Kelp Forest Food Webs as Hot Spots for the Accumulation of Microplastic and Polybrominated Diphenyl Ether Pollutants.

Kelp forests (KFs) are one of the most significant marine ecosystems in the planet. They serve as a refuge for a wide variety of marine species of ecological and economic importance. Additionally, they aid with carbon sequestration, safeguard the coastline, and maintain water quality. Microplastic (MP) and polybrominated diphenyl ethers (PBDEs) concentrations were analyzed across trophic levels in KFs around Todos Santos Bay. Spatial variation patterns were compared at three sites in 2021 and temporal change at Todos Santos Island (TSI) in 2021 and 2022. We analyzed these MPs and PBDEs in water, primary producers (Macrocystis pyrifera), grazers (Strongylocentrotus purpuratus), predators (Semicossyphus pulcher), and kelp detritus. MPs were identified in all samples (11 synthetic and 1 semisynthetic polymer) and confirmed using Fourier-transform infrared microspectroscopy-attenuated total reflectance (µ-FTIR-ATR). The most abundant type of MP is polyester fibers. Statistically significant variations in MP concentration were found only in kelps, with the greatest average concentrations in medium-depth kelps from TSI in 2022 (0.73 ± 0.58 MPs g-1 ww) and in the kelp detritus from TSI in 2021 (0.96 ± 0.64 MPs g-1 ww). Similarly, PBDEs were found in all samples, with the largest concentration found in sea urchins from Punta San Miguel (0.93 ± 0.24 ng g-1 ww). The similarity of the polymers can indicate a trophic transfer of MPs. This study shows the extensive presence of MP and PBDE subtropical trophic web of a KF, but correlating these compounds in environmental samples is highly complex, influenced by numerous factors that could affect their presence and behavior. However, this suggests that there is a potential risk to the systems and the services that KFs offer.

Short-term effects of community-based marine reserves on green abalone, as revealed by population studies.

Marine reserves (MRs) are implemented worldwide to protect, restore, and manage marine ecosystems and species. However, it is important to document the positive effects those marine reserves have on slow-growth, temperate invertebrates such as abalone. Abalone, Haliotis spp., are marine gastropods of high economic value extracted worldwide for decades, which has led to fisheries-driven population decreases. In this work, we focused on a case study and assessed the short-term (1-2 years) effects of marine reserves established and managed by a local fishing cooperative at Guadalupe Island, Mexico. We evaluated the population status of green abalone, H. fulgens, by conducting (1) an assessment of the green abalone population around Guadalupe Island through subtidal monitoring and (2) an evaluation of the effect of two recently established marine reserves on population parameters such as the increase in density (individuals·m2), biomass, number of aggregated abalone, egg production, and proportion of individuals bigger than 150 mm (minimum harvest size) compared to fished areas. To assess the population around Guadalupe Island, we surveyed 11,160 m2 during 2020 and 2021. We recorded 2327 green abalones with a mean ± SE shell length of 135.978 ± 0.83 mm and a mean density of 0.21 ± 0.02 individuals·m2. All variables were statistically higher at the MRs except for shell length in 2021. In this work, we report for the first time the green abalone population status at Guadalupe Island and a positive short-term biological response to community-based marine reserves. This study suggests that a network of MRs combined with good management could help abalone populations in the short term in Guadalupe Island, potentially leading to more sustainable fishing practices and social-ecological resilience.

MRI features of benign peripheral nerve sheath tumors: how do sporadic and syndromic tumors differ?

OBJECTIVES: To compare MRI features of sporadic and neurofibromatosis syndrome-related localized schwannomas and neurofibromas. METHODS: In this retrospective study, our pathology database was searched for "neurofibroma" or "schwannoma" from 2014 to 2019. Exclusion criteria were lack of available MRI and intradural or plexiform tumors. Qualitative and quantitative anatomic (location, size, relationship to nerve, signal, muscle denervation) and functional (arterial enhancement, apparent diffusion-weighted coefficient) MRI features of sporadic and syndrome-related tumors were compared. Statistical significance was assumed for p < 0.05. RESULTS: A total of 80 patients with 64 schwannomas (sporadic: 42 (65.6%) v. syndrome-related: 22 (34.4%)) and 19 neurofibromas (sporadic: 7 (36.8%) v. syndrome-related: 12 (41.7%)) were included. Only signal heterogeneity (T2W p=0.001, post-contrast p=0.03) and a diffused-weighted imaging target sign (p=0.04) were more frequent with schwannomas than neurofibromas. Sporadic schwannomas were similar in size to syndrome-related schwannomas (2.9±1.2cm vs. 3.7±3.2 cm, p = 0.6), but with greater heterogeneity (T2W p = 0.02, post-contrast p = 0.01). Sporadic neurofibromas were larger (4.6±1.5cm vs. 3.4±2.4 cm, p = 0.03) than syndrome-related neurofibromas, also with greater heterogeneity (T2W p=0.03, post-contrast p=0.04). Additional tumors along an affected nerve were only observed with syndrome-related tumors). There was no difference in apparent diffusion coefficient values or presence of early perfusion between sporadic and syndrome-related tumors (p > 0.05). CONCLUSIONS: Although syndrome-related and sporadic schwannomas and neurofibromas overlap in their anatomic, diffusion and perfusion features, signal heterogeneity and presence of multiple lesions along a nerve are differentiating characteristics of syndrome-related tumors.

Axial T1-weighted imaging of the lumbar spine: a redundancy or an asset?

OBJECTIVE: To determine the diagnostic value of axial T1-weighted imaging for patients suffering from lower back pain. MATERIALS AND METHODS: In this retrospective study, 100 consecutive lumbar spine MRIs obtained in patients with chronic low back pain were reviewed in two sessions: First, readers viewed core sequences (sagittal T1-weighted, STIR and T2-weighted, and axial T2-weighted) with axial T1-weighted sequences, and second, readers viewed cores sequences alone. Readers recorded the presence of disc degeneration, nerve root compromise, facet joint arthritis, and stenosis at each lumbar spine level as well as the presence of lipoma of filum terminale (LFT), spondylolisthesis, transitional vertebrae, and fractures. The McNemar, Wilcoxon signed-rank, and student T tests were utilized. RESULTS: For 100 studies, 5 spine levels were evaluated (L1-L2 through L5-S1). There were cases of disc disease (444/500 bulges, 56/500 herniations), nerve root compromise (1/500 nerve enlargement, 36/500 contact only, 20/500 displacement or compression), facet arthritis (438/500), stenosis (58/500 central canal, 64/500 lateral recess, 137/500 neuroforaminal), 6/100 LFTs, and other abnormalities (58/500 spondylolisthesis, 10/100 transitional vertebrae, 10/500 fracture/spondylolysis). There was no difference in diagnostic performance between the interpretation sessions (with and without axial T1-weighted imaging) at any level (p > 0.05), although four small additional LFTs were identified with axial T1-weighted imaging availability. CONCLUSION: There was no clinically significant difference in the interpretation of lumbar spine MRI viewed with and without axial T1-weighted imaging, suggesting that the axial T1-weighted sequence does not add diagnostic value to routine lumbar spine MRI.

MR imaging of thoracic annular fissures.

OBJECTIVE: Annular fissures are common findings on MR studies of the lumbar spine but have not been specifically examined in the thoracic spine. We sought to review the prevalence and stability of MRI imaging features of thoracic annular fissures and the association of thoracic AFs with intervertebral degenerative disk changes. MATERIALS AND METHODS: We surveyed 10 years of MRI studies in which patients had one or more repeated examinations of the thoracic spine. For every annular fissure, we recorded its imaging features on all pulse sequences and the evolution of those imaging findings across all time periods. RESULTS: We reviewed 210 patients and discovered that 66 (31.4%) had at least one thoracic annular fissure. The presence of annular fissures was positively correlated with older age and male gender. The initial annular fissure was always hyperintense on T2WI and annular fissures remained hyperintense on T2WI over time in all cases but showed less hyperintensity in 23.9% (n = 39/163) and more hyperintensity in 4.9% (n = 8/163). The rate of concomitant disk bulges was 85.8% (n = 140/163). Of the 71 annular fissures in which gadolinium-enhanced studies were performed, 20 (28.1%) showed enhancement and 14/20 (70%) annular fissures showed persistent enhancement over time (mean follow-up = 39.6 ± 44.1 months). CONCLUSION: Thoracic annular fissures rarely resolve, remain hyperintense on T2WI, and, if they enhance, that enhancement generally persists.

Longitudinal assessment of annular fissures of the cervical spine: overlooked and static.

Background: Cervical annular fissures (AFs) have not been studied specifically as to their prevalence, imaging features, and persistence over time. We sought to determine the prevalence and natural history of cervical AFs. We hypothesized that these are static lesions that are not prevalent in the population. Methods: This was a cross-sectional retrospective study of cervical MRI examinations performed between 2011-2021. We retrospectively reviewed the studies of 115 consecutive patients (63 female, 52 male) who had 2 or more MRI studies of the cervical spine to identify (1) imaging features of cervical AFs on various pulse sequences, (2) the concurrence of disc bulges/herniations, (3) changes in those imaging findings over time (mean follow-up 39.3 months) and (4) rate at which cervical AFs were mentioned in radiology reports. 620 initial and follow-up studies were reviewed. Results: 50/115 (43.5%) patients had cervical AFs; 21 patients had a single AF and 29 patients had multi-level AFs (total 109 AFs). The most common levels affected were C4-C5 (28%, n = 31) and C5-C6 (27%, n = 30). All cervical AFs were hyperintense on T2WI and, over time, 95% (n = 104/109) of the AFs remained hyperintense; 22% (n = 25) showed less hyperintensity, 10% (n = 11) more hyperintensity, and 60% (n = 66) the same hyperintensity. 5 AFs (4%) resolved completely. Only 2 (8%) of 25 cervical AFs enhanced with gadolinium. The rate of concomitant disc bulges and herniations was 71% (n = 78) and 22% (n = 24) respectively. The presence of cervical AFs did not increase the risk of progression to bulges or herniations. None of the cervical AFs were mentioned in the radiology reports. Conclusions: Cervical AFs occurred in 43.5% of patients but were rarely reported. They usually remained bright on T2W but their brightness could vary over time. Cervical AFs were often associated with disc bulges/herniations and enhanced less frequently (8%) than lumbar disk AFs.

The value of ecosystem services in global marine kelp forests.

While marine kelp forests have provided valuable ecosystem services for millennia, the global ecological and economic value of those services is largely unresolved. Kelp forests are diminishing in many regions worldwide, and efforts to manage these ecosystems are hindered without accurate estimates of the value of the services that kelp forests provide to human societies. Here, we present a global estimate of the ecological and economic potential of three key ecosystem services - fisheries production, nutrient cycling, and carbon removal provided by six major forest forming kelp genera (Ecklonia, Laminaria, Lessonia, Macrocystis, Nereocystis, and Saccharina). Each of these genera creates a potential value of between $64,400 and $147,100/hectare each year. Collectively, they generate between $465 and $562 billion/year worldwide, with an average of $500 billion. These values are primarily driven by fisheries production (mean $29,900, 904 Kg/Ha/year) and nitrogen removal ($73,800, 657 Kg N/Ha/year), though kelp forests are also estimated to sequester 4.91 megatons of carbon from the atmosphere/year highlighting their potential as blue carbon systems for climate change mitigation. These findings highlight the ecological and economic value of kelp forests to society and will facilitate better informed marine management and conservation decisions.

Complete response to alectinib in ALK-fusion metastatic salivary ductal carcinoma.

The advent of next-generation sequencing (NGS) has allowed for the identification of novel therapeutic targets for patients with uncommon cancers. It is well known that fusion translocations are potent driver of cancer pathogenesis and can render tumors exquisitely sensitive to matching targeted therapies. Here we describe a patient with ALK-fusion positive widely metastatic salivary ductal carcinoma, who achieved a durable complete response from alectinib, a potent and specific ALK tyrosine kinase inhibitor. This case serves as another reminder that ALK-fusions can be targeted regardless of histology and can afford patients dramatic and durable benefit. It also emphasizes the need for insurance coverage for such beneficial therapies. While ALK fusions are exceedingly rare in salivary ductal carcinoma, the presence of multiple other targetable aberrations supports the recommendation for universal NGS testing for such tumors.

Shading by giant kelp canopy can restrict the invasiveness of Undaria pinnatifida (Laminariales, Phaeophyceae).

The spread of non-indigenous and invasive seaweeds has increased worldwide, and their potential effects on native seaweeds have raised concern. Undaria pinnatifida is considered among the most prolific non-indigenous species. This species has expanded rapidly in the Northeast Pacific, overlapping with native communities such as the iconic giant kelp forests (Macrocystis pyrifera). Canopy shading by giant kelp has been argued to be a limiting factor for the presence of U. pinnatifida in the understory, thus its invasiveness capacity. However, its physiological plasticity under light limitation remains unclear. In this work, we compared the physiology and growth of juvenile U. pinnatifida and M. pyrifera sporophytes transplanted to the understory of a giant kelp forest, to juveniles growing outside of the forest. Extreme low light availability compared to that outside (~0.2 and ~4.4 mol photon ⋅ m-2 ⋅ d-1 , respectively) likely caused a "metabolic energy crisis" in U. pinnatifida, thus restricting its photoacclimation plasticity and nitrogen acquisition, ultimately reducing its growth. Despite M. pyrifera juveniles showing photoacclimatory responses (e.g., increases in photosynthetic efficiency and lower compensation irradiance, Ec ), their physiological/vegetative status deteriorated similarly to U. pinnatifida, which explains the low recruitment inside the forest. Generally, our results revealed the ecophysiological basis behind the limited growth and survival of juvenile U. pinnatifida sporophytes in the understory.

A Decade of Death and Other Dynamics: Deepening Perspectives on the Diversity and Distribution of Sea Stars and Wasting.

AbstractMass mortality events provide valuable insight into biological extremes and also ecological interactions more generally. The sea star wasting epidemic that began in 2013 catalyzed study of the microbiome, genetics, population dynamics, and community ecology of several high-profile species inhabiting the northeastern Pacific but exposed a dearth of information on the diversity, distributions, and impacts of sea star wasting for many lesser-known sea stars and a need for integration across scales. Here, we combine datasets from single-site to coast-wide studies, across time lines from weeks to decades, for 65 species. We evaluated the impacts of abiotic characteristics hypothetically associated with sea star wasting (sea surface temperature, pelagic primary productivity, upwelling wind forcing, wave exposure, freshwater runoff) and species characteristics (depth distribution, developmental mode, diet, habitat, reproductive period). We find that the 2010s sea star wasting outbreak clearly affected a little over a dozen species, primarily intertidal and shallow subtidal taxa, causing instantaneous wasting prevalence rates of 5%-80%. Despite the collapse of some populations within weeks, environmental and species variation protracted the outbreak, which lasted 2-3 years from onset until declining to chronic background rates of ∼2% sea star wasting prevalence. Recruitment began immediately in many species, and in general, sea star assemblages trended toward recovery; however, recovery was heterogeneous, and a marine heatwave in 2019 raised concerns of a second decline. The abiotic stressors most associated with the 2010s sea star wasting outbreak were elevated sea surface temperature and low wave exposure, as well as freshwater discharge in the north. However, detailed data speaking directly to the biological, ecological, and environmental cause(s) and consequences of the sea star wasting outbreak remain limited in scope, unavoidably retrospective, and perhaps always indeterminate. Redressing this shortfall for the future will require a broad spectrum of monitoring studies not less than the taxonomically broad cross-scale framework we have modeled in this synthesis.

Approach to the intoxicated pediatric patient in the emergency services / Abordaje del paciente pediátrico intoxicado en urgencias

Las intoxicaciones en la población pediátrica son una gran parte de las causas de atención en los servicios de urgencias, pero así mismo representan en muchos casos eventos fatídicos, en nuestro país. La exposición a un tóxico o veneno y sus efectos adversos se pueden convertir en emergencias médicas de gran magnitud, por lo que muchos autores las consideran como: "Trauma múltiple de origen químico". Es por esto que el manejo de un paciente pediátrico intoxicado tiene un enfoque único debido al desafío diagnóstico que representa. La atención oportuna y sistematizada de un paciente pediátrico en el contexto de una intoxicación puede representar el éxito de la atención oportuna, valoración correcta y de un adecuado proceso de atención. El objetivo de este trabajo es presentar un enfoque general para el paciente pediátrico intoxicado en cuanto al manejo inicial, el abordaje, y los datos clínicos que nos puedan orientar en el servicio de urgencias ante un paciente pediátrico intoxicado.

Intoxications in the pediatric population account for a significant portion of the causes of care in emergency services, but they are also fatal in many cases in our country. Exposure to a toxic or poison and its adverse effects can become medical emergencies of great magnitude, which is why many authors consider them "multiple traumas of chemical origin." This is why the management of an intoxicated pediatric patient has a unique approach due to the diagnostic challenge that it represents. Timely and systematized care of a pediatric patient in the context of poisoning can represent the success of timely care, correct assessment, and an adequate care process. The objective of this work is to present a general approach for the intoxicated pediatric patient regarding the initial management, the approach, and the clinical data that can guide us in the emergency department when faced with an intoxicated pediatric patient.

Imaging in Musculoskeletal Oncology: Special Considerations in the Elderly.

A variety of imaging modalities are used to assess oncologic disorders in the elderly. The composition of bone marrow (BM) and its radiologic manifestation changes physiologically or pathologically while aging. The most important contributing factors include normal aging, oncology-related treatments, and osteoporosis. For accurate image interpretation, a radiologist should take into account these alterations. For evaluating BM and soft tissue abnormalities, MRI is an optimal precise noninvasive imaging modality. The challenges of imaging the elderly patient with the oncologic disease will be discussed in this chapter, focusing on the frequent use of MRI in assessing the bone marrow, bone tumors, and soft-tissue masses.

MRI evaluation of soft tissue tumors: comparison of a fast, isotropic, 3D T2-weighted fat-saturated sequence with a conventional 2D T2-weighted fat-saturated sequence for tumor characteristics, resolution, and acquisition time.

OBJECTIVES: To test whether a 4-fold accelerated 3D T2-weighted (T2) CAIPIRINHA SPACE TSE sequence with isotropic voxel size is equivalent to conventional 2DT2 TSE for the evaluation of intrinsic and perilesional soft tissue tumors (STT) characteristics. METHODS: For 108 patients with histologically-proven STTs, MRI, including 3DT2 (CAIPIRINHA SPACE TSE) and 2DT2 (TSE) sequences, was performed. Two radiologists evaluated each sequence for quality (diagnostic, non-diagnostic), tumor characteristics (heterogeneity, signal intensity, margin), and the presence or absence of cortical involvement, marrow edema, and perilesional edema (PLE); tumor size and PLE extent were measured. Signal-to-noise (SNR) and contrast-to-noise (CNR) ratios and acquisition times for 2DT2 in two planes and 3DT2 sequences were reported. Descriptive statistics and inter-method agreement were reported. RESULTS: Image quality was diagnostic for all sequences (100% [108/108]). No difference was observed between 3DT2 and 2DT2 tumor characteristics (p < 0.05). There was no difference in mean tumor size (3DT2: 2.9 ± 2.5 cm, 2DT2: 2.8 ± 2.6 cm, p = 0.4) or PLE extent (3DT2:0.5 ± 1.2 cm, 2DT2:0.5 ± 1.0 cm, p = 0.9) between the sequences. There was no difference in the SNR of tumors, marrow, and fat between the sequences, whereas the SNR of muscle was higher (p < 0.05) on 3DT2 than 2DT2. CNR measures on 3DT2 were similar to 2DT2 (p > 0.1). The average acquisition time was shorter for 3DT2 compared with 2DT2 (343 ± 127 s vs 475 ± 162 s, respectively). CONCLUSION: Isotropic 3DT2 MRI offers higher spatial resolution, faster acquisition times, and equivalent assessments of STT characteristics compared to conventional 2DT2 MRI in two planes. 3DT2 is interchangeable with a 2DT2 sequence in tumor protocols. KEY POINTS: • Isotropic 3DT2 CAIPIRINHA SPACE TSE offers higher spatial resolution than 2DT2 TSE and is equivalent to 2DT2 TSE for assessments of soft tissue tumor intrinsic and perilesional characteristics. • Multiplanar reformats of 3DT2 CAIPIRINHA SPACE TSE can substitute for 2DT2 TSE acquired in multiple planes, thereby reducing the acquisition time of MRI tumor protocols. • 3DT2 CAIPIRINHA SPACE TSE and 2DT2 TSE had similar CNR of tissues.

Open vs Minimally Invasive Scarf Osteotomy for Hallux Valgus Correction: A Randomized Controlled Trial.

BACKGROUND: Minimally invasive (MI) surgery is becoming increasingly popular in the treatment of hallux valgus (HV). The scarf osteotomy is an effective procedure with a track record in open HV surgery. We adapted this effective osteotomy to MI surgery as a novel technique never reported before. The aim of this study was to compare the clinical and radiologic outcomes of patients who underwent open or MI scarf. METHODS: Between 2017 and 2018, 58 patients were randomized to either open or MI scarf to treat HV deformity. Prospective patient-reported outcome measures and weightbearing radiographs were obtained. Data included the AOFAS score, radiologic angular correction, operative time, fluoroscopy radiation dose, and postoperative pain on visual analog scale (VAS). RESULTS: The mean follow-up was of 21 (range, 12-38) months. Radiologic measurements (postoperative hallux valgus angle, first-to-second intermetatarsal angle, and distal metaphyseal articular angle) were similar in both groups and showed statistically significant improvement from preoperative measures. The mean operative time for the MI group was 16.7 vs 26.1 minutes in the open group, a statistically significant difference. Radiation exposure was 14 times higher in the MI group when compared to the open group (mean: 34 vs 2.4 mGy/cm2, P < .001). There were no major complications in either group. CONCLUSIONS: The MI scarf provides a clinically and radiologically equivalent outcome to open scarf for the treatment of HV with reduced operative time and immediate postoperative VAS for pain but is associated with a small increase in radiation exposure. LEVEL OF EVIDENCE: Level I, randomized controlled trial.

Five-Minute Five-Sequence Knee MRI Using Combined Simultaneous Multislice and Parallel Imaging Acceleration: Comparison with 10-Minute Parallel Imaging Knee MRI.

Background Rapid knee MRI using combined simultaneous multislice (SMS) technique and parallel imaging (PI) acceleration can add value through reduced acquisition time but requires validation of clinical efficacy. Purpose To evaluate the performance of clinical fourfold SMS-PI-accelerated, 5-minute, five-sequence, multicontrast knee MRI protocols compared with standard twofold PI-accelerated, 10-minute knee MRI protocols. Materials and Methods Adults with painful knee conditions were prospectively enrolled from April 2018 to October 2019. Participants underwent fourfold SMS-PI-accelerated, 5-minute, turbo spin-echo (TSE) knee MRI and standard-of-care twofold PI-accelerated, 10-minute, TSE knee MRI at either 1.5 T or 3.0 T. Three radiologists independently evaluated the knee MRI studies for meniscal, tendinous, ligamentous, and osseocartilaginous injuries. Statistical analyses included k-based intermethod agreements and diagnostic performance testing. P < .05 was considered indicative of a statistically significant difference. Results A total of 252 adults were evaluated (mean age ± standard deviation, 47 years ± 17; 134 men). Among the participants, 104 (mean age, 42 years ± 18; 57 women) were in the 1.5-T arm and 148 (mean age, 46 years ± 17; 87 men) were in the 3.0-T arm. Twenty-nine participants (mean age, 38 years ± 12; 15 men) in the 1.5-T arm and 42 (mean age, 41 years ± 16; 24 men) in the 3.0-T arm underwent arthroscopy a mean of 45 days ± 31 and 45 days ± 22 after MRI, respectively. Intermethod agreements were good at 1.5 T (κ >0.71 [95% CI: 0.56, 0.83]) and very good at 3.0 T (κ >0.85 [95% CI: 0.69, 0.96]). The diagnostic performances of corresponding 5-minute and 10-minute MRI protocols were similar for 1.5 T, with areas under the receiver operating characteristic curve (AUCs) greater than 0.78 (95% CI: 0.71, 0.84) (P > .32), and 3.0 T, with AUCs greater than 0.83 (95% CI: 0.78, 0.88) (P > .32). Conclusion Comparisons of 5-minute five-sequence simultaneous multislice- and parallel imaging (PI)-accelerated and 10-minute five-sequence PI-accelerated turbo spin-echo MRI of the knee suggest similar performances at 1.5 and 3.0 T. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Subhas in this issue.

Forecasting ocean acidification impacts on kelp forest ecosystems.

Ocean acidification is one the biggest threats to marine ecosystems worldwide, but its ecosystem wide responses are still poorly understood. This study integrates field and experimental data into a mass balance food web model of a temperate coastal ecosystem to determine the impacts of specific OA forcing mechanisms as well as how they interact with one another. Specifically, we forced a food web model of a kelp forest ecosystem near its southern distribution limit in the California large marine ecosystem to a 0.5 pH drop over the course of 50 years. This study utilizes a modeling approach to determine the impacts of specific OA forcing mechanisms as well as how they interact. Isolating OA impacts on growth (Production), mortality (Other Mortality), and predation interactions (Vulnerability) or combining all three mechanisms together leads to a variety of ecosystem responses, with some taxa increasing in abundance and other decreasing. Results suggest that carbonate mineralizing groups such as coralline algae, abalone, snails, and lobsters display the largest decreases in biomass while macroalgae, urchins, and some larger fish species display the largest increases. Low trophic level groups such as giant kelp and brown algae increase in biomass by 16% and 71%, respectively. Due to the diverse way in which OA stress manifests at both individual and population levels, ecosystem-level effects can vary and display nonlinear patterns. Combined OA forcing leads to initial increases in ecosystem and commercial biomasses followed by a decrease in commercial biomass below initial values over time, while ecosystem biomass remains high. Both biodiversity and average trophic level decrease over time. These projections indicate that the kelp forest community would maintain high productivity with a 0.5 drop in pH, but with a substantially different community structure characterized by lower biodiversity and relatively greater dominance by lower trophic level organisms.

Imaging of non-neurogenic peripheral nerve malignancy-a case series and systematic review.

OBJECTIVE: To evaluate the frequency, clinico-pathologic and imaging features of malignant tumors in peripheral nerves which are of non-neurogenic origin (non-neurogenic peripheral nerve malignancy-PNM). MATERIALS AND METHODS: We retrospectively reviewed our pathology database for malignant peripheral nerve tumors from 07/2014-07/2019 and performed a systematic review. Exclusion criteria were malignant peripheral nerve sheath tumor (MPNST). Clinico-pathologic and imaging features, apparent diffusion coefficient (ADCmin), and standard uptake values (SUVmax) are reported. RESULTS: After exclusion of all neurogenic tumors (benign = 196, MPNST = 57), our search yielded 19 non-neurogenic PNMs (7%, n = 19/272), due to primary intraneural malignancy (16%, n = 3/19) and secondary perineural invasion from an adjacent malignancy (16%, n = 3/19) or metastatic disease (63%, n = 12/19). Non-neurogenic PNMs were located in the lumbosacral plexus/sciatic nerves (47%, n = 9/19), brachial plexus (32%, n = 6/19), femoral nerve (5%, n = 1/19), tibial nerve (5%, n = 1/19), ulnar nerve (5%, n = 1/19), and radial nerve (5%, n = 1/19). On MRI (n = 14/19), non-neurogenic PNM tended to be small (< 5 cm, n = 10/14), isointense to muscle on T1-W (n = 14/14), hyperintense on T2-WI (n = 12/14), with enhancement (n = 12/12), low ADCmin (0.5-0.7 × 10-3 mm2/s), and variable metabolic activity (SUVmax range 2.1-13.1). A target sign was absent (n = 14/14) and fascicular sign was rarely present (n = 3/14). Systematic review revealed 89 cases of non-neurogenic PNM. CONCLUSION: Non-neurogenic PNMs account for 7% of PNT in our series and occur due to metastases and primary intraneural malignancy. Although non-neurogenic PNMs exhibit a non-specific MRI appearance, they lack typical signs of neurogenic tumors such as the target sign. Quantitative imaging features identified by DWI (low ADC) and F18-FDG PET/CT (high SUV) may be helpful clues to the diagnosis.

Determination of skeletal tumor extent: is an isotropic T1-weighted 3D sequence adequate?

OBJECTIVES: To test the hypothesis that an accelerated, T1-weighted 3D CAIPIRINHA SPACE sequence with isotropic voxel size offers a similar performance to conventional T1-weighted 2D TSE (turbo spin echo) for the evaluation of bone tumor extent and characteristics. METHODS: Thirty-four patients who underwent 3-T MRI with 3DT1 (CAIPIRINHA SPACE TSE) and 2DT1 (TSE) were included. Sequence acquisition time was reported. Two radiologists independently evaluated each technique for tumor location, size/length, tumor-to-joint distance, signal intensity, margin/extraosseous extension, and signal-to-noise (SNR) and contrast-to-noise (CNR) ratios. RESULTS: Tumors were located in long (20/36, 55.5%) and pelvic (16/36, 44.4%) bones. 3DT1 sequence required an average acquisition time of 235 s (± 42 s, range 156-372), while two plane 2DT1 sequences combined (coronal and axial) had an average acquisition time of 381 s (± 73 s, range 312-523). There was no difference in the measurements of tumor length and tumor-to-joint distance (p = 0.95) between 3DT1 and 2DT1 images. Tumors were hypointense (17/36, 47.2% vs 17/36, 47.2%), isointense (12/36, 33.3% vs 12/36, 33.3%), or hyperintense (7/36, 19.4% vs 7/36, 19.4%) on 3DT1 vs 2DT1, respectively. Assessment of tumor margins and extraosseous extension was similar, and there was no difference in tumor SNR or CNR (p > 0.05). CONCLUSIONS: An accelerated 3D CAIPIRINHA SPACE T1 sequence provides comparable assessments of intramedullary bone tumor extent and similar tumor characteristics to conventional 2DT1 MRI. For the assessment of bone tumors, the isotropic volume acquisition and multiplanar reformation capability of the 3DT1 datasets can obviate the need for 2DT1 acquisitions in multiple planes. KEY POINTS: • 3DT1 offers an equivalent performance to 2DT1 for the assessment of bone tumor characteristics, with faster and higher resolution capability, obviating the need for acquiring 2DT1 in multiple planes. • There was no difference in the measurements of tumor length and tumor-to-joint distance obtained on 3DT1 and 2DT1 images. • There was no difference in signal-to-noise ratio (SNR) or contrast-to-noise ratio (CNR) measures between 3DT1 and 2DT1.

A Deep Learning System for Synthetic Knee Magnetic Resonance Imaging: Is Artificial Intelligence-Based Fat-Suppressed Imaging Feasible?

MATERIALS AND METHODS: This single-center study was approved by the institutional review board. Artificial intelligence-based FS MRI scans were created from non-FS images using a deep learning system with a modified convolutional neural network-based U-Net that used a training set of 25,920 images and validation set of 16,416 images. Three musculoskeletal radiologists reviewed 88 knee MR studies in 2 sessions, the original (proton density [PD] + FSPD) and the synthetic (PD + AFSMRI). Readers recorded AFSMRI quality (diagnostic/nondiagnostic) and the presence or absence of meniscal, ligament, and tendon tears; cartilage defects; and bone marrow abnormalities. Contrast-to-noise rate measurements were made among subcutaneous fat, fluid, bone marrow, cartilage, and muscle. The original MRI sequences were used as the reference standard to determine the diagnostic performance of AFSMRI (combined with the original PD sequence). This is a fully balanced study design, where all readers read all images the same number of times, which allowed the determination of the interchangeability of the original and synthetic protocols. Descriptive statistics, intermethod agreement, interobserver concordance, and interchangeability tests were applied. A P value less than 0.01 was considered statistically significant for the likelihood ratio testing, and P value less than 0.05 for all other statistical analyses. RESULTS: Artificial intelligence-based FS MRI quality was rated as diagnostic (98.9% [87/88] to 100% [88/88], all readers). Diagnostic performance (sensitivity/specificity) of the synthetic protocol was high, for tears of the menisci (91% [71/78], 86% [84/98]), cruciate ligaments (92% [12/13], 98% [160/163]), collateral ligaments (80% [16/20], 100% [156/156]), and tendons (90% [9/10], 100% [166/166]). For cartilage defects and bone marrow abnormalities, the synthetic protocol offered an overall sensitivity/specificity of 77% (170/221)/93% (287/307) and 76% (95/125)/90% (443/491), respectively. Intermethod agreement ranged from moderate to substantial for almost all evaluated structures (menisci, cruciate ligaments, collateral ligaments, and bone marrow abnormalities). No significant difference was observed between methods for all structural abnormalities by all readers (P > 0.05), except for cartilage assessment. Interobserver agreement ranged from moderate to substantial for almost all evaluated structures. Original and synthetic protocols were interchangeable for the diagnosis of all evaluated structures. There was no significant difference for the common exact match proportions for all combinations (P > 0.01). The conspicuity of all tissues assessed through contrast-to-noise rate was higher on AFSMRI than on original FSPD images (P < 0.05). CONCLUSIONS: Artificial intelligence-based FS MRI (3D AFSMRI) is feasible and offers a method for fast imaging, with similar detection rates for structural abnormalities of the knee, compared with original 3D MR sequences.