Procedural description and prospective evaluation of short-term outcome for the use of prostatic artery embolization in dogs with carcinoma of the prostate.

OBJECTIVE: To describe the procedure of prostatic artery embolization (PAE) in dogs with prostatic carcinoma and to evaluate the short-term outcome for treated dogs. ANIMALS: 20 client-owned dogs with prostatic carcinomas between May 2014 and July 2017. PROCEDURES: In this prospective cohort study, dogs with carcinoma of the prostate underwent PAE with fluoroscopic guidance. Before and after PAE, dogs underwent CT and ultrasonographic examinations of the prostate, and each owner completed a questionnaire about the dog's clinical signs. Results for before versus after PAE were compared. RESULTS: Prostatic artery embolization was successfully performed in all 20 dogs. Tenesmus, stranguria, and lethargy were significantly less common 30 days after PAE (n = 2, 1, and 0 dogs, respectively), compared with before PAE (9, 10, and 6 dogs, respectively). Median prostatic volume was significantly less 30 days after PAE (14.8 cm3; range, 0.4 to 48.1 cm3; interquartile [25th to 75th percentile] range, 6.7 to 19.5 cm3), compared with before PAE (21.7 cm3; range, 2.9 to 77.7 cm3; interquartile range, 11.0 to 35.1 cm3). All dogs had a reduction in prostatic volume after PAE, with a median prostatic volume loss of 39.4% (95% CI, 20.3% to 59.3%). CONCLUSIONS AND CLINICAL RELEVANCE: Prostatic artery embolization was associated with decreased prostate volume and improved clinical signs in this cohort. The short-term response to PAE appears promising, and evaluation of the long-term impact on survival time is needed.

Use of percutaneous microwave ablation in the treatment of retroperitoneal neoplasia in three dogs.

CASE DESCRIPTION: 3 dogs with retroperitoneal masses (2 renal and 1 located near the diaphragm) were treated by percutaneous microwave ablation (MWA). CLINICAL FINDINGS: Dogs between 11 and 13 years of age weighing between 13.7 and 43.8 kg had either a renal mass (n = 2) or a mass located in the caudodorsal aspect of the retroperitoneal space near the right side of the diaphragm (1). Cytology revealed that one of the renal masses and the mass located near the diaphragm were malignant neoplasias. Findings on cytologic evaluation of a sample of the other renal mass was nondiagnostic. Maximum mass diameters ranged between 1.4 and 2.5 cm. TREATMENT AND OUTCOME: All dogs were treated by percutaneous MWA. Probes were directed into tumors by use of ultrasound and CT guidance, and microwave energy was applied to each mass. Findings on imaging of each mass following MWA was consistent with successful treatment. No intraprocedural or major postprocedural complications occurred, and all dogs were discharged from the hospital within 3 days of treatment. Two dogs died at 3 and 21 months after MWA with no known local recurrence; 1 dog was still alive 64 months after treatment. CLINICAL RELEVANCE: Although the indications for MWA in the treatment of neoplasia in companion animals are limited, the outcomes of dogs in the present report provided preliminary evidence that percutaneous MWA can be safely used to effectively treat retroperitoneal neoplasia. This procedure was successfully performed with image guidance in all 3 dogs.

Ethylene vinyl alcohol copolymer to treat an intracranial arteriovenous malformation in a dog.

A 6-year-old neutered male German shepherd dog was evaluated for obtundation, blindness, and bilateral exophthalmos. A magnetic resonance imaging scan of the brain was performed and identified an arteriovenous malformation (AVM) with several feeding arterial branches, and venous drainage through the cavernous sinus. Venous vessels rostral to the AVM were severely distended and extended into the retrobulbar spaces. Liquid embolization by injection of ethylene vinyl alcohol copolymer was performed from access points in the maxillary arteries and internal carotid arteries. No intraprocedural complications were encountered, and the dog was discharged the next day. Bilateral enucleation eventually was performed because of exposure keratopathy. At 31 months post-embolization, owners reported that the dog was doing very well clinically with high activity level and normal appetite, and the dog also appeared to be pain free. Although intracranial AVMs are very rare in companion animals, successful treatment using liquid embolization is possible and should be considered.

Percutaneous radiologically guided gastrostomy tubes: Procedural description and biomechanical comparison in a canine model.

OBJECTIVE: To describe the novel placement of percutaneous radiologically guided gastrostomy (PRG) tubes in a canine cadaveric model and to biomechanically compare PRG and percutaneous endoscopic gastrostomy (PEG) tube constructs. STUDY DESIGN: Descriptive and biomechanical experimental study. ANIMALS: Fifteen large breed (>25 kg) canine cadavers. METHODS: Percutaneous endoscopic gastrostomy tubes, low-profile PRG tubes, and standard PRG tubes were each placed in five canine cadavers. Body wall and stomach (with attached gastrostomy tube constructs) were harvested and biomechanically tested. Data regarding the maximal load to failure and procedure time were statistically analyzed. RESULTS: Percutaneous endoscopic gastrostomy and PRG tube placement was successful in all cadavers with no procedure-related complications. Gastrostomy tube placement time was longer for the PEG group vs the low-profile PRG (P = .005) and standard PRG (P = .037) groups. Peak construct strength was lower for the PEG group vs the low-profile PRG (P = .002) and standard PRG (P = .010) groups. The site of failure varied among groups. CONCLUSION: Percutaneous radiologically guided gastrostomy tubes were successfully placed in all cases with shorter placement time and greater peak construct strength compared with PEG tubes. CLINICAL SIGNIFICANCE: Due to the increased load to failure as well as decreased placement time recorded for PRG tubes relative to PEG tubes, PRG tubes may be considered as an alternative minimally invasive gastrostomy option in large breed canine patients. Further evaluation in clinical animals is required. Results of this work were presented at the 2019 American College of Veterinary Surgeons Surgery Summit; October 16-19, 2019; Las Vegas, Nevada.

Description and Biomechanical Comparison of a Percutaneous Radiologic Gastropexy Technique in a Canine Cadaver Model.

OBJECTIVE: To describe a novel percutaneous radiologic gastropexy (PRG) technique in a canine model and to biomechanically compare this technique to open incisional gastropexy (OIG) and laparoscopic-assisted incisional gastropexy (LAG). STUDY DESIGN: Randomized ex vivo biomechanical study. ANIMALS: Canine cadavers. METHODS: Fifteen cadavers were randomized to 1 of 3 surgical interventions: OIG, LAG, and PRG. For the PRG procedure, the stomach was distended with air, and a preloaded T-fastener device was utilized to attach the stomach to the body wall with fluoroscopic-guidance. The procedural times of the 3 techniques were recorded. After completion of the procedure, the stomach and body wall overlying the stomach wall were harvested and the maximum tensile strength of the gastropexies was determined. RESULTS: The maximal tensile strength was not significantly different between groups. The total procedural time for the PRG procedure (5 minutes) was significantly shorter than both OIG (28 minutes) and LAG (20 minutes) procedures. CONCLUSION: The PRG technique described in this study demonstrated a similar maximal tensile strength to commonly employed gastropexy techniques (OIG and LAG) in an acute canine model. Additionally, the PRG procedure was significantly faster to perform. The clinical relevance of this technique will be determined by further study to assess the applicability and efficacy of this procedure in clinical patients by determining the likelihood of adhesion development and the ability of the adhesion to prevent gastric volvulus.

Efficacy of Two Radiologic-Assisted Prophylactic Gastropexy Techniques.

OBJECTIVE: To describe the technique and clinical outcome of prophylactic percutaneous radiologic-assisted gastropexy (PRG) and radiologic-assisted incisional gastropexy (RIG) in client-owned dogs. STUDY DESIGN: Prospective, nonrandomized clinical trial. ANIMALS: Fourteen client-owned, large, and giant breed dogs. METHODS: Four dogs underwent PRG with fluoroscopic guidance to place 2 T-fasteners into the pyloric antrum and secure it to the right body wall. Ten dogs underwent RIG, which was a modification of PRG. For RIG, the T-fasteners were first used to approximate the pyloric antrum and body wall, then a full thickness incision through the body wall was made and the pyloric antrum was sutured to the internal abdominal wall. The duration and complications of each procedure were recorded. The gastropexy was assessed by abdominal ultrasound at day 1, week 2, and week 8 postoperative and by barium gastrogram at week 8 postoperative. RESULTS: No dogs undergoing PRG had a gastropexy present at week 2. All dogs undergoing RIG had ultrasonographic evidence of gastropexy at day 1, week 2, and week 8 postoperative. Gastrograms in 9/9 dogs were consistent with an intact gastropexy, appropriate gastric positioning and appropriate gastric emptying began. No major complications were noted. CONCLUSION: The PRG was unsatisfactory and did not result in a permanent gastropexy. The RIG was safe and created a gastropexy that remained intact at 8 weeks postoperative. The RIG should be considered as a minimally invasive option for prophylactic gastropexy in dogs of at-risk breeds.

Percutaneous ureteral stent placement for the treatment of a benign ureteral obstruction in a Sumatran tiger (Panthera tigris sumatrae).

A 15-year-old, 113 kg intact male Sumatran tiger (Panthera tigris sumatrae) was evaluated for weight loss, polydipsia, and intermittent hematuria. The tiger was immobilized for diagnostic testing including blood work, urinalysis, and abdominal ultrasound. Laboratory testing demonstrated macro- and microhematuria, azotemia, and an increased urine protein:creatinine ratio. Abdominal ultrasound revealed bilateral ureterolithiasis as well as hydronephrosis and ureteral dilation. Ultrasonography performed 5 months later revealed worsening of the right-sided hydronephrosis and hydroureter and a decrease in the severity of dilation on the left side presumably from passage of the left-sided ureteral calculi. Nephroureteral decompression via the placement of a stent was elected. A pigtail ureteral catheter (8.2 French diameter) was placed in the right ureter via an antegrade percutaneous approach utilizing ultrasound and fluoroscopic-guidance. Following stent placement, macrohematuria resolved although microhematuria was noted in opportunistic urine samples. Five months after stent placement, the azotemia had mildly progressed, the urine protein:creatinine ratio was improved, the right hydronephrosis and hydroureter had completely resolved, and the ureteral stent remained in the appropriate position. The tiger had clinically improved with a substantial increase in appetite, weight, and activity level. Ureteral stenting allowed for nephroureteral decompression in the captive large felid of this report, and no complications were encountered. Ureteral stenting provided a minimally invasive method of managing ureteral obstruction in this patient and could be considered in future cases due to the clinical improvement and low morbidity.

Use of ethylene-vinyl alcohol copolymer as a liquid embolic agent to treat a peripheral arteriovenous malformation in a dog.

CASE DESCRIPTION: An 11-year-old castrated male Tibetan Mastiff was evaluated because of a visibly enlarged blood vessel and progressively worsening swelling of the right hind limb. CLINICAL FINDINGS: On physical examination, the right hind limb was markedly larger than the left hind limb and the dog was minimally weight bearing on the affected limb. A bruit was auscultated over the affected region. Ultrasonography of the tarsal region of the right hind limb revealed an artery with turbulent flow that communicated with venous drainage. A CT scan confirmed the presence of an arteriovenous malformation (AVM). TREATMENT AND OUTCOME: Embolization of the AVM with a liquid embolic agent (ethylene-vinyl alcohol copolymer dissolved in dimethyl sulfoxide) was elected. An arteriogram was performed prior to treatment and delineated the vessels that were targeted for embolization. The embolic agent was infused into the AVM, and a postinjection arteriogram confirmed complete occlusion of the AVM nidus and normal arterial flow to the paw with subsequent normal venous drainage. The circumference of the abnormal paw was 51 cm before the procedure and 22.9 cm at 4 weeks after the procedure. Additionally, the gait of the dog dramatically improved. No complications associated with the procedure developed. CLINICAL RELEVANCE: Peripheral AVMs in dogs are uncommon, and described treatment options are limited and generally associated with serious morbidity. A liquid embolic agent, ethylene-vinyl alcohol copolymer dissolved in dimethyl sulfoxide, was successfully administered in this case, and no morbidity was observed secondary to the procedure. Clinical success was characterized by substantial improvement in limb swelling and marked improvement in the gait of the dog.

Simulation in training: one-year experience using an efficiency index to assess interventional radiology fellow training status.

PURPOSE: To compare objective fellow and expert efficiency indices for an interventional radiology renal artery stenosis skill set with the use of a high-fidelity simulator. MATERIALS AND METHODS: The Mentice VIST simulator was used for three different renal artery stenosis simulations of varying difficulty, which were used to grade performance. Fellows' indices at three intervals throughout 1 year were compared to expert baseline performance. Seventy-four simulated procedures were performed, 63 of which were captured as audiovisual recordings. Three levels of fellow experience were analyzed: 1, 6, and 12 months of dedicated interventional radiology fellowship. The recordings were compiled on a computer workstation and analyzed. Distinct measurable events in the procedures were identified with task analysis, and data regarding efficiency were extracted. Total scores were calculated as the product of procedure time, fluoroscopy time, tools, and contrast agent volume. The lowest scores, which reflected efficient use of tools, radiation, and time, were considered to indicate proficiency. Subjective analysis of participants' procedural errors was not included in this analysis. RESULTS: Fellows' mean scores diminished from 1 month to 12 months (42,960 at 1 month, 18,726 at 6 months, and 9,636 at 12 months). The experts' mean score was 4,660. In addition, the range of variance in score diminished with increasing experience (from a range of 5,940-120,156 at 1 month to 2,436-85,272 at 6 months and 2,160-32,400 at 12 months). Expert scores ranged from 1,450 to 10,800. CONCLUSIONS: Objective efficiency indices for simulated procedures can demonstrate scores directly comparable to the level of clinical experience.

Analysis of simulated angiographic procedures. Part 2: extracting efficiency data from audio and video recordings.

PURPOSE: To create and test methods of extracting efficiency data from recordings of simulated renal stent procedures. MATERIALS AND METHODS: Task analysis was performed and used to design a standardized testing protocol. Five experienced angiographers then performed 16 renal stent simulations using the Simbionix AngioMentor angiographic simulator. Audio and video recordings of these simulations were captured from multiple vantage points. The recordings were synchronized and compiled. A series of efficiency metrics (procedure time, contrast volume, and tool use) were then extracted from the recordings. The intraobserver and interobserver variability of these individual metrics was also assessed. The metrics were converted to costs and aggregated to determine the fixed and variable costs of a procedure segment or the entire procedure. RESULTS: Task analysis and pilot testing led to a standardized testing protocol suitable for performance assessment. Task analysis also identified seven checkpoints that divided the renal stent simulations into six segments. Efficiency metrics for these different segments were extracted from the recordings and showed excellent intra- and interobserver correlations. Analysis of the individual and aggregated efficiency metrics demonstrated large differences between segments as well as between different angiographers. These differences persisted when efficiency was expressed as either total or variable costs. CONCLUSIONS: Task analysis facilitated both protocol development and data analysis. Efficiency metrics were readily extracted from recordings of simulated procedures. Aggregating the metrics and dividing the procedure into segments revealed potential insights that could be easily overlooked because the simulator currently does not attempt to aggregate the metrics and only provides data derived from the entire procedure. The data indicate that analysis of simulated angiographic procedures will be a powerful method of assessing performance in interventional radiology.

Analysis of simulated angiographic procedures: part 1--capture and presentation of audio and video recordings.

PURPOSE: To assess different methods of recording angiographic simulations and to determine how such recordings might be used for training and research. MATERIALS AND METHODS: Two commercially available high-fidelity angiography simulations, the Mentice Vascular Interventional Simulation Trainer and the Simbionix AngioMentor, were used for data collection. Video and audio records of simulated procedures were created by different methods, including software-based screen capture, video splitters and converters, and external cameras. Recording parameters were varied, and the recordings were transferred to computer workstations for postprocessing and presentation. RESULTS: The information displayed on the simulators' computer screens could be captured by each method. Although screen-capture software provided the highest resolution, workflow considerations favored a hardware-based solution that duplicated the video signal and recorded the data stream(s) at lower resolutions. Additional video and audio recording devices were used to monitor the angiographer's actions during the simulated procedures. The multiple audio and video files were synchronized and composited with personal computers equipped with commercially available video editing software. Depending on the needs of the intended audience, the resulting files could be distributed and displayed at full or reduced resolutions. CONCLUSIONS: The capture, editing, presentation, and distribution of synchronized multichannel audio and video recordings holds great promise for angiography training and simulation research. To achieve this potential, technical challenges will need to be met, and content will need to be tailored to suit the needs of trainees and researchers.

Patient factors affecting thermal lesion size with an impedance-based radiofrequency ablation system.

PURPOSE: To evaluate factors that affect the size of the thermal lesion created from radiofrequency ablation (RFA) with an impedance-based system. MATERIALS AND METHODS: Thirty-two nonresectable liver tumors, including hepatocellular carcinomas (HCC) (N=20; 63%) or metastatic tumors (N=12; 37%) were treated in 29 patients with an impedance based RFA system. Tumor diameter was measured at pre-procedure cross sectional imaging. Follow-up imaging was obtained at 1 month and every 3 months afterward to determine the short axis of the resultant thermal lesion. Success at durable tumor destruction was tracked as well as size of the resulting thermal lesion and the resulting thermal lesion/electrode ratio. Time to impedance roll-off was also correlated with treatment success. RESULTS: Twenty-eight (88%) of the 32 tumors were durably ablated in a single session. Two patients had residual disease and two had local recurrence. All residual or recurrent lesions were in patients with cirrhosis. Three of these patients were retreated resulting in a durable result in 97% of lesions with a mean/median follow up 443/503 days. Mean tumor diameter and resulting thermal lesion size was similar for HCC and metastatic lesions. A significant difference (P=.02) was observed when comparing the thermal lesion/electrode ratios of HCC (1.01+/-0.36) with metastases (1.26+/-0.22). Nine of 20 HCC ablations (45%) resulted in a ratio>1.0, whereas 11 of 12 metastatic ablations (92%) attained a ratio>1.0 (P=.01). Thermal lesion size did not correlate with time to impedance roll-off for the entire group (r=-0.22; P=.90) or by tumor type (HCC r=0.10; P=.68; metastases r=-0.36; P=.23). CONCLUSION: Thermal lesion size and the ability to obtain a margin of normal tissue are significantly affected by the presence of cirrhosis when using an impedance-based system. Given this limitation, the majority of small hepatic neoplasms can still be successfully treated with RFA.

Correlation between preprocedural MRI findings and clinical outcomes in the treatment of chronic symptomatic vertebral compression fractures with percutaneous vertebroplasty.

OBJECTIVE: The purpose of our study was to correlate findings of prevertebroplasty MRI with outcomes in the treatment of chronic osteoporotic compression fractures. MATERIALS AND METHODS: Forty-five patients with osteoporotic spinal compression fractures of more than 1 year's duration were treated with vertebroplasty. Changes in pain and mobility were assessed by follow-up of 1-28 months. Preprocedural MR images were reviewed using the Modic criteria and were correlated with outcomes. RESULTS: Fifteen patients (33%) had marrow edema on MRI and 30 (67%) of the 45 patients did not. All 15 of the patients with edema had clinical benefit: six patients (40%) achieved complete relief and nine (60%) experienced symptom improvement. Ten patients (67%) had improvement in mobility, and the remaining five patients (33%) had no change. Of patients with no marrow edema (n = 30), five (17%) had complete resolution of pain, 19 (63%) were improved, and six (20%) were unchanged. None had worsening of their symptoms. Mobility was improved in 17 (57%) and unchanged in 10 (33%). Mobility was diminished in three patients (10%). In two cases, impaired mobility was due to causes other than spine disorders. CONCLUSION: Most (87%) of the 45 patients with compression fractures older than 1 year derived clinical benefit from vertebroplasty irrespective of MRI findings. Although 100% of patients with bone marrow edema had clinical benefit, no direct correlation was seen between symptom resolution and the presence of edema on preprocedural MRI. In our experience, absence of abnormal marrow signal does not definitively predict the outcome of vertebroplasty in chronic fractures.

Reversible neuropathy caused by overuse following radiofrequency ablation of metastatic pelvic lesions.

Adverse events following radiofrequency ablation of skeletal metastases are uncommon. This report describes two patients who developed a delayed neuropathy following radiofrequency ablation of pelvic metastases. Both patients had significant pain relief and normal neurological examinations following the procedure. Each patient's neuropathy developed following acute significant increases of activity or stress on surrounding tissues allowed by the pain relief from therapy. Both patients completely recovered after a course of corticosteroids.

Giant mycotic aneurysm of the internal carotid artery in a child: endovascular treatment.

We present a case of a giant mycotic aneurysm of the left internal carotid artery in a child, the result of direct extension of a deep neck space infection. This lesion is life threatening and may put the patient at risk of unwarranted biopsy or drainage if not recognized. Diagnosis and treatment planning rely heavily on cross-sectional imaging, and angiography is frequently necessary. This case is unique for two reasons: (1) we present for the first time the MRI findings and (2) we describe an alternative to surgical ligation -- neurointerventional embolotherapy. Minimally invasive transcatheter embolization was successfully performed on our patient to occlude the abnormal left internal carotid artery segment.