Prospective pilot study utilizing changes in quantitative values obtained on serial fluorine-18 fluorodeoxyglucose (18F-FDG) positron emission tomography-computed tomography (PET/CT) in dogs with appendicular osteosarcoma before and after stereotactic body radiation therapy (SBRT) and carboplatin chemotherapy to assess for prediction of survival and therapeutic effectiveness.

Serial fluorine 18 fluorodeoxyglucose (18F-FDG) positron emission tomography-CT (PET/CT) is commonly used in human oncology to prognosticate and evaluate for therapeutic effectiveness. In this pilot study, dogs with naturally occurring appendicular osteosarcoma were evaluated with serial 18F-FDG PET/CT in an attempt to assess for response to therapy, prognostic factors, and appropriateness of imaging intervals. Fourteen dogs were enrolled in the trial. All dogs had the initial 18F-FDG PET/CT (PET1), with nine dogs having their end-of-therapy 18F-FDG PET/CT (EoT PET) 3 months after stereotactic body radiation therapy (SBRT) to the primary tumor. The median percent change from the PET1 to the EoT PET for the standard uptake value maximum (SUVmax%) was -58% (range: -17 to -88%), metabolic tumor volume (MTV%) was -99.8% (range: -65 to -100%), and total lesion glycolysis (TLG%) was -99.8% (range: -75 to -100%), all of which were significant (P < .05, <.05, and <.05, respectively). On evaluation, it was found that volumes of GTV and CTV were significant for survival (P < .05 and <.05), MTV1, TLG1, and SUVmax on the EoT PET (SUVmaxEoT) were predictive of metastasis (P < .05), and the SUVmax% was significantly correlated to the time to first event (P < .05). Based on this data, serial 18F-FDG PET/CT performed 3 months after SBRT can show a significant reduction in avidity, and the quantitative data collected may help predict metastatic disease in canine appendicular osteosarcoma.

Primary extraskeletal osteosarcoma of the post-hepatic caudal vena cava in a dog-Case report.

Extraskeletal osteosarcoma (EOSA) in dogs is a rare malignant mesenchymal tumor of somatic soft tissues or more commonly visceral organs with a poor prognosis. In dogs, EOSAs have been described as arising from multiple locations, but differently from humans, never from a main vessel. In this report, we describe the first case of an EOSA arising from the post-hepatic caudal vena cava in a 7-year-old male neutered mix breed dog. This report focuses on the description of the diagnostic challenges to obtain a preoperative diagnosis, highlights the importance of histopathology for a correct diagnosis, and introduces a new differential diagnosis for an animal presenting with a suspected thrombus of the vena cava.

A retrospective study of sinonasal tumors in 182 dogs treated with stereotactic radiotherapy (3 × 10 Gy) (2010-2015).

BACKGROUND: Stereotactic radiotherapy (SRT) is an emerging treatment for sinonasal tumors in dogs. Reported results regarding tumor control and incidence of acute and late radiation morbidities are inconsistent. OBJECTIVES: To determine treatment efficacy and prognostic indicators of SRT in dogs with sinonasal tumors and to quantify acute and late radiation morbidities. ANIMALS: One hundred and eighty-two client-owned dogs with sinonasal tumors diagnosed cytologically, histologically, or radiographically that underwent SRT. METHODS: Single-arm retrospective study by reviewing medical records of dogs treated with SRT (10 Gy × 3) between 2010 and 2015. Kaplan-Meier analysis was used to determine overall survival (OST; from the first day of SRT to death by any cause) and disease-specific survival times (DSST; OST but censoring tumor/treatment-unrelated death). Tumors were staged using modified Adams criteria. RESULTS: Median OST and DSST of dogs treated with 1 course of SRT was 441 (95% CI: 389-493 days) and 482 (428-536 days) days, respectively with skin/oral cavity acute morbidities observed in 3% of dogs. DSST in dogs with stage 4 disease showed no statistical difference compared to other stages (P = .64). Oro-nasal (n = 2) or naso-cutaneous (n = 11) fistula development occurred in 7.1% of dogs with median time of 425 days (range: 83-1733 days). Possible chronic rhinitis after SRT was recorded in 54 of 88 dogs (61%) where information was available. CONCLUSIONS AND CLINICAL IMPORTANCE: Results are comparable to other reports of treatment of SRT. Acute morbidities were minimal. Modified Adams stage scheme appeared to be inappropriate for prognostication for dogs with sinonasal tumors treated with SRT.

Retrospective study evaluating the efficacy of stereotactic body radiation therapy for the treatment of confirmed or suspected primary pulmonary carcinomas in dogs.

Canine primary pulmonary carcinomas (PCCs) are commonly treated with surgery with overall median survival times (MST) around a year; however, due to extent of disease, prognosis, or client preference, alternative treatments have been considered. Stereotactic body radiation therapy (SBRT) has been utilized in human cancer patients for local control of lung tumours as a surgical alternative. Twenty-one PCCs in 19 dogs that received SBRT for local control were retrospectively evaluated. Dogs were staged according to the canine lung carcinoma stage classification (CLCSC) system with three as Stage 1, five as Stage 2, three as Stage 3, and eight as Stage 4. Overall MST was 343 days with 38% of patients alive at 1 year. Stage did not significantly impact survival time (p = .72). Five (26%) dogs had lymphadenopathy and MST was not significantly different from dogs without lymphadenopathy (343 vs. 353 days; p = .54). Five out of 18 evaluable dogs (28%) experienced acute lung VRTOG effects and 2 of 12 dogs (17%) experienced late lung VRTOG effects. Median lung dose, V5, V20, and D30 to the lung did not correlate significantly with the development of adverse radiation events. Twelve dogs had follow-up imaging and the best response included a complete response (17%), partial response (42%), and stable disease (42%). Progressive disease was noted in seven dogs a median of 229 days after SBRT. SBRT was documented to be a safe and effective alternative to surgery and may have survival advantages for Stage 3 or 4 dogs according to the CLCSC.

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.

Lymphotropic nanoparticle magnetic resonance imaging for diagnosing metastatic lymph nodes in dogs with malignant head and neck tumours.

Lymphotropic nanoparticle magnetic resonance imaging (LNMRI) utilises ultrasmall paramagnetic iron nanoparticles (USPIOs) for imaging of metastatic lymph nodes in patients afflicted with cancer. LNMRI has been shown to be a highly effective and accurate way to diagnose metastasis in humans but has not been commonly reported on in veterinary medicine. USPIOs are phagocytised by macrophages and then localised to lymph nodes where they create a susceptibility artefact on gradient echo MRI sequences. In this study dogs (n = 24) with naturally occurring head and neck tumours were imaged with LNMRI then had mandibular and retropharyngeal lymph nodes extirpated for histological analysis. Subjective and objective analysis of the LNMRI images was performed and imaging results compared to histology as the gold standard. A total of 149 lymph nodes were included in this study. The overall sensitivity, specificity and accuracy was 64%, 94.4% and 89.3% respectively. However, if dogs with mast cell tumours were excluded from analysis the sensitivity, specificity and accuracy rose to 85.7%, 95.7% and 94.6%. LNMRI is potentially an accurate way to determine the presence of lymph node metastasis in dogs with some types of head and neck tumours. However, LNMRI has only moderate accuracy in dogs with oral or mucocutaneous mast cell tumours in this region.

Thoracic CT incidental pulmonary bullae in dogs: Characterization, interobserver variability, and general anesthesia risks.

Ruptures of pulmonary blebs and bullae are the most common cause of spontaneous pneumothorax in dogs. Incidental bullae/blebs have been documented in otherwise healthy people, however information for veterinary patients is currently lacking. Objectives of this retrospective, observer agreement, analytical study were to characterize incidental bullae in thoracic CT studies of dogs, assess interobserver variability for characterizing the bullae, and assess anesthesia risks. Inclusion criteria were dogs presenting for non-pneumothorax related reasons that had a thoracic CT at a single specialty and emergency hospital from 2012 to 2021 and had a bulla listed in the CT report. Medical records for dogs meeting inclusion criteria were reviewed to collect data on signalment, weight, total number of general anesthesia procedures 2 years prior and 2 years following the CT scan, and adverse anesthesia events. In addition, the CT images were reviewed by three American College of Veterinary Radiology-certified veterinary radiologists to collect data on the location, size, number of bullae and thickness of the bulla wall. A total of 1119 dogs met initial inclusion criteria and 74 dogs were included in analyses. There was no sex predilection for incidental pulmonary bullae. Bullae were more commonly found in older (median age 11.3 years), large breed dogs (median weight 20.7 kg). A solitary bulla of less than 1 cm was the most common finding with no apparent predilection for a particular lung lobe. There was strong correlation among the three radiologists for bulla location, size, and number, but weak correlations for bulla wall thickness. No adverse anesthesia events were found following CT anesthesia or following repetitive anesthesia procedures.

Diagnostic imaging and histopathologic features of rounded atelectasis in four cats and one dog: A descriptive case series study.

In humans, rounded atelectasis is defined as focal lung collapse that radiologically appears as a round mass-like lesion in the periphery of the lung. In general, human patients with rounded atelectasis have a history of pleural effusion and abnormal pleura and characteristic CT findings help to distinguish rounded atelectasis from pulmonary neoplasia without the need for invasive surgical biopsy. This retrospective multi-center case series describes rounded atelectasis in four cats and one dog. Chylothorax was seen in four patients and an eosinophilic and lymphoplasmacytic effusion was seen in one patient. All patients had solitary or multifocal subpleural pulmonary masses (26 masses total in 5 patients) with diffuse, multifocal, or focal visceral and parietal pleural thickening. All the masses but one were broad-based towards the visceral pleura. Masses were most common in the ventral or lateral aspect of the lungs. Indistinctness at the hilar aspect of the lesion was seen in all masses; a "comet tail" sign was seen in 14 of 26 masses. On postcontrast images, the lesions were homogeneously enhanced in 24 of 26 masses and heterogeneous in two of 26 masses. Other findings include ground glass opacities (n = 5), parenchymal bands (n = 4), mild to moderate lymphadenopathy (n = 4), and compensatory hyperinflation of the lung lobes not affected by atelectasis (n = 2). Histopathology of four cases revealed atelectasis with fixed pleural folds, chronic pleuritis, and mild to moderate pleural fibrosis. Awareness of rounded atelectasis in veterinary species will enable inclusion of a benign etiology into the differential diagnosis for subpleural masses in cases with pleural abnormalities.

Multi-modality imaging and therapeutics used in a case of canine spinal nephroblastoma.

A 4-year-old castrated male golden retriever dog was brought to a veterinary teaching hospital for evaluation of acute progressive paraparesis. Neurological examination indicated a spinal cord lesion between the third thoracic vertebra and third lumbar vertebrae. Magnetic resonance imaging (MRI) revealed an intradural, extra medullary, and/or intramedullary mass centered over the eleventh and twelfth thoracic disc space. The dog underwent cytoreductive surgery and histopathologic analysis diagnosed a nephroblastoma. Following this, the dog underwent multimodal therapy, including multiple surgeries, 2 courses of radiation, and combination chemotherapy. The dog had serial restaging using MRI, computed tomography (CT), and fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography throughout the course of therapy. The dog survived 350 d from date of first presentation until humane euthanasia was elected due to worsening of neurologic status. During postmortem examination, extensive infiltration of the spinal cord by nephroblastoma cells was discovered as well as pulmonary metastatic disease. Key clinical message: Based on the literature search, this is the first case in which surgery, radiation therapy, and chemotherapy were all used for the treatment of canine spinal nephroblastoma. This case report details the aggressive nature of a case of canine spinal nephroblastoma despite multi-modal therapy.

Méthode d'imagerie et de thérapies multimodales utilisées dans un cas de néphroblastome spinal canin. Un chien golden retriever mâle castré âgé de 4 ans a été présenté dans un hôpital d'enseignement vétérinaire pour l'évaluation d'une paraparésie progressive aiguë. L'examen neurologique a révélé une lésion de la moelle épinière entre la troisième vertèbre thoracique et la troisième vertèbre lombaire. L'imagerie par résonance magnétique (MRI) a révélé une masse intradurale, extra-médullaire et/ou intramédullaire centrée sur les onzième et douzième espace de disque thoracique. Le chien a subi une chirurgie de cytoréduction et une analyse histopathologique a diagnostiqué un néphroblastome. Par la suite, le chien a subi une thérapie multimodale, comprenant plusieurs interventions chirurgicales, deux cycles de radiothérapie et une chimiothérapie combinée. Le chien a subi une reclassification en série par MRI, tomodensitométrie (CT) et tomographie par émission de positrons au fluor-18 fluorodésoxyglucose/tomodensitométrie tout au long du traitement. Le chien a survécu 350 jours à partir de la date de la première présentation jusqu'à ce que l'euthanasie soit choisie en raison de l'aggravation de l'état neurologique. Au cours de l'examen post-mortem, une infiltration étendue de la moelle épinière par des cellules de néphroblastome a été découverte ainsi qu'une maladie métastatique pulmonaire.Message clinique clé :D'après la recherche documentaire, il s'agit du premier cas dans lequel la chirurgie, la radiothérapie et la chimiothérapie ont toutes été utilisées pour le traitement du néphroblastome spinal canin. Ce rapport de cas détaille la nature agressive d'un cas de néphroblastome spinal canin malgré une thérapie multimodale.(Traduit par Dr Serge Messier).

What Is Your Diagnosis?

In collaboration with the American College of Veterinary Radiology.

Clinical outcomes of thyroid tumours with concurrent epithelial and mesenchymal components in 14 dogs (2006-2020).

BACKGROUND: While rare, multiple individual case reports have described mixed thyroid tumours in dogs containing both epithelial and mesenchymal neoplastic components. OBJECTIVES: In this retrospective case series, we describe the clinical presentation, treatment and outcome of 14 dogs of canine thyroid tumours with concurrent mesenchymal and epithelial neoplastic populations. METHODS: Fourteen cases were retrospectively abstracted from nine institutions. Histopathologic samples and reports were collected from 10/14 dogs and reviewed by a single board-certified anatomic pathologist. RESULTS: All 14 dogs had curative-intent surgery to remove the thyroid neoplasm. The most common surgery performed was a unilateral thyroidectomy (10/14 dogs). Postoperatively, systemic therapy was administered in eight dogs. Six dogs developed local recurrence with a median time to loco-regional recurrence of 53 days. Ten dogs developed metastatic disease with the most common metastatic site being the lungs (6/10 dogs), with a median time to metastasis of 93 days. Ten dogs were euthanised due to locoregional or distant progression of their mixed thyroid neoplasm. The overall median survival time was 156 days (95%CI: 49-244). The median survival time for dogs treated with adjuvant therapy was 189 days (95%CI: 24-244), whereas dogs without adjuvant therapy had a median survival time of 156 days (95%CI: 35-upper limit could not be calculated; p = 0.62). CONCLUSION: The thyroid tumours with both mesenchymal and epithelial components in this small sample set were associated with a poor prognosis after surgical excision with or without adjunctive therapy.

Outcome of stereotactic body radiation for treatment of nasal and nasopharyngeal lymphoma in 32 cats.

BACKGROUND: The safety and efficacy of stereotactic body radiation therapy (SBRT) in the treatment of localized nasal lymphoma in cats has not been described. HYPOTHESIS: Stereotactic body radiation therapy with or without adjuvant chemotherapy is an effective and well-tolerated treatment for localized nasal lymphoma in cats. ANIMALS: Thirty-two client owned cats referred to Colorado State University for the treatment of nasal lymphoma. METHODS: Retrospective study of cats treated with SBRT between 2010 and 2020 at Colorado State University. Diagnosis of nasal lymphoma was obtained via cytology or histopathology. Signalment, radiation protocol, concurrent treatments, adverse effects, and survival were recorded. RESULTS: Progression free survival was 225 days (95% CI 98-514) and median survival time (MST) was 365 days (95% CI 123-531). No significant difference in survival was identified between cats that received 1 versus greater than 1 fraction (MST 427 vs. 123 days, P = 0.88). Negative prognostic factors included cribriform lysis (MST 121 vs. 876 days, P = 0.0009) and intracalvarial involvement (MST 100 vs. 438 days, P = 0.0007). Disease progression was noted in 38% (12/32), locally in 22% (7/32), and systemically in 16% (5/32). No cats developed acute adverse effects. Ten cats developed late adverse effects: keratitis/keratitis sicca (n = 2), alopecia (n = 4), and leukotrichia (n = 4). Twenty-four cats (75%) had signs consistent with chronic rhinitis. CONCLUSIONS: SBRT is effective and well tolerated for treating localized nasal lymphoma in cats. Outcomes for cats with lower stage disease (canine modified Adam's stage 3 and lower) are comparable to historic data of cats treated with fractionated radiation therapy.

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.

What Is Your Diagnosis?

In collaboration with the American College of Veterinary Radiology.

The prognostic significance of metabolic tumour volume and total lesion glycolysis for dogs staged for appendicular osteosarcoma with fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography.

Metabolic tumour volumes (MTV) and total lesion glycolysis (TLG) are metabolic parameters that are becoming more commonly reported in human medicine to quantify tumours detected on fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (18 F-FDG PET/CT). In this retrospective study dogs afflicted with appendicular osteosarcoma that were staged with 18 F-FDG PET/CT had MTV and TLG at a variety of set and fixed thresholds calculated by two observers. These values, along with SUVmax , were evaluated for prognostic significance in this population of dogs. There was excellent correlation between two observers for all values. Multiple volumetric parameters were significantly associated with survival. SUVmax had the highest sensitivity for survival and TLG at 2.5 SUV*cm3 had the highest specificity for prediction of survival based on ROC calculations. The SUVmax , MTV at 2.5 SUV and TLG at 2.5 SUV*cm3 were significantly different between dogs that survived more than or less than 1 year. This study is the first of its kind in veterinary medicine that retrospectively evaluated volumetric tumour values for prognostic significance and may provide a basis for standardized method of reporting 18 F-FDG PET/CT results.

CT characteristics and proposed scoring scheme are predictive of pathologic fracture in dogs with appendicular osteosarcoma treated with stereotactic body radiation therapy.

Stereotactic body radiation therapy (SBRT) is an established limb-sparing treatment for dogs with appendicular osteosarcoma (OSA) and pathologic fractures are a common sequela. The objectives of this retrospective, observational, and descriptive study were to develop and evaluate objective CT criteria for predicting pathologic fractures and assess impacts on survival time. Included dogs had confirmed or suspected appendicular OSA, available CT scans, available outcome data, and were treated with SBRT. For each study, the number of quartiles affected by lysis on the most severely affected transverse slice, longest measurable length of contiguous full cortical lysis, presence of subchondral bone lysis, and ratio of the length of the affected bone to normal bone were recorded. A scoring system was developed for assigning grades (summed score 1-4 = grade 1, 5-7 = grade 2, and 8 or greater = grade 3.) A total of 127 CT datasets were sampled (123 patients). The median summed score was 7. The grade was correlated with pathologic fracture development (23% of grade 1, 35% of grade 2, and 57% of grade 3 resulting in fracture, P = 0.028). Subchondral bone lysis was correlated with fracture (odds ratio, 2.2, P = 0.02). Percent affected bone ≥40% was associated with decreased survival (P = 0.002). Dogs with <40% of affected bone had a median survival of 256 days versus 178 days for dogs with ≥40% affected bone. Findings from the current study can be used to assist in determining prognosis and planning radiation therapy for future dogs affected by appendicular OSA.

Complement opsonization of nanoparticles: Differences between humans and preclinical species.

The complement system plays a key role in opsonization and immune clearance of engineered nanoparticles. Understanding the efficiency, inter-subject, and inter-strain differences of complement opsonization in preclinical species can help with translational nanomedicine development and improve our ability to model complement response in humans. Dextran-coated superparamagnetic iron oxide (SPIO) nanoparticles and a wide range of non-magnetic iron oxide nanoparticle formulations are widely used in magnetic resonance imaging and as clinically approved iron supplements. Previously we found that opsonization of SPIO nanoworms (NW) with the third complement protein (C3) proceeds mostly via the alternative pathway in humans, and via the lectin pathway in mice. Here, we studied the pathway and efficiency of opsonization of 106 nm SPIO NW with C3 in different preclinical species and commonly used laboratory strains. In sera of healthy human donors (n = 6), C3 opsonization proceeded exclusively through the alternative pathway. On the other hand, the C3 opsonization in dogs (6 breeds), rats (4 strains) and mice (5 strains) sera was either partially or completely dependent on the complement Ca2+-sensitive pathways (lectin and/or classical). Specifically, C3 opsonization in sera of Long Evans rat strain, and mouse strains widely used in nanomedicine research (BALB/c, C57BL/6 J, and A/J) was only through the Ca2+-dependent pathways. Dogs and humans had the highest between-subject variability in C3 opsonization levels, while rat and mouse sera showed the lowest between-strain variability. Furthermore, using a panel of SPIO nanoparticles of different sizes and dextran coatings, we found that the level of C3 opsonization (C3 molecules per milligram Fe) in human sera was lower than in animal sera. At the same time, there was a strong predictive value of complement opsonization in dog and rat sera; nanoparticles with higher C3 deposition in animals showed higher deposition in humans, and vice versa. Notably, the opsonization decreased with decreasing size in all sera. The studies highlight the importance of the consideration of species and strains for predicting human complement responses (opsonization) towards nanomedicines.

Use of stereotactic body radiation therapy for treatment of a pancreatic tumor in a cat.

CASE DESCRIPTION: A 16-year old castrated male domestic shorthair cat was evaluated at a veterinary teaching hospital because of polyuria, polydipsia, and weight loss of 2 months' duration. CLINICAL FINDINGS: Hematologic and biochemical examination results were within respective reference ranges except for moderately high pancreas-specific lipase concentration. Ultrasonographic and cytologic evaluation revealed a hepatic mass with findings consistent with mild cholestasis and inflammation and a pancreatic mass that was initially identified as a neuroendocrine tumor. TREATMENT AND OUTCOME: The cat underwent additional CT assessment and stereotactic body radiation therapy (SBRT; 3 fractions of 8 Gy, administered every other day) for treatment of the pancreatic tumor. Follow-up ultrasonographic and CT examinations indicated a partial response to SBRT, with a maximum CT-measured size reduction from 3.6 × 4.8 × 4.0 cm at the time of treatment planning to 2.0 × 2.0 × 1.9 cm 8 months later. Increased pancreatic tumor size and signs of carcinomatosis were detected 15 months after SBRT treatment; the initial cytologic diagnosis was changed to exocrine pancreatic carcinoma on reevaluation of the slides by another veterinary pathologist. Carboplatin treatment was elected, and signs of carcinomatosis resolved. The cat was euthanized without further testing because of weakness 589 days after SBRT was started. CLINICAL RELEVANCE: To the authors' knowledge, this is the first report of SBRT for suspected exocrine pancreatic carcinoma in a cat. Further investigation is needed to determine optimal fractionation schedules for SBRT of pancreatic tumors and utility of SBRT of exocrine pancreatic carcinoma in cats.

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.