Diagnostic investigation of an unusually large osseous cyst-like lesion of the radial carpal bone

A 10-year-old Irish Sports Horse presented for intermittent, fluctuating lameness of the left forelimb. Nuclear scintigraphy, radiography and computed tomography identified a large osseous cyst-like lesion (OCLL) occupying approximately 50% of the radial carpal bone with an articular communication to the antebrachiocarpal joint. A transcortical surgical approach was used to curette the lining of the lesion prior to injection with triamcinolone acetonide. This imaging report describes the detailed diagnostic findings of an unusually extensive OCLL in the radial carpal bone.     

Semi‐quantitative methods yield greater inter‐ and intraobserver agreement than subjective methods for interpreting 99mtechnetium‐hydroxymethylene‐diphosphonate uptake in equine thoracic processi spinosi

Scintigraphy is a standard diagnostic method for evaluating horses with back pain due to suspected thoracic processus spinosus pathology. Lesion detection is based on subjective or semi‐quantitative assessments of increased uptake. This retrospective, analytical study is aimed to compare semi‐quantitative and subjective methods in the evaluation of scintigraphic images of the processi spinosi in the equine thoracic spine. Scintigraphic images of 20 Warmblood horses, presented for assessment of orthopedic conditions between 2014 and 2016, were included in the study. Randomized, blinded image evaluation was performed by 11 veterinarians using subjective and semi‐quantitative methods. Subjective grading was performed for the analysis of red‐green‐blue and grayscale scintigraphic images, which were presented in full‐size or as masked images. For the semi‐quantitative assessment, observers placed regions of interest over each processus spinosus. The uptake ratio of each processus spinosus in comparison to a reference region of interest was determined. Subsequently, a modified semi‐quantitative calculation was developed whereby only the highest counts‐per‐pixel for a specified number of pixels was processed. Inter‐ and intraobserver agreement was calculated using intraclass correlation coefficients. Inter‐ and intraobserver intraclass correlation coefficients were 41.65% and 71.39%, respectively, for the subjective image assessment. Additionally, a correlation between intraobserver agreement, experience, and grayscale images was identified. The inter‐ and intraobserver agreement was significantly increased when using semi‐quantitative analysis (97.35% and 98.36%, respectively) or the modified semi‐quantitative calculation (98.61% and 98.82%, respectively). The proposed modified semi‐quantitative technique showed a higher inter‐ and intraobserver agreement when compared to other methods, which makes it a useful tool for the analysis of scintigraphic images. The association of the findings from this study with clinical and radiological examinations requires further investigation.     

Evaluation of a wireless ambulatory capsule (SmartPill®) to measure gastrointestinal tract pH, luminal pressure and temperature, and transit time in ponies

Reasons for performing study: This study investigated the use of a wireless ambulatory capsule (WAC; SmartPill^® pH.p GI Monitoring System) to determine WAC‐gastric emptying time (GET) in ponies. Objectives: To measure WAC‐GET and compare it to those findings with GET assessed by nuclear scintigraphy (S‐GET). Hypothesis: WAC‐GET will be slower than S‐GET, but will be significantly correlated. Methods: Seven healthy adult mixed‐breed pony mares were used in this study. Feed was withheld for 12 h prior to the WAC administration. After administration, a complete‐feed diet was fed to allow the WAC to pass into the stomach. Luminal pH, temperature and pressure were collected by a modified receiver secured to the pony. Once the pH reached a value of ≥8.0, it was determined that gastric emptying had occurred, and ponies were fed grass hay. After 5 days, data were downloaded and analysed using proprietary software. During the second period of the study, after at least 2 weeks, 4 of the ponies underwent a standard S‐GET test. Results: The WAC was successfully administered, and data were collected from all ponies. The mean percentage of data packets collected by the receiver was 84.9 ± 3.51% (range 66.8–95.1%). Mean WAC‐GET was 7.38 h (range 0.15–46.65 h). Mean gastric pH was 4.75 (range 2.07–6.99). Mean small intestinal transit time was 4.6 h. The mean pH for the small intestine was 8.0. The mean S‐GET time (in hours) when 10% of the radioactive feed is present in the stomach (T‐90%) was 2.3 h. The S‐GET did not correlate significantly with the WAC‐GET. Conclusions and potential relevance: The WAC was safely administered to ponies, and data were collected using a modified receiver. The WAC‐GET varied considerably between ponies, but was ≤3 h in 5 of the 6 ponies. The WAC used in this study provided a noninvasive technique that produced novel information about the pony gastrointestinal tract, but owing to the substantial variability in GET values and long transit time it may not be a reliable clinical tool at this time.     

Intravenous technetium-99m labelled PEG-liposomes in horses: a safety and biodistribution study

Reasons for performing study: Liposomes are phospholipid nanoparticles that extravasate at sites of increased vascular permeability. They have potential in equine medicine for targeted drug delivery and diagnostic imaging of infectious, inflammatory and neoplastic lesions. Objectives: This study evaluates the safety and biodistribution of i.v. polyethyleneglycol(PEG) liposomes in normal horses. Methods: PEG‐liposomes were prepared by the film hydration method and labelled using ^99mTc‐hexamethyl‐propylene‐amine‐oxime. A single dose of 0.24 µmol/kg bwt ^99mTc‐PEG‐liposomes and 2.4 µmol/kg bwt unlabelled PEG‐liposomes was administered to 10 conscious horses via i.v. infusion at a rate of 6 µmol/min for the first 15 min and 60 µmol/min thereafter. Clinical parameters, haematology, plasma biochemistry and serum complement activity were monitored serially. Scintigraphic imaging was performed at 1, 12 and 21 h post infusion (PI). Six horses were subjected to euthanasia at 24 h PI. The percentage injected dose per kilogram of tissue was calculated for multiple organs. Results were analysed using repeated measures ANOVA. Results: Horses did not demonstrate adverse reactions during or after liposome infusion. There was a significant elevation in heart rate and respiratory rate at 20 and 25 min PI. No significant complement consumption was detected, although a trend for decreased total haemolytic complement values at 20 min PI was present. Scintigraphic studies revealed a prolonged vascular phase that lasted to 21 h PI, with a reproducible pattern of organ distribution. Biodistribution studies revealed the highest concentrations of radiopharmaceutical within the lung, kidney, liver and spleen. Conclusions: Intravenous liposome administration appears to be safe in horses. When administered in combination with PEG‐liposomes, ^99mTc‐PEG‐liposomes have long circulating characteristics and a reproducible pattern of organ distribution in horses. Potential relevance: Radiolabelled liposomes may be useful for detecting infection, inflammation and neoplasia in the horse. Liposomes have significant potential for targeted drug delivery in the horse. This study establishes the scintigraphic findings and tissue distribution of 99mTc‐PEG‐liposomes after i.v. administration in healthy horses.     

SCINTIGRAPHIC AND RADIOGRAPHIC APPEARANCE OF THE SACROILIAC REGION IN HORSES WITH GAIT ABNORMALITIES OR POOR PERFORMANCE

Nuclear bone scintigraphy is commonly used in the diagnosis of sacroiliac disease in horses. The aim of the present retrospective study was to determine if there was an association between radiopharmaceutical uptake pattern and radiographic appearance of the sacroiliac region in horses. Seventy-nine horses undergoing bone scintigraphy with Tc-99 m-HDP and radiography of the pelvis because of lameness or poor performance were studied. Subjective and semiquantitative methods were used to characterize and compare radiopharmaceutical uptake between horses. Ventrodorsal radiographs of the region were obtained and were evaluated. Subjectively, 70 horses (88.6%) had an abnormal uptake pattern. In nine horses, the sacroiliac region was normal (11.4%). There was no association between subjective evaluation of the scintigraphic images and semiquantitative methods. There was a significant association between radiopharmaceutical uptake and conformation (T- or Y-like form) and shape (butterfly-, wing-, leaf-, or horn-like) of the sacrum. The radiopharmaceutical uptake of the tubera sacralia was significantly higher in males (left side P =0.002, right side P =0.003). In conclusion, the conformation of the sacrum may play an important role in the scintigraphic appearance and may be the cause of increased radiopharmaceutical uptake.     

IMAGING DIAGNOSIS—ENOSTOSIS-LIKE LESION IN THE FEMUR OF A HORSE

An enostosis-like lesion was diagnosed in the left femur of a Swedish Warmblood horse that had a left hindlimb lameness of 3 weeks duration. With scintigraphy using technetium 99m-hydroxymethylene diphosphonate (^99m Tc-HDP) a marked regional focal increase in radioactivity was identified in the medullary cavity of the left femur. Radiographically there was a corresponding focal increase in bone opacity in the middiaphysis of the left femur. Histopathologically, a 5 cm area of bone matrix was present in the diaphysis of the left femur and confirmed as an enostosis-like lesion. Enostosis-like lesions should be considered as a source of pain in horses with difficult to localize, moderate to severe chronic lameness.     

Bilateral ureterocystostomy to correct left ureteral atresia and right ureteral ectopia in an 8-month-old standardbred filly

OBJECTIVES: To report the diagnosis and outcome after surgical correction of bilateral distal ureteral anomalies in a Standardbred filly. STUDY DESIGN: Clinical case report. ANIMAL: An 8-month-old, 310 kg Standardbred filly with left ureteral atresia and right ureteral ectopia. METHODS: The filly was admitted for evaluation of incontinence since birth and severe urine scalding of the hindquarters. Diagnosis was made by both direct (cystoscopy and vaginoscopy) and indirect (intravenous pyelography, ultrasonography, and scintigraphy) evaluation of the ureters and bladder. The filly had left ureteral atresia, hydronephrosis, and decreased left-sided renal function and right ureteral ectopia before surgery. Surgical correction was performed on the left by an end-to-side stapled anastomosis technique and on the right by a side-to-side hand-sewn anastomosis technique. RESULTS: Surgical correction was successful. The filly had no postoperative complications and remained continent 18 months after surgery. Left renal function improved. CONCLUSION: Ureteral anomalies can be successfully repaired in larger (>300 kg) foals and some renal function may be restored after surgical correction. CLINICAL RELEVANCE: Scintigraphy should be considered in diagnosis of ureteral anomalies, assessing renal function, and determining prognosis for horses with hydronephrosis caused by ureteral ectopia and atresia.