Helical TomoTherapy Total Lymphoid Irradiation and Hematopoietic Cell Transplantation for Kidney Transplant Tolerance in Rhesus Macaques

Development of a post-transplant kidney transplant tolerance induction protocol involving a novel total lymphoid irradiation (TLI) conditioning method in a rhesus macaque model is described. We examined the feasibility of acheiving tolerance to MHC 1-haplotype matched kidney transplants by establishing a mixed chimeric state with infusion of donor hematopoietic cells (HC) using TomoTherapy TLI. The chimeric state was hypothesized to permit the elimination of all immunosuppressive (IS) medications while preserving allograft function long-term without development of graft-versus-host-disease (GVHD) or rejection. An experimental group of 11 renal transplant recipients received the tolerance induction protocol and outcomes were compared to a control group (n = 7) that received the same conditioning but without donor HC infusion. Development of mixed chimerism and operational tolerance was accomplished in two recipients in the experimental group. Both recipients were withdrawn from all IS and continued to maintain normal renal allograft function for 4 years without rejection or GVHD. None of the animals in the control group achieved tolerance when IS was eliminated. This novel experimental model demonstrated the feasibility for inducing of long-term operational tolerance when mixed chimerism is achieved using a TLI post-transplant conditioning protocol in 1-haplotype matched non-human primate recipients of combined kidney and HC transplantation.

Comparison of injuries between US Army paratroopers and their non-paratrooper soldier counterparts

INTRODUCTION

Military studies have investigated acute injuries associated with parachute jumps, but the literature does not address paratroopers' cumulative microtraumatic (CMT) injury risk, nor does it compare injury risks between paratroopers and the rest of the military population. This study determined whether US active duty Army paratroopers experienced greater injury risks than their non-paratrooper soldier counterparts and whether their injuries cost more to treat suggesting greater injury severity.

METHODS

This retrospective study evaluated electronic medical records (2016-2018) for 31 621 paratroopers and a randomly selected comparison group of 170 715 non-paratrooper soldiers. Analyses included univariate and multivariate regression to quantify odds of injuries associated with risk variables and additional descriptive statistics.

RESULTS

Paratroopers had a 57% increase in the odds of experiencing one or more injuries (OR=1.57, 95% CI: 1.52 to 1.62) after controlling for sex, race and age, with a greater proportion of acute injuries (OR=1.38, 95% CI: 1.34 to 1.42), relative to comparison group soldiers. Injury types proportionally higher among paratroopers included head trauma and shoulder injuries. Average injury cost among paratroopers was 13% lower than for non-paratroopers ($2470 vs $2830 per injury). Among both populations, acute injury costs were notably higher than for CMT injuries (paratroopers, $1710/$630; non-paratroopers, $1860/$880 per injury).

CONCLUSIONS

Paratroopers were more likely to incur injury, especially an acute injury, than non-paratroopers. However, paratroopers' average injury costs were less. This may be due to higher return-to-duty motivations, fitness levels, and/or facility-specific cost of care. Future studies should investigate causes of injuries found to be proportionally higher among paratroopers.

Pectoralis major injuries in the military: a surveillance approach to reduce an underestimated problem

INTRODUCTION

Multiple studies report increasing cases of surgically treated pectoralis major (PM) muscle and tendon ruptures in military populations. Studies associate this with a growing popularity of weight-training and bench press exercises. Mild-to-moderate non-surgical PM traumas and overuse injuries have not been included in these studies despite evidence that these types of outpatient injuries account for the majority of the military's injury medical burden.

METHODS

To assess rates of all PM injuries (ruptures, tears, strains, overuse), regardless of form of treatment, a PM injury surveillance definition was derived from International Classification of Disease (ICD) diagnostic codes used in routine US Army injury surveillance. A detailed clinical examination of 2016 Active Duty Army medical records was used to identify ICD codes commonly associated with PM injuries. Cost data were calculated and the definition applied to medical data from 2016 through 2018to assess trends.

RESULTS

The estimated incidence of PM cases among soldiers was over 95% greater than if only considering severe surgical cases. Over 96% of army annual PM injury costs (direct medical and indirect from lost labour) were for outpatient services. PM injury incidence rates were not statistically different from 2016 to 2018.

CONCLUSIONS

The PM injury surveillance definition provides a consistent means to monitor trends over time and evaluate the effectiveness of prevention efforts. PM injuries have a larger military impact than previously recognised and prioritised prevention strategies are needed to reduce them. Future interventions could focus on the bench press given its observed association with PM injuries.

Cor triatriatum dexter in 17 dogs

OBJECTIVES

The objective of this study was to report the signalment, presentation, clinical and imaging findings, interventions, and outcomes in a group of dogs with cor triatriatum dexter (CTD).

ANIMALS

Seventeen client-owned dogs.

METHODS

Medical records were reviewed retrospectively for signalment, history, physical examination findings, imaging and diagnostic findings, presence of concurrent congenital cardiac defects, description of interventional procedures, therapy information, and outcomes.

RESULTS

Age at presentation ranged from two to 110 months, with 10 of 17 dogs (59%) aged <12 months. There was an equal distribution between the sexes. Peritoneal effusion was the most common presenting complaint, in 10 of 17 dogs (59%). The CTD was an isolated finding in 3 of 17 dogs (18%); the remaining 14 of 17 (82%) dogs had concurrent cardiac disease, with congenital anomalies present in 12 of 17 (70%). All except one of these 12 dogs had at least one additional condition affecting the right heart. Tricuspid valve dysplasia was the most common congenital comorbidity, present in 9 of 17 dogs (53%). Seven dogs (41%) underwent interventional treatment of their CTD. In 7 of 17 (41%) cases, the CTD was considered to be incidental and the dogs were asymptomatic; therefore, no interventions were performed. The remaining three cases were euthanized or lost to follow-up.

CONCLUSIONS

Cor triatriatum dexter in dogs is commonly seen in association with other right-sided congenital cardiac anomalies and may be an incidental finding. Dogs with CTD obstructing right atrial inflow can have a good outcome after intervention. Dogs with no clinical signs associated with the CTD may remain asymptomatic into adulthood.

SINGLE INSTITUTION VARIABILITY IN INTENSITY MODULATED RADIATION TARGET DELINEATION FOR CANINE NASAL NEOPLASIA

Contouring variability is a significant barrier to the accurate delivery and reporting of radiation therapy. The aim of this descriptive study was to determine the variation in contouring radiation targets and organs at risk by participants within our institution. Further, we also aimed to determine if all individuals contoured the same normal tissues. Two canine nasal tumor datasets were selected and contoured by two ACVR-certified radiation oncologists and two radiation oncology residents from the same institution. Eight structures were consistently contoured including the right and left eye, the right and left lens, brain, the gross tumor volume (GTV), clinical target volume (CTV), and planning target volume (PTV). Spinal cord, hard and soft palate, and bulla were contoured on 50% of datasets. Variation in contouring occurred in both targets and normal tissues at risk and was particularly significant for the GTV, CTV, and PTV. The mean metric score and dice similarity coefficient were below the threshold criteria in 37.5-50% and 12.5-50% of structures, respectively, quantitatively indicating contouring variation. This study refutes our hypothesis that minimal variation in target and normal tissue delineation occurs. The variation in contouring may contribute to different tumor response and toxicity for any given patient. Our results also highlight the difficulty associated with replication of published radiation protocols or treatments, as even with replete contouring description the outcome of treatment is still fundamentally influenced by the individual contouring the patient.

Characterization of a 0.35T MR system for phantom image quality stability and in vivo assessment of motion quantification

ViewRay is a novel MR‐guided radiotherapy system capable of imaging in near real‐time at four frames per second during treatment using 0.35T field strength. It allows for improved gating techniques and adaptive radiotherapy. Three cobalt‐60 sources (∼15,000 Curies) permit multiple‐beam, intensity‐modulated radiation therapy. The primary aim of this study is to assess the imaging stability, accuracy, and automatic segmentation algorithm capability to track motion in simulated and in vivo targets. Magnetic resonance imaging (MRI) characteristics of the system were assessed using the American College of Radiology (ACR)‐recommended phantom and accreditation protocol. Images of the ACR phantom were acquired using a head coil following the ACR scanning instructions. ACR recommended T1‐ and T2‐weighted sequences were evaluated. Nine measurements were performed over a period of seven months, on just over a monthly basis, to establish consistency. A silicon dielectric gel target was attached to the motor via a rod. 40 mm total amplitude was used with cycles of 3 to 9 s in length in a sinusoidal trajectory. Trajectories of six moving clinical targets in four canine patients were quantified and tracked. ACR phantom images were analyzed, and the results were compared with the ACR acceptance levels. Measured slice thickness accuracies were within the acceptance limits. In the 0.35 T system, the image intensity uniformity was also within the ACR acceptance limit. Over the range of cycle lengths, representing a wide range of breathing rates in patients imaged at four frames/s, excellent agreement was observed between the expected and measured target trajectories. In vivo canine targets, including the gross target volume (GTV), as well as other abdominal soft tissue structures, were visualized with inherent MR contrast, allowing for preliminary results of target tracking.

PACS number: 87.61.Tg

Molecular imaging biomarkers of resistance to radiation therapy for spontaneous nasal tumors in canines

PURPOSE

Imaging biomarkers of resistance to radiation therapy can inform and guide treatment management. Most studies have so far focused on assessing a single imaging biomarker. The goal of this study was to explore a number of different molecular imaging biomarkers as surrogates of resistance to radiation therapy.

METHODS AND MATERIALS

Twenty-two canine patients with spontaneous sinonasal tumors were treated with accelerated hypofractionated radiation therapy, receiving either 10 fractions of 4.2 Gy each or 10 fractions of 5.0 Gy each to the gross tumor volume. Patients underwent fluorodeoxyglucose (FDG)-, fluorothymidine (FLT)-, and Cu(II)-diacetyl-bis(N4-methylthiosemicarbazone) (Cu-ATSM)-labeled positron emission tomography/computed tomography (PET/CT) imaging before therapy and FLT and Cu-ATSM PET/CT imaging during therapy. In addition to conventional maximum and mean standardized uptake values (SUV(max); SUV(mean)) measurements, imaging metrics providing response and spatiotemporal information were extracted for each patient. Progression-free survival was assessed according to response evaluation criteria in solid tumor. The prognostic value of each imaging biomarker was evaluated using univariable Cox proportional hazards regression. Multivariable analysis was also performed but was restricted to 2 predictor variables due to the limited number of patients. The best bivariable model was selected according to pseudo-R(2).

RESULTS

The following variables were significantly associated with poor clinical outcome following radiation therapy according to univariable analysis: tumor volume (P=.011), midtreatment FLT SUV(mean) (P=.018), and midtreatment FLT SUV(max) (P=.006). Large decreases in FLT SUV(mean) from pretreatment to midtreatment were associated with worse clinical outcome (P=.013). In the bivariable model, the best 2-variable combination for predicting poor outcome was high midtreatment FLT SUV(max) (P=.022) in combination with large FLT response from pretreatment to midtreatment (P=.041).

CONCLUSIONS

In addition to tumor volume, pronounced tumor proliferative response quantified using FLT PET, especially when associated with high residual FLT PET at midtreatment, is a negative prognostic biomarker of outcome in canine tumors following radiation therapy. Neither FDG PET nor Cu-ATSM PET were predictive of outcome.

Patient characteristics influencing the variability of distributed parameter-based models in DCE-CT kinetic analysis

Kinetic parameter variability may be sensitive to kinetic model choice, kinetic model implementation or patient-specific effects. The purpose of this study was to assess their impact on the variability of dynamic contrast-enhanced computed tomography (DCE-CT) kinetic parameters. A total of 11 canine patients with sinonasal tumours received high signal-to-noise ratio, test-double retest DCE-CT scans. The variability for three distributed parameter (DP)-based models was assessed by analysis of variance. Mixed-effects modelling evaluated patient-specific effects. Inter-model variability (CV_inter ) was comparable to or lower than intra-model variability (CV_intra ) for blood flow (CV_inter :[4-28%], CV_intra :[28-31%]), fractional vascular volume (CV_inter :[3-17%], CV_intra :[16-19%]) and permeability-surface area product (CV_inter :[5-12%], CV_intra :[14-15%]). The kinetic models were significantly (P<0.05) impacted by patient characteristics for patient size, area underneath the curve of the artery and of the tumour. In conclusion, DP-based models demonstrated good agreement with similar differences between models and scans. However, high variability in the kinetic parameters and their sensitivity to patient size may limit certain quantitative applications.

Reproducibility and feasibility of acoustoelastography in the superficial digital flexor tendons of clinically normal horses

OBJECTIVE

To evaluate the feasibility and repeatability of in vivo measurement of stiffness gradients by means of acoustoelastography in the superficial digital flexor tendons (SDFTs) of clinically normal horses.

ANIMALS

15 clinically normal horses.

PROCEDURES

For each horse, stiffness gradient index and dispersion values for SDFTs in both forelimbs were evaluated in longitudinal orientation by use of acoustoelastography at 3 sites (5, 10, and 15 cm distal to the accessory carpal bone) by 2 observers; for each observer, data were acquired twice per site. The left forelimb was always scanned before the right forelimb. Lifting of the contralateral forelimb with the carpus flexed during image acquisition resulted in the required SDFT deformation in the evaluated limb. Interobserver repeatability, intraobserver repeatability, and right-to-left limb symmetry for stiffness gradient index and dispersion values were evaluated.

RESULTS

Stiffness gradient index and dispersion values for SDFTs at different locations as well as effects of age or sex did not differ significantly among the 15 horses. Interclass correlation coefficients for interobserver repeatability, intraobserver repeatability, and limb symmetry revealed good to excellent agreement (intraclass correlation coefficients, > 0.74).

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that acoustoelastography is a feasible and repeatable technique for measuring stiffness gradients in SDFTs in clinically normal horses, and could potentially be used to compare healthy and diseased tendon states.

Spatiotemporal stability of Cu-ATSM and FLT positron emission tomography distributions during radiation therapy

PURPOSE

In dose painting, in which functional imaging is used to define biological targets for radiation therapy dose escalation, changes in spatial distributions of biological properties during treatment can compromise the quality of therapy. The goal of this study was to assess the spatiotemporal stability of 2 potential dose painting targets--hypoxia and proliferation--in canine tumors during radiation therapy.

METHODS AND MATERIALS

Twenty-two canine patients with sinonasal tumors (14 carcinoma and 8 sarcoma) were imaged before hypofractionated radiation therapy with copper(II)-diacetyl-bis(N4-methylthiosemicarbazone) (Cu-ATSM) positron emission tomography/computed tomography (PET/CT) for hypoxia and 3'-deoxy-3'-(18)F-fluorothymidine (FLT) PET/CT for proliferation. The FLT scans were repeated after 2 fractions and the Cu-ATSM scans after 3 fractions. Midtreatment PET/CT images were deformably registered to pretreatment PET/CT images. Voxel-based Spearman correlation coefficients quantified the spatial stability of Cu-ATSM and FLT uptake distributions between pretreatment and midtreatment scans. Paired t tests determined significant differences between the patients' respective Cu-ATSM and FLT correlations coefficients. Standardized uptake value measures were also compared between pretreatment and midtreatment scans by use of paired t tests.

RESULTS

Spatial distributions of Cu-ATSM and FLT uptake were stable through midtreatment for both sarcomas and carcinomas: the population mean ± standard deviation in Spearman correlation coefficient was 0.88 ± 0.07 for Cu-ATSM and 0.79 ± 0.13 for FLT. The patients' Cu-ATSM correlation coefficients were significantly higher than their respective FLT correlation coefficients (P=.001). Changes in Cu-ATSM SUV measures from pretreatment to midtreatment were histology dependent: carcinomas experienced significant decreases in Cu-ATSM uptake (P<.05), whereas sarcomas did not (P>.20). Both histologies experienced significant decreases in FLT uptake (P<.05).

CONCLUSIONS

Spatial distributions of Cu-ATSM were very stable after a few fractions of radiation therapy. FLT spatial distributions were generally stable early in therapy, although they were significantly less stable than Cu-ATSM distributions. Canine tumors had significantly lower proliferative activity at midtreatment than at pretreatment, and they experienced histology-dependent changes in Cu-ATSM uptake.

Heterogeneity in intratumor correlations of 18F-FDG, 18F-FLT, and 61Cu-ATSM PET in canine sinonasal tumors

Intratumor heterogeneity in biologic properties and in relationships between various phenotypes may present a challenge for biologically targeted therapies. Understanding the relationships between different phenotypes in individual tumor types could help inform treatment selection. The goal of this study was to characterize spatial correlations of glucose metabolism, proliferation, and hypoxia in 2 histologic types of tumors.

METHODS

Twenty canine veterinary patients with spontaneously occurring sinonasal tumors (13 carcinomas and 7 sarcomas) were imaged with (18)F-FDG, (18)F-labeled 3'-deoxy-3'-fluorothymidine ((18)F-FLT), and (61)Cu-labeled diacetyl-bis(N(4)-methylthiosemicarbazone) ((61)Cu-ATSM) PET/CT on 3 consecutive days. Precise positioning and immobilization techniques coupled with anesthesia enabled motionless scans with repeatable positioning. Standardized uptake values (SUVs) of gross sarcoma and carcinoma volumes were compared by use of Mann-Whitney U tests. Patient images were rigidly registered together, and intratumor tracer uptake distributions were compared. Voxel-based Spearman correlation coefficients were used to quantify intertracer correlations, and the correlation coefficients of sarcomas and carcinomas were compared. The relative overlap of the highest uptake volumes of the 3 tracers was quantified, and the values were compared for sarcomas and carcinomas.

RESULTS

Large degrees of heterogeneity in SUV measures and phenotype correlations were observed. Carcinoma and sarcoma tumors differed significantly in SUV measures, with carcinoma tumors having significantly higher (18)F-FDG maximum SUVs than sarcoma tumors (11.1 vs. 5.0; P = 0.01) as well as higher (61)Cu-ATSM mean SUVs (2.6 vs. 1.2; P = 0.02). Carcinomas had significantly higher population-averaged Spearman correlation coefficients than sarcomas in comparisons of (18)F-FDG and (18)F-FLT (0.80 vs. 0.61; P = 0.02), (18)F-FLT and (61)Cu-ATSM (0.83 vs. 0.38; P < 0.0001), and (18)F-FDG and (61)Cu-ATSM (0.82 vs. 0.69; P = 0.04). Additionally, the highest uptake volumes of the 3 tracers had significantly greater overlap in carcinomas than in sarcomas.

CONCLUSION

The relationships of glucose metabolism, proliferation, and hypoxia were heterogeneous across different tumors, with carcinomas tending to have high correlations and sarcomas having low correlations. Consequently, canine carcinoma tumors are robust targets for therapies that target a single biologic property, whereas sarcoma tumors may not be well suited for such therapies. Histology-specific PET correlations have far-reaching implications for the robustness of biologic target definition.

Feasibility and repeatability for in vivo measurements of stiffness gradients in the canine gastrocnemius tendon using an acoustoelastic strain gauge

B-mode ultrasound is an established imaging modality for evaluating canine tendon injury. However, full extent of tendon injury often remains difficult to estimate, as small changes in sonographic appearance are associated with large changes in biomechanical strength. The acoustoelastic strain gauge (ASG) is an ultrasound-based tissue evaluation technique that relates the change in echo intensity observed during relaxation or stretching of tendons to the tissue's mechanical properties. This technique deduces stiffness gradient (the rate of change of normalized stiffness as a function of tissue strain) by analyzing the ultrasound dynamic images captured from gradually deforming tissue. ASG has been proven to accurately model strain and stiffness within tendons in vitro. To determine the feasibility and repeatability for in vivo ASG measurements of canine tendon function, stiffness gradients for the gastrocnemius tendons of 10 clinically normal dogs were recorded by two nonindependent observers at three sites (musculotendinous junction, mid tendon, and insertion). Average stiffness gradient indices (0.0132, 0.0141, 0.0136) and dispersion values (0.0053, 0.0054, 0.0057) for each site, respectively, were consistent with published mechanical properties for normal canine tendon. Mean differences of the average stiffness gradient index and dispersion value between observers and between limbs for each site were less than 16%. Using interclass coefficients (ICC), intra-observer (ICC 0.79-0.98) and interobserver (ICC 0.77-0.95) reproducibility was good to excellent. Right and left limb values were symmetric (ICC 0.74-0.92). Findings from this study indicated that ASG is a feasible and repeatable technique for measuring stiffness gradients in canine tendons.

Helical tomotherapy setup variations in canine nasal tumor patients immobilized with a bite block

The purpose of our study was to compare setup variation in four degrees of freedom (vertical, longitudinal, lateral, and roll) between canine nasal tumor patients immobilized with a mattress and bite block, versus a mattress alone. Our secondary aim was to define a clinical target volume (CTV) to planning target volume (PTV) expansion margin based on our mean systematic error values associated with nasal tumor patients immobilized by a mattress and bite block. We evaluated six parameters for setup corrections: systematic error, random error, patient-patient variation in systematic errors, the magnitude of patient-specific random errors (root mean square [RMS]), distance error, and the variation of setup corrections from zero shift. The variations in all parameters were statistically smaller in the group immobilized by a mattress and bite block. The mean setup corrections in the mattress and bite block group ranged from 0.91 mm to 1.59 mm for the translational errors and 0.5°. Although most veterinary radiation facilities do not have access to Image-guided radiotherapy (IGRT), we identified a need for more rigid fixation, established the value of adding IGRT to veterinary radiation therapy, and define the CTV-PTV setup error margin for canine nasal tumor patients immobilized in a mattress and bite block.

Hydrocephalus in a yellow-headed Amazon parrot (Amazona ochrocephala oratrix)

A 37-year-old female yellow-headed Amazon parrot (Amazona ochrocephala oratrix) was presented after a 4-month-period behavior change and intermittent episodes of obtunded mentation. Clinical findings on physical examination included ataxia, a weak grasp, and reluctance to move. Results of magnetic resonance imaging were consistent with severe hydrocephalus without evidence of cerebrospinal fluid obstruction. The bird was treated with tapering dosages of prednisolone over a 4-month period, during which time the episodes did not occur. Discontinuation of treatment was attempted several times but resulted in relapse. After 3.5 years of maintenance treatment with prednisolone, the bird was presented subsequent to a 5-hour episode of obtunded mentation and worsening neurologic signs. Despite increasing the dose of prednisolone and providing additional supportive care, the bird's condition worsened, and euthanasia was elected. Necropsy findings included severe hydrocephalus with significant loss of right cerebral parenchyma and no evidence of cerebrospinal fluid obstruction. Histologic examination of the remaining cerebral parenchyma revealed a moderate, multifocal, cellular infiltrate; encephalomalacia; fibrosis; and hemosiderosis in tissue adjacent to the distended ventricles. Other findings included hepatic vacuolar degeneration. Diagnostic imaging and postmortem findings were consistent with a diagnosis of hydrocephalus ex vacuo. To our knowledge, this is the first report of hydrocephalus in an Amazon parrot as well as the first report of hydrocephalus in any avian species associated with long-term follow-up and prolonged corticosteroid treatment.

Modified ear canal ablation and lateral bulla osteotomy for management of otitis media in an alpaca

OBJECTIVE

To report surgical treatment of severe otitis media in an alpaca by a modification of a subtotal ear canal ablation and lateral bulla osteotomy technique used in dogs.

STUDY DESIGN

Case report.

ANIMALS

An 11-week-old female alpaca cria.

METHODS

The cria had a 2-week history of right otitis media, nonresponsive to medical treatment, as well as right facial nerve paralysis, and a melting corneal ulcer of the right eye. Otitis media was confirmed by computed tomography. Right subtotal ear canal ablation and lateral bulla osteotomy were performed using a modification of a technique reported in dogs.

RESULTS

There were no surgical complications and the alpaca was discharged from the hospital 5 days later. At 10 months, moderate motor function had been restored to the pinna with the ear standing partially erect. The otitis had resolved, and the alpaca was reportedly well integrated into the herd.

CONCLUSION

Subtotal ear canal ablation and lateral bulla osteotomy, a technique modified from that performed in dogs, were successful in providing complete clinical resolution of otitis media in an alpaca.

Image-guided transnasal cryoablation of a recurrent nasal adenocarcinoma in a dog

An eight-year-old female spayed Airedale terrier with rapid recurrence of a nasal adenocarcinoma following image-guided intensity-modulated radiation therapy was treated with transnasal, image-guided cryotherapy. Ice ball size and location were monitored real-time with computed tomography-fluoroscopy to verify that the entire tumour was enveloped in ice. Serial computed tomography scans demonstrated reduction in and subsequent resolution of the primary tumour volume corresponding visually with the ice ball imaged during the ablation procedure. Re-imaging demonstrated focallysis of the cribriform plate following ablation that spontaneously resolved by 13 months. While mild chronic nasal discharge developed following cryoablation, no other clinical signs of local nasal neoplasia were present. Twenty-one months after nasal tumour cryoablation the dog was euthanased as a result of acute haemoabdomen. Image-guided cryotherapy may warrant further investigation for the management of focal residual or recurrent tumours in dogs, especially in regions where critical structures preclude surgical intervention.

Proof of principle of ocular sparing in dogs with sinonasal tumors treated with intensity-modulated radiation therapy

Intensity-modulated radiation therapy (IMRT) allows optimization of radiation dose delivery to complex tumor volumes with rapid dose drop-off to surrounding normal tissues. A prospective study was performed to evaluate the concept of conformal avoidance using IMRT in canine sinonasal cancer. The potential of IMRT to improve clinical outcome with respect to acute and late ocular toxicity was evaluated. Thirty-one dogs with sinonasal cancer were treated definitively with IMRT using helical tomotherapy and/or dynamic multileaf collimator (DMLC) delivery. Ocular toxicity was evaluated prospectively and compared with a comparable group of historical controls treated with conventional two-dimensional radiotherapy (2D-RT) techniques. Treatment plans were devised for each dog using helical tomotherapy and DMLC that achieved the target dose to the planning treatment volume and limited critical normal tissues to the prescribed dose-volume constraints. Overall acute and late toxicities were limited and minor, detectable by an experienced observer. This was in contrast to the profound ocular morbidity observed in the historical control group treated with 2D-RT. Overall median survival for IMRT-treated and 2D-treated dogs was 420 and 411 days, respectively. Compared with conventional techniques, IMRT reduced dose delivered to eyes and resulted in bilateral ocular sparing in the dogs reported herein. These data provide proof-of-principle that conformal avoidance radiotherapy can be delivered through high conformity IMRT, resulting in decreased normal tissue toxicity as compared with historical controls treated with 2D-RT.

Dosimetric impact of daily setup variations during treatment of canine nasal tumors using intensity-modulated radiation therapy

Intensity-modulated radiation therapy (IMRT) can be employed to yield precise dose distributions that tightly conform to targets and reduce high doses to normal structures by generating steep dose gradients. Because of these sharp gradients, daily setup variations may have an adverse effect on clinical outcome such that an adjacent normal structure may be overdosed and/or the target may be underdosed. This study provides a detailed analysis of the impact of daily setup variations on optimized IMRT canine nasal tumor treatment plans when variations are not accounted for due to the lack of image guidance. Setup histories of ten patients with nasal tumors previously treated using helical tomotherapy were replanned retrospectively to study the impact of daily setup variations on IMRT dose distributions. Daily setup shifts were applied to IMRT plans on a fraction-by-fraction basis. Using mattress immobilization and laser alignment, mean setup error magnitude in any single dimension was at least 2.5 mm (0-10.0 mm). With inclusions of all three translational coordinates, mean composite offset vector was 5.9 +/- 3.3 mm. Due to variations, a loss of equivalent uniform dose for target volumes of up to 5.6% was noted which corresponded to a potential loss in tumor control probability of 39.5%. Overdosing of eyes and brain was noted by increases in mean normalized total dose and highest normalized dose given to 2% of the volume. Findings suggest that successful implementation of canine nasal IMRT requires daily image guidance to ensure accurate delivery of precise IMRT distributions when non-rigid immobilization techniques are utilized. Unrecognized geographical misses may result in tumor recurrence and/or radiation toxicities to the eyes and brain.

Postoperative radiotherapy and mitoxantrone for anal sac adenocarcinoma in the dog: 15 cases (1991-2001)

The medical records of 15 dogs with anal sac adenocarcinoma (ASAC) treated with concurrent curative-intent radiotherapy and mitoxantrone (MX) after surgical removal of the primary tumour were reviewed retrospectively. Radiation was prescribed at 15 daily fractions of 3.2 Gy for a total dose of 48 Gy. MX was given intravenously at a dosage of 5 mg m(-2) every 3 weeks for five treatment sessions. Twelve dogs received pelvic irradiation to include the regional lymph nodes (LNs) and three received radiation only to the perineum. At the time of diagnosis, four dogs were hypercalcaemic and seven dogs presented with regional LN metastasis. All the dogs with regional LN metastasis received pelvic irradiation, and in three cases, metastatic LNs were treated in the macroscopic disease setting. The median event-free survival was 287 days, and the median overall survival was 956 days. Acute and chronic radiation complications were common and non-life threatening, although chronic complications contributed to the decision to euthanize two dogs. The results observed in this retrospective analysis compare favourably with cases of ASAC in the literature related to treatment with surgery and/or chemotherapy.

Prognostic significance of tumor histology and computed tomographic staging for radiation treatment response of canine nasal tumors

Prognostic significance of tumor histology and four computed tomography (CT) staging methods was tested retrospectively in dogs from three treatment centers that underwent intent-to-cure-radiotherapy for intranasal neoplasia. Disease-free and overall survival times were available for 94 dogs. A grouping of anaplastic, squamous cell, and undifferentiated carcinomas had a significantly shorter median disease-free survival (4.4 mo) than a grouping of all sarcomas (10.6 months). Disease-free survivals were not significantly different, when all carcinomas were compared with all sarcomas. The published original and modified WHO staging methods did not significantly relate to either survival endpoint. A modified human maxillary tumor staging system previously applied to canine nasal tumors was prognostically significant for both survival endpoints; a further modified version of that CT-based staging system resulted in improved significance for both survival endpoints. Dogs with unilateral intranasal involvement without bone destruction beyond the turbinates on CT, had longest median survival (23.4 months); CT evidence of cribriform plate involvement was associated with shortest median survival (6.7 months). Combining CT and histology statistically improved prognostic significance for both survival endpoints over the proposed CT staging method alone. Significance was lost when CT stages were collapsed to < four categories or histopathology groupings were collapsed to < three categories.

Comparison of computed tomography and magnetic resonance imaging for the evaluation of canine intranasal neoplasia

OBJECTIVES

Canine intranasal neoplasia is commonly evaluated using computed tomography to indicate the diagnosis, to determine disease extent, to guide histological sampling location and to plan treatment. With the expanding use of magnetic resonance imaging in veterinary medicine, this modality has been recently applied for the same purpose. The aim of this study was to compare the features of canine intranasal neoplasia using computed tomography and magnetic resonance imaging.

METHODS

Twenty-one dogs with confirmed intranasal neoplasia underwent both computed tomography and magnetic resonance imaging. The images were reviewed retrospectively for the bony and soft tissue features of intranasal neoplasia.

RESULTS

Overall computed tomography and magnetic resonance imaging performed very similarly. However, lysis of bones bordering the nasal cavity and mucosal thickening was found on computed tomography images more often than on magnetic resonance images. Small amounts of fluid in the nasal cavity were more often seen on magnetic resonance images. However, fluid in the frontal sinuses was seen equally well with both modalities.

CLINICAL SIGNIFICANCE

We conclude that computed tomography is satisfactory for evaluation of canine intranasal neoplasia, and no clinically relevant benefit is gained using magnetic resonance imaging for intranasal neoplasia without extent into the cranial cavity.

Radiobiological and treatment planning study of a simultaneously integrated boost for canine nasal tumors using helical tomotherapy

Feasibility of delivering a simultaneously integrated boost to canine nasal tumors using helical tomotherapy to improve tumor control probability (TCP) via an increase in total biological equivalent uniform dose (EUD) was evaluated. Eight dogs with varying size nasal tumors (5.8-110.9 cc) were replanned to 42 Gy to the nasal cavity and integrated dose boosts to gross disease of 45.2, 48.3, and 51.3 Gy in 10 fractions. EUD values were calculated for tumors and mean normalized total doses (NTD(mean)) for organs at risk (OAR). Normal Tissue Complication Probability (NTCP) values were obtained for OARs, and estimated TCP values were computed using a logistic dose-response model and based on deliverable EUD boost doses. Significant increases in estimated TCP to 54%, 74%, and 86% can be achieved with 10%, 23%, and 37% mean relative EUD boosts to the gross disease, respectively. NTCP values for blindness of either eye and for brain necrosis were < 0.01% for all boosts. Values for cataract development were 31%, 42%, and 46% for studied boost schemas, respectively. Average NTD(mean) to eyes and brain for mean EUD boosts were 10.2, 11.3, and 12.1 Gy3, and 7.5, 7.2, and 7.9 Gy2, respectively. Using helical tomotherapy, simultaneously integrated dose boosts can be delivered to increase the estimated TCP at 1-year without significantly increasing the NTD(mean) to eyes and brain. Delivery of these treatments in a prospective trial may allow quantification of a dose-response relationship in canine nasal tumors.

Correlation of ultrasonographic appearance of lesions and cytologic and histologic diagnoses in splenic aspirates from dogs and cats: 32 cases (2002–2005)

OBJECTIVE

To determine the accuracy of cytologic diagnosis, compared with histologic diagnosis, in determination of disease in ultrasound-guided fine-needle aspirates of splenic lesions.

DESIGN

Retrospective study.

SAMPLE POPULATION

Splenic specimens from 29 dogs and 3 cats.

PROCEDURES

Records were searched for dogs and cats that had undergone ultrasound-guided splenic aspiration. Criteria for inclusion were ultrasonographic identification of splenic lesions and cytologic and histologic evaluation of tissue from the same lesion. Cytologic samples were obtained by fine-needle aspiration, and histologic specimens were obtained via surgical biopsy, ultrasound-guided biopsy, or necropsy.

RESULTS

Cytologic diagnoses corresponded with histologic diagnoses in 19 of 31 (61.3%) cases and differed in 5 of 31(16.1%) cases, and 1 aspirate was inadequate for evaluation. In 7 of 31 (22.6%) cases, histologic evaluation of tissue architecture was required to distinguish between reactive and neoplastic conditions. On the basis of histologic diagnosis in 14 animals with nonneoplastic conditions, the cytologic diagnosis was correct in 11 cases, not definitive in 2 cases, and incorrect in 1 case. In 17 animals with malignant neoplastic diseases, the cytologic diagnosis was correct in 8 cases, not definitive but consistent with possible neoplasia in 5 cases, and incorrect in 4 cases. Multiple similar-appearing nodules were significantly associated with malignancy, whereas single lesions were more often benign.

CONCLUSIONS AND CLINICAL RELEVANCE

Ultrasound-guided aspiration of splenic lesions is a minimally invasive tool for obtaining specimens for cytologic evaluation. Although cytologic diagnoses often reflect histologic results, if missampling or incomplete sampling occurs or tissue architecture is required to distinguish between reactive and neoplastic conditions, accurate diagnosis with fine-needle aspiration may not be possible.

Magnetic Resonance Imaging of the Canine Shoulder: An Anatomic Study

OBJECTIVES

To describe the normal anatomy of the soft tissue stabilizing components of the canine shoulder identified by magnetic resonance imaging (MRI) and to evaluate specific acquisition sequences and planes for observing structures of diagnostic interest.

STUDY DESIGN

Descriptive study.

ANIMAL

Canine cadavers (n=3).

METHODS

T1-weighted, proton density fat saturation (PD), and T2(*)-weighted gradient echo (GE) MRI sequences were obtained in the sagittal, transverse, and dorsal planes of the left shoulder of 3 canine cadavers. After imaging, each shoulder was embedded and thin sectioned. The corresponding right shoulder was frozen and thick sectioned. The anatomic structures on the histologic and frozen thick sections were visually correlated with the MR images.

RESULTS

The sagittal plane provided a longitudinal view of the bicep, infraspinatus, and supraspinatus tendons. The biceps, supraspinatus, infraspinatus, and subscapularis tendons, and the medial and lateral glenohumeral ligaments were identified in the transverse and dorsal planes. The dorsal plane allowed for the bicep tendon to be evaluated transversely as it passed over the humeral head. The GE sequence was more useful in identifying tendons and ligaments. The PD sequence was more helpful in identifying fluid accumulations in the joint and around tendons.

CONCLUSIONS

The tendinous and ligamentous structures that stabilize the canine shoulder joint can be readily identified with MRI.

CLINICAL RELEVANCE

MRI has the potential to be a useful tool in the diagnosis of canine soft tissue shoulder injuries.

Radiation Therapy for Incompletely Excised Grade II Canine Mast Cell Tumors

Forty-five dogs with incompletely excised grade II mast cell tumors were treated with radiation using a cobalt 60 teletherapy unit (15 fractions of 3.2 Gy for a total of 48 Gy). Twenty-four of the dogs underwent prophylactic regional lymph node irradiation. Three (6.7%) dogs had tumor recurrence, two (4.4%) dogs developed metastasis, and 14 (31%) dogs developed a second cutaneous mast cell tumor. No difference in overall survival rate was observed between the dogs receiving and not receiving prophylactic irradiation of the regional lymph node.

Development of a retrobulbar injection technique for ocular surgery and analgesia in dogs

OBJECTIVE

To develop and compare 3 techniques for retrobulbar injection of local anesthetic agents for ocular surgery and analgesia in dogs.

DESIGN

Prospective study.

ANIMALS

17 dogs (including 9 cadavers).

PROCEDURES

Inferior-temporal palpebral (ITP), perimandibular, and combined superior-inferior peribulbar injection techniques were compared by assessing the distribution of latex after injection into the orbits of 5 canine cadavers; magnetic resonance imaging (MRI) evaluation of the distribution of contrast agent after injection in the retrobulbar space of 4 canine cadavers; and assessment of the efficacy and MRI evaluation of the anatomic distribution of injections of a lidocainecontrast agent mixture in 4 anesthetized, nonrecovery dogs. By use of the preferred technique (ITP), the ocular effects of lidocaine anesthesia were evaluated in 4 dogs; during a 2-week period after treatment, dogs underwent ophthalmic examination, Schirmer tear testing (STT), intraocular pressure (IOP) measurement, and Cochet-Bonnet esthesiometry.

RESULTS

Of the 3 techniques, the ITP technique was the preferred method for retrobulbar administration of anesthetic agent in dogs because it was efficacious (pupil dilation and central rotation of the globe achieved in all eyes), easiest to perform, and provided thorough coverage of the intraconal retrobulbar space without complication. During the 2-week follow-up period, the ITP injection did not significantly affect STT, IOP, or Cochet-Bonnet esthesiometry values in dogs.

CONCLUSIONS AND CLINICAL RELEVANCE

In dogs, retrobulbar administration of anesthetic agents via the ITP technique is a potential alternative to systemic administration of neuromuscular blocking agents for ophthalmic surgery and provides the additional benefit of local ocular analgesia.

PET/CT FOLLOWING INTENSITY-MODULATED RADIATION THERAPY FOR PRIMARY LUNG TUMOR IN A DOG

A primary lung tumor in a dog treated with intensity-modulated radiation therapy was imaged approximately 6 weeks and 1-year posttreatment with combined positron emission tomography (PET) and computed tomography, utilizing the radiotracers 18F-fluorodeoxyglucose and 18F-fluorothymidine. These two tracers allowed discrimination of tumor from inflammation, and demonstrated spread of tumor along airways over time after treatment. Fusion of functional imaging with anatomic imaging is a useful tool, particularly in the field of oncology, with the potential for PET markers that delineate tumor from normal or reactive tissue, and potential or actual response to therapy.

Outcome of accelerated radiotherapy alone or accelerated radiotherapy followed by exenteration of the nasal cavity in dogs with intranasal neoplasia: 53 cases (1990-2002)

OBJECTIVE

To compare long-term results of radiotherapy alone versus radiotherapy followed by exenteration of the nasal cavity in dogs with malignant intranasal neoplasia.

DESIGN

Retrospective study.

ANIMALS

53 dogs with malignant intranasal neoplasia.

PROCEDURE

All dogs underwent radiotherapy consisting of administration of 10 fractions of 4.2 Gy each on consecutive weekdays. For dogs in the surgery group (n=13), follow-up computed tomography was performed, and dogs were scheduled for surgery if persistent or recurrent tumor was seen.

RESULTS

Perioperative complications for dogs that underwent surgery included hemorrhage requiring transfusion (2 dogs) and subcutaneous emphysema (8). Rhinitis and osteomyelitis-osteonecrosis occurred significantly more frequently in dogs in the radiotherapy and surgery group (9 and 4 dogs, respectively) than in dogs in the radiotherapy-only group (4 and 3 dogs, respectively). Two- and 3-year survival rates were 44% and 24%, respectively, for dogs in the radiotherapy group and 69% and 58%, respectively, for dogs in the surgery group. Overall median survival time for dogs in the radiotherapy and surgery group (477 months) was significantly longer than time for dogs in the radiotherapy-only group (19.7 months).

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that exenteration of the nasal cavity significantly prolongs survival time in dogs with intranasal neoplasia that have undergone radiotherapy. Exenteration after radiotherapy may increase the risk of chronic complications.

The utility of megavoltage computed tomography images from a helical tomotherapy system for setup verification purposes

PURPOSE

To evaluate the utility of relatively low-dose megavoltage computed tomography (MVCT) images from a clinical helical tomotherapy system for setup verification purposes.

METHODS AND MATERIALS

Cross-sectional kilovolt computed tomography (kVCT) images were obtained for treatment planning purposes on a diagnostic third-generation CT scanner, followed by MVCT images from a helical tomotherapy system in 8 pet dogs with spontaneously occurring tumors. The kVCT and MVCT images were aligned for setup verification purposes, allowing repositioning before treatment delivery.

RESULTS

Tumors are readily visualized on the MVCT images. At a dose of 2-3 cGy, the MVCT images are of sufficient quality for verification of treatment setup, but soft-tissue contrast is inferior to that with conventional kVCT. The MV and kVCT images were successfully aligned. When necessary, patients undergoing helical tomotherapy were repositioned before treatment.

CONCLUSIONS

Megavoltage CT image quality is sufficient for tumor identification and three-dimensional setup verification in dogs with spontaneous tumors. The MVCT images can be aligned with the planning kVCT to ensure proper patient registration before treatment. Image alignment was successful in these canine patients, despite no skin markings defining patient positioning between the two scans. MVCT images facilitate setup verification, and their tomographic nature offers improvements over conventional portal imaging.

Efficacy and toxicity of paclitaxel (Taxol) for the treatment of canine malignant tumors

Paclitaxel (Taxol) was administered to 25 dogs with histologically confirmed malignant tumors at a dosage of 165 mg/m2 i.v. over 3-6 hours every 3 weeks. Dogs received premedication with antihistimines and corticosteroids to reduce hypersensitivity reactions. However, 64% of the dogs still experienced allergic reactions. Six dogs (24%) had grade 3 or 4 neutropenia, 6 dogs (24%) required hospitalization and 3 dogs (12%) died of sepsis. Five dogs (20%) had a partial response (osteosarcoma [2 dogs] mammary carcinoma [2 dogs] and malignant histiocytosis [1 dog]) for a median duration of 53 days. The overall toxicity was unacceptable at the 165 mg/m2 dose. Therefore, subsequent evaluations of paclitaxel in tumor-bearing dogs should a starting dose of 132 mg/m2 i.v. every 3 weeks.

Piroxicam, Mitoxantrone, and Coarse Fraction Radiotherapy for the Treatment of Transitional Cell Carcinoma of the Bladder in 10 Dogs: A Pilot Study

Ten dogs with transitional cell carcinoma (TCC) of the bladder were treated with a combination of once-weekly coarse fraction radiation therapy (six weekly fractions of 5.75 Gray [Gy]), mitoxantrone chemotherapy, and piroxicam. All dogs completed the radiation therapy protocol, and only minimal side effects were observed. Only two (22%) dogs achieved a measurable partial response; however, 90% of the dogs had amelioration of their urinary clinical signs. The median survival time for all dogs was 326 days. While this treatment protocol was well tolerated, the response rate and overall survival duration was not superior to reports using mitoxantrone and piroxicam without radiation therapy in dogs with TCC.

A vacuum-formable mattress for veterinary radiotherapy positioning: comparison with conventional methods

This prospective study was undertaken to compare the positioning repeatability and setup time of a rigid immobilization device (Vac-Lok mattress) to conventional positioning methods (sandbags, tape, foam wedges) in the clinical veterinary radiotherapy setting. Positioning repeatability was determined by using port films to verify appropriate patient positioning. Setup time was determined by recording the time required to set up each patient using each positioning method. Sixty-seven patients receiving radiotherapy were positioned using both the Vac-Lok mattresses and conventional positioning methods during their treatments. Seventy-eight total sites were treated. Forty-eight were treated daily (Monday through Friday, 2 to 4 weeks) and 30 were treated once weekly (4 weeks). Patients were grouped according to the site treated: head (29), neck/body (24), and limb (25). Vac-Lok mattresses were similar to conventional means in positioning repeatability and setup time. Vac-Lok mattresses are potentially advantageous in specific situations, including use during pre-radiotherapy tumor imaging. These mattresses are not recommended for distal limb positioning.

Effect of perineural anesthesia on the ultrasonographic appearance of equine palmar metacarpal structures

The purpose of this study was to describe ultrasonographic changes of the equine palmar metacarpal area attributed to the infiltration of local anesthetic solution and to determine whether these changes were noted immediately or at 24 h. The palmar metacarpal region of one forelimb in each of six horses was examined ultrasonographically with a 10-MHz linear array transducer and a 7.5-MHz curvilinear transducer. Transverse and longitudinal images were recorded at 5-cm intervals distal to the accessory carpal bone. High and low palmar and palmar metacarpal nerve blocks were performed with a 2% mepivacaine hydrochloride solution. Ultrasonographic examinations similar to the initial examination then were performed immediately, 1 h and 24 h postinjection. Cross-sectional area and mean pixel value were determined for the superficial and deep digital flexor tendons, the accessory ligament of the deep digital flexor tendon, the suspensory ligament, and the suspensory branches at each level and time period. Subjective ultrasonographic changes also were noted. No significant difference was noted in the cross-sectional area or mean pixel value of any structure at any level or time period compared to baseline. Subjective changes in the tendons and ligaments were not noted. There was mild hypoechoic swelling of the surrounding soft tissues and gas in the region of the injections. Gas could interfere with the evaluation of the origin of the suspensory ligament and the proximal portion of the accessory ligament of the deep digital flexor tendon within the first hour but was not detectable ultrasonographically at 24 h. Based on these findings, if gas interferes with an ultrasonographic examination performed temporally close to perineural anesthesia, a repeat examination at 24 h is recommended.

Four fraction palliative radiotherapy for osteosarcoma in 24 dogs

Twenty-four dogs underwent palliative radiotherapy consisting of four 8 gray (Gy) fractions of 60Co radiation on days 0, 7, 14, and 21 at 26 sites for axial (n=11) or appendicular (n=15) osteosarcoma. Response was noted in 92% of sites treated. Seventeen dogs were euthanized due to local or metastatic disease, one dog died of metastatic disease, five dogs died of unrelated causes, and one dog is alive. The four fraction protocol is effective for palliation of clinical signs associated with axial or appendicular osteosarcoma and may result in a higher response rate and longer survival time than three fraction palliative protocols.

Radiographic appearance of bronchoalveolar carcinoma in nine cats

Thoracic radiographs of nine cats with confirmed bronchoalveolar carcinoma (BAC) were reviewed retrospectively. Radiographic appearance of BAC was divided into three categories: mixed bronchoalveolar pattern, ill-defined alveolar mass, or mass with cavitation. In addition to these radiographic signs, all nine cats had evidence of some form of bronchial disease. Cavitary lesions were the most common finding (n = 5). In addition, three cats in this category had diffuse bronchointerstitial opacity and one cat had focal peribronchial cuffing. Five cats had either a mixed bronchoalveolar pattern with bronchiectasis (n = 3) or an ill-defined alveolar mass with peribronchial cuffing (n = 2). One cat had both a mixed bronchoalveolar pattern and a cavitary mass. Each of these nine cats had some form of bronchial disease (bronchointerstitial pattern, peribronchial cuffing, or bronchiectasis), which aids in the radiographic diagnosis of bronchoalveolar carcinoma and may represent airway metastasis.

Postoperative radiotherapy for canine soft tissue sarcoma

Thirty-five dogs with 37 soft tissue sarcoma tumors that were incompletely excised and treated with radiotherapy in the postoperative, adjuvant setting were reviewed. Variables evaluated included age, sex, tumor site, tumor histology, total tumor radiation dose, radiotherapy field size. time to recurrence, and survival. The majority of tumors were fibrosarcomas and hemangiopericytomas, but small numbers of other tumor types were also represented. Total tumor radiation dose ranged from 42 to 57 Gy given in 3- to 4.2-Gy daily fractions on a Monday through Friday schedule. Overall median survival was 1,851 days. Median time to local recurrence was greater than 798 days. Soft-tissue sarcoma tumors at oral sites had a statistically significant lower median survival (540 days) as compared to other tumor sites (2,270 days). Radiotherapy may be a useful adjuvant therapy for incompletely excised soft-tissue sarcomas with a reasonable expectation for long-term patient survival.

Computed tomographic evaluation of radiation pneumonitis in a canine model

The objective of this study was to document the utility of computed tomography (CT) and a three-dimensional (3-D) radiotherapy treatment planning system for assessing the development of acute radiation pneumonitis in a canine model. Fourteen dogs were randomly assigned to a nonirradiated control group or one of three radiation dose groups receiving a single fraction of either 12, 15, or 18 Gy delivered to two-thirds of the right hemithorax. CT and survey radiographs were performed in all dogs prior to and at defined intervals for up to 13 weeks following irradiation. All images were subjectively evaluated for development of radiation pneumonitis and CT images were quantitatively analyzed. Radiation pneumonitis was detected earlier with CT images than with radiographs. Quantitatively, functional lung volume and radiation pneumonitis lesion volume on CT images changed over time in all irradiated dogs. However, there was no statistically significant difference between the three radiation dose groups, but a marked difference between irradiated dogs and nonirradiated controls. These data suggest that CT is superior to survey radiography for the evaluation and quantification of acute radiation pneumonitis in this canine model. Quantification of acute radiation pneumonitis suggests future promise for evaluating the efficacy of modifiers to lessen the effects of irradiating normal lung tissue in this canine model.

Rickets caused by excessive renal phosphate loss and apparent abnormal vitamin D metabolism in a cat

Rickets was diagnosed in a 1-year-old cat with a history of weakness, osteopenia, and recurrent fractures. Processes causing rickets include vitamin D deficiency caused by inadequate, nutrition, lack of exposure to sunlight, defective metabolism of parent vitamin D to active metabolites, inherited vitamin D receptor defects, hypoparathyroidism, chronic renal failure, renal loss of phosphate, or malabsorptive states resulting from gastrointestinal or hepatic diseases. On the basis of analysis of serum 25-hydroxyvitamin D3 and 1,25-dihydroxyvitamin D2 and D3 concentrations, serum biochemical analysis, and urinary fractional clearance of electrolytes, the causes of rickets in our cat, were most compatible with a combination of excessive loss of phosphorus via the kidneys and deficient or abnormal hepatic 25-hydroxylation of vitamin D. Calcifediol treatment and twice daily administration of phosphate salts resulted in clinical improvement and increases in mineralization of the skeleton, as evidenced on radiographic evaluation.

Radiographic measurement of cardiac size in normal ferrets

Right lateral, left lateral and ventrodorsal radiographs were obtained in 20 normal ferrets (11 male). Three independent observers recorded measurements of the cardiac silhouette and results for each parameter were averaged. Long axis (length), short axis (width) and total of length plus width (L+W) were recorded in each view. Comparative measurements were calculated, including the ratio of L+W/length of thoracic vertebrae 5-8, and a modified vertebral heart score (VHS) method, measuring the heart in vertebral units. Measurements made in ventrodorsal views were usually larger than corresponding measurements in lateral views. Weight and most absolute measurements differed significantly between male and female ferret (P<0.05), but the differences in absolute measurements were not apparent when related to measures of body size (Ratio and modified VHS methods). Given the variability in body weight and size in ferrets, measurements of the cardiac silhouette normalized for body size may be more universally applicable than absolute measurements.

Inhalation chemotherapy for macroscopic primary or metastatic lung tumors: proof of principle using dogs with spontaneously occurring tumors as a model

This study represents part of an effort to determine the safety and efficacy of inhaled antineoplastic drugs, using pet dogs with spontaneously arising primary and metastatic lung cancers (including sarcoma, carcinoma, and malignant melanoma) as a model. Dogs received new formulations of either paclitaxel (PTX) or doxorubicin (DOX) by the inhalation route every 2 weeks using a specially designed aerosol device. Response was assessed radiographically using the indices of tumor nodule number and volume measurement of discrete pulmonary nodules. Dogs experiencing progressive disease after two consecutive treatments were crossed over to receive the alternate compound. In 24 dogs, 6 (25%) responses were noted including 5 partial responses (PR) and 1 complete response. These include 4 (22.2%) of 18 responses to DOX and 2 (13.3%) of 15 responses to PTX. Responses were noted with osteosarcoma (including three dogs with metastatic osteosarcoma that had failed prior systemic chemotherapy), liposarcoma, hemangiosarcoma, and undifferentiated sarcoma. One dog with mammary carcinoma experienced a 47% reduction in volume after PTX inhalation, just shy of PR criteria. One dog with liposarcoma is experiencing a long-term (>12 months) stabilization of disease on PTX. To date, no systemic toxicities have been observed with either PTX or DOX inhalations. Local (pulmonary) toxicity was not observed with PTX; however, changes consistent with pneumonitis/fibrosis were observed in some dogs receiving DOX. Only one of these dogs showed clinical signs, which were responsive to steroid and antitussive therapy. These data represent "proof of principle" for the avoidance of systemic toxicity while delivering efficacious local drug levels by the inhalation route.

The head: excluding the brain and orbit

Applications for computed tomography (CT) and magnetic resonance imaging (MRI) scans of the head (excluding the brain and orbit) include the evaluation of neoplastic, inflammatory, and traumatic disorders of the skull (including the cranium, maxilla, mandible, and temporomandibular joints); of the nasal and oral cavities; of the nasopharynx and paranasal sinuses; and of the tympanic bullae. CT and MRI provide information not obtained with routine radiography and should be considered whenever advanced surgical or radiation therapy is anticipated. In this article, the role of CT and MRI in the diagnosis of head disorders will be reviewed and illustrated with case examples.