution at the base and within the extraocular muscle cone (EOMC), and injectate distribution around the optic nerve. Intraocular pressure (IOP) was measured before and after injections. Mixed-effects linear regression with post hoc Bonferroni contrast adjustments was performed. Significance was set at 0.05. RESULTS: A difference in injectate volume of distribution within or at the base of the EOMC was not detected among groups. The median optic nerve circumference of injectate distribution was significantly higher in the RB injected group than in the PB-2 group. Injectate distribution following RB, PB-1 and PB-2 injections was graded as likely to provide regional anesthesia within the EOMC in 40%, 19% and 31% of eyes, and at the EOMC base in 60%, 63% and 50% of eyes, respectively. The probability of likelihood to provide regional anesthesia was lower in dogs of higher body weights. The IOP was significantly higher than baseline following PB-1 (18 ± 14 mmHg) and in comparison with RB (2 ± 3 mmHg), but not different from PB-2 injection (10 ± 11 mmHg). CONCLUSIONS AND CLINICAL RELEVANCE: None of the techniques reliably produced 'successful' injectate distribution based on this study's definitions; however, clinical assessment of anesthetic success is required.

The Notch of Harty (Pseudodefect of the Tibial Plafond): Frequency and Characteristic Findings at MRI of the Ankle.

OBJECTIVE: The purpose of this study is to report the frequency and characteristic findings of the notch of Harty as seen on MRI. MATERIALS AND METHODS: One hundred six consecutive ankle MRI studies performed at 1.5 or 3 T were reviewed retrospectively by two radiologists. Findings relating to the notch of Harty and ankle joint were recorded and analyzed, including qualitative assessment of the presence of the notch, focal chondral thinning or focal subcortical osteosclerosis at the notch, notch width and depth, osteochondral lesions elsewhere in the ankle, subchondral edema signal or cystic change at the tibial plafond, and the presence of an ankle joint effusion. RESULTS: The study group of 106 patients consisted of 48 male and 58 female patients, with a mean age of 44.5 years (SD, 17.5 years). The notch was identified in 48 of 106 patients (45%) (24 male and 24 female patients; mean age, 43.1 years; range, 7-79 years). When present, the notch averaged 6.2 mm (SD, 1.6 mm) in width and 1.2 mm (SD, 0.5 mm) in depth. The notch was graded as prominent in six of the 106 ankle MRI examinations (6%). Subchondral edemalike signal or cystic change was not localized to the notch in any case. Between patients with versus those without a notch, there was no statistically significant difference in age, sex, subjacent subcortical osteosclerosis, ankle joint effusion, osteochondral lesions elsewhere in the ankle, or subchondral bone marrow edema at the tibial plafond. CONCLUSION: The notch of Harty can be observed as an anatomic variant on MRI and should be differentiated from a traumatic osteochondral lesion.

ABNORMAL IMAGING FINDINGS OF THE FEMORAL THIRD TROCHANTER IN 20 HORSES.

Injuries involving the femoral third trochanter are an uncommon but important source of equine lameness; however, clinical localization can be challenging. The purpose of this retrospective study was to describe ultrasonographic and scintigraphic findings in a group of horses with presumed third trochanter injury. Medical records of an equine referral hospital were searched from 2004-2014, and 20 horses met the inclusion criteria. Lesions consistent with third trochanter fracture were identified with ultrasound in 14/20 horses. Onset of lameness was acute (11), insidious (2), or unknown (1). All but one horse was lame at presentation, ranging from Grade 2-4/5. Ultrasound was the primary diagnostic modality in 5/14 horses with fragmentation, while scintigraphic findings of intense (3), moderate (5), and mild (1) increased radiopharmaceutical uptake (IRU) prompted ultrasonographic examinations in 9/14 fractured horses. A nondisplaced fracture was suspected in an additional horse with intense IRU and negative ultrasound findings. In the remaining five horses, imaging findings included only mild IRU. Lameness was localized to other regions in these cases. Six of 12 fractured horses with available outcome data were returned to function after a prolonged rehabilitation of 8-18 months. Scintigraphic findings helped to direct focused ultrasound exams in the majority of fracture cases. Horses with evidence of third trochanter fracture had similar clinical characteristics to that reported for pelvic fractures and authors therefore recommend ultrasonographic examination of both regions, especially when scintigraphy is unavailable. Prognosis for return to function in horses of the current study was less favorable than previously reported.

Atlanto-axial approach for cervical myelography in a Thoroughbred horse with complete fusion of the atlanto-occipital bones.

A 2-year-old Thoroughbred gelding with clinical signs localized to the first 6 spinal cord segments (C1 to C6) had complete fusion of the atlanto-occipital bones which precluded performing a routine myelogram. An ultrasound-assisted myelogram at the intervertebral space between the atlas and axis was successfully done and identified a marked extradural compressive myelopathy at the level of the atlas and axis, and axis and third cervical vertebrae.

Approche atlanto-axiale pour une myélographie cervicale chez un cheval Thoroughbred avec la fusion complète des os occipito-atloïdiens. Un hongre Thoroughbred âgé de 2 ans avec des signes cliniques localisés aux 6 premiers segments de la colonne vertébrale (C1 à C6) avait une fusion complète des os occipito-atloïdiens qui empêchait la réalisation d'un myélogramme de routine. Un myélogramme par échographie à l'espace intervertébral entre l'atlas et l'axis a été réalisé avec succès et a identifié une myélopathie extradurale compressive prononcée au niveau de l'atlas et de l'axis ainsi que de l'axis et de la troisième vertèbre cervicale.(Traduit par Isabelle Vallières).

Restrictive orbital myofibroblastic sarcoma in a cat--cross-sectional imaging (MRI & CT) appearance, treatment, and outcome.

A 16-year-old spayed female cat was evaluated for lagophthalmos and chronic exposure keratitis in both eyes. Ophthalmic examination revealed upper and lower eyelid entropion of the left eye (OS) and markedly decreased retropulsion, restricted eye movement, marked episcleral congestion, and severe keratitis of both eyes (OU). Magnetic resonance imaging of both orbits revealed extensive, irregular, contrast-enhancing tissue without evidence of osteolysis considered compatible with diffuse inflammatory tissue. Feline herpesvirus DNA was not detected in conjunctival samples. Partial temporary tarsorrhaphies were placed OU, and the cat was treated with topically administered erythromycin ointment OU, orally administered famciclovir and prednisolone, and sublingually administered buprenorphine. Little improvement was noted after 2 weeks. Six weeks after initial presentation, a left exenteration was performed and histopathology was consistent with idiopathic sclerosing orbital pseudotumor (ISOP). Ten weeks after initial presentation, the patient represented for weight loss and jaw pain. Computed tomography demonstrated disease progression in the right orbit and the patient was euthanized. Histopathology of the decalcified skull revealed an aggressive and highly infiltrative mass involving the right orbit with extension to the maxilla, hard palate, nasal cavity and gingiva most consistent with feline restrictive orbital myofibroblastic sarcoma (FROMS). Clinical data from this patient support the reclassification of ISOP as FROMS. MRI and CT may provide supportive evidence for FROMS, but histopathology is necessary for definitive diagnosis. Aggressive and early surgical treatment, including bilateral exenteration, with adjunctive radiotherapy and/or chemotherapy should be considered for patients with FROMS.

Retrobulbar and peribulbar regional techniques in cats: a preliminary study in cadavers.

OBJECTIVE: To compare injectate distribution and potential complications of retrobulbar and peribulbar injections in cat cadavers. STUDY DESIGN: Prospective randomized masked study. ANIMALS: Ten cat cadavers (20 eyes). METHODS: A dorsomedial retrobulbar injection (RB) of 1 mL of 0.5% bupivacaine and iopamidol (1:1) was performed in seven eyes. A dorsomedial peribulbar injection (PB-1) of 4 mL of the same injectate was performed in seven eyes, and two peribulbar injections (PB-2) of the same injectate, divided equally between the dorsomedial and ventrolateral regions (2 mL each) were performed in six eyes. Intraocular pressure (IOP) was measured before, immediately and 15 minutes after injection. Cadavers underwent computed tomography before and following injections. A radiologist scored injectate distribution within the intraconal space (none, moderate, or large) and around the optic nerve (degrees). An injection was defined as likely to provide adequate regional anesthesia if the volume of distribution of intraconal injectate was 'large' and it contacted over 270° of the optic nerve circumference. RESULTS: The success rate (95% confidence interval) of RB, PB-1, and PB-2 injections was 71% (29.0-96.3%), 86% (42.1-99.6%), and 67% (22.3-95.7%), respectively. With all three techniques, IOP increased significantly after injection, but returned to baseline by 15 minutes following RB injection. No intraocular, intravascular, intrathecal, or intraneural injectate was observed. CONCLUSION AND CLINICAL RELEVANCE: The single-peribulbar injection technique may be superior to retrobulbar or double-peribulbar injections, however, all techniques require further studies in live cats to determine safety and efficacy prior to clinical use.

Quantitative and qualitative computed tomographic characteristics of bronchiectasis in 12 dogs.

Bronchiectasis is an irreversible dilatation of the bronchi resulting from chronic airway inflammation. In people, computed tomography (CT) has been described as the noninvasive gold standard for diagnosing bronchiectasis. In dogs, normal CT bronchoarterial ratios have been described as <2.0. The purpose of this retrospective study was to describe quantitative and qualitative CT characteristics of bronchiectasis in a cohort of dogs with confirmed disease. Inclusion criteria for the study were thoracic radiography, thoracic CT, and a diagnosis of bronchiectasis based on bronchoscopy and/or histopathology. For each included dog, a single observer measured CT bronchoarterial ratios at 6 lobar locations. Qualitative thoracic radiography and CT characteristics were recorded by consensus opinion of two board-certified veterinary radiologists. Twelve dogs met inclusion criteria. The mean bronchoarterial ratio from 28 bronchiectatic lung lobes was 2.71 ± 0.80 (range 1.4 to 4.33), and 23/28 measurements were >2.0. Averaged bronchoarterial ratios from bronchiectatic lung lobes were significantly larger (P < 0.01) than averaged ratios from nonbronchiectatic lung lobes. Qualitative CT characteristics of bronchiectasis included lack of peripheral airway tapering (12/12), lobar consolidation (11/12), bronchial wall thickening (7/12), and bronchial lumen occlusion (4/12). Radiographs detected lack of airway tapering in 7/12 dogs. In conclusion, the most common CT characteristics of bronchiectasis were dilatation, a lack of peripheral airway tapering, and lobar consolidation. Lack of peripheral airway tapering was not visible in thoracic radiographs for some dogs. For some affected dogs, bronchoarterial ratios were less than published normal values.

Magnetic resonance imaging features of intracranial granular cell tumors in six dogs.

Magnetic resonance (MR) imaging characteristics of intracranial granular cell tumors (GCTs) have been previously reported in three dogs. The goal of this retrospective study was to examine a larger number of dogs and determine whether distinctive MR characteristics of intracranial GCTs could be identified. Six dogs with histologically confirmed intracranial GCTs and MR imaging were included. Tumor location, size, mass effect, T1- and T2-weighted signal intensity, and peritumoral edema MR characteristics were recorded. In all dogs, GCTs appeared as well-defined, extra-axial masses with a plaque-form, sessile distribution involving the meninges. All tumors were located along the convexity of the cerebrum, the falx cerebri, or the ventral floor of the cranial vault. All tumors were mildly hyperintense on T1-weighted images, and iso- to hyperintense on T2-weighted images. A moderate-to-severe degree of peritumoral edema and mass effect were evident in all dogs. Findings indicated that, while several MR imaging characteristics were consistently identified in canine cerebral GCTs, none of these characteristics were unique or distinctive for this tumor type alone.

Stereological analysis of bacterial load and lung lesions in nonhuman primates (rhesus macaques) experimentally infected with Mycobacterium tuberculosis.

Infection with Mycobacterium tuberculosis primarily produces a multifocal distribution of pulmonary granulomas in which the pathogen resides. Accordingly, quantitative assessment of the bacterial load and pathology is a substantial challenge in tuberculosis. Such assessments are critical for studies of the pathogenesis and for the development of vaccines and drugs in animal models of experimental M. tuberculosis infection. Stereology enables unbiased quantitation of three-dimensional objects from two-dimensional sections and thus is suited to quantify histological lesions. We have developed a protocol for stereological analysis of the lung in rhesus macaques inoculated with a pathogenic clinical strain of M. tuberculosis (Erdman strain). These animals exhibit a pattern of infection and tuberculosis similar to that of naturally infected humans. Conditions were optimized for collecting lung samples in a nonbiased, random manner. Bacterial load in these samples was assessed by a standard plating assay, and granulomas were graded and enumerated microscopically. Stereological analysis provided quantitative data that supported a significant correlation between bacterial load and lung granulomas. Thus this stereological approach enables a quantitative, statistically valid analysis of the impact of M. tuberculosis infection in the lung and will serve as an essential tool for objectively comparing the efficacy of drugs and vaccines.

Ultrasound-guided nerve blocks of the pelvic limb in dogs.

OBJECTIVES: To evaluate the efficacy of ultrasound-guidance in nerve blockade of the sciatic and saphenous nerves in dogs and to determine if this technique could allow lower anaesthetic doses to be used with predictable onset and duration of effect. STUDY DESIGN: Prospective randomized (for dose and leg) blinded experimental crossover trial with 10 day washout period. ANIMALS: Six healthy female Hound dogs aged 12.3 +/- 0.5 (mean +/- SD) months and weighing 18.7 +/- 0.8 (mean +/- SD) kg. METHODS: An ultrasound-guided, perineural injection was used with saline at 0.2 mL kg(-1) (Sal) or bupivacaine 0.5% at 0.05 (low dose; LD), 0.1 (medium dose; MD), or 0.2 (high dose; HD) mL kg(-1), divided 2/3 at the sciatic nerve and 1/3 at the saphenous nerve. Blocks were performed using dexmedetomidine sedation with atipamezole reversal immediately after completion of the injections. Motor/proprioceptive and sensory functions were scored using a 0-8 and a 0-2 scale, respectively. Clinically relevant blocks were defined as a motor score > or =2 and sensory score > or =1. Nonparametric methods were used for statistical analysis. RESULTS: No adverse effects were noted. There was a significant difference between the treatments with bupivacaine and the saline control, but not between the three bupivacaine treatments. Success rates of clinically relevant sciatic and saphenous blocks were both 67% (CI 95% 0.22-0.96). Onset and duration of the blocks were variable; 20-160 and 20-540 minutes, respectively. CONCLUSION AND CLINICAL RELEVANCE: None of the bupivacaine doses was significantly superior, though there was a tendency for a better block with the high bupivacaine dose. Either the technique or the doses used need further modification before this method will be useful in clinical practice.

Quantitative evaluation of hip joint laxity in 22 Border Collies using computed tomography.

The purpose of this study was to obtain the computed tomography (CT) data for the hip joints of 22 Border Collies. The dorsolateral subluxation (DLS) score, lateral center edge angle (LCEA), dorsal acetabular rim angle (DARA) and center distance (CD) index were measured on the CT images in a weight-bearing position. Radiographic Norberg angle (NA) was also measured. The mean values were 45.7 +/- 10.2% for DLS score, 85.9 degrees +/- 10.3 degrees for LCEA, 18.5 degrees +/- 7.3 degrees for DARA, 0.40 +/- 0.17 for CD index and 102.7 degrees +/- 6.9 degrees for NA. Since the DLS score and LCEA showed strong correlation, combined use of these parameters might improve diagnostic accuracy. We consider CT evaluation in a weight-bearing position to be a useful method for multidirectional evaluation of hips.

Effect of body position on respiratory system volumes in anesthetized red-tailed hawks (Buteo jamaicensis) as measured via computed tomography.

OBJECTIVE: To determine the effects of body position on lung and air-sac volumes in anesthetized and spontaneously breathing red-tailed hawks (Buteo jamaicensis). ANIMALS: 6 adult red-tailed hawks (sex unknown). PROCEDURES: A crossover study design was used for quantitative estimation of lung and air-sac volumes in anesthetized hawks in 3 body positions: dorsal, right lateral, and sternal recumbency. Lung volume, lung density, and air-sac volume were calculated from helical computed tomographic (CT) images by use of software designed for volumetric analysis of CT data. Effects of body position were compared by use of repeated-measures ANOVA and a paired Student t test. RESULTS: Results for all pairs of body positions were significantly different from each other. Mean +/- SD lung density was lowest when hawks were in sternal recumbency (-677 +/- 28 CT units), followed by right lateral (-647 +/- 23 CT units) and dorsal (-630 +/- 19 CT units) recumbency. Mean lung volume was largest in sternal recumbency (28.6 +/- 1.5 mL), followed by right lateral (27.6 +/- 1.7 mL) and dorsal (27.0 +/- 1.5 mL) recumbency. Mean partial air-sac volume was largest in sternal recumbency (27.0 +/- 19.3 mL), followed by right lateral (21.9 +/- 16.1 mL) and dorsal (19.3 +/- 16.9 mL) recumbency. CONCLUSIONS AND CLINICAL RELEVANCE: In anesthetized red-tailed hawks, positioning in sternal recumbency resulted in the greatest lung and air-sac volumes and lowest lung density, compared with positioning in right lateral and dorsal recumbency. Additional studies are necessary to determine the physiologic effects of body position on the avian respiratory system.

Computed tomographic lymphography of the thoracic duct by mesenteric lymph node injection.

OBJECTIVE: To document a novel technique to image the thoracic duct and its tributaries by contrast enhanced computed tomography (CT) lymphography. STUDY DESIGN: Clinical report. ANIMALS: Dogs (n=6) idiopathic chylothorax. METHODS: Ultrasonography was used to guide percutaneous injection of intestinal lymph nodes with nonionic iodinated contrast medium for preoperative CT lymphography of the thoracic duct in 6 dogs with chylothorax. Thoracic CT images were acquired immediately after contrast medium injection. All dogs had subtotal pericardectomy and thoracic duct ligation. Postoperative thoracic duct lymphography was performed in 3 dogs. Superficial cervical lymph node lymphography was performed in 2 dogs to determine cervical lymphatic contribution to thoracic effusions. RESULTS: Preoperative thoracic duct lymphography using this technique was successful in delineating the cisterna chyli, thoracic duct, and associated lymphatic vessels in all dogs. Immediate postoperative lymphography performed in 2 dogs revealed successful duct ligation in 1 dog and persistent lymphatic leakage in the other. A 1-month postoperative thoracic duct lymphogram performed in 1 dog revealed unsuccessful ligation or recannulation of 1 of 3 redundant vessels seen preoperatively. CONCLUSION: Percutaneous CT lymphography results in excellent detection of the thoracic duct and abnormal thoracic duct drainage patterns both pre- and postoperatively. The contribution of superficial cervical lymph node drainage to reoccurrence of effusions can be evaluated. CLINICAL RELEVANCE: Percutaneous CT lymphography using ultrasound-guided contrast medium injection should be considered as an alternative to conventional open abdominal approaches to radiographic or CT lymphography.

Quantitative assessment of blood volume, blood flow, and permeability of the brain of clinically normal dogs by use of dynamic contrast-enhanced computed tomography.

OBJECTIVE: To determine effects of regional variation, interobserver variability, and vessel selection on quantitative vascular variables derived by dynamic contrast-enhanced computed tomography (DCE-CT) of the brain of clinically normal dogs. ANIMALS: 14 adult dogs with no evidence of CNS dysfunction. PROCEDURES: Dogs were randomly assigned to 4 groups, and DCE-CT was performed at the level of the frontal lobe, rostral portion of the parietal-temporal lobes, caudal portions of the parietal-temporal lobes, or occipital lobe-cerebellum for groups 1 to 4, respectively. Cerebral blood flow (CBF), cerebral blood volume (CBV), and permeability in gray and white matter for both a large and small artery were calculated and compared. Values among 3 observers and 4 regions of the brain were calculated and compared. RESULTS: Significant interobserver variability was detected for CBF and permeability in white matter. Values calculated for large and small arteries were correlated for CBV and CBF but not for permeability. Overall mean +/- SD for CBF, CBV, and permeability in gray matter was 53.5 +/- 27.7 mL/min/100 g, 2.9 +/- 1.4 mL/100 g, and 1.4 +/- 2.2 mL/min/100 g, respectively. Mean for CBF, CBV, and permeability in white matter was 44.2 +/- 28.5 mL/min/100 g, 2.5 +/- 1.5 mL/100 g, and 0.9 +/- 0.7 mL/min/100 g, respectively. Values did not differ significantly among brain regions. CONCLUSIONS AND CLINICAL RELEVANCE: Significant regional variations were not detected for quantitative vascular variables in the brain of clinically normal dogs. However, interobserver variability and vessel selection have an important role in variable estimation.