Clinical application of ultrashort echo time (UTE) and zero echo time (ZTE) magnetic resonance (MR) imaging in the evaluation of osteoarthritis.

Novel compositional magnetic resonance (MR) imaging techniques have allowed for both the qualitative and quantitative assessments of tissue changes in osteoarthritis, many of which are difficult to characterize on conventional MR imaging. Ultrashort echo time (UTE) and zero echo time (ZTE) MR imaging have not been broadly implemented clinically but have several applications that leverage contrast mechanisms for morphologic evaluation of bone and soft tissue, as well as biochemical assessment in various stages of osteoarthritis progression. Many of the musculoskeletal tissues implicated in the initiation and progression of osteoarthritis are short T2 in nature, appearing dark as signal has already decayed to its minimum when image sampling starts. UTE and ZTE MR imaging allow for the qualitative and quantitative assessments of these short T2 tissues (bone, tendon, calcified cartilage, meniscus, and ligament) with both structural and functional reference standards described in the literature [1-3]. This review will describe applications of UTE and ZTE MR imaging in musculoskeletal tissues focusing on its role in knee osteoarthritis. While the review will address tissue-specific applications of these sequences, it is understood that osteoarthritis is a whole joint process with involvement and interdependence of all tissues. KEY POINTS: • UTE MR imaging allows for the qualitative and quantitative evaluation of short T2 tissues (bone, calcified cartilage, and meniscus), enabling identification of both early degenerative changes and subclinical injuries that may predispose to osteoarthritis. • ZTE MR imaging allows for the detection of signal from bone, which has some of the shortest T2 values, and generates tissue contrast similar to CT, potentially obviating the need for CT in the assessment of osseous features of osteoarthritis.

Magnetic resonance imaging appearance of breaststroker's knee.

Breaststroker's knee is an overuse syndrome resulting from similar repetitive movements in competitive swimmers that has been described in the orthopedic literature. The typical symptoms are medial knee pain with tenderness to palpation at the tibial collateral ligament or inferomedial patella. Despite these localizing symptoms on clinical exam, arthroscopic studies have failed to demonstrate a specific structural abnormality corresponding to this syndrome, although some have reported thickened medial synovial plica, medial-predominant synovitis or patellofemoral cartilage loss in association knee pain with breaststroke swimmers. We present a case of medial knee pain in a young breaststroke swimmer with magnetic resonance imaging (MRI) findings of marrow edema in the anterior aspect of the medial femoral condyle. To our knowledge, this is the first reported case of MRI findings in breaststroker's knee .

Osteochondritis dissecans of the talar dome in patients with tarsal coalition.

OBJECTIVE: Tarsal coalition is known to cause abnormal talocrural stress, hindfoot malalignment, and ankle sprains. These can all be associated with osteochondritis dissecans (OCD) of the talar dome. We present the first detailed description of a series of talar OCDs occurring in patients with tarsal coalition, with the goal of determining whether there is an increased prevalence of OCDs among patients with tarsal coalition. MATERIALS AND METHODS: We studied ankle MRIs in 57 patients with tarsal coalitions, excluding those with a reported inciting traumatic event. The MRIs were performed on magnetic field strengths ranging from 0.3 to 1.5 T and included axial, coronal, and sagittal T1 and T2 or PD fat-suppressed sequences. We evaluated the morphology and location of classically described OCDs in these patients, type and location of concomitant tarsal coalition, and, when available, the presence of pes planus and hindfoot valgus on weight-bearing radiographs. Chi-squared analysis was used to compare categorical variables and a Student's t test was used for parametric continuous variables. Additionally, logistic regression was used to compute the odds ratio of talar OCD associated with patient age, gender, laterality, pes planus status, hindfoot valgus status, and coalition type. RESULTS: Eighty-nine percent of tarsal coalitions were non-osseous coalitions and the calcaneonavicular space was the most common site of abnormal tarsal connection (54.4%). In the 29 patients with tarsal coalitions and talar OCDs, OCDs commonly occurred medially (75.9%). In the sagittal plane, talar OCDs occurred centrally, with only one case sparing the central talar dome. The mean surface area of the 29 OCDs was 89.7 mm2. Both osseous coalition and hindfoot valgus were associated with smaller talar OCD mean surface area (p = 0.015 and p = 0.0001, respectively). There was no association between depth and surface area of talar OCD with either coalition location or presence of pes planus (coalition location: p = 0.455 for depth and p = 0.295 for surface area; presence of pes planus: p = 0.593 for depth and p = 0.367 for surface area). CONCLUSION: Talar OCD prevalence is higher in patients with tarsal coalition than that reported for the general population. This occurrence may relate to altered biomechanics and repetitive talocrural stress owing to altered subtalar motion, particularly given the findings of increased odds of talar OCD in older patients, as well as weak associations between OCD surface area and both non-osseous coalition and hindfoot alignment. However, we did not find any specific OCD morphologic features attributable to the precise location of the tarsal coalition.

Odour boosts visual object approach in flies.

Multisensory integration is synergistic-input from one sensory modality might modulate the behavioural response to another. Work in flies has shown that a small visual object presented in the periphery elicits innate aversive steering responses in flight, likely representing an approaching threat. Object aversion is switched to approach when paired with a plume of food odour. The 'open-loop' design of prior work facilitated the observation of changing valence. How does odour influence visual object responses when an animal has naturally active control over its visual experience? In this study, we use closed-loop feedback conditions, in which a fly's steering effort is coupled to the angular velocity of the visual stimulus, to confirm that flies steer toward or 'fixate' a long vertical stripe on the visual midline. They tend either to steer away from or 'antifixate' a small object or to disengage active visual control, which manifests as uncontrolled object 'spinning' within this experimental paradigm. Adding a plume of apple cider vinegar decreases the probability of both antifixation and spinning, while increasing the probability of frontal fixation for objects of any size, including a normally typically aversive small object.

Neuromodulation of insect motion vision.

Insects use vision to choose from a repertoire of flexible behaviors which they perform for survival. Decisions for behavioral plasticity are achieved through the neuromodulation of sensory processes, including motion vision. Here, we briefly review the anatomy of the insect motion vision system. Next, we review the neuromodulatory influences on motion vision. Serotonin modulates peripheral visual processing, whereas octopamine modulates all stages of visual processing tested to date. The physiological and behavioral states that elicit neuromodulation of motion vision include locomotion, changes in internal physiological state such as hunger, and changes in the external environment such as the presence of additional sensory cues. The direction of influence between these states and neuromodulators remains unknown. The influence of neuromodulators on motion vision circuitry has been revealed mostly through pharmacological application, which broadcasts widely with unnatural spatiotemporal dynamics. Thus, insight from this method is limited. Aminergic neurons likely act in local hierarchical fashion rather than globally as a group. As genetic tools advance in Drosophila, future work restricting the experimental focus to subpopulations of modulatory neurons will provide insight into the local functional modifications of visual circuits by interacting neuromodulators.

Quantitative assessments reveal improved neuroscience engagement and learning through outreach.

Lack of resources and exposure to neuroscience in K-12 education has resulted in a limited number of K-12 students pursuing higher education in the field. Meanwhile, the rapid expansion of the field of neuroscience has encouraged many higher educational institutes to offer neuroscience majors. This has opened up the opportunity to engage faculty, as well as graduate and undergraduate students in bringing the most needed knowledge and awareness about neuroscience into K-12 classrooms. However, undergraduate neuroscience curricula have limited formal opportunities to engage in outreach, and few existing programs have assessments to determine their effectiveness. To address these needs, we developed quantitative assessment tools that complement an existing neuroscience outreach program-Project Brainstorm-at the University of California, Los Angeles (UCLA). 29 UCLA undergraduates enrolled in the 2016 and 2017 programs participated in this study, along with 298 K-12 students from local schools across the Los Angeles area. In undergraduate students, we assessed (a) improvement in students' teaching/communication abilities across the course of the outreach program, and (b) confidence in explaining neuroscience topics and interest in pursuing teaching career. In K-12 students, we evaluated (a) knowledge gain in neuroscience topics and (b) interest in pursuing higher education. Overall, Project Brainstorm showed significant improvement in all the above-mentioned categories. The assessment tools and data presented here provide a data-driven approach for optimizing neuroscience outreach programs and can easily be adapted to other outreach programs within neuroscience and in other STEM fields.

Visuomotor strategies for object approach and aversion in Drosophila melanogaster.

Animals classify stimuli to generate appropriate motor actions. In flight, Drosophila melanogaster classify equidistant large and small objects with categorically different behaviors: a tall object evokes approach whereas a small object elicits avoidance. We studied visuomotor behavior in rigidly and magnetically tethered D. melanogaster to reveal strategies that generate aversion to a small object. We discovered that small-object aversion in tethered flight is enabled by aversive saccades and smooth movement, which vary with the stimulus type. Aversive saccades in response to a short bar had different dynamics from approach saccades in response to a tall bar and the distribution of pre-saccade error angles was more stochastic for a short bar. Taken together, we show that aversive responses in D. melanogaster are driven in part by processes that elicit signed saccades with distinct dynamics and trigger mechanisms. Our work generates new hypotheses to study brain circuits that underlie classification of objects in D. melanogaster.

Evaluation and Treatment of Entrapped Peripheral Nerve Catheters: A Case Report and Review.

Methods to remove retained peripheral nerve catheters range from non-invasive techniques to open surgical procedures. This study reviews two cases requiring surgical intervention for catheter remnant removal after catheter breakage and presents a systematic review describing the diagnosis and treatment of retained perineural catheters. While still very rare, our case report and systematic review demonstrate that retained nerve catheters can occur as the result of kinking or knotting, but also from catheter breakage. We recommend risk mitigation strategies for providers placing or caring for patients with regional nerve catheters.

The Buford Complex Redefined: A Pathologic Morphology in Sheep's Clothing.

Background: Considered a normal anatomic variant, the Buford complex has not been studied in children. Hypothesis: A Buford complex is not a normal anatomic variant and would, therefore, be present at a lower rate than that seen in the adult population. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Measurements were recorded from magnetic resonance imaging performed over 13 years in children aged ≤11 years for various pathologies unrelated to glenohumeral instability. Interrater reliability was determined to identify Buford complexes, sublabral foramens and tears, and normal shoulders via 16 preadolescent and adolescent patients with confirmed arthroscopic correlation. The Buford complex and labral foramen rates were then compared with a published rate in adults using a binomial probability test. Results: A total of 122 children (62 girls; mean age, 6.4 years [age range, 2 months-10.9 years]) were evaluated. Interrater reliability was 0.846 (95% CI, 0.56-1) to identify anterosuperior labral variants. The expected sublabral foramen count was 23 children, but only 1 was identified (P < .001). The expected Buford complex count was 8 children, but none could be identified (P < .001). Conclusion: The absence of Buford complexes and the significant reduction in sublabral foramen abundance in younger children suggest that these anatomic variants are more likely to be developmental than congenital. The distinct possibility that these previously considered normal variants are truly pathologic findings cannot be ignored. Evidence of a Buford complex could potentially signify an underlying, long-term shoulder instability issue to the treating provider that warrants further investigation or management.

High-Field MRI Advantages and Applications in Rheumatology.

Imaging of rheumatologic diseases has historically been performed using conventional radiography. MRI offers an opportunity for detection of altered marrow signal in early disease that is not visible on other imaging modalities such as radiography, computed tomography, or sonography. This review describes the advantages of current MRI techniques in the diagnosis and treatment monitoring of rheumatologic diseases. In addition, this review discusses novel MRI techniques at high-field magnetic strength which may be deployed in the future to allow for improved imaging resolution and quantitative assessment of both axial and peripheral joints.

Global change in brain state during spontaneous and forced walk in Drosophila is composed of combined activity patterns of different neuron classes.

Movement-correlated brain activity has been found across species and brain regions. Here, we used fast whole brain lightfield imaging in adult Drosophila to investigate the relationship between walk and brain-wide neuronal activity. We observed a global change in activity that tightly correlated with spontaneous bouts of walk. While imaging specific sets of excitatory, inhibitory, and neuromodulatory neurons highlighted their joint contribution, spatial heterogeneity in walk- and turning-induced activity allowed parsing unique responses from subregions and sometimes individual candidate neurons. For example, previously uncharacterized serotonergic neurons were inhibited during walk. While activity onset in some areas preceded walk onset exclusively in spontaneously walking animals, spontaneous and forced walk elicited similar activity in most brain regions. These data suggest a major contribution of walk and walk-related sensory or proprioceptive information to global activity of all major neuronal classes.

The Association of Metabolic Syndrome and Obesity With Clinical Hip Osteoarthritis in the Study of Osteoporotic Fractures and the Osteoporotic Fractures in Men Study Cohorts.

OBJECTIVE: Metabolic dysregulation frequently co-occurs with obesity, which has been shown to be a risk factor for lower extremity osteoarthritis (OA). We evaluated the association between metabolic syndrome (MetS), alone and in combination with obesity, and hip OA. METHODS: In two parallel cross-sectional analyses, we studied 403 women from the Study of Osteoporotic Fractures (SOF) and 2354 men from the Osteoporotic Fractures in Men (MrOS) study. We used multivariable logistic regression to evaluate associations of obesity (body mass index ≥30 kg/m2 ) and/or MetS (three of five National Cholesterol Education Program Adult Treatment Panel III criteria) with clinical hip OA, defined as a modified Croft score of 2 or more or total hip replacement, and pain or limited range of motion. Our analysis adjusted for demographics. RESULTS: Approximately 3.5% of SOF women and 5.4% of MrOS men had clinical hip OA. Among women, obesity was not associated with hip OA, yet those with MetS had a 365% higher odds of hip OA (95% CI: 1.37-15.83). Among men, those who had obesity had a 115% higher odds of hip OA (95% CI: 1.39-3.32), yet MetS was not associated with hip OA. There was no interaction between MetS, obesity, and hip OA in either women or men. CONCLUSION: In women, but not in men, MetS was associated with hip OA. In men, but not in women, obesity was associated with hip OA. These findings suggest that mechanical effects of obesity may predominate in the pathogenesis of hip OA in men, whereas metabolic effects predominate in women.

Knee Cartilage Imaging.

Articular cartilage injury and degeneration represent common causes of knee pain, which can be evaluated accurately and noninvasively using MRI. This review describes the structure of cartilage focusing on its histologic appearance to emphasize that structure will dictate patterns of tissue failure as well as MR appearance. In addition to identifying cartilage loss, MRI can demonstrate signal changes that correspond to intrinsic structural abnormalities which place the cartilage at risk for subsequent more serious injury or premature degeneration, allowing for earlier intervention and treatment of important causes of pain and morbidity.

Metabolic Syndrome Is Associated With Higher Risk of Wound Complications After Total Hip Arthroplasty.

BACKGROUND: Obesity is prevalent among patients undergoing total hip arthroplasty and has been associated with the risk of wound complications, particularly when an anterior approach is used. However, most studies have focused on obesity defined by the body mass index (BMI), without considering the metabolic effects of adiposity. Thus, in this study, we investigated the independent effects of the BMI and metabolic syndrome on wound complications after total hip arthroplasty. METHODS: Among 804 consecutive patients undergoing total hip arthroplasty between October 2013 and July 2016, we evaluated the associations between obesity (BMI ≥30 mg/kg2), metabolic syndrome (defined by the National Cholesterol Education Program Adult Treatment Panel III guidelines), and wound complication (defined as documented wound dehiscence, drainage, erythema, hematoma, infection, or seroma) over a 1-year follow-up period. We used Cox proportional hazards models adjusting for demographics, smoking status, and hospital length of stay. RESULTS: Patients' mean age at time of surgery was 62.0 ± 11.9 years. Forty-seven percent were male, 27.9% were obese, and 11.6% met the definition for metabolic syndrome. Metabolic syndrome was associated with a 4-fold higher risk of wound complication (95% confidence interval: 1.4-11.1) after adjusting for all covariates including the BMI. In unadjusted analysis, obesity was associated with a higher risk of wound complication (hazard ratio: 2.8, 95% confidence interval: 1.3-6.2). However, obesity was not associated with the risk of wound complication after adjusting for the metabolic syndrome (P = .16). CONCLUSIONS: Metabolic syndrome, but not obesity, defined by a BMI ≥30, was associated with wound complications, suggesting that metabolic effects of adiposity may represent a distinct risk factor in the development of wound complications from a higher BMI alone.

Olfactory and Neuromodulatory Signals Reverse Visual Object Avoidance to Approach in Drosophila.

Behavioral reactions of animals to environmental sensory stimuli are sometimes reflexive and stereotyped but can also vary depending on contextual conditions. Engaging in active foraging or flight provokes a reversal in the valence of carbon dioxide responses from aversion to approach in Drosophila [1, 2], whereas mosquitoes encountering this same chemical cue show enhanced approach toward a small visual object [3]. Sensory plasticity in insects has been broadly attributed to the action of biogenic amines, which modulate behaviors such as olfactory learning, aggression, feeding, and egg laying [4-14]. Octopamine acts rapidly upon the onset of flight to modulate the response gain of directionally selective motion-detecting neurons in Drosophila [15]. How the action of biogenic amines might couple sensory modalities to each other or to locomotive states remains poorly understood. Here, we use a visual flight simulator [16] equipped for odor delivery [17] to confirm that flies avoid a small contrasting visual object in odorless air [18] but that the same animals reverse their preference to approach in the presence of attractive food odor. An aversive odor does not reverse object aversion. Optogenetic activation of either octopaminergic neurons or directionally selective motion-detecting neurons that express octopamine receptors elicits visual valence reversal in the absence of odor. Our results suggest a parsimonious model in which odor-activated octopamine release excites the motion detection pathway to increase the saliency of either a small object or a bar, eliciting tracking responses by both visual features.

Calcium hydroxyapatite deposition disease: Imaging features and presentations mimicking other pathologies.

OBJECTIVE: Calcium hydroxyapatite depositional disease (HADD) is usually asymptomatic and self-limiting; however, when there is an associated inflammatory process or HADD occurs in an unusual location, it may mimic trauma, infection, or neoplasm. The purpose of this article is to review the imaging features of HADD and how to distinguish it from more worrisome entities that can have similar appearances. CONCLUSION: An understanding of the presentations of HADD is important to allow early and confident diagnosis. In particular, familiarity with presentations that resemble more ominous pathologies is essential to avoid costly and time-consuming workup or intervention.