Contouring in the optic plane improves the accuracy of computed tomography-based segmentation of the optic pathway.

Canine optic pathway structures are often contoured on CT images, despite the difficulty of visualizing the optic pathway with CT using standard planes. The purpose of this prospective, analytical, diagnostic accuracy study was to examine the accuracy of optic pathway contouring by veterinary radiation oncologists (ROs) before and after training on optic plane contouring. Optic pathway contours used as the gold standard for comparison were created based on expert consensus from registered CT and MRI for eight dogs. Twenty-one ROs contoured the optic pathway on CT using their preferred method, and again following atlas and video training demonstrating contouring on the optic plane. The Dice similarity coefficient (DSC) was used to assess contour accuracy. A multilevel mixed model with random effects to account for repeated measures was used to examine DSC differences. The median DSC (5th and 95th percentile) before and after training was 0.31 (0.06, 0.48) and 0.41 (0.18, 0.53), respectively. The mean DSC was significantly higher after training compared with before training (mean difference = 0.10; 95% CI, 0.08-0.12; P < 0.001) across all observers and patients. DSC values were comparable to those reported (0.4-0.5) for segmentation of the optic chiasm and nerves in human patients. Contour accuracy improved after training but remained low, potentially due to the small optic pathway volumes. When registered CT-MRI images are not available, our study supports routine addition of an optic plane with specific window settings to improve segmentation accuracy in mesaticephalic dogs ≥11 kg.

Staging canine patients with appendicular osteosarcoma utilizing fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography compared to whole body computed tomography.

Few studies have investigated the diagnostic performance of fluorine-18-fluorodeoxyglucose (18 F-FDG) positron emission tomography/computed tomography (PET/CT) for staging veterinary patients with appendicular osteosarcoma. The purpose of this study was to evaluate the efficacy of 18 F-FDG-PET/CT compared to whole-body CT (WBCT) for staging canine patients with appendicular osteosarcoma. The 18 F-FDG-PET/CT imaging studies of 66 dogs with appendicular osteosarcoma were anonymized and separated into two detached studies (one with whole body pre- and post-contrast CT images and the other with the whole body pre- and post-contrast CT images with the associated 18 F-FDG-PET overlay). Image assessment was performed retrospectively by five board-certified veterinary radiologists. The radiologists were instructed to assign a predefined categorical score (1-4) to each pre-designated anatomic region based on a devised lesional scoring system. A score of 1 was normal, 2 abnormal but not neoplastic, 3 abnormal and concerning for neoplasia, and 4 abnormal, most likely neoplastic. Overall, the likelihood of detection of '3 or 4' was found to be significantly higher with 18 F-FDG PET/CT when compared to WBCT after adjusting for the effect of evaluator and the subject. Most significantly, 13 osseous lesions concerning for metastasis (scored 3-4) were identified in 10/66 dogs by at least one reviewer on 18 F-FDG PET/CT, which were not identified by any reviewer on WBCT. Additionally, four comorbid neoplastic lesions were identified with 18 F-FDG PET/CT and not with WBCT. The results of this study suggest that 18 F-FDG PET/CT is more efficacious in detecting metastatic and comorbid neoplastic lesions compared to WBCT in dogs with appendicular osteosarcoma.

Computed tomography features of presumed normal mandibular and medial retropharyngeal lymph nodes in dogs.

Computed tomographic (CT) features of lymph nodes are used for diagnosis, staging, and response evaluation in veterinary patients. The objectives of this study were to describe maximum short- and long-axis transverse diameters (SATD and LATD, respectively), volume, and attenuation of presumed normal canine mandibular lymph nodes (MLNs) and medial retropharyngeal lymph nodes (MRLNs), to investigate the effect of variables on these features, and to describe inter-observer reliability of transverse diameter and attenuation measurement. Computed tomography studies of 161 dogs were retrospectively reviewed. Median values for SATD were 5.2 and 5.4 mm, median values for volume were 0.26 and 0.54 cm3, and median values for attenuation were 32.3 and 31.8 Hounsfield units (HU) for MLN and MRLN, respectively. Median LATD was 11 mm for MLNs. Height of the first cervical vertebra (HCV1) and weight were positively associated with transverse diameters of both MLNs and MRLNs (P < 0.001). Grade of dental disease was negatively associated with transverse diameters of both MLNs (P = 0.001) and MRLNs (P < 0.03). The intraclass correlation coefficient (ICC) was 0.94 [95% confidence interval (CI): 0.94 to 0.95] for transverse diameter measurement. This study provides descriptive data on the CT characteristics of presumed normal MLNs and MRLNs in dogs and describes a highly reliable method of measuring transverse diameter.

Les caractéristiques tomodensitométriques (CT) des ganglions lymphatiques sont utilisées pour le diagnostic, la stadification et l'évaluation de la réponse chez les patients vétérinaires. Les objectifs de cette étude étaient de décrire les diamètres transversaux maximaux à axe court et long (SATD et LATD, respectivement), le volume et l'atténuation des ganglions lymphatiques mandibulaires canins (MLN) et des ganglions lymphatiques rétropharyngés médians (MRLN) présumés normaux, afin d'étudier l'effet de variables sur ces caractéristiques, et pour décrire la fiabilité inter-observateur de la mesure du diamètre transversal et de l'atténuation. Des études de tomodensitométrie de 161 chiens ont été examinées rétrospectivement. Les valeurs médianes pour la SATD étaient de 5,2 et 5,4 mm, les valeurs médianes pour le volume étaient de 0,26 et 0,54 cm3, et les valeurs médianes pour l'atténuation étaient de 32,3 et 31,8 unités Hounsfield (HU) pour MLN et MRLN, respectivement. Le LATD médian était de 11 mm pour les MLN. La hauteur de la première vertèbre cervicale (VHC1) et le poids étaient positivement associés aux diamètres transversaux des MLN et des MRLN (P < 0,001). Le grade de maladie dentaire était négativement associé aux diamètres transversaux des MLN (P = 0,001) et des MRLN (P < 0,03). Le coefficient de corrélation intraclasse (ICC) était de 0,94 [intervalle de confiance (IC) à 95 % : 0,94 à 0,95] pour la mesure du diamètre transversal. Cette étude fournit des données descriptives sur les caractéristiques CT des MLN et MRLN présumés normaux chez le chien et décrit une méthode très fiable de mesure du diamètre transversal.(Traduit par Docteur Serge Messier).

Computed tomographic appearance of sialoceles in 12 dogs.

Published findings on the computed tomographic (CT) appearance of sialoceles are limited to brief descriptions from reported cases in eight dogs and one cat. The authors have seen sialoceles with CT characteristics that are not consistent with these previous reports. The purpose of this multicenter, retrospective, descriptive, case series study was to provide more detailed descriptions of the CT appearance of confirmed sialoceles in dogs. Dogs over a 10-year period with cytologically or histologically confirmed sialoceles and pre- and postcontrast CT studies of the head were included. Multiple qualitative and quantitative features were described for each sialocele with histological correlation. Twelve dogs with a total of 13 sialoceles were identified, including: seven cervical sialoceles, three complex (combined cervical and sublingual) sialoceles, two sublingual sialoceles, and one zygomatic sialocele. All sialoceles were characterized by fluid attenuating, non-contrast enhancing contents (median 18.5 HU) and soft tissue attenuating, contrast-enhancing walls. The external margins of all sialocele walls were smooth; however, the internal margins in six sialoceles were irregular with poorly defined nodular to frond-like protrusions. Mineralized foci of variable size (range < 1 mm to 4.8 mm) and attenuation (range 119 to 1253 HU) were present in seven sialoceles and histologically identified as sialoliths (three sialoceles) and osseous metaplasia (two sialoceles). A unique finding in the sialoceles in this study was the presence of intraluminal nodular to frond-like protrusions arising from the wall. This study also reports the CT appearance of cervical and complex sialoceles and sialocele mineralizations.

Inter- and intraobserver agreement for CT measurement of mandibular and medial retropharyngeal lymph nodes is excellent in dogs with histologically confirmed oral melanoma.

Mandibular and medial retropharyngeal lymph nodes are routinely evaluated with CT when staging dogs with oral melanomas. While size alone is considered inadequate for detecting nodal metastasis, it is critical in evaluating treatment response, as clinical decisions are based on changes in size. It is common for different radiologists to measure the size of pre- and posttreatment lymph nodes in the same patient. The objective of this retrospective, observer agreement study was to evaluate the inter- and intraobserver agreement in measuring canine mandibular and medial retropharyngeal lymph nodes by a diverse population of veterinary radiologists and trainees. Fourteen dogs with documented oral melanoma and head CT studies identified from records of a single institution were included in this study. North American veterinary radiologists and trainees were recruited to measure the mandibular and medial retropharyngeal lymph nodes; in triplicate. Prior to performing the study measurements, participants completed a training tool demonstrating the lymph node measurements. Overall, interobserver intraclass correlation coefficient (ICC) was 0.961 (95% confidence interval [CI]: 0.946, 0.972) and intraobserver ICC was 0.977 (95% CI: 0.968, 0.983), indicating excellent agreement (ICC > 0.9 considered excellent). Similar findings were noted following sub-analysis for most variables (experience, size, laterality, axis of measurement). These results suggest that follow-up measurement of the long and short axis of the mandibular lymph nodes and short axis of the medial retropharyngeal lymph nodes in the transverse plane, performed by different veterinary radiologists using the same method of measure, should have minimal impact on clinical decision making.

Multicenter, randomized, double-blinded, placebo-controlled study of rabacfosadine in dogs with lymphoma.

BACKGROUND: Rabacfosadine (RAB, Tanovea-CA1) is a novel chemotherapy agent conditionally approved for the treatment of lymphoma in dogs. HYPOTHESIS/OBJECTIVES: To determine the efficacy and safety of RAB in dogs with lymphoma. ANIMALS: One hundred and fifty-eight client-owned dogs with naïve or relapsed multicentric lymphoma were prospectively enrolled from January to October 2019. METHODS: Dogs were randomized to receive RAB or placebo at a 3 : 1 ratio. Treatment was given every 21 days for up to 5 treatments. Study endpoints included progression-free survival (PFS), overall response rate (ORR) at a given visit, best overall response rate (BORR), and percent progression free 1 month after treatment completion. Safety data were also collected. RESULTS: The median PFS was significantly longer in the RAB group compared to placebo (82 vs 21 days; P < .0001, HR 6.265 [95% CI 3.947-9.945]). The BORR for RAB-treated dogs was 73.2% (50.9% complete response [CR], 22.3% partial response [PR]) and 5.6% (0% CR, 5.6% PR) for placebo-treated dogs (P < .0001). One month after the last treatment, 37 RAB-treated dogs (33%) were progression free compared with no placebo-treated dogs (P < .0001). The most common adverse events observed in the RAB group were diarrhea (87.5%), decreased appetite (68.3%), and vomiting (68.3%) and were generally low grade and reversible. Serious adverse events were reported in 24 RAB-treated (20%) and 5 placebo-treated dogs (13%). CONCLUSIONS AND CLINICAL IMPORTANCE: Rabacfosadine demonstrated statistically significant antitumor efficacy in dogs with lymphoma when administered every 21 days for up to 5 treatments as compared to placebo.

Self-reported radiation safety behaviors among veterinary specialists and residents performing fluoroscopic procedures on small animals.

OBJECTIVE: To describe the radiation safety behaviors of veterinary specialists performing small animal fluoroscopic procedures and examine potential risk factors for these behaviors, including knowledge of radiation risk and training regarding machine operating parameters. SAMPLE: 197 veterinary specialists and residents in training. PROCEDURES: An electronic questionnaire was distributed to members of the American Colleges of Veterinary Internal Medicine (subspecialties of cardiology and small animal internal medicine), Veterinary Radiology, and Veterinary Surgery. RESULTS: The overall survey response rate was 6% (240/4,274 email recipients). Of the 240 respondents, 197 (82%) had operated an x-ray unit for a small animal fluoroscopic procedure in the preceding year and fully completed the questionnaire. More than 95% of respondents believed that radiation causes cancer, yet approximately 60% of respondents never wore hand or eye protection during fluoroscopic procedures, and 28% never adjusted the fluoroscopy machine operating parameters for the purpose of reducing their radiation dose. The most common reasons for not wearing eye shielding included no requirement to wear eyeglasses, poor fit, discomfort, and interference of eyeglasses with task performance. Respondents who had received training regarding machine operating parameters adjusted those parameters to reduce their radiation dose during procedures significantly more frequently than did respondents who had not received training. CONCLUSIONS AND CLINICAL RELEVANCE: On the basis of the self-reported suboptimal radiation safety practices among veterinary fluoroscopy users, we recommend formal incorporation of radiation safety education into residency training programs. All fluoroscopy machine operators should be trained regarding the machine operating parameters that can be adjusted to reduce occupational radiation exposure.

Retrospective analysis of use of fluorine-18 fluorodeoxyglucose-positron emission tomography/computed tomography (18F-FDG PET/CT) for detection of metastatic lymph nodes in dogs diagnosed with appendicular osteosarcoma.

The purpose of this retrospective analysis was to determine if fluorine-18 fluorodeoxyglucose-positron emission tomography/computed tomography (18F-FDG PET/CT) could potentially be an accurate staging tool for detecting metastatic lymph nodes in dogs with appendicular osteosarcoma based on the quantitative measurement of the maximum standard uptake value (SUVmax) of lymph nodes. A total of 53 dogs were identified that presented for staging via 18F-FDG PET/CT for primary appendicular osteosarcoma. Patients were categorized according to lymph node status of having either metastatic or non-metastatic nodes based on cytological or histological analysis. Maximum standard uptake (SUVmax) values of the sampled lymph node(s) were recorded and 3/77 (3.9%) of sampled lymph nodes were confirmed metastatic. A Mann-Whitney test revealed a statistical difference in the SUVmax of the metastatic versus non-metastatic lymph nodes [median: 6.6 to 95% confidence interval (CI): 2.56 to 14.37 versus 2.18 95% CI: 2.32 to 3.17, respectively, P-value = 0.05]. This retrospective analysis revealed a significant difference in the SUVmax as measured on 18F-FDG PET/CT between metastatic lymph nodes and non-metastatic lymph nodes in canine patients afflicted with appendicular osteosarcoma, in spite of the small numbers analyzed. While these results are promising, they should be interpreted with caution and further studies are justified.

Le but de cette analyse rétrospective était de déterminer si la tomographie par émission de positons avec le fluor-18 fluorodésoxyglucose/tomodensitométrie (18F-FDG TEP/CT) pourrait potentiellement être un outil de stadification précis pour la détection des ganglions lymphatiques métastatiques chez les chiens atteints d'ostéosarcome appendiculaire basé sur la quantification de la valeur standard maximale d'absorption (SUVmax) des ganglions lymphatiques. Les auteurs ont identifié 53 chiens qui furent classifiés avec le 18F-FDG TEP/CT pour l'ostéosarcome appendiculaire primaire. Les patients ont été classés, selon l'état des ganglions lymphatiques, à avoir des ganglions métastatiques ou non métastatiques sur la base d'une analyse cytologique ou histologique. Les valeurs d'absorption standard maximale (SUVmax) du ou des ganglions lymphatiques échantillonnés ont été enregistrées et 3/77 (3,9 %) des ganglions lymphatiques échantillonnés ont été confirmés métastatiques. Un test de Mann-Whitney a révélé une différence statistique du SUVmax des ganglions lymphatiques métastatiques versus non métastatiques [médiane: 6,6 à 95 % intervalle de confiance (IC): 2,56 à 14,37 versus 2,18 IC à 95 %: 2,32 à 3,17, respectivement, valeur de P = 0,05]. Cette analyse rétrospective a révélé une différence significative dans le SUVmax tel que mesuré sur 18F-FDG TEP/CT entre les ganglions lymphatiques métastatiques et les ganglions lymphatiques non métastatiques chez les patients canins atteints d'ostéosarcome appendiculaire, malgré le petit nombre analysé. Bien que ces résultats soient prometteurs, ils doivent être interprétés avec prudence et des études complémentaires sont justifiées.(Traduit par Docteur Serge Messier).

The use of fluorine-18-fluorodeoxyglucose-positron emission tomography/computed tomography as an effective method for staging in dogs with primary appendicular osteosarcoma.

Fluorine-18-fluorodeoxyglucose (18 F-FDG) positron emission tomography/computed tomography (PET/CT) has been utilized in veterinary medicine to improve the detection and characterization of primary, recurrent, and secondary neoplasms; but its use as a staging tool for dogs diagnosed with appendicular osteosarcoma has not been published. The purpose of this retrospective, case series, descriptive study was to detail the use of 18 F-FDG PET/CT for staging a population of dogs with appendicular osteosarcoma, report the detection rate of secondary neoplastic lesions, and compare findings with published detection rates for other historically used imaging modalities. Seventy-one client-owned dogs with a confirmed diagnosis of appendicular osteosarcoma and staged with a whole-body 18 F-FDG PET/CT scan near the time of initial diagnosis were included. Each PET/CT study was re-evaluated for malignancy distinct from the primary disease entity based on a collective qualitative and quantitative assessment of 18 F-FDG uptake, CT appearance, and contrast enhancement characteristics. Following re-evaluation of each study, information pertaining to tissue sampling performed on identified lesions was retrieved from the medical record when available. Staging with 18 F-FDG PET/CT identified 17 of 71 (23.9%) and 12 of 71 (16.3%) dogs with a high suspicion or confirmation of a metastatic or comorbid malignant neoplasm respectively, with eight of 71 (11.3%) having both metastatic and comorbid lesions. The results of this study are suggestive that 18 F-FDG PET/CT is effective in identifying both osseous and soft tissue secondary neoplastic lesions in dogs afflicted with appendicular osteosarcoma, yielding an increased detection rate of all lesions compared those previously reported for skeletal scintigraphy or whole-body CT.

Use of MRI increases interobserver agreement on gross tumor volume for imaging-diagnosed canine intracranial meningioma.

There is a lack of information regarding interobserver agreement on canine meningioma gross tumor volume (GTV) delineation, and on the impact of MRI on this agreement. The objectives of this retrospective, secondary analysis, observer agreement study were to describe agreement between veterinary radiation oncologists on GTV for canine intracranial meningioma, and to compare interobserver agreement between delineation based on CT alone and delineation based on fused CT-MRI. Eighteen radiation oncologists delineated GTV for 13 dogs with an imaging diagnosis of meningioma on pre- and postcontrast CT, pre- and postcontrast T1-weighted magnetic resonance, and T2-weighted magnetic resonance images. Dice similarity coefficient (DSC), concordance index (CI), and center of volume (COV) were used to quantify interobserver agreement. Multilevel mixed models were used to examine the difference in volume, DSC, CI and COV 3D distance between CT and CT-MR imaging. The mean volume for GTV contours delineated using fused CT-MRI was larger than when CT alone was used for delineation (mean difference CT-MR - CT = 0.89 cm3, 95% CI 0.66 to 1.12, P < .001). Interobserver agreement on GTV was improved when MRI was used; the mean DSC and CI were higher, and the mean COV 3D distance was lower, when fused CT-MRI was used than when CT alone was used (P < .001 for all differences). Based on our results, fused CT-MRI is recommended for radiation therapy planning of canine intracranial meningioma.

A pilot study of optical neuronavigation-guided brain biopsy in the horse using anatomic landmarks and fiducial arrays for patient registration.

BACKGROUND: Optical neuronavigation-guided intracranial surgery has become increasingly common in veterinary medicine, but its use has not yet been described in horses. OBJECTIVES: To determine the feasibility of optical neuronavigation-guided intracranial biopsy procedures in the horse, compare the use of the standard fiducial array and anatomic landmarks for patient registration, and evaluate surgeon experience. ANIMALS: Six equine cadaver heads. METHODS: Computed tomography images of each specimen were acquired, with the fiducial array rigidly secured to the frontal bone. Six targets were selected in each specimen. Patient registration was performed separately for 3 targets using the fiducial array, and for 3 targets using anatomic landmarks. In lieu of biopsy, 1 mm diameter wire seeds were placed at each target. Postoperative images were coregistered with the planning scan to calculate Euclidian distance from the tip of the seed to the target. RESULTS: No statistical difference between registration techniques was identified. The impact of surgeon experience was examined for each technique using a Mann-Whitney U test. The experienced surgeon was significantly closer to the intended target (median = 2.52 mm) than were the novice surgeons (median = 6.55 mm) using the fiducial array (P = .001). Although not statistically significant (P = .31), for the experienced surgeon the median distance to target was similar when registering with the fiducial array (2.47 mm) and anatomic landmarks (2.58 mm). CONCLUSIONS AND CLINICAL IMPORTANCE: Registration using both fiducial arrays and anatomic landmarks for brain biopsy using optical neuronavigation in horses is feasible.

Canine tonsillar neoplasia and tonsillar metastasis from various primary neoplasms.

Tonsillar metastasis from distant primary tumours has not been described in dogs, and reports are rare in humans. The aims of this study were to determine whether tumour metastasis occurs to the canine palatine tonsils and evaluate whether afferent lymphatics drain to the palatine tonsils via skull indirect computed tomography lymphangiography (ICTL). Retrospective review of the diagnostic laboratory tonsillar histopathology submissions was performed. ICTL studies (n = 53) were retrospectively reviewed by a single radiologist. Of 882 total tonsil histopathology samples, 492 (56%) were considered neoplastic, with 8% of them benign. Of the primary malignant neoplasms of the tonsil, squamous cell carcinoma (55%), lymphoma (17%) and melanoma (12%) were most common. Tonsillar metastasis was confirmed in 41 cases; histopathologic evaluation revealed melanoma (25), carcinoma (10), hemangiosarcoma (2) and one each of fibrosarcoma, malignant histiocytosis, basal cell tumour and undifferentiated sarcoma. A total of 53 tonsillar melanoma cases were identified, of which 25 represented metastasis from a known distant primary tumour and 28 were solely tonsillar, with 9 of these cases having concurrent lymph node metastasis. No ICTL cases had lymphatic contrast drainage to the palatine tonsil. The palatine tonsil is an important site of metastasis for a variety of primary tumour types from many locations. ICTL did not reveal lymphatics draining to the palatine tonsil, which is highly supportive of hematogenous route of metastasis to the tonsil. Tonsillar metastasis may be more common than previously thought. It is recommended to perform a thorough oral examination, including the tonsils, for all oral tumours and melanoma cases.

The development of an indirect computed tomography lymphography protocol for sentinel lymph node detection in head and neck cancer and comparison to other sentinel lymph node mapping techniques.

Identification of metastatic disease critically impacts the care and prognosis of patients with neoplasia. Multiple techniques exist for identifying the sentinel or first lymph node(s) that receive draining tumour lymph. Identification of the sentinel lymph node enables accurate tissue sampling for determination of lymphatic metastasis. The aims of this study were to develop a computed tomography (CT) protocol for identifying the sentinel lymph node in dogs with tumours of the head and neck. In addition, indirect CT lymphography was compared to lymphoscintigraphy and vital dye injection to determine which technique more reliably identified the sentinel lymph node. CT indirect lymphography using intratumoral injection of iodinated contrast identified draining lymphatic vessels in eight of 18 dogs and identified the sentinel lymph node in five of 18 dogs. CT indirect lymphography employing four-quadrant peritumoral injection of iodinated contrast identified draining lymphatic vessels in 18 of 20 dogs and identified the sentinel lymph node in 11 of 20 dogs. Vital dye injection and lymphoscintigraphy identified the sentinel lymph node in 17 of 18 and 20 of 20 dogs, respectively. Identified sentinel lymph nodes were either ipsilateral or bilateral to the primary tumour. Both CT techniques were found to be safe and simple. Peritumoral injection has the greatest promise for the detection of sentinel lymph nodes in various head and neck cancers using CT, while lymphoscintigraphy had the greatest success of the compared techniques.

CT imaging features of canine thymomas.

Canine thymomas have been evaluated based on clinical features, treatment options, surgical excision, and outcomes with limited information on specific CT features. The objective of this retrospective, descriptive, cross-sectional study was to describe the CT characteristics of confirmed thymomas and to compare these imaging features to outcome. A total of 22 dogs met the inclusion criteria of histologically confirmed thymomas with concurrent CT imaging. Tumor size varied widely ranging from small and well-circumscribed to large and invasive. Delayed-phase, contrast-enhanced CT studies were best for determining the degree of contrast enhancement in tumors. Of these, 19 of 22 masses had heterogeneous enhancement and three of 22 masses had homogeneous enhancement. Vascular invasion was present in seven of 22 cases. Larger tumors were associated with vascular invasion (height: P = .04; width and volume: P = .02). On precontrast CT, larger tumors (16/21) were heterogeneous and cystic, with smaller tumors (5/21) being more homogeneous (all values P < .05). A larger size was associated with recurrence in fully resected masses (height: P = .03), but not a shorter outcome (P > .3 for all size dimensions). Postoperative complications and incomplete tumor resection were associated with shorter outcome (both values P < .01). Metastasis was confirmed in four cases. There were six cases with lymphadenopathy noted on CT; five of the six cases did not have evidence of metastasis. Larger tumors were more likely to be cystic and associated with vascular invasion.

Click Conjugation of Cloaked Peptide Ligands to Microbubbles.

Interest in the use of targeted microbubbles for ultrasound molecular imaging (USMI) has been growing in recent years as a safe and efficacious means of diagnosing tumor angiogenesis and assessing response to therapy. Of particular interest are cloaked microbubbles, which improve specificity by concealing the ligand from blood components until they reach the target vasculature, where the ligand can be transiently revealed for firm receptor-binding by ultrasound acoustic radiation force pulses. Herein, a bio-orthogonal "click" conjugation chemistry is introduced to decorate the surface of cloaked 4-5-µm-diameter microbubbles as part of a sterile and reproducible production process. Azido-functionalized antagonists for the angiogenic biomarkers αVß3 integrin (cRGD) and VEGFR2 (A7R) proteins were conjugated to bimodal-brush microbubbles via strain-promoted [3 + 2] azide-alkyne cycloaddition (SPAAC) click chemistry. Ligand conjugation was validated by epifluorescent microscopy, flow cytometry, and Fourier-transform infrared spectroscopy. Sterility was validated by bacterial culture and endotoxin analysis. Additionally, clinically normal dogs receiving escalating microbubble doses were shown to experience no pathologic changes in physical examination, complete blood count, serum biochemistry profile, or coagulation panel. This bio-orthogonal microbubble conjugation process for cloaked peptide ligands may be leveraged for future USMI studies of tumor angiogenesis for translation to preclinical and clinical applications.

Pilot study utilizing Fluorine-18 fluorodeoxyglucose-positron emission tomography/computed tomography for glycolytic phenotyping of canine mast cell tumors.

The goal of this prospective pilot study was to use naturally occurring canine mast cell tumors of various grades and stages as a model for attempting to determine how glucose uptake and markers of biologic behavior are correlated. It was hypothesized that enhanced glucose uptake, as measured by 2-[fluorine-18]fluoro-d-glucose-positron emission tomography/computed tomography (F18 FDG PET-CT), would correlate with histologic grade. Dogs were recruited for this study from a population referred for treatment of cytologically or histologically confirmed mast cell tumors. Patients were staged utilizing standard of care methods (abdominal ultrasound and three view thoracic radiographs), followed by a whole body F18 FDG PET-CT. Results of the F18 FDG PET-CT were analyzed for possible metastasis and standard uptake value maximum (SUVmax ) of identified lesions. Incisional or excisional biopsies of the accessible mast cell tumors were obtained and histology performed. Results were then analyzed to look for a possible correlation between the grade of mast cell tumors and SUVmax . A total of nine animals were included in the sample. Findings indicated that there was a correlation between grade of mast cell tumors and SUVmax as determined by F18 FDG PET-CT (p-value = 0.073, significance ≤ 0.1). Based on the limited power of this study, it is felt that further research to examine the relationship between glucose utilization and biologic aggressiveness in canine mast cell tumors is warranted. This study was unable to show that F18 FDG PET-CT was a better staging tool than standard of care methods.

Clinical and imaging findings, treatments, and outcomes in 27 dogs with imaging diagnosed trigeminal nerve sheath tumors: A multi-center study.

The clinical behavior of canine trigeminal nerve sheath tumors and benefits of previously reported treatments are incompletely defined. Aims of this retrospective, multicenter, observational study were to describe clinical signs, tumor localization characteristics, treatments, and clinical outcomes in a group of dogs with this neoplasm. Databases at four hospitals were reviewed for dogs with a trigeminal nerve sheath tumor diagnosis, magnetic resonance imaging (MRI) studies, and presentation between 2004 and 2014. A single observer recorded medical record findings and two observers recorded MRI characteristics by consensus. A total of 27 dogs met inclusion criteria (15 treated with stereotactic radiation therapy and 12 unirradiated). Two unirradiated dogs were excluded from outcome analyses. The most common presenting signs were masticatory muscle atrophy (26 dogs), neurologic signs referable to intracranial disease (13), and ocular disease (12). Based on MRI findings, all dogs had disease extending centrally at the level of the brainstem. The most commonly affected trigeminal nerve branches were the mandibular (26 dogs), maxillary (22), and ophthalmic (10). Of 15 dogs treated with stereotactic radiation therapy, one had improved muscle atrophy, and six had poor ocular health after treatment. Neurologic signs improved in 4/5 dogs with intracranial signs. Overall median survival time for the 10 unirradiated dogs with available follow-up was 12 days and 441 days for the 15 stereotactic radiation therapy dogs. Mean survival times between these groups were not significantly different (mean 95% CI for unirradiated dogs was 44-424 days and mean 95% CI for stereotactic radiation therapy dogs was 260-518 days).

Associations between thoracic radiographic changes and severity of pulmonary arterial hypertension diagnosed in 60 dogs via Doppler echocardiography: A retrospective study.

Doppler echocardiography is a noninvasive method for estimating and grading pulmonary arterial hypertension. No current literature associates significance of radiographic findings with severity of pulmonary arterial hypertension. We hypothesized that the number and conspicuity of radiographic findings suggestive of pulmonary arterial hypertension would be greater based on the severity of pulmonary arterial hypertension. Dogs with pulmonary arterial hypertension and normal control dogs were included in this retrospective, case control study. Three radiologists blinded to echocardiographic results scored thoracic radiographs for right ventricular and main pulmonary artery enlargement and pulmonary lobar artery enlargement, tortuosity, and blunting by multiple methods. Presence or absence of each finding was scored in an additive fashion and averaged for each grade of pulmonary arterial hypertension severity. Seventy-one dogs (60 dogs with pulmonary arterial hypertension and 11 control dogs) of which some had multiple studies were included: 20 mild, 21 moderate, 25 severe, and 11 absent pulmonary arterial hypertension. The following radiographic findings were significantly associated with increasing pulmonary arterial hypertension severity: right ventricular enlargement by "reverse D" and "3/5-2/5 cardiac ratio" methods, main pulmonary artery enlargement, and caudal lobar artery enlargement by the "3rd rib" method. Mean scores for severe pulmonary arterial hypertension and normal dogs were significantly different (P-value < 0.0001). Mean scores between different pulmonary arterial hypertension grades increased with severity but were not statistically significant. Individually and in combination, radiographic findings performed poorly in differentiating severity of pulmonary arterial hypertension. Findings indicated that thoracic radiographs should be utilized in conjunction with Doppler echocardiography in a complete diagnostic work-up for dogs with suspected pulmonary arterial hypertension.

Renal pelvic and ureteral ultrasonographic characteristics of cats with chronic kidney disease in comparison with normal cats, and cats with pyelonephritis or ureteral obstruction.

Objectives The objective was to describe ultrasonographic characteristics of cats with stable chronic kidney disease (CKD) and determine if these were significantly different from cats with pyelonephritis (Pyelo) and ureteral obstruction (UO), to aid in clinical assessment during uremic crisis. Methods Sixty-six cats with stable CKD were prospectively enrolled, as well as normal control cats (n = 10), cats with a clinical diagnosis of Pyelo (n = 13) and cats with UO confirmed by surgical resolution (n = 11). Renal ultrasound was performed and routine still images and cine loops were obtained. Analysis included degree of pelvic dilation, and presence and degree of ureteral dilation. Measurements were compared between groups using non-parametric one-way ANOVA with Dunn's post-hoc analysis. Results In total, 66.6% of CKD cats had measurable renal pelvic dilation compared with 30.0% of normal cats, 84.6% of Pyelo cats and 100% of UO cats. There was no statistically significant difference in renal pelvic widths between CKD cats and normal cats, or CKD cats and Pyelo cats. On almost all measurement categories, UO cats had significantly greater renal pelvic widths compared with CKD cats and normal cats ( P <0.05) but not Pyelo cats. Six percent of stable CKD cats had measurable proximal ureteral dilation on one or both sides vs 46.2% of Pyelo cats and 81.8% of UO cats. There was no statistically significant difference in proximal ureteral width between normal and CKD cats, or between Pyelo and UO cats. There was a statistically significant difference in proximal ureteral width between CKD and Pyelo cats, CKD and UO cats, normal and UO cats, and normal and Pyelo cats. Conclusions and relevance No significant difference in renal pelvic widths between CKD cats and Pyelo cats was seen. These data suggest CKD cats should have a baseline ultrasonography performed so that abnormalities documented during a uremic crisis can be better interpreted.

Use of PET/CT and Stereotactic Radiation Therapy for the Diagnosis and Treatment of Osteosarcoma Metastases.

This case report describes the use of two new concepts in the diagnosis and treatment of metastatic osteosarcoma (OSA) in one dog. The dog was initially presented for positron emission tomography and computed tomography (PET/CT) as full-body staging following amputation and adjuvant chemotherapy for treatment of OSA of the proximal tibia. The initial PET/CT did not show evidence of metastatic disease. Six mo after OSA, diagnosis pulmonary metastatic nodules were identified and oral toceranib phosphate was initiated. Twelve mo postdiagnosis the dog developed neck pain and non-ambulatory tetraparesis and was diagnosed with a C7 vertebral metastatic lesion based on magnetic resonance imaging. A second PET/CT was performed to screen for further metastatic lesions, and a nodule within the right ischium was identified. The C7 and ischial lesions were treated with stereotactic radiation therapy (SRT). Sixteen mo postdiagnosis, a third PET/CT was performed due to increasing size of the pulmonary nodules and a right-sided liver metastasis was detected. The liver mass was treated with SRT. The PET/CT scans facilitated identification of gross metastatic lesions that were subsequently treated with SRT, which resulted in clinical improvement of the dog's neurological signs.