Providing comparison normal examples alongside pathologic thoracic radiographic cases can improve veterinary students' ability to identify abnormal findings or diagnose disease.

Learning by comparison is a frequently employed education strategy used across many disciplines and levels. Interpreting radiographs requires both skills of perception and pattern recognition, which makes comparison techniques particularly useful in this field. In this randomized, prospective, parallel-group study, students enrolled in second and third-year radiology veterinary courses were given a case-based thoracic radiographic interpretation assignment. A cohort of the participants was given cases with side-by-side comparison normal images while the other cohort only had access to the cases. Twelve cases in total were presented to the students, with 10 cases depicting examples of common thoracic pathologies, while 2 cases were examples of normal. Radiographs of both feline and canine species were represented. Correctness of response to multiple choice questions was tracked, as was year and group (group 1: non compare, Control; group 2: compare, Intervention). Students assigned to group 1 had a lower percentage of correct answers than students assigned to group 2 (45% Control vs. 52% Intervention; P = 0.01). This indicates that side-by-side comparison to a normal example is helpful in identifying disease. No statistical significance was noted for the correctness of responses according to the year of training (P = 0.90). The overall poor performance on the assignment, regardless of group or year, shows that students in the early years of undergraduate veterinary radiology training struggle with the interpretation of common pathologies, likely a result of a lack of exposure to a multitude of cases and normal variants.

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.

Use of CT and MR imaging in radiation therapy planning of imaging-diagnosed canine intracranial meningioma achieves better tumor coverage than CT alone.

The aim of this retrospective, secondary analysis study was to quantify the dosimetric impact of the lack of interobserver agreement on gross tumor volume (GTV) delineation for canine meningioma. This study used a previously reported population of 13 dogs with GTVs contoured on CT alone and on registered CT-MR by 18 radiation oncologists. The "true" GTV was generated for each dog using a simultaneous truth and performance-level estimation algorithm, and "true" brain was defined as the whole brain minus true GTV. Treatment plans were generated for each dog and observer combination, using criteria applied to the observer's GTV and brain contours. Plans were then categorized as a pass (met all planning criteria for true GTV and true brain) or fail. A mixed-effects linear regression was performed to examine differences in metrics between CT and CT-MR plans and mixed-effects logistic regression was performed to examine differences in percentages of pass/fail between CT and CT-MRI plans. The mean percent coverage of true GTV by prescribed dose was higher for CT-MR plans than for CT plans (mean difference 5.9%; 95% CI, 3.7-8.0; P < 0.001). There was no difference in the mean volume of true brain receiving ≥24 Gy and in maximum true brain dose between CT plans and CT-MR plans (P ≥ 0.198). CT-MR plans were significantly more likely to pass the criteria for true GTV and true brain than CT plans (OR 1.75; 95% CI, 1.02-3.01; P = 0.044). This study demonstrated significant dosimetric impact when GTV contouring was performed on CT alone compared with CT-MR.

Workers should take steps to mitigate surface lead exposure when using lead-containing personal protective equipment.

Veterinary workers use lead shielding for protection against harm from ionizing radiation during diagnostic imaging. Surface lead on shielding has been reported as a potential exposure hazard. The purpose of this prospective, analytical, descriptive study was to measure surface lead on lead-containing shielding in the field service and small animal radiology areas of a veterinary teaching hospital, and to examine potential risk factors for surface lead. Surface lead on a convenience sample of 54 lead shielding items was measured in a commercial laboratory using inductively coupled plasma mass spectrometry. The median and range of surface lead for aprons, thyroid collars, and gloves were 3.6 µg/dm2 (range, 1.3-22.4 µg/dm2 ), 23.1 µg/dm2 (range, 2.6-116 µg/dm2 ), and 134 µg/dm2 (range, 1.5-155 µg/dm2 ), respectively. In the final multivariable analysis, the mean surface lead on thyroid collars and gloves was higher than on aprons (relative differences 4.8, 95% confidence interval [CI] 2.2, 10.5, P < 0.001; and 9.5, 95% CI 4.4, 20.6, P < 0.001, respectively). The mean surface lead on shielding in the worst condition was higher than on shielding in the intermediate and best conditions (P < 0.001). Lead shielding provides effective protection against the harmful effects of ionizing radiation, and shielding should always be worn during radiation exposure. Based on our findings and the common use of lead shielding in veterinary workplaces, we recommend that employers inform workers of this hazard and provide training on steps to mitigate exposure, including the use of disposable gloves when wearing lead shielding and handwashing after use.

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.

A 7-min video training intervention improves worker short-term radiation safety behavior during small animal diagnostic radiography.

Although manual restraint for small animal diagnostic radiography is common, worker protection is often not optimized, particularly for hands and eyes. Radiation safety training videos generally include hours of material on content other than personal protective equipment (PPE), have limited content, if any, on reducing dose to the lens of the eye, and are presented at the level of veterinary professionals. The objectives of this prospective, observational study were to develop a short, open access video training intervention at the layperson level, focused on proper use of PPE, and to test the effectiveness of the training video in changing behavior of workers. The use of PPE, optimal head position, and body position relative to the source of scattered radiation were compared before and after the video training was completed by workers. Results of unconditional and multivariable analyses were similar. In final multivariable analysis, workers wore gloves correctly more frequently (odds ratio [OR] = 2.09; 95% confidence interval [CI], 1.68-2.59; P < .001) and wore eyewear more frequently (OR = 1.85; 95% CI, 1.23-2.78; P = .003) after completing the training intervention. Workers also had an optimal head position more frequently (OR = 1.27; 95% CI, 1.03-1.58; P = .03) and stood straight or leaned back more frequently (OR = 1.85; 95% CI, 1.48-2.23; P < .001) after completing the training. The video training developed in this study is an effective tool that can be incorporated into a radiation protection program to improve worker radiation safety behaviors during manual restraint for small animal diagnostic radiography.

Contrast enhanced computed tomography assessment of superficial inguinal lymph node metastasis in canine mammary gland tumors.

Mammary gland neoplasms are predominant in dogs. However, sentinel lymph node (SLN) status assessment criteria have not been established for these cases. In this retrospective, secondary analysis, diagnostic case control study, CT images of 65 superficial inguinal SLNs were obtained before and 1, 3, 5, and 10 min after intravenous administration of contrast agent (iopamidol 370 mgI/mL). The presence and degree of postcontrast enhancement were assessed, by means of the median absolute density value and the maximum absolute density value at any time point in the center and in the periphery of each SLN measured in Hounsfield units (HU), before and after contrast agent administration. These values were compared with histopathological findings postsurgical excision. Receiver operating characteristic analysis was conducted. The absolute density values ranged widely at each time point and within each group of nodes (negative, positive, control group). At all time points, the median density value in the center and in the periphery was significantly higher in metastatic than in non-metastatic SLNs (P ≤ .014). Among the parameters tested, the median absolute density value measured in the periphery of the SLN 3 min after injection showed the highest sensitivity, specificity, and accuracy (AUC) (87.5%, 82.1%, and 92.1% respectively), with a cutoff value of 50.9 HU. The maximum absolute density value at any time point in the center and periphery of the SLNs was also significantly higher in metastatic SLNs compared to non-metastatic (P ≤ .001). With a cutoff value of 59.5 HU, the maximum absolute density value in the periphery of the SLN displayed high sensitivity and specificity (87.5% and 89.3%, respectively). The results of this study support the hypothesis that contrast enhanced CT imaging may aid in the assessment of SLN metastasis in dogs with mammary gland neoplasms.

Radiation safety practices among Canadian equine veterinary workers during diagnostic procedures with portable X-ray equipment.

The objective of this study was to report observed radiation safety practices among equine workers using portable X-ray units at 3 veterinary practices in Canada. Practice 1 was comprised of equine field service workers from an academic institution, whereas Practices 2 and 3 were comprised of workers from private equine referral practices. Out of 2969 exposure-worker observations, protective aprons were worn for > 99% (2968/2969), thyroid shields for 87% (2584/2969), and eyeglasses for 10% (310/2969). The cassette was held by hand for 97% (1078/1114) of observations, and the X-ray unit was held by hand for 100% (1293/1293) of observations. Gloves were used for 54% (606/1114) and < 1% (5/1293) of observations involving cassette holders and X-ray tube operators, respectively. Use of gloves was more frequent among technologists than DVMs (P = 0.004), and among workers in Practices 1 and 3 than in Practice 2 (P < 0.001). In conclusion, given that workers commonly hold cassettes and X-ray tubes by hand, improvement in shielding use is needed. Consideration should be given to specific behavior recommendations in radiation regulations.

Pratiques de radioprotection chez les travailleurs vétérinaires équins canadiens pendant les procédures de diagnostic avec un équipement de radiographie portable. L'objectif de la présente étude était de rapporter les pratiques de radioprotection observées chez les travailleurs équins utilisant des appareils de radiographie portatifs dans trois pratiques vétérinaires au Canada. La pratique 1 était composée de travailleurs équins sur le terrain d'une institution universitaire, tandis que les pratiques 2 et 3 étaient composées de travailleurs sur le terrain issus de pratiques de référence équines privées. Sur 2969 observations de travailleurs exposés, des tabliers de protection ont été portés pour > 99 % (2968/2969), des écrans thyroïdiens pour 87 % (2584/2969) et des lunettes pour 10 % (310/2969). La cassette a été tenue à la main pour 97 % (1078/1114) des observations et l'unité de radiographie a été tenue à la main pour 100 % (1293/1293) des observations. Des gants ont été utilisés pour 54 % (606/1114) et < 1 % (5/1293) des observations impliquant des porteurs de cassette et des opérateurs de tubes à rayons X, respectivement. L'utilisation de gants était plus fréquente chez les technologues que chez les vétérinaires (P = 0,004) et chez les travailleurs des Pratiques 1 et 3 que ceux de la Pratique 2 (P < 0,001). En conclusion, étant donné que les travailleurs tiennent généralement des cassettes et des tubes à rayons X à la main, une amélioration de l'utilisation du blindage est nécessaire. Il faudrait tenir compte des recommandations de comportement spécifiques dans les réglementations relatives aux rayonnements.(Traduit par Dr Serge Messier).

Comparing Two Resources Used to Teach Pulmonary Patterns for a Flipped Veterinary Radiology Course.

The flipped classroom has been gaining momentum within medical education circles. Pre-class assignments are an important component of this pedagogical approach. In this study, a section of the introductory course to veterinary medical imaging was taught using a flipped classroom, and the effectiveness of two different pre-classroom assignments was evaluated. The pre-classroom assignments consisted of either short videos or readings. Both had similar content, which included basic information about pulmonary patterns of disease on chest radiographs. Learning outcomes were assessed by in-classroom and final examination questions. Student learning self-assessments and student satisfaction were also evaluated via an online survey. Students in the video group answered more of the in-classroom questions correctly (71% video vs. 63% reading group; p = .01) and had higher scores on the final examination (83% video vs. 75% reading group; p = .02). There was also a higher student satisfaction with the videos versus the reading assignment. However, we found no significant difference in the student self-assessments of learning or participation in class. An additional finding of this study related to the ongoing difficulties students were having with the learning objectives, including differentiating a pathological process from a normal, or normal variant, recognizing the different pulmonary patterns, and developing a differential diagnoses list, despite the pre-classroom assignments and large group learning sessions. This speaks to the difficulty in developing confidence in pulmonary pattern recognition on chest radiographs, a skill that requires considerable training and time investment.

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.

Use of protective hand shielding by veterinary workers during small animal radiography.

Federal government guidelines recommend wearing hand shielding that provides full protection for the entire hand during manual restraint of animals for radiography. The primary objective of this cross-sectional survey of 143 Saskatchewan veterinary workers was to describe behaviors of workers who do not follow guidelines for effective hand shielding, and to examine the factors associated with these behaviors. An electronic invitation to complete an online questionnaire was sent to 1261 members of the provincial veterinary medical and veterinary technologist associations. More than half of the workers reported that their hand protection was visible on a radiograph at least once a month, and 1/5 reported visible unshielded body parts at least once a month. More than 1/3 of workers never used shielding that fully enclosed their hands. Use of fully enclosing gloves or mittens was more likely for workers in academic workplaces (P < 0.001).

Usage d'une protection pour les mains par les préposés vétérinaires durant la radiographie des petits animaux. Les lignes directrices du gouvernement fédéral recommandent le port d'une protection pour les mains qui offre une protection complète pour l'ensemble de la main durant la retenue manuelle des animaux lors de la radiographie. L'objectif primaire de cette enquête ponctuelle auprès de 143 préposés vétérinaires de la Saskatchewan consistait à décrire les comportements des préposés qui ne respectent pas les lignes directrices en matière de protection efficace des mains et à examiner les facteurs associés avec ces comportements. Une invitation électronique à répondre au questionnaire en ligne a été envoyée aux 1261 membres des associations provinciales de médecins vétérinaires et de technologues vétérinaires. Plus de la moitié des préposés ont signalé que leur protection était visible sur une radiographie au moins une fois par mois et 1/5 a signalé des parties du corps visibles non protégées au moins une fois par mois. Plus de 1/3 des préposés n'utilisait jamais une protection complète des mains. L'usage de gants ou de mitaines entièrement fermées était plus probable pour les préposés travaillant en milieu universitaire (P < 0,001).(Traduit par Isabelle Vallières).

Use of personal protective equipment in a radiology room at a veterinary teaching hospital.

The use of personal protective equipment by veterinary workers during radiographic imaging is inconsistent. While the self-reported use of leaded aprons and thyroid shields approaches 100% in some studies, the use of leaded gloves and eyeglasses is much lower. Previous studies describing personal protective equipment use are based on self-reporting. Objectives of this prospective, observational study were to describe use of leaded personal protective equipment during radiographic imaging by veterinary workers, and to compare observed use with self-reported use. Use of leaded personal protective equipment during radiographic imaging by veterinary workers was observed over a 10 week period using two motion-triggered video cameras, and a questionnaire was then completed by workers on their use of personal protective equipment. Workers restrained the animal during 91.8% (753/820) of exposures. An apron and a securely closed thyroid shield were worn for >99% of studies. Gloves were used correctly for 43.6% (156/358) of radiographic studies. Leaded eyeglasses were worn for 1.7% (6/358) of studies. Correct glove use was more frequent during regular working hours than after-hours for both veterinarians (odds ratio 32.7, P = 0.001) and veterinary students (odds ratio 75.1, P < 0.001). The number of workers in the room was lower when animals were sedated (P = 0.002) or anesthetized (P = 0.017). Workers overestimated their frequency of glove use (P <0.001). In conclusion, workers use personal protective equipment less frequently in an unsupervised environment, and overestimate their use of personal protective equipment. Use of sedation or anesthesia decreases worker exposure to ionizing radiation.

Frequency of an accessory popliteal efferent lymphatic pathway in dogs.

Staging and therapeutic planning for dogs with malignant disease in the popliteal lymph node are based on the expected patterns of lymphatic drainage from the lymph node. The medial iliac lymph nodes are known to receive efferent lymph from the popliteal lymph node; however, an accessory popliteal efferent pathway with direct connection to the sacral lymph nodes has also been less frequently reported. The primary objective of this prospective, anatomic study was to describe the frequency of various patterns of lymphatic drainage of the popliteal lymph node. With informed client consent, 50 adult dogs with no known disease of the lymphatic system underwent computed tomographic lymphography after ultrasound-guided, percutaneous injection of 350 mg/ml iohexol into a popliteal lymph node. In all 50 dogs, the popliteal lymph node drained directly to the ipsilateral medial iliac lymph node through multiple lymphatic vessels that coursed along the medial thigh. In 26% (13/50) of dogs, efferent vessels also drained from the popliteal lymph node directly to the internal iliac and/or sacral lymph nodes, coursing laterally through the gluteal region and passing over the dorsal aspect of the pelvis. Lymphatic connections between the right and left medial iliac and right and left internal iliac lymph nodes were found. Based on our findings, the internal iliac and sacral lymph nodes should be considered when staging or planning therapy for dogs with malignant disease in the popliteal lymph node.

Blood and Hand Surface Lead in Veterinary Workers Using Lead Shielding During Diagnostic Radiography.

OBJECTIVES: The objectives are to compare lead blood concentrations in veterinary workers using lead shielding with concentrations in a control population, to measure hand surface lead before and after use of shielding, and to compare hand surface lead with and without the use of disposable gloves worn under hand shielding. METHODS: Blood and hand wipe samples were analyzed for lead using inductively coupled plasma mass spectrometry. RESULTS: There was no difference in blood lead between exposed and control groups. After lead glove use, 69% (18/26) of hand surface lead samples from workers not using disposable gloves were greater than 500 µg, 42% (11/26) were greater than 1000 µg, and 12% (3/26) were greater than 2000 µg. CONCLUSIONS: If lead shielding use is unavoidable, disposable gloves should be worn, and skin should be decontaminated after use.

Necrotizing fasciitis caused by methicillin-resistant Staphylococcus pseudintermedius at a previously irradiated site in a dog.

A great Dane dog was presented with a small, superficial wound on the left tarsus that rapidly progressed to a large necrotic area. The dog had undergone radiation therapy in the left tarsal region 33 months previously. Necrotizing fasciitis was diagnosed on histopathological examination, and bacterial culture revealed methicillin-resistant Staphylococcus pseudintermedius.

Fasciite nécrosante causée parStaphylococcus pseudintermediusrésistant à la méthicilline à un site antérieurement irradié chez un chien. Un chien Grand danois a été présenté avec une petite blessure superficielle sur le tarse gauche qui a rapidement progressé pour devenir une grande région nécrotique. Le chien avait subi de la radiothérapie dans la région du tarse gauche 33 mois auparavant. La fasciite nécrosante a été diagnostiquée à l'examen histopathologique et la culture bactérienne a révélé Staphylococcus pseudintermedius résistant à la méthicilline.(Traduit par Isabelle Vallières).

Retrospective study and review of ocular radiation side effects following external-beam Cobalt-60 radiation therapy in 37 dogs and 12 cats.

This retrospective study evaluated the ocular side effects of cancer-bearing dogs and cats treated with external-beam Cobalt-60 (Co-60) radiation in which one or both orbit(s) were included in the radiation field. A total of 37 dogs and 12 cats presented to the Ontario Veterinary College during the 10-year study period (1999-2009) were evaluated. The radiation protocols ranged from a maximum of 60 Gray (Gy) in 24 fractions for curative intent to a minimum of 8 Gy in 1 fraction for palliative treatment. The main ocular side effect reported in both dogs and cats was conjunctivitis (79% and 55%, respectively). Other common ocular side effects included eyelid lesions in dogs (44%), ulcerative keratitis in cats (36%), and keratoconjunctivitis sicca in both dogs and cats (44% and 27%, respectively). The high incidence of ocular side effects in both patient populations indicates a need for regular ophthalmic examinations as a component of routine follow-up for radiation therapy involving the orbit. Radiation damage to ocular tissues is also reviewed.

Étude rétrospective et examen des effets secondaires de la radiation oculaire après une radiothérapie externe au cobalt-60 chez 37 chiens et 12 chats. Cette étude rétrospective a évalué les effets secondaires oculaires chez des chiens et des chats atteints du cancer traités avec une radiation externe au cobalt-60 (Co-60) lorsque l'une ou l'autre des orbites étaient incluses dans le champ de radiation. Un total de 37 chiens et de 12 chats présentés à l'Ontario Veterinary College durant la période d'étude de 10 ans (1999­2009) ont été évalués. Les protocoles de radiation s'échelonnaient de 60 Gray (Gy) en 24 fractions pour un traitement curatif à un minimum de 8 Gy en 1 fraction pour un traitement palliatif. Le principal effet secondaire oculaire signalé chez les chiens et les chats était la conjonctivite (79 % et 55 %, respectivement). D'autres effets secondaires communs étaient des lésions des paupières chez les chiens (44 %), une kératite ulcérative chez les chats (36 %) et une kératoconjonctivite sèche chez les chiens et les chats (44 % et 27 %, respectivement). L'incidence élevée d'effets secondaires oculaires dans les deux populations de patients signale le besoin d'examens ophtalmologiques réguliers comme élément d'un suivi de routine pour la radiothérapie touchant l'orbite. Les dommages de la radiation aux tissus oculaires sont également examinés.(Traduit par Isabelle Vallières).

Indirect magnetic resonance lymphography of the head and neck of dogs using Gadofluorine M and a conventional gadolinium contrast agent: a pilot study.

The purpose of this pilot study was to evaluate lymph node enhancement with an indirect magnetic resonance (MR) lymphography technique using 2 different contrast agents in the head and neck region of healthy dogs. Five dogs were imaged at various times after intradermal injection of gadoversetamide and Gadofluorine M (minimum of 1 week apart) in the right and left mandibular, temporal, and lateral neck regions. We observed consistent progressive enhancement with time in the mandibular, retropharyngeal, and superficial cervical lymph nodes. The node enhancement was comparable for both contrast agents. Contrast enhancement of the parotid lymph nodes was not seen. We conclude that this technique of indirect MR lymphography using either agent could be used to identify those lymph nodes at highest risk of metastatic disease in dogs with cancer, and to guide staging and treatment.

Lymphographie par résonance magnétique indirecte de la tête et du cou des chiens en utilisant Gadofluorine M et un agent de contraste conventionnel au gadolinium : étude pilote. Le but de cette étude pilote était d'évaluer le contraste des ganglions lymphatiques à l'aide d'une technique de lymphographie par résonance magnétique (RM) indirecte en utilisant 2 agents de contraste différents dans la région de la tête et du cou des chiens en santé. L'imagerie de 5 chiens a été réalisée à divers moments après l'injection intradermique de gadoversétamide et de Gadofluorine M (avec un intervalle minimum de 1 semaine) dans les régions mandibulaires droite et gauche, temporale et du cou. Nous avons observé une augmentation progressive constante dans le temps dans les ganglions mandibulaires, rétropharyngiens et cervicaux superficiels. Le contraste des ganglions était comparable pour les deux agents. L'augmentation de contraste des ganglions lymphatiques parotidiens n'a pas été vue. Nous concluons que cette technique de lymphographie par RM indirecte, en utilisant l'un ou l'autre des agents, pourrait être utilisée pour identifier les ganglions lymphatiques les plus à risque de maladie métastasique chez les chiens atteints de cancer et pour guider la détermination des stades et le traitement.(Traduit par Isabelle Vallières).