Distraction Stabilization of Degenerative Lumbosacral Stenosis: Technique and Mid- to Long-Term Outcome in 30 Cases.

OBJECTIVE: To describe the dorsal laminectomy, annulectomy and distraction stabilization with pins and polymethylmethacrylate technique, its complications and outcome in the management of canine degenerative lumbosacral stenosis. To determine pre- and post-surgical foraminal width and vertebral step changes. STUDY DESIGN: Multi-institutional retrospective clinical study. METHODS: Medical records (2005-2020) of dogs treated (n = 30). Clinical signs, Modified Frankel Score, Texas Spinal Cord Injury Score, pain score (dorsal palpation of spine, tail dorsiflexion), imaging findings and complications were retrieved pre-operatively, perioperatively and at long-term follow-up. RESULTS: The most common presurgical imaging findings were disc protrusion (24/25) and sclerosis of the caudal end-plate of L7 (23/30). On short- to long-term assessment 18 out of 21 dogs exhibited clinical improvement and all exhibited improved pain scores (p < 0.0001). Catastrophic complications occurred in 3 dogs, and major complications occurred in 5, of which 3 required additional surgery. Mean lumbosacral step defect reduced 60% (1.8 mm ± 2.5 mm pre-surgery to 0.7mm ± 0.9mm post-surgery, p = 0.1585). Mean foraminal width significantly increased 50% long-term (3.3 mm ± 1.0 mm pre-surgery to 5.0 mm ± 0.9 mm post-surgery, p < 0.0001). CLINICAL SIGNIFICANCE: Dorsal laminectomy, annulectomy and distraction stabilization is a complex procedure which can significantly increase foraminal width, reduce pain and improve gait characteristics in dogs in the short- to long-term, and should be performed by surgeons experienced in lumbosacral pin placement.

Clinical relevance of splenic nodules or heterogeneous splenic parenchyma assessed by cytologic evaluation of fine-needle samples in 125 dogs (2011-2015).

BACKGROUND: Splenic nodules and heterogeneous parenchyma are seen frequently in abdominal ultrasound examinations of dogs, but the clinical importance of these lesions remains unclear. OBJECTIVES: To determine whether specific ultrasonographic findings correlate with clinically relevant cytologic diagnoses and determine what sonographic features are correlated with these diagnoses. Another objective was to develop a scoring rubric to help clinicians make decisions on whether or not certain ultasonographic findings of the spleen warrant evaluation by fine-needle cytology. ANIMALS: One-hundred twenty-five adult client-owned dogs with ultrasonographically identified splenic nodules, heterogeneous parenchyma, or both. METHODS: Medical records were retrospectively searched for ultrasound-guided splenic fine-needle cytology reports. Ultrasonographic images were assessed for nodule number, size, echogenicity and distal enhancement, degree of splenic heterogeneity, and peritoneal fluid. Dogs were divided into 2 groups: those with clinically important or clinically irrelevant cytologic findings. Potentially useful and discriminatory ultrasonographic findings were identified by statistical analysis, and the most useful findings were used to generate the scoring rubric. RESULTS: The clinically important group included 25 of 125 dogs (22 malignancies, 3 suppurative inflammation). Splenic nodules 1-2 cm in diameter, peritoneal fluid, and >1 targetoid nodule were associated with clinically important cytologic findings. Receiver operator characteristic analysis showed that the scoring rubric was useful for identifying dogs in the clinically important group. CONCLUSIONS AND CLINICAL IMPORTANCE: Splenic fine-needle cytologic findings identified a clinically relevant diagnosis in 20% of dogs, and larger nodule size, number of targetoid lesions, and presence of peritoneal fluid increase the likelihood of detection of clinically important disease.

CT angiography and MRI imaging features do not predict the tumor type and grade of feline injection site sarcoma.

Computed tomographic angiography (CTA) and magnetic resonance imaging (MRI) have been described as methods for preoperative surgical planning in cats with feline injection site sarcomas (FISS), however, few published studies have compared these modalities. The objective of this retrospective, secondary analysis study was to determine if imaging features of FISS on CTA and MRI are predictive of neoplastic peritumoral projections. Archived data from a previous prospective study were retrieved for 10 cats with FISS. All cats had been evaluated in a single anesthetic episode with MRI and dual phase CT (CTA) imaging followed by surgical removal. Histopathological grading and targeted histopathology of imaging-identified peritumoral projections were performed. Two observers evaluated the CTA and MRI studies for FISS shape, margination, size, enhancement pattern, postcontrast uniformity, pre- and postcontrast margination, the number of muscles involved, mass mineralization, and bone lysis. Metal was present in the imaging field of three of 10 cats, resulting in one nondiagnostic MRI. Peritumoral projections were detected in all cats with both imaging modalities, and most were benign. At least one neoplastic peritumoral projection was detected in six cats using MRI, five cats using CTA, and three cats with both modalities. Higher grade FISS were larger than low grade using MRI, and FISS were larger using MRI. Other FISS imaging features using MRI and CTA were similar. Findings supported use of either MRI or CTA for detecting neoplastic peritumoral projections in cats with FISS. Authors recommend CTA for cats with known metallic objects in the scan field.

Clinical Findings in Dogs Trained for Awake-MRI.

Training dogs for awake-MRI began in 2012 for the study of canine cognition. Although originally envisioned as a research technique to understand the neural mechanisms of canine cognitive function, its potential as a new diagnostic clinical tool has become apparent. A high-quality structural scan of the brain can be acquired without sedation or anesthesia in as little as 30 s in a well-trained dog. This has opened the possibility of longitudinal imaging of CNS disease with MRI both as a means of monitoring treatment and potentially as a surveillance tool for inflammatory and neoplastic brain diseases in high-risk breeds. This same training can be used to image other body regions, such as the abdomen, enabling clinicians to screen for abdominal disease using cross sectional imaging without the need for anesthesia and without exposing the patient to ionizing radiation. We present four examples of dogs trained for awake-MRI who developed: (1) nasal carcinoma; (2) brain tumor; (3) abdominal lipoma; (4) idiopathic epilepsy.

Randomized, controlled, prospective clinical trial of autologous greater omentum free graft versus autogenous cancellous bone graft in radial and ulnar fractures in miniature breed dogs.

OBJECTIVE: To determine the rate of radiographic healing, complications, vascularization, and bone density after repair of radial and ulnar fractures in dogs <6 kg that were treated with an autogenous cancellous bone graft (BG) or free autologous omentum graft (OG). STUDY DESIGN: Prospective, randomized, controlled clinical trial with owners/radiologists blinded to treatment. ANIMALS: 25 dogs with naturally occurring traumatic radial/ulnar fractures. METHODS: Fractures underwent plate fixation with OG or BG. Power Doppler ultrasonographic, computed tomographic (CT), and radiographic examinations of the affected antebrachium were performed preoperatively and every 3 weeks postoperatively until healed. Pressure-sensitive walkway gait analysis and owner and veterinarian assessments were obtained preoperatively (0 weeks) and 3, 6, 9, 12, and 24 weeks postoperatively. RESULTS: Owner/veterinarian assessments improved postoperatively but did not differ significantly between groups. The improvement in peak vertical force/vertical impulse was greater in dogs with OG than in those with BG, beginning 3 weeks postoperatively. Radiographic healing occurred earlier in bones treated with OG (median, 9 weeks) than in those treated with BG (12 weeks). Cortical bone density derived from CT of the distal ulna was higher in bones with BG compared with bones with OG. Signal intensity and the number of vessels in the fracture callus declined over time in both groups, according to results of ultrasonography. However, bones retained more vessels and greater signal intensity when treated with OG compared with treatment with BG, according to multiple views at 6 and 9 weeks postoperatively. CONCLUSION: Omental grafting was not associated with major complications, and it accelerated bone healing and return to weight bearing in dogs. CLINICAL SIGNIFICANCE: Omental grafting should be considered as an adjunct to stabilization of antebrachial fractures in toy and small breed dogs.

Quantification of surgical margin length changes after excision of feline injection site sarcomas-A pilot study.

OBJECTIVE: To evaluate degree length change of lateral surgical margins at various stages of processing for histological examination and quantify the length change between grossly normal surgical margins (GNSM) and pathologist-reported histologic tumor-free margin (HTFM) in widely resected feline injection site sarcoma (FISS) specimens. STUDY DESIGN: Prospective clinical study. ANIMALS: Five client-owned cats with injection site sarcomas. METHODS: All cats underwent wide surgical excision (35-55 mm gross lateral margins, 2 fascial planes deep). Gross normal lateral margin measurements from tumor edge were recorded in 4 directions (cranial, caudal, dorsal, ventral) at 5 time points: intra-op (in vivo GNSM); immediately following excision (ex vivo GNSM); following formalin fixation (post-fixation GNSM); after trimming and mounting on glass slides (on-slide GNSM); and HTFM at the narrowest point from the HTFM from the same slides used for on-slide GNSM. Percent change in lateral margin length from in vivo measurements was quantified at each time point and compared using 1-way repeated measures ANOVA. RESULTS: The largest mean decrease in percent GNSM length occurred immediately after excision (in vivo to ex vivo GNSM = 29%; P = .016). Formalin fixation, trimming, and mounting on slides did not result in additional significant changes in length. Mean HTFM length was significantly decreased compared to both in vivo GNSM (33%; P = .014) and on-slide GNSM (7%; P = .024). CONCLUSION: Significant decreases in surgical margin length in FISS specimens occur immediately following excision (prior to formalin fixation). Subgross evaluation of tumor-free margins from on-slide GNSM to HTFM overestimates the actual (histologic) tumor-free margins.

Analysis of risk factors for elbow dysplasia in giant breed dogs.

OBJECTIVE: Identify radiographic risk factors for development of elbow dysplasia in giant breed dogs less than one year of age. METHODS: Twenty-five giant breed puppies (Bernese Mountain dogs, English Mastiff, and Newfoundland) were studied. Both elbows of each dog were radiographed monthly from two to six months of age, then every other month until radial and ulnar physeal closure, followed two months later by bilateral elbow computed tomography. Radiographic parameters measured included the presence or absence of a separate centre of ossification of the anconeal process (SCOAP), medial coronoid disease (MCD), ununited anconeal process, humeral osteochondrosis, elbow incongruity, as well as the length of the radius and ulna, radius-to-ulna ratio, and date of closure of the radial and ulnar physes. RESULTS: Fifteen dogs completed the study. Two Bernese Mountain dogs were diagnosed with MCD. Risk factors significantly associated with medial coronoid disease included dyssynchronous physeal closure and a decreased radius-to-ulna ratio, both detected between eight to 11 months of age. A separate centre of ossification of the anconeal process was present in 60% of the dogs, and was not a risk factor for development of elbow dysplasia. CLINICAL SIGNIFICANCE: Transient, dyssynchronous growth of the radius and ulna may be a risk factor for development of MCD in Bernese Mountain dogs. Dyssynchronous physeal closure or decreased radius-to-ulna ratio prior to radiographic closure of the distal ulnar and radial physes warrants further study in Bernese Mountain dogs and other breeds subject to MCD development.

Changes in the dimension and volume of feline injection-site sarcomas following formalin fixation as determined by use of the ellipsoid volume formula and three-dimensional computed tomography software.

OBJECTIVE To evaluate changes in the dimension and volume of feline injection-site sarcomas (FISSs) before (in vivo) and after surgical excision and formalin fixation (ex vivo) as determined by measurements obtained from 2-D and 3-D CT images. SAMPLE 10 excised FISSs. PROCEDURES The maximum length, width, and depth of each FISS were measured on contrast-enhanced 2-D CT images of the tumor obtained in vivo and ex vivo. Those measurements were used to estimate tumor volume with the standard ellipsoid formula. Tumor volume was also calculated from 3-D CT images with software that used a volume-rendering algorithm. Student paired t tests were used for comparisons between the in vivo and ex vivo assessments. RESULTS Small decreases were detected in maximum tumor length, width, and depth between the in vivo and ex vivo assessments; however, tumor length was the only dimension that decreased significantly between the 2 assessments. Median tumor volume decreased significantly between the in vivo and ex vivo assessments regardless of the method used to estimate it. Tumor volume estimated by the ellipsoid formula was significantly lower than that estimated by the 3-D CT software at both assessments. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that shrinkage of FISSs following excision and formalin fixation was small and may be less than that of grossly normal tissue. Tumor volume estimated by the ellipsoid formula was consistently less than that estimated by 3-D CT software and should not be used when accuracy of tumor volume is of particular concern and advanced CT imaging is available.

Microscopic Evaluation of Peritumoral Lesions of Feline Injection Site Sarcomas Identified by Magnetic Resonance Imaging and Computed Tomography.

OBJECTIVE: Determine whether dual-phase computed tomography angiogram (CTA) or magnetic resonance imaging (MRI) detect more peritumoral lesions of feline injection site sarcoma (FISS) and determine whether CTA or MRI imaging characteristics of peritumoral lesions correspond with microscopic findings. STUDY DESIGN: Prospective clinical study. ANIMALS: Ten client-owned cats with FISS. METHODS: A fiducial marker detectable on CTA and MRI was sutured to the skin over the FISS as a standard reference point. All cats received MRI and CTA of the FISS, immediately followed by wide surgical excision. Targeted microscopic evaluation was performed on tissue with imaging-identified lesions and on the surgical margins. RESULTS: A total of 87 imaging-identified peritumoral lesions were examined microscopically (median 4 per cat, range 3-9) with 17/87 (20%) categorized as neoplastic, 51/87 (59%) as nonneoplastic, and 19/87 (22%) as equivocal. In 25 instances, peritumoral lesions were seen on both imaging modalities at the same location. Unique imaging characteristics were seen in 5/17 neoplastic peritumoral lesions (4 cats; all different lesions; 1 CTA, 4 MRI). The CTA and MRI appearances of the remaining 12/17 neoplastic lesions were nonspecific, being observed across more than 1 microscopic category. CONCLUSION: CTA and MRI identified a similar number of peritumoral lesions. The extensive overlap between imaging features of neoplastic and nonneoplastic lesions precludes definitive identification of neoplastic peritumoral FISS lesions using CTA or MRI.

COMBINATION OF COMPUTED TOMOGRAPHIC IMAGING CHARACTERISTICS OF MEDIAL RETROPHARYNGEAL LYMPH NODES AND NASAL PASSAGES AIDS DISCRIMINATION BETWEEN RHINITIS AND NEOPLASIA IN CATS.

Feline nasal diseases are a diagnostic challenge. The objective of this retrospective, cross-sectional study was to determine whether computed tomography (CT) imaging characteristics of the medial retropharyngeal lymph nodes (MRPLN), alone or in combination with CT imaging characteristics of the nasal passages, could aid in differentiation between rhinitis and nasal neoplasia. Cats were recruited from record archives at two veterinary facilities during the period of 2008-2012. Selection criteria were presentation for chronic nasal discharge, contrast-enhanced CT of the head that included the MRPLN, and rhinoscopic nasal biopsy resulting in diagnosis of rhinitis or neoplasia. For each CT scan, two board-certified veterinary radiologists recorded MRPLN size, attenuation, heterogeneity, contrast-medium enhancement, margination, shape, presence of a lymph node hilus, perinodal fat, turbinate lysis, paranasal bone lysis, and nasal mass. Both readers were unaware of patient information at the time of CT interpretation. Thirty-four cats with rhinitis and 22 cats with neoplasia were included. Computed tomographic characteristics significantly associated with neoplasia included abnormal MRPLN hilus (OR 5.1), paranasal bone lysis (OR 5.6), turbinate lysis (5.6), mass (OR 26.1), MRPLN height asymmetry (OR 4.5), and decreased MRPLN precontrast heterogeneity (OR 7.0). The combined features predictive of neoplasia were a nasal mass with abnormal hilus (OR 47.7); lysis of turbinates/paranasal bones with abnormal MRPLN hilus (OR 16.2). Findings supported the hypothesis that combining CT features of the nasal passages and MRPLN aided in differentiating rhinitis from neoplasia in cats.

Evaluation of the Diagnostic Accuracy of Conventional 2-Dimensional and 3-Dimensional Computed Tomography for Assessing Canine Sacral and Pelvic Fractures by Radiologists, Orthopedic Surgeons, and Veterinary Medical Students.

OBJECTIVE: To determine, using 3 groups of evaluators of varying experience reading orthopedic CT studies, if 3-dimensional computed tomography (3D-CT) provides a more accurate and time efficient method for diagnosis of canine sacral and pelvic fractures, and displacements of the sacroiliac and coxofemoral joints compared with 2-dimensional computed tomography (2D-CT). STUDY DESIGN: Retrospective clinical and prospective study. ANIMALS: Dogs (n = 23): 12 dogs with traumatic pelvic fractures, 11 canine cadavers with pelvic trauma induced by a lateral impactor. METHODS: All dogs had a 2D-CT exam of the pelvis and subsequent 3D-CT reconstructions from the 2D-CT images. Both 2D-CT and 3D-CT studies were anonymized and randomly presented to 2 veterinary radiologists, 2 veterinary orthopedic surgeons, and 2 veterinary medical students. Evaluators classified fractures using a confidence scale and recorded the duration of evaluation for each modality and case. RESULTS: 3D-CT was a more time-efficient technique for evaluation of traumatic sacral and pelvic injuries compared with 2D-CT in all evaluator groups irrespective of experience level reading orthopedic CT studies. However, for radiologists and surgeons, 2D-CT was the more accurate technique for evaluating sacral and pelvic fractures. CONCLUSION: 3D-CT improves sacral and pelvic fracture diagnosis when added to 2D-CT; however, 3D-CT has a reduced accuracy for evaluation of sacral and pelvic fractures if used without concurrent evaluation of 2D-CT images.

Comparison of 2 fluid ingress/egress systems for canine stifle arthroscopy using computed tomography.

OBJECTIVE: To evaluate volume of extra-articular fluid egress and complications associated with 2 fluid ingress/egress techniques for stifle arthroscopy. STUDY DESIGN: Ex vivo study. STUDY SUBJECTS: Canine cadavers (n = 14). METHODS: Four cadavers (8 stifles) were used to validate 3D computed tomographic (CT) methods to quantify stifle joint intra- and extra-articular volumes of iodinated contrast medium. Ten canine cadavers (20 stifles) had preoperative CT, followed by stifle arthroscopy using a 10% solution of iodinated contrast enhanced ingress fluid delivered by pressure bag (2PB) or by arthroscopic peristaltic pump (3FP). All 3FP limbs had an additional fluid egress portal placed by cannula and obturator. Arthroscopy was limited to 20 minutes/joint. The volume of the contrast medium egress into the soft tissues was measured on postoperative 3D CT reconstructed images. RESULTS: Mean percentage of total ingress fluids administered that remained in the joint and extra-articular tissues postoperatively was 8.8 ± 1.2% in 3FP and 33.2 ± 8% in 2PB (P = .014). Two 3FP joints had 4-5 mm egress obturator tracks on the proximal medial trochlear ridge. Two 2PB joints had severe joint collapse from extracapsular fluid precluding further examination. Intermittent visual blurring by joint fluid mixing or fat pad fragmentation/dissolution was noted in 2PB joints. CONCLUSIONS: A superior technique was not identified: 2PB had greater egress fluid tissue accumulation, whereas 3FP had better viewing of intra-articular structures with less tissue egress fluid accumulation; however, cartilage damage was induced with the egress obturator.

Usefulness of a half-fourier acquisition single-shot turbo spin-echo pulse sequence in identifying arachnoid diverticula in dogs.

Single-shot turbo spin-echo sequences are heavily T2-weighted sequences that are exceptionally well suited to evaluate the subarachnoid space. In the T2-weighted fast spin-echo sequences that are used routinely in spinal magnetic resonance (MR) imaging, the subarachnoid space is not well differentiated from the surrounding epidural fat, which could lead to decreased detection of lesions of the subarachnoid space such as arachnoid diverticula. Our purpose was to determine the added value of a single-shot turbo spin-echo sequence in identifying cystic lesions of the subarachnoid space in dogs. MR images of six dogs with a confirmed arachnoid diverticulum and 24 dogs with other spinal disease were included. Six observers were asked to interpret only T2-weighted images initially, and in a second session, T2-weighted and half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequences. The MR images were anonymized, and no signalment, history, or clinical information was provided. Without the HASTE sequences, 25% of arachnoid diverticula were identified. Adding the HASTE sequence increased the diagnosis of arachnoid diverticulum to 52.8%. The resulting difference, after adding the HASTE sequence, of 27.8% was statistically significant (P = 0.002). No false-positive diagnoses of arachnoid diverticulum were made with either sequence. Although sensitivity in this study was likely artificially low, the significantly increased detection rate of arachnoid diverticula when using HASTE imaging indicates that this sequence is a valuable addition to MR imaging protocols for the canine spine.

Comparison of thoracic radiographs and single breath-hold helical CT for detection of pulmonary nodules in dogs with metastatic neoplasia.

Imaging studies in people indicate that x-ray computed tomography (CT) is a more sensitive technique than thoracic radiography for the detection of pulmonary metastasic neoplasia. Systematic studies comparing CT and thoracic radiographic techniques in veterinary patients have not been performed. The present retrospective study was designed to directly compare the efficacy of these 2 techniques in detecting pulmonary nodules in dogs. Eighteen dogs with histologically confirmed pulmonary metastatic neoplasia had contemporaneous thoracic radiographs and pulmonary CT scans compared. Quantitative analyses included estimation of pulmonary nodule size, number, and lobar distribution on thoracic radiographs and CT images. Only 9% of CT-detected pulmonary nodules were identified on thoracic radiographs (P < .003). The lower size threshold was approximately 1 mm to detect pulmonary nodules on CT images and 7-9 mm to reliably detect nodules on radiographs (P < .0001). Additionally, pulmonary nodules were detected in a significantly greater number of lung lobes using CT as compared with thoracic radiographs (P < .0001). These data indicate that CT is significantly more sensitive than thoracic radiography for detecting soft-tissue nodules in dogs. As such, thoracic CT should be considered in any patient with neoplasia that has potential for pulmonary metastasis to more reliably stage the disease, particularly when accurate characterization of the extent and distribution of pulmonary metastatic disease affects therapeutic planning.

Assessment of locus and extent of neurotoxic lesions in monkeys using neuroimaging techniques: a replication.

In a recent study, [Hippocampus 11 (2001) 361] demonstrated that in vivo neuroimaging techniques could be used to accurately quantify the extent of neuronal damage after ibotenic acid injections in non-human primates. The present study was undertaken to replicate these findings and to further estimate whether the concentration of ibotenic acid used (10-15 mg/ml) to produce the neuronal loss did not affect the fibers coursing within or around the targeted brain area. Magnetic resonance (MR) images (T1-weighted and FLAIR) were acquired in three monkeys before and after they received neurotoxic lesions of the hippocampal formation. The postsurgical FLAIR images were taken 7-10 days after surgery to visualize the hyperintense signals produced by increased edema at the injection sites. One year post-surgically, T1-weighted images were acquired and compared with T1-weighted images obtained pre-surgery to estimate reduction in hippocampal volume resulting from neuronal loss. Estimated neuronal loss was then compared with actual cell loss found during histological evaluation of brain tissue. Both neuroimaging techniques accurately estimated the extent of hippocampal damage and damage to surrounding structures. In addition, the concentration of ibotenic acid (10 mg/ml) used in the present study did not appear to have significantly damaged or de-myelinated fibers coursing through or around the hippocampal formation. Together with the previous results of [Hippocampus 11 (2001) 361], the present data strongly demonstrate that in vivo neuroimaging techniques provide powerful tools to estimate reliably and rapidly the extent and localization of brain lesions in non-human primates.