Use of contrast media in computed tomography and magnetic resonance imaging in horses: Techniques, adverse events and opportunities

Immunology of Physical Exercise: Is Equus caballus an Appropriate Animal Model for Human Athletes?

Domestic horses routinely participate in vigorous and various athletic activities. This enables the horse to serve as a model for studying athletic physiology and immunology in other species, including humans. For instance, as a model of physical efforts, such as endurance rides (long-distance running/aerobic exercise) and races (anaerobic exercise), the horse can be useful in evaluating post-exercise response. Currently, there has been significant interest in finding biomarkers, which characterize the advancement of training and adaptation to physical exercise in the horse. The parallels in cellular responses to physical exercises, such as changes in receptor expression and blood cell activity, improve our understanding of the mechanisms involved in the body's response to intense physical activity. This study focuses on the changes in levels of the pro- and anti-inflammatory cytokines and cellular response in the context of post-exercise immune response. Both the direction of changes in cytokine levels and cellular responses of the body, such as proliferation and expression of surface markers on lymphocytes, monocytes and neutrophils, show cross-functional similarities. This review reveals that horses are robust research models for studying the immune response to physical exercise in human athletes.

Does Direct MRI Tenography Improve the Diagnostic Performance of Low-Field MRI to Identify Artificially Created Soft-Tissue Lesions within the Equine Cadaveric Digital Flexor Tendon Sheath?

Tenosynovitis of the digital flexor tendon sheath (DFTS) is diagnosed using ultrasonography and contrast tenography. Nevertheless, making a precise preoperative diagnosis is challenging. This study aimed to determine and compare the sensitivity and specificity of low-field MRI and MRI tenography (MRIt) to detect artificially created soft-tissue lesions in the DFTS. In 21 DFTSs, 118 lesions were made tenoscopically in the superficial digital flexor tendon (SDFT), deep digital flexor tendon (DDFT), manica flexoria (MF) and proximal scutum. MRI and MRI, following intrathecal gadolinium administration (MRIt), were performed. The sensitivity and specificity of MRI and MRIt were calculated and compared. Proximal scutum lesions were less frequently identified by MRI (Sensitivity 38%, specificity 96%) compared to MRIt (Sensitivity: 50%, p = 0.80; specificity: 96%, p = 1). This was similar for SDFT lesions (Sensitivity: 39% versus 54%, p = 0.72; specificity: 93% versus 96%, p = 1). MRI detected DDFT lesions (sensitivity 34%; specificity 100%) better than MRIt (sensitivity 32%, p = 0.77; specificity 98%, p = 1). This was similar for MF lesions (MRI sensitivity 61%; specificity 100% vs. MRIt sensitivity 50%, p = 0.68; specificity 96%, p = 1). Lesion size was significantly associated with MRI or MRIt diagnosis (p = 0.001). The intrathecal administration of gadolinium did not significantly improve the ability of low-field MRI to diagnose artificial DFTS tendon lesions. Small lesion length was a significant discriminating factor for lesion detection. MRI and MRIt specificity were high, thus being helpful in diagnosing an intact structure.

A pilot study to determine the optimal dose of scAAVIL-1ra in a large animal model of post-traumatic osteoarthritis

Gene therapy approaches using adeno-associated viral vectors have been successfully tested in the equine post-traumatic osteoarthritis (PTOA) model. Owing to differences in the levels of transgene expression and adverse tissue reactions observed in published studies, we sought to identify a safe therapeutic dose of scAAVIL-1ra in an inflamed and injured joint that would result in improved functional outcomes without any adverse events. scAAVIL-1ra was delivered intra-articularly over a 100-fold range, and horses were evaluated throughout and at the end of the 10-week study. A dose-related increase in IL-1ra levels with a decrease in PGE2 levels was observed, with the peak IL-1ra concentration being observed 7 days post-treatment in all groups. Perivascular infiltration with mononuclear cells was observed within the synovial membrane of the joint treated with the highest viral dose of 5 × 1012 vg, but this was absent in the lower-dosed joints. The second-highest dose of scAAVeqIL-1ra 5 × 1011 vg demonstrated elevated IL-1ra levels without any cellular response in the synovium. Taken together, the data suggest that the 10-fold lower dose of 5 × 1011vg scAAVIL-1ra would be a safe therapeutic dose in an equine model of PTOA.

Development of a three-dimensional computer model of the equine heart using a polyurethane casting technique and in vivo contrast-enhanced computed tomography

INTRODUCTION/OBJECTIVES

Insight into the three-dimensional (3D) anatomy of the equine heart is essential in veterinary education and to develop minimally invasive intracardiac procedures. The aim was to create a 3D computer model simulating the in vivo anatomy of the adult equine heart.

ANIMALS

Ten horses and five ponies.

MATERIALS AND METHODS

Ten horses, euthanized for non-cardiovascular reasons, were used for in situ cardiac casting with polyurethane foam and subsequent computed tomography (CT) of the excised heart. In five anaesthetized ponies, a contrast-enhanced electrocardiogram-gated CT protocol was optimized to image the entire heart. Dedicated image processing software was used to create 3D models of all CT scans derived from both methods. Resulting models were compared regarding relative proportions, detail and ease of segmentation.

RESULTS

The casting protocol produced high detail, but compliant structures such as the pulmonary trunk were disproportionally expanded by the foam. Optimization of the contrast-enhanced CT protocol, especially adding a delayed phase for visualization of the cardiac veins, resulted in sufficiently detailed CT images to create an anatomically correct 3D model of the pony heart. Rescaling was needed to obtain a horse-sized model.

CONCLUSIONS

Three-dimensional computer models based on contrast-enhanced CT images appeared superior to those based on casted hearts to represent the in vivo situation and are preferred to obtain an anatomically correct heart model useful for education, client communication and research purposes. Scaling was, however, necessary to obtain an approximation of an adult horse heart as cardiac CT imaging is restricted by thoracic size.

Computed tomographic evaluation of the distal limb in the standing sedated horse: Technique, imaging diagnoses, feasibility, and artifacts

In several veterinary institutions, adjustments of CT machines have been made that allow for imaging of the standing horse. The risk of general anesthesia is eliminated and the shorter scan completion time reduces cost to clients. The objective of this retrospective, analytical study was to evaluate the technique, imaging diagnoses, feasibility, and image artifacts of multi-slice helical CT of horses' distal limbs acquired under standing sedation. The CT images of 250 horses of various breeds, aged 3-23 years, that underwent standing distal limb CT were evaluated. Three observers assessed the CT images for artifacts and inter-observer agreement was calculated. Eighty-six percent (95% confidence interval (CI), 81-90) of the scans were carried out on the forelimbs, while 14% (95% CI, 10-19) were of the hindlimbs. A total of 65% (95% CI, 59-71) of horses that underwent standing sedated CT had single imaging diagnoses. Seventy-one percent (95% CI, 65-77) of the cases had unilateral lesions, 27% (95% CI, 22-33) had bilateral lesions and 2% (95% CI, 1-4) had no diagnosed lesions. The average CT acquisition time was 17.5 minutes (range = 15-20). The average number of acquisitions per horse was 1.7 (median = 1; range = 1-4). There was good to excellent agreement between all three observers for the presence of motion artifact in the metacarpo/metatarsophalangeal joints, identification of marked beam hardening artifact, mild solar/ skin dirt, and photon starvation artifact (kappa 0.61-0.80). No complications were encountered. Standing examination of the distal limb achieved diagnostic image quality that was obtained with minimal acquisition attempts and in a timely manner.

Dual-contrast micro-CT enables cartilage lesion detection and tissue condition evaluation ex vivo

BACKGROUND

Post-traumatic osteoarthritis is a frequent joint disease in the horse. Currently, equine medicine lacks effective methods to diagnose the severity of chondral defects after an injury.

OBJECTIVES

To investigate the capability of dual-contrast-enhanced computed tomography (dual-CECT) for detection of chondral lesions and evaluation of the severity of articular cartilage degeneration in the equine carpus ex vivo.

STUDY DESIGN

Pre-clinical experimental study.

METHODS

In nine Shetland ponies, blunt and sharp grooves were randomly created (in vivo) in the cartilage of radiocarpal and middle carpal joints. The contralateral joint served as control. The ponies were subjected to an 8-week exercise protocol and euthanised 39 weeks after surgery. CECT scanning (ex vivo) of the joints was performed using a micro-CT scanner 1 hour after an intra-articular injection of a dual-contrast agent. The dual-contrast agent consisted of ioxaglate (negatively charged, q = -1) and bismuth nanoparticles (BiNPs, q = 0, diameter ≈ 0.2 µm). CECT results were compared to histological cartilage proteoglycan content maps acquired using digital densitometry.

RESULTS

BiNPs enabled prolonged visual detection of both groove types as they are too large to diffuse into the cartilage. Furthermore, proportional ioxaglate diffusion inside the tissue allowed differentiation between the lesion and ungrooved articular cartilage (3 mm from the lesion and contralateral joint). The mean ioxaglate partition in the lesion was 19 percentage points higher (P < 0.001) when compared with the contralateral joint. The digital densitometry and the dual-contrast CECT findings showed good subjective visual agreement.

MAIN LIMITATIONS

Ex vivo study protocol and a low number of investigated joints.

CONCLUSIONS

The dual-CECT methodology, used in this study for the first time to image whole equine joints, is capable of effective lesion detection and simultaneous evaluation of the condition of the articular cartilage.

Gene therapy approaches for equine osteoarthritis

With an intrinsically low ability for self-repair, articular cartilage injuries often progress to cartilage loss and joint degeneration resulting in osteoarthritis (OA). Osteoarthritis and the associated articular cartilage changes can be debilitating, resulting in lameness and functional disability both in human and equine patients. While articular cartilage damage plays a central role in the pathogenesis of OA, the contribution of other joint tissues to the pathogenesis of OA has increasingly been recognized thus prompting a whole organ approach for therapeutic strategies. Gene therapy methods have generated significant interest in OA therapy in recent years. These utilize viral or non-viral vectors to deliver therapeutic molecules directly into the joint space with the goal of reprogramming the cells' machinery to secrete high levels of the target protein at the site of injection. Several viral vector-based approaches have demonstrated successful gene transfer with persistent therapeutic levels of transgene expression in the equine joint. As an experimental model, horses represent the pathology of human OA more accurately compared to other animal models. The anatomical and biomechanical similarities between equine and human joints also allow for the use of similar imaging and diagnostic methods as used in humans. In addition, horses experience naturally occurring OA and undergo similar therapies as human patients and, therefore, are a clinically relevant patient population. Thus, further studies utilizing this equine model would not only help advance the field of human OA therapy but also benefit the clinical equine patients with naturally occurring joint disease. In this review, we discuss the advancements in gene therapeutic approaches for the treatment of OA with the horse as a relevant patient population as well as an effective and commonly utilized species as a translational model.

Use of a novel helical fan beam imaging system for computed tomography of the distal limb in sedated standing horses: 167 cases (2019–2020)

OBJECTIVE

To evaluate the diagnostic capabilities of a novel helical fan beam CT system used for imaging of horses with a range of clinical distal limb problems.

ANIMALS

167 horses.

PROCEDURES

Medical records were reviewed of horses presented for CT of the distal limb at 2 university-based veterinary hospitals. The following data were recorded: age, sex, breed, presenting complaint, sedation used for imaging, scanning time, procedure time, other diagnostic imaging methods performed, imaging diagnosis, clinical diagnosis, and complications during imaging.

RESULTS

Most horses were Thoroughbreds and Quarter Horses. Procedure times ranged from 15 to 40 minutes, with scanning completed in 15 to 45 seconds for each region of interest. The foot or pastern region was commonly scanned (88/167 [53%] horses), with navicular bone disease diagnosed in 42 of 88 (48%) horses. The fetlock region was also commonly scanned (42/167 [40%] horses), with palmar or plantar osteochondral disease diagnosed in 17 of 42 (40%) horses. Horses were compliant during scanning, and no complications with sedation or damage to the scanner occurred. A specific imaging diagnosis for the lameness was achieved more frequently with CT imaging (166/167 [99%]) than with planar digital radiography (26/58 [45%]).

CLINICAL RELEVANCE

The helical fan beam CT system could be used safely to scan sedated standing horses from the carpal or tarsal region distally. Subjectively, the machine was easy to operate, allowing CT to be incorporated into lameness investigations. CT imaging was very likely to result in a clinical diagnosis in horses with distal limb lameness.

Use of a novel helical fan beam imaging system for computed tomography of the head and neck in sedated standing horses: 120 cases (2019–2020)

OBJECTIVE

To evaluate the diagnostic capabilities of a novel helical fan beam CT system used for imaging of horses with clinical problems of the head and neck.

ANIMALS

120 horses.

PROCEDURES

Medical records were reviewed of horses presented for CT of the head or neck at 2 university hospitals. The following data were recorded: age, sex, breed, presenting complaint, sedation used for imaging, scanning time, procedure time, other diagnostic imaging methods performed, imaging diagnosis, clinical diagnosis, and complications during imaging.

RESULTS

Quarter Horses and Warmbloods were the most common breeds, and the most common complaint was nasal discharge. The head (101/120 [84%] horses) was scanned most frequently, and the most common diagnoses were primary dental disease and a space-occupying lesion of the paranasal sinuses. Nuchal bursitis was the most common imaging diagnosis in the neck region. Procedure time ranged from 20 to 45 minutes with a scanning time of 30 to 40 seconds. No complications with horse sedation occurred, and horses tolerated scanning well. An imaging diagnosis was more frequently achieved with CT (109/120 [91%] horses) than with planar digital radiography (23/61 [38%] horses).

CLINICAL RELEVANCE

The helical fan beam CT system had fast scanning times and could be used safely for routine imaging of the teeth and sinuses in horses. The caudal extent of scanning in the neck region was limited by the shape of the horse’s neck and thorax.

Equine flexor tendon imaging part 2: Current status and future directions in advanced diagnostic imaging, with focus on the deep digital flexor tendon

Flexor tendon injuries are a common cause of lameness and early retirement in equine athletes. While ultrasonography is most frequently utilised, advanced diagnostic imaging modalities are becoming more widely available for detection and monitoring of flexor tendon lesions. Part two of this literature review details current experience with low- and high-field magnetic resonance imaging (MRI) and computed tomography (CT) for the diagnosis of equine flexor tendinopathy with a focus on the deep digital flexor tendon. Implications of the 'magic angle' artefact as well as injection techniques and the use of contrast media are discussed. Future developments in tendon imaging aim to gain enhanced structural information about the tendon architecture with the prospect to prevent injury. Techniques as described for the assessment of the human Achilles tendon including ultra-high field MRI and positron emission tomography are highlighted.

Contrast Enhanced Computed Tomography Findings in 105 Horse Distal Extremities

The poor soft tissue conspicuity of CT can be improved by using intra-arterial CT Angiography (CTA), and intra-articular and intra-bursal contrast enhanced CT (CTAR). This retrospective study describes a combination protocol of CT and CTA of the horse's foot, and CTAR of the distal interphalangeal joint and navicular bursa. It is hypothesized this would provide a comprehensive overview of the range and severity of distal limb pathology. Radiology reports of all horses admitted for distal limb CT over a 5 year period were reviewed. All horses with a complete four stage CT examination and radiology report with lameness isolated to the foot were included. Twenty seven imaging findings using a four grade semiquantitative severity scoring system contributing towards six main diagnostic categories were described. One hundred and five examinations on 56 horses revealed a diagnosis of navicular bone disease in 64%, deep digital flexor tendinopathy in 43%, distal interphalangeal osteoarthritis in 35%, navicular bursitis in 31%, distal interphalangeal collateral ligament desmopathy in 26%, and hoof capsule and distal phalanx pathology in 10%. Only 25% of the navicular bone disease cases were considered clinically significant. The majority of deep digital flexor tendon lesions (77%) and distal interphalangeal joint osteoarthritis (51%) were considered significant. Approximately one third of navicular bursa (37%) and collateral ligament (33%) abnormalities were considered significant. Navicular bursa abnormalities were associated with navicular bone and deep digital flexor tendon lesions. The findings support the hypothesis and the use of this protocol for evaluation of foot lameness.

Use of cone-beam computed tomography for advanced imaging of the equine patient

Access to volumetric imaging modalities, such as magnetic resonance imaging (MRI) and computed tomography (CT), has increased over the past decade and has revolutionised the way clinicians evaluate equine anatomy. More recent advancements have resulted in the development of multiple commercially available cone-beam CT (CBCT) scanners for equine use. CBCT scanners modify the traditional fan-shaped beam of ionising radiation into a three-dimensional pyramidal- or cone-shaped beam of radiation. This modification enables the scanner to acquire sufficient data to create diagnostic images of a region of interest after a single rotation of the gantry. The rapid acquisition of data and divergent X-ray beam causes some artifacts to be more prominent on CBCT images-as well as the unique cone-beam artifact-resulting in decreased contrast resolution. While the use of CT for evaluation of the equine musculoskeletal anatomy is not new, there is a paucity of literature and scientific studies on the capabilities of CBCT for equine imaging. CBCT units do not require a specialised table for imaging and in some cases are portable for imaging in the standing or anaesthetised patient. This review article summarises the basic physics of CT technology, including how CBCT imaging differs, and provides objective information about the strengths and limitations of this modality. Finally, potential future applications and techniques for imaging with CT which will need to be explored in order to fully consider the capabilities of CT imaging in the horse are discussed.

Quantitative Evaluation of Equine Articular Cartilage Using Cationic Contrast-Enhanced Computed Tomography

OBJECTIVE

To investigate the diffusion trajectory of a cationic contrast medium (CA4+) into equine articular cartilage, and to assess normal and degenerative equine articular cartilage using cationic contrast-enhanced computed tomography (CECT).

DESIGN

In the first experiment (Exp1), equine osteochondral specimens were serially imaged with cationic CECT to establish the diffusion time constant and time to reach equilibrium in healthy articular cartilage. In a separate experiment (Exp2), articular cartilage defects were created on the femoral trochlea (defect joint) in a juvenile horse, while the opposite joint was a sham-operated control. After 7 weeks, osteochondral biopsies were collected throughout the articular surfaces of both joints. Biopsies were analyzed for cationic CECT attenuation, glycosaminoglycan (GAG) content, mechanical stiffness (Eeq), and histology. Imaging, biochemical and mechanical data were compared between defect and control joints.

RESULTS

Exp1: The mean diffusion time constant was longer for medial condyle cartilage (3.05 ± 0.1 hours) than lateral condyle cartilage (1.54 ± 0.3 hours, P = 0.04). Exp2: Cationic CECT attenuation was lower in the defect joint than the control joint (P = 0.005) and also varied by anatomic location (P = 0.045). Mean cationic CECT attenuation from the lateral trochlear ridge was lower in the defect joint than in the control joint (2223 ± 329 HU and 2667 ± 540 HU, respectively; P = 0.02). Cationic CECT attenuation was strongly correlated with both GAG (ρ = 0.79, P < 0.0001) and Eeq (ρ = 0.61, P < 0.0001).

CONCLUSIONS

The equilibration time of CA4+ into equine articular cartilage is affected by tissue volume. Quantitative cationic CECT imaging reflects the biochemical, biomechanical and histological state of normal and degenerative equine articular cartilage.

Feasibility, indications, and radiographically confirmed diagnoses of standing extremity cone beam computed tomography in the horse

OBJECTIVE

To report on the feasibility, indications, and diagnostic yield of cone beam computed tomography (CBCT) of horses' extremities performed under standing sedation.

STUDY DESIGN

Retrospective clinical case series.

SAMPLE POPULATION

Fifty-nine CBCT examinations in 58 horses.

METHODS

Examinations were categorized for indications for CBCT dependent on a suspicion, presence, or absence of a diagnosis prior to CBCT. The number of acquisitions per examination, total time for the examination, diagnostic score of each acquisition (diagnostic, diagnostic-compromised, nondiagnostic), and additional diagnostic information regarding preexisting diagnostic information were recorded.

RESULTS

Three (median) acquisitions were performed per examination in a median study time of 14 minutes. In 24 of 33 cases with a suspected diagnosis, this diagnosis was confirmed or definitively refuted; in seven of 33 cases, the suspected diagnosis was refuted without a new diagnosis; and, in two of 33 cases, the suspected diagnosis could not be confirmed nor could a new diagnosis be made. In five of nine cases without a preexisting diagnosis, a diagnosis was established. In 16 cases with a diagnosis prior to CBCT, additional information was recorded, or a surgical plan was prepared. In 14 of 18 cases in which additional contrast techniques were used, additional information was gained.

CONCLUSION

Standing CBCT of the horses' extremities is feasible and can produce diagnostic information in a timely fashion.

CLINICAL SIGNIFICANCE

The results provide evidence of the practicality and diagnostic potential of standing CBCT of horses' extremities.

Osteochondral fragmentation of the cervical articular process joints; prevalence in horses undergoing CT for investigation of cervical dysfunction

BACKGROUND

Computed tomography (CT) imaging of the cervical spine of mature horses under general anaesthesia is becoming increasingly accessible. Osteochondral fragmentation (OF) of the cervical articular process joints (APJs) has been identified on CT imaging; the prevalence, clinical features and significance of this finding are currently unknown.

OBJECTIVES

To describe the prevalence and clinical features of a population of horses with CT evidence of OF within the cervical APJs.

STUDY DESIGN

Retrospective, descriptive case series.

METHODS

The study population consisted of all horses undergoing CT imaging of the entire cervical spine between April 2016 and December 2019 at Liphook Equine Hospital for investigation of clinical signs localised to this region. CT scans were examined for evidence of OF within the APJs and additional case features were recorded.

RESULTS

A total of 55 horses underwent CT imaging during the study period. OF was identified in 13 horses, giving a CT prevalence of 24% in the study population. OF occurred in a range of ages, breeds and uses of equine, presenting with varied clinical signs. It was identified at every level of the neck. Additional cervical pathology was identified in 11/13 OF cases.

MAIN LIMITATIONS

Retrospective analysis of a clinical caseload with a lack of clinically normal controls or post mortem confirmation of imaging findings. Low case numbers.

CONCLUSIONS

OF within the cervical APJs is recognised on CT imaging in horses with cervical dysfunction. Fragments are commonly identified in combination with additional cervical pathology. Further investigation is required to confirm their clinical significance and develop potential treatment options where necessary.

Computational technology for nasal cartilage-related clinical research and application

Surgeons need to understand the effects of the nasal cartilage on facial morphology, the function of both soft tissues and hard tissues and nasal function when performing nasal surgery. In nasal cartilage-related surgery, the main goals for clinical research should include clarification of surgical goals, rationalization of surgical methods, precision and personalization of surgical design and preparation and improved convenience of doctor-patient communication. Computational technology has become an effective way to achieve these goals. Advances in three-dimensional (3D) imaging technology will promote nasal cartilage-related applications, including research on computational modelling technology, computational simulation technology, virtual surgery planning and 3D printing technology. These technologies are destined to revolutionize nasal surgery further. In this review, we summarize the advantages, latest findings and application progress of various computational technologies used in clinical nasal cartilage-related work and research. The application prospects of each technique are also discussed.

Computed tomographic cervical myelography in horses: Technique and findings in 51 clinical cases

Background

Three‐dimensional computed tomographic (CT) evaluation of the cervical vertebral column enables more accurate identification of osseous and soft tissue lesions than traditional latero‐lateral radiography. However, examination of the complete cervical vertebral column has been limited by horse size, preventing evaluation of the caudal cervical vertebrae.

Objectives

To describe a technique to enable CT myelography of the complete cervical spine and describe the findings in 51 horses.

Animals

Records of 51 horses presented for evaluation of cervical vertebral lesions.

Methods

A retrospective review of clinical records from all horses presented for CT myelography to further investigate possible cervical vertebral lesions was performed. A description of a novel approach to CT myelography in horses and retrospective review of the findings in clinical cases has been included.

Results

Degenerative joint disease was identified at 1 or more dorsal articular process joint in 50/51 horses, of which 44/51 had a site of grade 2 or greater. Spinal cord compression was observed on CT myelography in 31/51 horses, whereas attenuation of the dorsal contrast column was identified radiographically in 11/50 horses. Thirty‐three horses showed narrowing or obliteration of the intervertebral foramina at 1 or more site and osteochondral fragments were seen in 11/51 horses.

Conclusions and Clinical Importance

Computed tomography myelography is relatively safe and an easily performed technique with the correct equipment, enabling evaluation of the cervical vertebral structures of horses in all planes and volumetrically. It is possible that lesion extent might be underestimated with this diagnostic modality, hence interpretation should be complimented with flexed and extended views radiographically.

Identification of Naturally Occurring Cartilage Damage in the Equine Distal Interphalangeal Joint Using Low-Field Magnetic Resonance Imaging and Magnetic Resonance Arthrography

Objectives: To describe detectable and non-detectable naturally occurring cartilage damage of the equine distal interphalangeal (DIP) joint using plain magnetic resonance (MR) imaging and gadolinium and saline MR arthrography. The second objective was to quantify the sensitivity, specificity and accuracy in detection of cartilage damage.

Methods: In a pilot study, the distal limbs of two horses with confirmed osteoarthritis of the DIP joint were imaged with low-field MR. Magnetic resonance images were assessed in consensus by three observers and compared to gross pathological findings. Subsequently, a prospective analytical cross-sectional study design was created to compare pre-contrast MR imaging and saline and gadolinium MR arthrography of isolated equine distal limbs to gross observation findings. Hallmarq® low-field MR (0.27T) scans were performed prior to DIP joint injection, saline/gadolinium post-injection scans were performed at 15 min intervals for 2 h. Joints were inspected and the articular cartilage graded subjectively for cartilage damage (0–3). The presence of detectable or non-detectable cartilage damage on MR images was identified, characterized and recorded in consensus by three observers. Sensitivity, specificity and accuracy in detection of cartilage damage related to gross pathology were calculated.

Results: The two clinical cases from the pilot study with confirmed osteoarthritis had full thickness cartilage defects; however, only one of these was correctly identified using low-field MRI. In the prospective study, the majority of naturally occurring cartilage damage could not be identified on plain MR or MR arthrography including extensive partial thickness cartilage erosions. Saline and gadolinium MR arthrography did not improve the detection of cartilage damage. The accuracy of cartilage damage detection was 0.63 with a sensitivity of 0.14 and specificity of 0.92.

Clinical Relevance: Both, plain low-field MRI and MR arthrography are not sensitive in detection of naturally occurring cartilage damage of the DIP joint. However, if an abnormal contour is seen in the articular cartilage, cartilage damage is likely to be present.

Contrast enhanced magnetic resonance imaging of the foot in horses using intravenous versus regional intraarterial injection of gadolinium

The use of contrast enhanced magnetic resonance imaging (MRI) for the detection of orthopedic pathologies in equine patients is poorly described. In few studies, enhanced MRI allowed to differentiate active lesions from chronic ones and to classify ambiguous lesions. The aim of this clinical prospective pilot study is to describe and compare the MRI lesions observed in horses with lameness localized to the foot using a single intravenous bolus dose of gadolinium contrast versus regional intraarterial bolus of contrast agent. Ten horses that underwent contrast enhanced MRI were included in the study. Gadolinium was injected intravenously in 3 patients and in 7 horses contrast agent was administered by intraarterial regional delivery. Regions of interest (ROI) were collected from both pre- and post-contrast images and ratios between pre- and post-contrast ROIs were calculated. No adverse reactions were noted after contrast agent injection. Injured structures that revealed greater increase in signal in post-contrast images were the deep digital flexor tendon (DDFT), the navicular spongiosa and the peritendinous tissues. Regional intraarterial administration of gadolinium provided higher ratio of contrast enhancement. Enhanced MRI using both intravenous or intraarterial injection of gadolinium, increased the diagnostic capability of MRI in horses with foot lesions. Nevertheless, regional intraarterial administration of gadolinium was considered the best choice due to the higher signal and lower volumes of contrast agent required.

Comparison of the efficacy and characteristics of metallic foreign body extraction by incision surgery and x-ray guided forceps after body-surface projection positioning: A STROBE-compliant article

A foreign body retained in soft tissue may give rise to infection and dysfunction, which may pose a potential threat to patient health. Our study is to compare the efficacy and characteristics of metallic foreign body (MFB) extraction from soft tissue by incision surgery and x-ray-guided forceps after body surface projection positioning.This study enrolled 775 patients who underwent percutaneous MFB extraction between January 2011 and December 2016. A total of 257 cases underwent extraction by incision surgery and 518 cases underwent x-ray-guided forceps extraction after body surface projection positioning.All patients were diagnosed by x-ray and the diagnostic accuracy rate was 100%. In the incision surgery group, MFB extraction was successful in 193 of 257 cases. All cases in the forceps extraction group were successful, and the success rate was significantly higher than that of the incision surgery group (100% vs.75.1%, P < .01). Sixty-four patients in the incision surgery group who failed treatment were subsequently treated with x-ray-guided forceps extraction and all MFBs were extracted. The symptoms in all patients were relieved, wound healing was good, and there were no major bleeding, incision infection, or other complications.Compared with incision surgery, x-ray-guided foreign body forceps extraction after body surface projection positioning is a less invasive, safer, and more effective treatment for MFB extraction.

Biomarkers for equine joint injury and osteoarthritis

We report the results of a symposium aimed at identifying validated biomarkers that can be used to complement clinical observations for diagnosis and prognosis of joint injury leading to equine osteoarthritis (OA). Biomarkers might also predict pre-fracture change that could lead to catastrophic bone failure in equine athletes. The workshop was attended by leading scientists in the fields of equine and human musculoskeletal biomarkers to enable cross-disciplinary exchange and improve knowledge in both. Detailed proceedings with strategic planning was written, added to, edited and referenced to develop this manuscript. The most recent information from work in equine and human osteoarthritic biomarkers was accumulated, including the use of personalized healthcare to stratify OA phenotypes, transcriptome analysis of anterior cruciate ligament (ACL) and meniscal injuries in the human knee. The spectrum of "wet" biomarker assays that are antibody based that have achieved usefulness in both humans and horses, imaging biomarkers and the role they can play in equine and human OA was discussed. Prediction of musculoskeletal injury in the horse remains a challenge, and the potential usefulness of spectroscopy, metabolomics, proteomics, and development of biobanks to classify biomarkers in different stages of equine and human OA were reviewed. The participants concluded that new information and studies in equine musculoskeletal biomarkers have potential translational value for humans and vice versa. OA is equally important in humans and horses, and the welfare issues associated with catastrophic musculoskeletal injury in horses add further emphasis to the need for good validated biomarkers in the horse. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:823-831, 2018.

Study on the Correlation between Barium Radiography and Pulmonary Infection rate in the Evaluation of Swallowing Function

OBJECTIVES

To compare the results respectively obtained from the utilization of 60% barium sulfate suspension and Iohexol as contrast agents for videofluoroscopic swallowing studies and the relationship between the clinical application of the two kinds of contrast agents and the incidence of pneumonia.

METHODS

Sixty cases of stroke patients with dysphagia were selected in rehabilitation department of our hospital, and the gender, age, position of the disease, and stroke nature between groups had no significant difference. Among which, 30 patients who were administered 350 mgI/ml Iohexol, and the other 30 patients with 60% barium sulfate suspension as contrast agent. We performed videofluoroscopic swallowing studies with barium 60% versus Iohexol within 1 week after admission and 2 weeks after admission.

RESULTS

After 2 weeks in hospital, the aspiration pneumonia incidence of two groups was statistically significant (p<0.05), the pneumonia incidence of Iohexol group was lower than barium sulfate group which might have a impossble relevance with barium aspiration.

CONCLUSIONS

During the videofluoroscopic swallowing study of dysphagia after stroke, barium sulfate can enhance the pneumonia incidence, and Iohexol can be widely applied in videofluoroscopic swallowing study.