Feasibility of targeting canine soft tissue sarcoma with MR-guided high-intensity focused ultrasound.

PURPOSE: Magnetic resonance imaging-guided high-intensity-focused ultrasound (MR-HIFU) is a non-invasive treatment modality that precisely focuses ultrasound energy within a tumour and can be customised to result in a wide range of local bioeffects. The purpose of this study was to determine the feasibility of using MR-HIFU to treat soft tissue sarcoma (STS) in dogs. MATERIALS AND METHODS: Medical records of dogs admitted to the Virginia-Maryland College of Veterinary Medicine from 1 January 2012 to 31 December 2016 were searched for a diagnosis of sarcoma with available cross-sectional imaging of the tumour (MRI or CT). Fifty-three (53) dogs were eligible for inclusion. Tumor tissue (in bone as well as in soft tissue) was considered targetable unless: (1) the ultrasound path was completely obstructed by bone or gas and (2) the MR-HIFU target was within the spinal cord or less than 1 cm from the margin of the spinal cord. Tumors were categorised as <50% targetable, ≥50% targetable or non-targetable. RESULTS: Eighty-one percent of STS (81.1%, 43/53) were targetable. The head/spine tumour sites had the highest proportion of non-targetable tumours (36%, 9/25). The majority of truncal and axillary tumours were ≥50% targetable (88.9%, 16/18) ,and all extremity tumours were considered ≥50% targetable (100%, 5/5). CONCLUSIONS: The majority of STS were targetable. This is the first study to evaluate MR-HIFU targetability of canine STS. HIFU has potential as a therapeutic modality for treating STS in dogs, and this veterinary application is a possible model for treatment of naturally occurring STS in humans.

An easy to produce and economical three-dimensional brain phantom for stereotactic computed tomographic-guided brain biopsy training in the dog.

OBJECTIVE: To develop and validate a three-dimensional (3D) brain phantom that can be incorporated into existing stereotactic headframes to simulate stereotactic brain biopsy (SBB) and train veterinary surgeons. STUDY DESIGN: Experimental study. SAMPLE POPULATION: Canine brain phantoms were fabricated from osteological skull specimens, agarose brain parenchyma, and cheddar and mozzarella cheese molds (simulating meningiomas and gliomas). METHODS: The neuroradiologic and viscoelastic properties of phantoms were quantified with computed tomography (CT) and oscillatory compression tests, respectively. Phantoms were validated by experienced and novice operators performing SBB on phantoms containing randomly placed, focal targets. Target yield and needle placement error (NPE) were compared between operators. RESULTS: Phantoms were produced in <4 hours, at an average cost of $92. The CT appearances of the phantom skull, agarose, and cheese components approximated the in vivo features of skull, brain parenchyma, and contrast-enhancing tumors of meningeal and glial origin, respectively. The complex moduli of the agarose and cheeses were comparable to the viscoelastic properties of in vivo brain tissues and brain tumors. The overall diagnostic yield of SBB was 88%. Although NPE did not differ between novice (median 3.68 mm; range, 1.46-14.54 mm) and experienced surgeons (median 1.17 mm, range, 0.78-1.58 mm), our results support the relevance of the learning curve associated with the SBB procedure. CONCLUSION: This 3D phantom replicates anatomical, CT, and tactile features of brain tissues and tumors and can be used to develop the technical skills required to perform SBB.

A novel dextran polymer hydrogel local antimicrobial therapy in dogs: A pilot study.

Our purpose was to evaluate physical, laboratory, and/or radiographic abnormalities associated with a novel dextran polymer hydrogel local antimicrobial agent impregnated with amikacin and clindamycin in dogs having tibial plateau leveling osteotomy implants removed due to suspected surgical site infection. A total of 28 client-owned dogs were enrolled and 20 completed the study. Routine plate explantation and bacterial cultures were performed and the polymer hydrogel was applied to the surgery site. No systemic antimicrobials were used after surgery. Serum biochemistry, hematology, urinalysis, physical examinations, and radiographs were monitored before surgery and up to 12 wk after surgery. Sixteen of the 20 dogs (80%) had a positive bacterial culture, 44% of which were methicillin resistant. There were no significant alterations of laboratory values, physical examination, or radiographs to indicate adverse reactions to the polymer hydrogel. There were no signs of inflammation or infection in any patient at the 12-week postoperative recheck.

Thérapie antimicrobienne innovatrice locale à l'hydrogel de polymère de dextrane chez les chiens : étude pilote. Notre but consistait à évaluer les anomalies physiques, de laboratoire et/ou radiographiques associées à un nouvel agent antimicrobien local d'hydrogel de polymère de dextrane imprégné d'amikacine et de clindamycine chez les chiens dont les implants d'ostéotomie de nivellement du plateau tibial avaient été enlevés en raison d'une infection suspectée du site de la chirurgie. Un total de 28 chiens appartenant à des clients ont été recrutés et 20 ont fait partie de l'étude. Une explantation de routine de la plaque et des cultures bactériennes ont été réalisées et l'hydrogel de polymère a été appliqué au site de la chirurgie. Aucun antimicrobien systémique n'a été utilisé après la chirurgie. Une biochimie sérique, l'hématologie, l'analyse d'urine, des examens physiques et des radiographies ont été réalisés avant la chirurgie et jusqu'à 12 semaines après la chirurgie. Seize des 20 chiens (80 %) avaient une culture bactérienne positive dont 44 % était résistante à la méthicilline. Il n'y avait aucune altération importante des valeurs de laboratoire, de l'examen physique ou des radiographies pour indiquer des réactions indésirables à l'hydrogel de polymère. Il n'y a eu aucun signe d'inflammation ou d'infection chez aucun patient lors d'un examen postopératoire à 12 semaines.(Traduit par Isabelle Vallières).

Effect of anisotropy and spatial compound imaging on renal cortical echogenicity in dogs.

The echogenicity of the renal cortex is an important parameter to consider in dogs that are suspected to have renal dysfunction. Focal increases in echogenicity have been attributed to neoplasia, infection, calcification, fibrosis, gas, and infarction. Anisotropic backscatter has been described as a source of focally increased renal cortical echogenicity in several species. The source of anisotropy appears to be the medullary rays, which are oriented perpendicular to the renal capsule. Spatial compound imaging (SCI) is an ultrasound setting that uses beam steering to acquire and average several overlapping scans of an object from different view angles, creating a compound image that is updated in real time. The impact of insonation angle and SCI on renal cortical echogenicity was evaluated ex vivo in eight kidneys from four dogs. Significant angle-dependent differences in cortical echogenicity were detected with both microconvex and linear transducers (P < 0.0001). Furthermore, the angle-dependent echogenicity differences persisted when SCI mode was used. Our finding that echogenicity was increased using a perpendicular insonation angle (90°) relative to the tubules, compared to a parallel insonation angle (0°) should assist in the interpretation of ultrasonographic images of the dog kidney.

Computed Tomography and Magnetic Resonance Imaging Are Equivalent in Mensuration and Similarly Inaccurate in Grade and Type Predictability of Canine Intracranial Gliomas.

While magnetic resonance imaging (MRI) is the gold-standard imaging modality for diagnosis of intracranial neoplasia, computed tomography (CT) remains commonly used for diagnosis and therapeutic planning in veterinary medicine. Despite the routine use of both imaging modalities, comparison of CT and MRI has not been described in the canine patient. A retrospective study was performed to evaluate CT and MRI studies of 15 dogs with histologically confirmed glioma. Multiple lesion measurements were obtained, including two-dimensional and volumetric dimensions in pre-contrast and post-contrast images. Similar measurement techniques were compared between CT and MRI. The glioma type (astrocytoma or oligodendroglioma) and grade (high or low) were predicted on CT and MRI independently. With the exception of the comparison between CT pre-contrast volume to T2-weighted MRI volume, no other statistical differences between CT and MRI measurements were identified. Overall accuracy for tumor grade (high or low) was 46.7 and 53.3% for CT and MRI, respectively. For predicted tumor type, accuracy of CT was 53.3% and MRI and MRI 60%. Based on the results of this study, both CT and MRI contrast measurement techniques are considered equivalent options for lesion mensuration. Given the low-to-moderate predictability of CT and MRI in glioma diagnosis, histopathology remains necessary for accurate diagnosis of canine brain tumors.

Imaging diagnosis--acquired pectus excavatum secondary to laryngeal paralysis in a dog.

A 13-year-old neutered female Labrador retriever had inspiratory dyspnea secondary to bilateral laryngeal paralysis. Radiographically, there was pectus excavatum with a mediastinal shift to the right. Arytenoid lateralization was performed, relieving the upper respiratory obstruction, and the sternal deformity also resolved. Chronic upper respiratory obstruction should be considered in dogs with pectus excavatum. Furthermore, correction of upper respiratory obstruction has the potential to result in resolution of pectus excavatum.