Outdoor air pollution and cancer: An overview of the current evidence and public health recommendations.

Outdoor air pollution is a major contributor to the burden of disease worldwide. Most of the global population resides in places where air pollution levels, because of emissions from industry, power generation, transportation, and domestic burning, considerably exceed the World Health Organization's health-based air-quality guidelines. Outdoor air pollution poses an urgent worldwide public health challenge because it is ubiquitous and has numerous serious adverse human health effects, including cancer. Currently, there is substantial evidence from studies of humans and experimental animals as well as mechanistic evidence to support a causal link between outdoor (ambient) air pollution, and especially particulate matter (PM) in outdoor air, with lung cancer incidence and mortality. It is estimated that hundreds of thousands of lung cancer deaths annually worldwide are attributable to PM air pollution. Epidemiological evidence on outdoor air pollution and the risk of other types of cancer, such as bladder cancer or breast cancer, is more limited. Outdoor air pollution may also be associated with poorer cancer survival, although further research is needed. This report presents an overview of outdoor air pollutants, sources, and global levels, as well as a description of epidemiological evidence linking outdoor air pollution with cancer incidence and mortality. Biological mechanisms of air pollution-derived carcinogenesis are also described. This report concludes by summarizing public health/policy recommendations, including multilevel interventions aimed at individual, community, and regional scales. Specific roles for medical and health care communities with regard to prevention and advocacy and recommendations for further research are also described.

Prospective study of e-cigarette use and respiratory symptoms in adolescents and young adults.

RATIONALE: Electronic cigarette (e-cigarette) aerosol contains volatile aldehydes, including flavourings and oxidant metals with known pulmonary toxicity. OBJECTIVES: To evaluate the associations of e-cigarette use with symptoms of wheeze, bronchitic symptoms and shortness of breath (SOB) across 4 years of prospective data. METHODS: Participants completed questionnaires on respiratory symptoms and past 30-day e-cigarette, cigarette and cannabis use in 2014 (wave 1; N=2094; mean age 17.3 years, SD=0.6 years). Follow-up information was collected in 2015 (wave 2; n=1609), 2017 (wave 3; n=1502) and 2018 (wave 4; n=1637) using online surveys. Mixed-effects logistic regression models evaluated associations of e-cigarette use with respiratory symptoms. MEASUREMENTS AND MAIN RESULTS: Participants were mostly Hispanic white (51.8%) and evenly representative by sex (49.6% female; 50.4% male). Compared with never e-cigarette users, past 30-day e-cigarette users reported increased odds of wheeze (OR 1.81; 95% CI 1.28, 2.56), bronchitic symptoms (OR 2.06; 95% CI 1.58, 2.69) and SOB (OR 1.78; 95% CI 1.23, 2.57), adjusting for study wave, age, sex, race, lifetime asthma diagnosis and parental education. Effect estimates were attenuated (wheeze (OR 1.41; 95% CI 0.99, 2.01), bronchitic symptoms (OR 1.55; 95% CI 1.18, 2.05), SOB (OR 1.48; 95% CI 1.01, 2.18)), after adjusting additionally for current cigarette use, cannabis use and secondhand exposure to e-cigarettes/cigarettes/cannabis. CONCLUSIONS: E-cigarette use in young adults was associated with respiratory symptoms, independent of combustible cannabis and cigarette exposures.

MSKI-RADS: An MRI-based Musculoskeletal Infection Reporting and Data System for the Diagnosis of Extremity Infections.

Background Current terms used to describe the MRI findings for musculoskeletal infections are nonspecific and inconsistent. Purpose To develop and validate an MRI-based musculoskeletal infection classification and scoring system. Materials and Methods In this retrospective cross-sectional internal validation study, a Musculoskeletal Infection Reporting and Data System (MSKI-RADS) was designed. Adult patients with radiographs and MRI scans of suspected extremity infections with a known reference standard obtained between June 2015 and May 2019 were included. The scoring categories were as follows: 0, incomplete imaging; I, negative for infection; II, superficial soft-tissue infection; III, deeper soft-tissue infection; IV, possible osteomyelitis (OM); V, highly suggestive of OM and/or septic arthritis; VI, known OM; and NOS (not otherwise specified), nonspecific bone lesions. Interreader agreement for 20 radiologists from 13 institutions (intraclass correlation coefficient [ICC]) and true-positive rates of MSKI-RADS were calculated and the accuracy of final diagnoses rendered by the readers was compared using generalized estimating equations for clustered data. Results Among paired radiographs and MRI scans from 208 patients (133 male, 75 female; mean age, 55 years ± 13 [SD]), 20 were category I; 34, II; 35, III; 30, IV; 35, V; 18, VI; and 36, NOS. Moderate interreader agreement was observed among the 20 readers (ICC, 0.70; 95% CI: 0.66, 0.75). There was no evidence of correlation between reader experience and overall accuracy (P = .94). The highest true-positive rate was for MSKI-RADS I and NOS at 88.7% (95% CI: 84.6, 91.7). The true-positive rate was 73% (95% CI: 63, 80) for MSKI-RADS V. Overall reader accuracy using MSKI-RADS across all patients was 65% ± 5, higher than final reader diagnoses at 55% ± 7 (P < .001). Conclusion MSKI-RADS is a valid system for standardized terminology and recommended management of imaging findings of peripheral extremity infections across various musculoskeletal-fellowship-trained reader experience levels. © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Schweitzer in this issue.

Enhancing Methodological Approaches for Studying Health Effects of High-Concentration THC Products.

For public health protection, informed decision-making relies on having a robust foundation of evidence concerning risks and their prevention. Application of an evidence-based framework depends on the availability of pertinent, scientifically sound data generated by well-directed and valid research endeavors. In this essay, we address the current state of research in humans and the evidential base concerning high-concentration delta-9-tetrahydrocannabinol (delta-9-THC) products, which are readily available in the United States. Furthermore, we explore the intricate challenges faced in carrying out research on these products, which reflect the full range of study design issues: measurement of exposure and outcomes, confounding, selection bias, and the generalizability of findings. We offer recommendations to guide future research toward providing more informative evidence. By following these recommendations, researchers and funders on this emerging topic could move toward generating the valid and comprehensive evidence needed to effectively inform public health initiatives and guide policy decisions regarding high-concentration delta-9-THC products and their use. The urgency of generating such evidence cannot be overstated, given the widespread legalization and increasing availability and use of these products. (Am J Public Health. 2024;114(S8):S639-S644. https://doi.org/10.2105/AJPH.2024.307724).

Assessing Adverse Health Effects of Long-Term Exposure to Low Levels of Ambient Air Pollution: The HEI Experience and What's Next?

Although concentrations of ambient air pollution continue to decline in high-income regions, epidemiological studies document adverse health effects at levels below current standards in many countries. The Health Effects Institute (HEI) recently completed a comprehensive research initiative to investigate the health effects of long-term exposure to low levels of air pollution in the United States (U.S.), Canada, and Europe. We provide an overview and synthesis of the results of this initiative along with other key research, the strengths and limitations of the research, and remaining research needs. The three studies funded through the HEI initiative estimated the effects of long-term ambient exposure to fine particulate matter (PM2.5), nitrogen dioxide, ozone, and other pollutants on a broad range of health outcomes, including cause-specific mortality and cardiovascular and respiratory morbidity. To ensure high quality research and comparability across studies, HEI worked actively with the study teams and engaged independent expert panels for project oversight and review. All three studies documented positive associations between mortality and exposure to PM2.5 below the U.S. National Ambient Air Quality Standards and current and proposed European Union limit values. Furthermore, the studies observed nonthreshold linear (U.S.), or supra-linear (Canada and Europe) exposure-response functions for PM2.5 and mortality. Heterogeneity was found in both the magnitude and shape of this association within and across studies. Strengths of the studies included the large populations (7-69 million), state-of-the-art exposure assessment methods, and thorough statistical analyses that applied novel methods. Future work is needed to better understand potential sources of heterogeneity in the findings across studies and regions. Other areas of future work include the changing and evolving nature of PM components and sources, including wildfires, and the role of indoor environments. This research initiative provided important new evidence of the adverse effects of long-term exposures to low levels of air pollution at and below current standards, suggesting that further reductions could yield larger benefits than previously anticipated.

Tobacco Constituents, Flavorants, and Paper Permeability of Factory-Made and Roll-Your-Own Cigarettes on the Australian Market.

INTRODUCTION: Roll-your-own (RYO) tobacco is a popular choice in Australia, with some people who smoke finding these products more attractive than factory-made cigarettes (FMC). Differences in visual and tactile properties and in the feel and taste of the smoke may contribute to this attractiveness. These differences may be driven by variation in tobacco constituents and wrapping paper permeability. However, to date, there has been no comparison of RYO and FMC products on the Australian market. AIMS AND METHODS: Chemical constituents, pH, flavorants, and paper permeability were compared in unburned RYO tobacco and tobacco from FMC. RYO and FMC products from matched brands were compared, as were products from the most popular FMC and RYO brands on the Australian market in 2018. RESULTS: RYO tobacco had higher moisture and humectant content (glycerol and propylene glycol) than FMC tobacco. RYO tobacco also had higher amounts of total and reducing sugars and lower nicotine when comparing the most popular brands. RYO papers were less permeable than FMC papers. Both RYO and FMC tobacco contained many chemicals identified as flavorants, including fourteen with known potential health risks. For most measured constituents and flavorants, RYO tobaccos had more in common with other RYO than FMC, with the commonalities remaining even when matched brands were compared. CONCLUSIONS: Higher levels of moisture, humectants, and sugars in Australian RYO tobacco compared to FMC may be increasing attractiveness of RYO by reducing the harsh taste of the smoke and increasing the moist feel of the tobacco. IMPLICATIONS: While price is the main factor driving the use of RYO tobacco, some people who smoke find these products more attractive. This study has shown that Australian RYO tobacco contains higher amounts of glycerol, propylene glycol, and sugars than FMC. These chemicals may be improving the taste of the tobacco, as well as creating a moist feel that is falsely perceived as indicating that the tobacco is "fresh" and "less chemically." Ironically, it may be that higher amounts of some added chemicals in RYO contribute to false perceptions of a more natural and less harmful product.

Health Effects of High-Concentration Cannabis Products: Scoping Review and Evidence Map.

Background. The concentration of pharmacologically active tetrahydrocannabinol (THC) in cannabis products has been increasing over the past decade. Concerns about potential harmful health effects of using these increasingly higher-concentration products have led some states to consider regulation of cannabis product THC concentration. We conducted a scoping review of health effects of high-concentration cannabis products to inform policy on whether the THC concentrations of cannabis product should be regulated or limited. Objectives. We conducted a scoping review to (1) identify and describe human studies that explore the relationship of high-concentration cannabis products with any health outcomes in the literature and (2) create an interactive evidence map of the included studies to facilitate further analyses. Search Methods. An experienced medical information specialist designed a comprehensive search strategy of 7 electronic databases. Selection Criteria. We included human studies of any epidemiological design with no restrictions by age, sex, health status, country, or outcome measured that reported THC concentration or included a known high-concentration cannabis product. Data Collection and Analysis. We imported search results into Distiller SR, and trained coders conducted artificial intelligence‒assisted screening. We developed, piloted, and revised data abstraction forms. One person performed data abstraction, and a senior reviewer verified a subset. We provide a tabular description of study characteristics, including exposures and outcomes measured, for each included study. We interrogated the evidence map published in Tableau to answer specific questions and provide the results as text and visual displays. Main Results. We included 452 studies in the scoping review and evidence map. There was incomplete reporting of exposure characteristics including THC concentration, duration and frequency of use, and products used. The evidence map shows considerable heterogeneity among studies in exposures, outcomes, and populations studied. A limited number of reports provided data that would facilitate further quantitative synthesis of the results across studies. Conclusions. This scoping review and evidence map support strong conclusions concerning the utility of the literature for characterizing risks and benefits of the current cannabis marketplace and the research approaches followed in the studies identified. Relevance of the studies to today's products is limited. Public Health Implications. High-quality evidence to address the policy question of whether the THC concentration of cannabis products should be regulated is scarce. The publicly available interactive evidence map is a timely resource for other entities concerned with burgeoning access to high-concentration cannabis. (Am J Public Health. 2023;113(12):1332-1342. https://doi.org/10.2105/AJPH.2023.307414).

Radon and lung cancer in the pooled uranium miners analysis (PUMA): highly exposed early miners and all miners.

OBJECTIVES: Radon is a ubiquitous occupational and environmental lung carcinogen. We aim to quantify the association between radon progeny and lung cancer mortality in the largest and most up-to-date pooled study of uranium miners. METHODS: The pooled uranium miners analysis combines 7 cohorts of male uranium miners with 7754 lung cancer deaths and 4.3 million person-years of follow-up. Vital status and lung cancer deaths were ascertained between 1946 and 2014. The association between cumulative radon exposure in working level months (WLM) and lung cancer was modelled as the excess relative rate (ERR) per 100 WLM using Poisson regression; variation in the association by temporal and exposure factors was examined. We also examined analyses restricted to miners first hired before 1960 and with <100 WLM cumulative exposure. RESULTS: In a model that allows for variation by attained age, time since exposure and annual exposure rate, the ERR/100 WLM was 4.68 (95% CI 2.88 to 6.96) among miners who were less than 55 years of age and were exposed in the prior 5 to <15 years at annual exposure rates of <0.5 WL. This association decreased with older attained age, longer time since exposure and higher annual exposure rate. In analyses restricted to men first hired before 1960, we observed similar patterns of association but a slightly lower estimate of the ERR/100 WLM. CONCLUSIONS: This new large, pooled study confirms and supports a linear exposure-response relationship between cumulative radon exposure and lung cancer mortality which is jointly modified by temporal and exposure factors.

Solidarity for the Anthropocene.

Social solidarity is essential to large-scale collective action, but the need for solidarity has received little attention from scholars of Earth Systems, sustainability and public health. Now, the need for solidarity requires recognition. We have entered a new planetary epoch - the Anthropocene - in which human-induced global changes are occurring at an unprecedented scale. There are multiple health crises facing humanity - widening inequity, climate change, biodiversity loss, diminishing resources, persistent poverty, armed conflict, large-scale migration, and others. These global challenges are so far-reaching, and call for such extensive, large-scale action, that solidarity is a sine qua non for tackling these challenges. However, the heightened need for solidarity has received little attention in the context of the Anthropocene and, in particular, how it can be created and nurtured has been overlooked. In this commentary, we explore the concept of solidarity from inter-species, intra-generational and inter-generational perspectives. We also propose strategies to enhance solidarity in the Anthropocene.

Traffic-related Air Pollution and Lung Cancer Incidence: The California Multiethnic Cohort Study.

Rationale: Although the contribution of air pollution to lung cancer risk is well characterized, few studies have been conducted in racially, ethnically, and socioeconomically diverse populations. Objectives: To examine the association between traffic-related air pollution and risk of lung cancer in a racially, ethnically, and socioeconomically diverse cohort. Methods: Among 97,288 California participants of the Multiethnic Cohort Study, we used Cox proportional hazards regression to examine associations between time-varying traffic-related air pollutants (gaseous and particulate matter pollutants and regional benzene) and lung cancer risk (n = 2,796 cases; average follow-up = 17 yr), adjusting for demographics, lifetime smoking, occupation, neighborhood socioeconomic status (nSES), and lifestyle factors. Subgroup analyses were conducted for race, ethnicity, nSES, and other factors. Measurements and Main Results: Among all participants, lung cancer risk was positively associated with nitrogen oxide (hazard ratio [HR], 1.15 per 50 ppb; 95% confidence interval [CI], 0.99-1.33), nitrogen dioxide (HR, 1.12 per 20 ppb; 95% CI, 0.95-1.32), fine particulate matter with aerodynamic diameter <2.5 µm (HR, 1.20 per 10 µg/m3; 95% CI, 1.01-1.43), carbon monoxide (HR, 1.29 per 1,000 ppb; 95% CI, 0.99-1.67), and regional benzene (HR, 1.17 per 1 ppb; 95% CI, 1.02-1.34) exposures. These patterns of associations were driven by associations among African American and Latino American groups. There was no formal evidence for heterogeneity of effects by nSES (P heterogeneity > 0.21), although participants residing in low-SES neighborhoods had increased lung cancer risk associated with nitrogen oxides, and no association was observed among those in high-SES neighborhoods. Conclusions: These findings in a large multiethnic population reflect an association between lung cancer and the mixture of traffic-related air pollution and not a particular individual pollutant. They are consistent with the adverse effects of air pollution that have been described in less racially, ethnically, and socioeconomically diverse populations. Our results also suggest an increased risk of lung cancer among those residing in low-SES neighborhoods.

Ultrasound of peripheral nerve injury.

Nerve injury in children is important to recognize early given the greater chance for recovery. Both children and adults have better outcomes the sooner nerve injuries are recognized and repaired. Children have even better functional results after surgical repair, thought to be related to their neural plasticity. Ultrasound is a powerful diagnostic tool for grading and mapping peripheral nerve injury and is complementary to electromyography and nerve conduction studies. Nerve injuries can be classified into low and high grade with ultrasound adding essential prognostic information and aiding in patient management. High-grade nerve injuries likely require surgical intervention. This article will review nerve anatomy and injury grading systems that radiologists can learn quickly in order to accurately communicate with their clinical partners. A practical approach to describe the sonographic appearance of nerve injury will be discussed. This article will show radiologists how the added value of ultrasound for peripheral nerve injury can directly affect clinical management.

Commentary: Role and communications of cancer hazard determinations.

This commentary is written in response to a recent commentary in Carcinogenesis that provides several viewpoints on the International Agency for Research on Cancer's (IARC) Monographs program on cancer hazard identification. This commentary offers an alternative viewpoint of the role of cancer hazard identification derived from cancer epidemiology studies in risk characterization, as well as clarification on the previous commentary's interpretation of the purpose of the Monographs and other programs of cancer hazard identification and how IARC communicates the findings of the Monographs.

Musculoskeletal Manifestations of COVID-19: Currently Described Clinical Symptoms and Multimodality Imaging Findings.

COVID-19, the clinical syndrome produced by infection with SARS-CoV-2, can result in multisystem organ dysfunction, including respiratory failure and hypercoagulability, which can lead to critical illness and death. Musculoskeletal (MSK) manifestations of COVID-19 are common but have been relatively underreported, possibly because of the severity of manifestations in other organ systems. Additionally, patients who have undergone sedation and who are critically ill are often unable to alert clinicians of their MSK symptoms. Furthermore, some therapeutic measures such as medications and vaccinations can worsen existing MSK symptoms or cause additional symptoms. Symptoms may persist or occur months after the initial infection, known as post-COVID condition or long COVID. As the global experience with COVID-19 and the vaccination effort increases, certain patterns of MSK disease involving the bones, muscles, peripheral nerves, blood vessels, and joints have emerged, many of which are likely related to a hyperinflammatory host response, prothrombotic state, or therapeutic efforts rather than direct viral toxicity. Imaging findings for various COVID-19-related MSK pathologic conditions across a variety of modalities are being recognized, which can be helpful for diagnosis, treatment guidance, and follow-up. The online slide presentation from the RSNA Annual Meeting is available for this article. ©RSNA, 2022.

Airborne Transmission of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2): What We Know.

We examine airborne transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) potential using a source-to-dose framework beginning with generation of virus-containing droplets and aerosols and ending with virus deposition in the respiratory tract of susceptible individuals. By addressing 4 critical questions, we identify both gaps in addressing 4 critical questions with answers having policy implications.

Estimating the Impact of Statewide Policies to Reduce Spread of Severe Acute Respiratory Syndrome Coronavirus 2 in Real Time, Colorado, USA.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic necessitated rapid local public health response, but studies examining the impact of social distancing policies on SARS-CoV-2 transmission have struggled to capture regional-level dynamics. We developed a susceptible-exposed-infected-recovered transmission model, parameterized to Colorado, USA‒specific data, to estimate the impact of coronavirus disease‒related policy measures on mobility and SARS-CoV-2 transmission in real time. During March‒June 2020, we estimated unknown parameter values and generated scenario-based projections of future clinical care needs. Early coronavirus disease policy measures, including a stay-at-home order, were accompanied by substantial decreases in mobility and reduced the effective reproductive number well below 1. When some restrictions were eased in late April, mobility increased to near baseline levels, but transmission remained low (effective reproductive number <1) through early June. Over time, our model parameters were adjusted to more closely reflect reality in Colorado, leading to modest changes in estimates of intervention effects and more conservative long-term projections.

Australian smokers' experiences and perceptions of recessed and firm filter cigarettes.

BACKGROUND: While cigarette filter modifications have long been used to increase product appeal and assuage health concerns, tighter marketing restrictions, including plain packaging, have further spurred the growth of filter variants. We explored and assessed experiences and perceptions of smokers who had tried and/or currently use recessed filter cigarettes (RFCs) and firm filter cigarettes (FFCs). METHOD: In November 2018, we undertook eight exploratory focus groups of Australian adult factory-made cigarette smokers (total n=56). In July 2019, we surveyed 999 smokers aged 18-69 years to quantify ever and current use of these products and associated beliefs and sensory experiences. RESULTS: Focus group and survey findings were consistent. Among 988 smokers who had at least tried factory-made cigarettes, 28.9% had tried FFCs and 11.1% currently smoked these, while 36.4% had tried RFCs and 7.5% currently smoked these. Smokers in both studies believed these filters may reduce harm and that FFCs increase appeal. In the survey, 58.9% of RFC triers agreed these hide the filter's brown stain and 48.9% agreed that RFCs keep harmful substances away from the mouth. Similarly, 58.4% of FFC triers agreed these trap more harmful substances than standard filters. Relative to standard filter cigarettes, more smokers experienced FFCs and RFCs as feeling clean (p=0.03) and more current FFC users experienced these as feeling smooth (p=0.01). CONCLUSION: RFCs and FFCs undermine plain packaging legislation, which aims to reduce appeal and minimise misperceptions about the relative harms of different tobacco products. Like other filter modifications, these filter variants should be disallowed.

Ultrasound-Guided Lateral Abdominal Wall Botulinum Toxin Injection Before Ventral Hernia Repair: A Review for Radiologists.

Preoperative ultrasound-guided lateral abdominal wall botulinum toxin injection is a promising method for improving patient outcomes and reducing recurrence rates after ventral hernia repair. A review of the literature demonstrates variability in the procedural technique, without current standardization of protocols. As radiologists may be increasingly asked to perform ultrasound-guided botulinum toxin injections of the lateral abdominal wall, familiarity with the procedure and current literature is necessary.

Pediatric solid intra-articular masses of the knee: prevalence, imaging features and etiologies.

BACKGROUND: The etiologies of pediatric solid intra-articular soft-tissue masses are not well described and can present diagnostic dilemmas. OBJECTIVE: Our hypothesis was that these entities have a limited differential diagnosis and are mostly benign. MATERIALS AND METHODS: We reviewed knee magnetic resonance imaging (MRI) scans performed at our tertiary care institution between 2001 and 2019 (n=3,915). Our inclusion criterion was knee MRI with a solid intra-articular soft-tissue mass. Our exclusion criteria were cases with no masses or non-solid intra-articular lesions with clear radiologic diagnoses. Multiple radiologic characteristics were evaluated. Radiologic and histological diagnoses were collected when available. Cases without histology were assigned a suspected diagnosis. RESULTS: Twenty-five out of 3,915 (<1%) cases met the inclusion/exclusion criteria. Twenty patients underwent biopsy. Patient age ranged from 1 to 19 years with a mean age of 12 years. Lesion size ranged from 1 to 7 cm with a mean of 3.3 cm. The top three histological diagnoses were pigmented villonodular synovitis (PVNS) (7/20, 35%), vascular malformations (2/20, 10%) and inflammatory arthritis (2/20, 10%). There was one malignant case of synovial sarcoma (1/20, 5%). Of the five cases without biopsies, PVNS was the most common diagnosis (3/5, 60%). Five out of 10 (50%) PVNS cases were focal and 5/10 (50%) were multifocal. All PVNS cases (10/10, 100%) had hypointense signal on T2. CONCLUSION: Solid intra-articular soft-tissue masses of the knee in children are rare, with a prevalence of <1% in our study. The vast majority are benign with PVNS being the most common diagnosis.

Pediatric discoid meniscus: can magnetic resonance imaging features coupled with clinical symptoms predict the need for surgery?

BACKGROUND: Magnetic resonance imaging (MRI) criteria for evaluating discoid meniscus is limited in the pediatric population. OBJECTIVE: To assess MRI features of intact discoid meniscus and correlate with clinical outcomes. MATERIALS AND METHODS: In this institutional review board (IRB)-approved retrospective cohort study, knee MRIs at our institution from 2008 to 2019 were reviewed. The inclusion criterion was diagnosis of discoid meniscus on MRI. Exclusion criteria were torn discoid meniscus at presentation, previous meniscal surgery and confounding knee conditions. MRI features of discoid meniscus collected were craniocaudal dimension, transverse dimension, transverse dimension to tibial plateau (TV:TP) ratio and increased intrameniscal signal. The clinical course was reviewed for knee pain, mechanical symptoms and treatment type. RESULTS: Two hundred and nineteen of 3,277 (6.7%) patients had discoid meniscus. Of the 219 patients, 71 (32.4%) satisfied inclusion criteria. Seven patients had discoid meniscus of both knees resulting in 78 discoid menisci. The average patient age was 11.1 years (min: 2.0, max: 17.0). The average follow-up was 30.6 months. Of the 78 discoid menisci, 14 (17.9%) required surgery. Increased intrameniscal signal was found more in discoid meniscus requiring surgery (surgical: 10/14, nonsurgical: 19/64, P=0.009). Surgically treated discoid meniscus had a statistically significant increase in transverse dimension (surgical: 18.3±5.0 mm, nonsurgical: 15.7±4.3 mm, P=0.045) and TV:TP ratio (surgical: 0.55±0.15, nonsurgical: 0.47±0.12, P=0.036). Mechanical symptoms (surgical: 9/11, nonsurgical: 21/60, P=8.4×10-6) and pain ≥1 month (surgical: 11/11, nonsurgical: 17/60, P=0.006) were found more often in surgical patients. Clinical and imaging criteria of mechanical symptoms and knee pain ≥1 month and at least one of (1) increased intrameniscal signal or (2) TV:TP ratio greater than 0.47 identified discoid menisci that developed a tear and/or required surgery with a sensitivity of 0.86 and specificity of 0.88. CONCLUSION: Mechanical symptoms and knee pain ≥1 month, and at least one of (1) increased intrameniscal signal or (2) TV:TP ratio greater than or equal to 0.47, identified discoid menisci that would go on to tear and/or require surgery with a sensitivity and specificity of 0.86 and 0.88, respectively.

Quantitative magnetic resonance imaging for determining bone marrow fat fraction at 1.5 T and 3.0 T: a technique to noninvasively assess cellularity and potential malignancy of the bone marrow.

BACKGROUND: Pediatric bone marrow assessment by MRI is challenging and primarily experiential and qualitative, with a paucity of clinically useful quantitative imaging techniques. OBJECTIVE: MRI fat fraction (MRI-FF) is a technique used to quantify the degree of fat in other organ systems. The purpose of this study was to assess whether MRI-FF accurately measures bone marrow composition. MATERIALS AND METHODS: This two-part study included a validation phase, followed by an application phase. For the validation phase, the MRI-FF of piglet bones (6 long bones, 8 axial bones) was performed at 1.5 tesla (T) and 3.0 T, and correlated to the histological fat fraction (H-FF). We used Bland-Altman plots to compare MRI-FF at 1.5 tesla T and 3.0 T. For the application phase, five children with malignant marrow disease were recruited along with seven age- and gender-matched control subjects. The MRI-FF in the children was correlated to the H-FF. Boxplots were used to compare the MRI-FF of patients and control subjects. RESULTS: For the validation animal study, the MRI-FF of piglet bones at both 1.5 T and 3.0 T demonstrated moderate positive correlation to H-FF (r=0.41 and 0.42, respectively). MRI-FF at 1.5 T and 3.0 T were in good agreement, on average 7.7% apart. For the application phase, we included 5 children (4 with leukemia, 1 rhabdomyosarcoma) with median age 7 years, range (3-10 years). All children had MRI-FF and H-FF below 10%. The MRI-FF in patients (3.8±1.2) was significantly lower than that of control subjects (46.1±12.3%) (P<0.01). CONCLUSION: MRI-FF is a valid technique to assess bone marrow fat fraction at both 1.5 T and 3.0 T. The MRI-FF in children with malignant marrow processes is significantly lower than in control subjects with normal marrow.