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Isoprene is a key trace component of the atmosphere emitted by vegetation and other organisms. It is highly reactive and can impact atmospheric composition and climate by affecting the greenhouse gases ozone and methane and secondary organic aerosol formation. Marine fluxes are poorly constrained due to the paucity of long-term measurements; this in turn limits our understanding of isoprene cycling in the ocean. Here we present the analysis of isoprene concentrations in the atmosphere measured across the Southern Ocean over 4 months in the summertime. Some of the highest concentrations ( >500 ppt) originated from the marginal ice zone in the Ross and Amundsen seas, indicating the marginal ice zone is a significant source of isoprene at high latitudes. Using the United Kingdom Earth System Model we show that current estimates of sea-to-air isoprene fluxes underestimate observed isoprene by a factor >20. A daytime source of isoprene is required to reconcile models with observations. The model presented here suggests such an increase in isoprene emissions would lead to >8% decrease in the hydroxyl radical in regions of the Southern Ocean, with implications for our understanding of atmospheric oxidation and composition in remote environments, often used as proxies for the pre-industrial atmosphere.

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BACKGROUND: The COVID-19 pandemic caused major disruptions in radiology departments throughout North America. Radiology residency programs were forced to make dramatic changes to their training programs, which had major impacts on resident academics and wellness. The goal of this review is to evaluate the impact of COVID-19 on radiology residents' academics and wellness in North America, while also identifying effective measures taken by programs to mitigate the effects of the pandemic. METHODS: The search strategy involved database search via PubMed, Embase, and Web of Science with specific key words related to COVID-19, radiology residents, education, wellness, and virtual learning. Studies discussing the education and wellness of radiology residents in North America published after 2020 were included. The data were analyzed using a narrative synthesis approach. RESULTS: The three main domains affected by the pandemic include the residency curriculum, research, and resident wellness. The decline in case volume and diversity of cases had negative overall impact on education of radiology residents, but simulated cases and virtual learning proved its value during the pandemic and may have lasting implications for the postpandemic world. Research initiatives transitioned to a remote format with greater emphasis on quality improvement and COVID-19-related studies. Reduced face-to-face interaction opportunities made it difficult to establish strong and meaningful interpersonal connections and had a negative impact on resident wellness, mentorship, and professional development. Implementing mentorship programs and virtual "town hall meetings" were effective measures to maintain connections during times of social distancing. Finally, the COVID-19 pandemic introduced unprecedented stressors and challenges for radiology residents that negatively impacted their mental health and wellness. Incorporating wellness initiatives such as wellness hours and team-building activities and using social media were helpful in promoting wellness and mental health for radiology residents. CONCLUSION: The COVID-19 pandemic has had a significant impact on the academics and wellness of radiology residents across North America but has taught us many lessons that can help us navigate the ongoing challenges of the pandemic, the postpandemic world, and future pandemics.

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OBJECTIVE: Automatic MR imaging segmentation of the prostate provides relevant clinical benefits for prostate cancer evaluation such as calculation of automated PSA density and other critical imaging biomarkers. Further, automated T2-weighted image segmentation of central-transition zone (CZ-TZ), peripheral zone (PZ), and seminal vesicle (SV) can help to evaluate clinically significant cancer following the PI-RADS v2.1 guidelines. Therefore, the main objective of this work was to develop a robust and reproducible CNN-based automatic prostate multi-regional segmentation model using an intercontinental cohort of prostate MRI. METHODS: A heterogeneous database of 243 T2-weighted prostate studies from 7 countries and 10 machines of 3 different vendors, with the CZ-TZ, PZ, and SV regions manually delineated by two experienced radiologists (ground truth), was used to train (n = 123) and test (n = 120) a U-Net-based model with deep supervision using a cyclical learning rate. The performance of the model was evaluated by means of dice similarity coefficient (DSC), among others. Segmentation results with a DSC above 0.7 were considered accurate. RESULTS: The proposed method obtained a DSC of 0.88 ± 0.01, 0.85 ± 0.02, 0.72 ± 0.02, and 0.72 ± 0.02 for the prostate gland, CZ-TZ, PZ, and SV respectively in the 120 studies of the test set when comparing the predicted segmentations with the ground truth. No statistically significant differences were found in the results obtained between manufacturers or continents. CONCLUSION: Prostate multi-regional T2-weighted MR images automatic segmentation can be accurately achieved by U-Net like CNN, generalizable in a highly variable clinical environment with different equipment, acquisition configurations, and population. KEY POINTS: • Deep learning techniques allows the accurate segmentation of the prostate in three different regions on MR T2w images. • Multi-centric database proved the generalization of the CNN model on different institutions across different continents. • CNN models can be used to aid on the diagnosis and follow-up of patients with prostate cancer.

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The Association of University Radiologists (AUR) convened its sixth annual Academic-Industry Roundtable in a hybrid fashion in March 2022, with academic radiology and radiology industry leaders gathered in person and via remote videoconference. The open discussion centered around on challenges facing radiology and specifically focused on the people in our field, including patients, radiologists, and radiology staff. Participants identified numerous opportunities for industry and radiology departments to collaborate to improve equitable access to healthcare, communication with patients, use of appropriate imaging, and the state of the radiology workforce.

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The fifth Association of University Radiologists (AUR) Academic Radiology and Leaders Roundtable took place the day after the conclusion of the AUR annual meeting in May 2021 and involved leaders in academic radiology departments across the United States, and industry from companies who provide quintessential services to radiology departments. The open-ended discussion identified the key challenges facing the practice and business of radiology as we jointly move forward after the COVID-19 pandemic. Particular attention was paid to the identification of viable solutions that radiology departments should embrace to sustain clinical productivity, innovation, and well-being, and the ways that industry could contribute significantly to that endeavor.

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RATIONALE AND OBJECTIVES: Multi-parametric Magnetic Resonance Imaging (mpMRI) is a novel procedure recommended by the American Urological Association for Prostate Cancer (PCa) diagnosis. In radiology, differences in utilization of expensive screening techniques are described but never reviewed for mpMRI. Thus, our article aims at summarizing disparities relating to the expensive yet revolutionary mpMRI in United States men with PCa while highlighting needed research areas. MATERIAL AND METHODS: Eligible articles were gathered via PubMed query, referred publications known to the authors or from the reference lists of the identified publications. We excluded studies that didn't specifically evaluate mpMRI technique, weren't conducted in the United States, or didn't directly assess the relationship between disparities and mpMRI. No date restrictions were applied, resulting articles were published through 2020. RESULTS: Out of 80 publications, 17 were selected. Two unique themes were identified: 1) disparities in mpMRI utilization, and 2) performance. While demographic factors such as race, age and socioeconomic status played a significant role in utilization, mpMRI demonstrated equal and sometimes superior performance in AAs. CONCLUSION: Our findings illustrate the importance of disparity awareness in PCa mpMRI and highlight the need to examine additional mpMRI disparities across other races and social determinants. A new area of inequity in PCa was theoretically illustrated, as lower utilization of mpMRI was detected in a group that could potentially benefit from it the most. Major limitation was the selected search terms. Our review is unique as disparities related to mpMRI were found to be multilayered, affecting utilization and performance. Continued research is needed to discover additional areas in efforts to reduce disparity gaps related to mpMRI and PCa.

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Teleradiology solutions are playing an essential role during the COVID-19 outbreak. Activity at radiology departments must be maintained and adapted to this new situation beyond teleradiology. Teleworking should be extended to the rest of non-medical radiology department areas. A comprehensive perspective based on our own experience during the COVID-19 outbreak has been performed highlighting the value of teleworking for almost all areas implied in the workflow of radiology departments beyond radiologists. Personal and technical requirements for successfully adapting to this new scenario are discussed including the opportunities that this unprecedent situation is bringing for reorganizing workflow and developing new projects. KEY POINTS: • Teleradiology solutions are playing an essential role during the COVID-19 outbreak. • Teleworking should be extended to the rest of non-medical radiology department areas whenever possible.

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RATIONALE AND OBJECTIVES: Iodine quantification (IQ) and virtual noncontrast (VNC) images produced by dual-energy CT (DECT) can be used for various clinical applications. We investigate the performance of dual-layer DECT (DLDECT) in different phantom sizes and varying radiation doses and tube voltages, including a low-dose pediatric setting. MATERIALS AND METHODS: Three phantom sizes (simulating a 10-year-old child, an average, and a large-sized adult) were scanned with iodine solution inserts with concentrations ranging 0-32 mg/ml, using the DLDECT. Each phantom size was scanned with CTDIvol 2-15 mGy at 120 and 140 kVp. The smallest phantom underwent additional scans with CTDIvol 0.9-1.8 mGy. All scans were repeated 3 times. Each iodine insert was analyzed using VNC and IQ images for accuracy and precision, by comparison to known values. RESULTS: For scans from 2 to 15 mGy mean VNC attenuation and IQ error in the iodine inserts in the small, medium, and large phantoms was 1.2 HU ± 3.2, -1.2 HU ± 14.9, 2.6 HU ± 23.6; and +0.1 mg/cc ± 0.4, -0.9 mg/cc ± 0.9, and -1.8 mg/cc ± 1.8, respectively. In this dose range, there were no significant differences (p ≥ 0.05) in mean VNC attenuation or IQ accuracy in each phantom size, while IQ was significantly less precise in the small phantom at 2 mGy and 10 mGy (p < 0.05). Scans with CTDIvol 0.9-1.8 mGy in the small phantom showed a limited, but statistically significantly lower VNC attenuation precision and IQ accuracy (-0.5 HU ± 5.3 and -0.3 mg/cc ± 0.5, respectively) compared to higher dose scans in the same phantom size. CONCLUSION: Performance of iodine quantification and subtraction by VNC images in DLDECT is largely dose independent, with the primary factor being patient size. Low-dose pediatric scan protocols have a significant, but limited impact on IQ and VNC attenuation values.

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The AUR Academic Radiology and Industry Leaders Roundtable was organized as an open discussion between academic leaders of top US academic radiology departments and industry leaders from top companies that provide equipment and services to radiology, including manufacturers, pharmaceutical companies, software developers and electronic medical record (EMR) providers. The format was that of a structured brainstorming session with pre-selected discussion topics. This roundtable was instrumental in widening perspectives and providing insights into the challenges and opportunities for our specialty, such as in the case of Artificial Intelligence (AI).

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INTRODUCTION: Bone mineral density (BMD) analysis by Dual-Energy x-ray Absorptiometry (DXA) can have some false negatives due to overlapping structures in the projections. Spectral Detector CT (SDCT) can overcome these limitations by providing volumetric information. We investigated its performance for BMD assessment and compared it to DXA and phantomless volumetric bone mineral density (PLvBMD), the latter known to systematically underestimate BMD. DXA is the current standard for BMD assessment, while PLvBMD is an established alternative for opportunistic BMD analysis using CT. Similarly to PLvBMD, spectral data could allow BMD screening opportunistically, without additional phantom calibration. METHODOLOGY: Ten concentrations of dipotassium phosphate (K2HPO4) ranging from 0 to 600 mg/ml, in an acrylic phantom were scanned using SDCT in four different, clinically-relevant scan conditions. Images were processed to estimate the K2HPO4 concentrations. A model representing a human lumbar spine (European Spine Phantom) was scanned and used for calibration via linear regression analysis. After calibration, our method was retrospectively applied to abdominal SDCT scans of 20 patients for BMD assessment, who also had PLvBMD and DXA. Performance of PLvBMD, DXA and our SDCT method were compared by sensitivity, specificity, negative predictive value and positive predictive value for decreased BMD. RESULTS: There was excellent correlation (R2 >0.99, p < 0.01) between true and measured K2HPO4 concentrations for all scan conditions. Overall mean measurement error ranged from -11.5 ± 4.7 mg/ml (-2.8 ± 6.0%) to -12.3 ± 6.3 mg/ml (-4.8 ± 3.0%) depending on scan conditions. Using DXA as a reference standard, sensitivity/specificity for detecting decreased BMD in the scanned patients were 100%/73% using SDCT, 100%/40% using PLvBMD provided T-scores, and 90-100%/40-53% using PLvBMD hydroxyapatite density classifications, respectively. CONCLUSIONS: Our results show excellent sensitivity and high specificity of SDCT for detecting decreased BMD, demonstrating clinical feasibility. Further validation in prospective clinical trials will be required.

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OBJECTIVE: The aim of this study was to investigate the quantitative and qualitative effects of virtual monoenergetic images (VMI) by spectral detector computed tomography (SDCT) on calcium blooming in coronary computed tomography angiography. METHODS: Coronary computed tomography angiography using SDCT was performed on 42 patients with coronary artery calcifications. Stenosis grading by diameter and area of calcified plaques and free lumen using VMI from 70 to 140 keV was performed and compared with measurements by conventional images. In addition, interobserver reliability and subjective image quality were assessed by 2 experienced readers. RESULTS: A total of 61 coronary arteries were evaluated. Stenosis grading by diameter and area showed significant incremental decrease, from 48.86% to 22.82% and from 41.18% to 11.33%, respectively, with increasing VMI (P < 0.05). Interobserver reliability was excellent (intraclass correlation coefficient >0.99). Overall image quality was best at 80 keV. CONCLUSIONS: Calcium blooming significantly decreases at higher monoenergetic levels from SDCT, increasing luminal dimensions and decreasing stenotic grading, with best overall subjective image quality using 80-keV VMI.

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RATIONALE AND OBJECTIVES: The objective of this study was to develop and quantitatively evaluate a radiology-pathology fusion method for spatially mapping tissue regions corresponding to different chemoradiation therapy-related effects from surgically excised whole-mount rectal cancer histopathology onto preoperative magnetic resonance imaging (MRI). MATERIALS AND METHODS: This study included six subjects with rectal cancer treated with chemoradiation therapy who were then imaged with a 3-T T2-weighted MRI sequence, before undergoing mesorectal excision surgery. Excised rectal specimens were sectioned, stained, and digitized as two-dimensional (2D) whole-mount slides. Annotations of residual disease, ulceration, fibrosis, muscularis propria, mucosa, fat, inflammation, and pools of mucin were made by an expert pathologist on digitized slide images. An expert radiologist and pathologist jointly established corresponding 2D sections between MRI and pathology images, as well as identified a total of 10 corresponding landmarks per case (based on visually similar structures) on both modalities (five for driving registration and five for evaluating alignment). We spatially fused the in vivo MRI and ex vivo pathology images using landmark-based registration. This allowed us to spatially map detailed annotations from 2D pathology slides onto corresponding 2D MRI sections. RESULTS: Quantitative assessment of coregistered pathology and MRI sections revealed excellent structural alignment, with an overall deviation of 1.50 ± 0.63 mm across five expert-selected anatomic landmarks (in-plane misalignment of two to three pixels at 0.67- to 1.00-mm spatial resolution). Moreover, the T2-weighted intensity distributions were distinctly different when comparing fibrotic tissue to perirectal fat (as expected), but showed a marked overlap when comparing fibrotic tissue and residual rectal cancer. CONCLUSIONS: Our fusion methodology enabled successful and accurate localization of post-treatment effects on in vivo MRI.

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BACKGROUND AND PURPOSE: To compare the utility of quantitative PET/MRI, dynamic susceptibility contrast (DSC) perfusion MRI (pMRI), and PET/CT in differentiating radiation necrosis (RN) from tumor recurrence (TR) in patients with treated glioblastoma multiforme (GBM). METHODS: The study included 24 patients with GBM treated with surgery, radiotherapy, and temozolomide who presented with progression on imaging follow-up. All patients underwent PET/MRI and pMRI during a single examination. Additionally, 19 of 24 patients underwent PET/CT on the same day. Diagnosis was established by pathology in 17 of 24 and by clinical/radiologic consensus in 7 of 24. For the quantitative PET/MRI and PET/CT analysis, a region of interest (ROI) was drawn around each lesion and within the contralateral white matter. Lesion to contralateral white matter ratios for relative maximum, mean, and median were calculated. For pMRI, lesion ROI was drawn on the cerebral blood volume (CBV) maps and histogram metrics were calculated. Diagnostic performance for each metric was assessed using receiver operating characteristic curve analysis and area under curve (AUC) was calculated. RESULTS: In 24 patients, 28 lesions were identified. For PET/MRI, relative mean ≥ 1.31 resulted in AUC of .94 with both sensitivity and negative predictive values (NPVs) of 100%. For pMRI, CBV max ≥3.32 yielded an AUC of .94 with both sensitivity and NPV measuring 100%. The joint model utilizing r-mean (PET/MRI) and CBV mode (pMRI) resulted in AUC of 1.0. CONCLUSION: Our study demonstrates that quantitative PET/MRI parameters in combination with DSC pMRI provide the best diagnostic utility in distinguishing RN from TR in treated GBMs.

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OBJECTIVE: Medical education has been an important topic in the literature, with many new attempts to revitalize and improve efforts to teach physicians and students. As a unique subspecialty that incorporates visual learning, knowledge of clinical management and presentation, basic science topics such as physics and mechanics, and procedural skills, radiology affords itself to new and more effective methods of teaching. CONCLUSION: Much of radiology education has currently focused on the concept of spoon-feeding information from the teacher to the learners. This article outlines the dangers of this approach in radiology and offers solutions for educators to improve their teaching skills and use the potential afforded by the diversity of the field.

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PURPOSE: The aim of this study was to investigate the state of integration between PACS and other IT systems relevant to radiologists' routine work across US academic radiology departments (ARDs). The results were intended to assess readiness for the ongoing transition to value-based health care by providing insights into currently challenging areas of integration but also areas associated with high levels of anticipated workflow efficiency improvements. METHODS: A cross-sectional survey was conducted using an online survey approved by the Society of Chairs of Academic Radiology Departments and sent to its members. Collected responses were analyzed with descriptive statistics and Fisher's exact tests. RESULTS: The response rate was 26% (34 of 132 members), and the respondents covered a large spectrum of ARDs considering location, size aspects, year of PACS introduction, and filmless production. Most notable findings included widespread high-level integration of PACS with dictation systems (>90%), low penetration of integration between PACS and critical notification systems (15%), and an overall better integration of PACS and radiology information systems (82%) than of PACS and electronic medical records (47%). CONCLUSIONS: Integration supporting radiologists' personal productivity is well spread among US ARDs, but as we transition into a value-based health care delivery model, there is a need to focus further integration efforts on systems with the greatest potential to document value in a patient-centric setting. Examples of such focus areas include integration of PACS and electronic medical records, adoption of vendor-neutral archives, and the use of workflow management systems.

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PURPOSE: Small bowel (SB) diverticulosis is a rare disorder that may entail serious complications, including SB diverticulitis. Both are often missed in imaging. Magnetic resonance enterography/enteroclysis (MRE) is increasingly used to assess SB disease; awareness of the appearance of SB diverticulitis is essential to ensure appropriate management. Our aim was to systematically describe imaging characteristics of SB diverticulosis and diverticulitis in MRE. METHODS: This retrospective, HIPAA-compliant study identified 186 patients with suspected SB diverticulosis/diverticulitis in medical databases of two tertiary medical centres between 2005 and 2011. Patients with surgically confirmed diagnoses of SB diverticulosis/diverticulitis were included. Two observers analyzed MR images for the presence, location, number, and size of diverticula, wall thickness, and mural and extramural patterns of inflammation. RESULTS: Seven patients were recruited. MRI analysis showed multiple diverticula in all (100 %). Diverticular size ranged from 0.5 to 6 cm. Prevalence of diverticula was higher in the proximal than the distal SB (jejunum 86 %, ileum 57 %, distal ileum43%). Diverticulitis occurred in 3/7 patients (43 %) showing asymmetric bowel wall thickening and focal mesenteric inflammation. CONCLUSION: SB diverticulitis demonstrates characteristic MRE imaging features to distinguish this rare disorder from more common diseases. Asymmetric, focal mesenteric and mural inflammation and presence of multiple diverticula are keys to diagnosis. KEY POINTS: • Small bowel diverticulosis and diverticulitis is rare and often missed in imaging • Acquired small bowel diverticula are variable in size and number • Small bowel diverticulitis demonstrates characteristic features on MR enterography/enteroclysis • A focal or segmental asymmetric small bowel inflammation should prompt the search for diverticula.

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Early detection of residual tumour and local tumour progression (LTP) after radiofrequency (RF) ablation is crucial in the decision whether or not to re-ablate. In general, standard contrast-enhanced computed tomography (CT) is used to evaluate the technique effectiveness; however, it is difficult to differentiate post-treatment changes from residual tumour. Dual-energy CT (DECT) is a relatively new technique that enables more specific tissue characterisation of iodine-enhanced structures because of the isolation of iodine in the imaging data. Necrotic post-ablation zones can be depicted as avascular regions by DECT on greyscale- and colour-coded iodine images. Synthesised monochromatic images from dual-energy CT with spectral analysis can be used to select the optimal keV to achieve the highest contrast-to-noise ratio between tissues. This facilitates outlining the interface between the ablation zone and surrounding tissue. Post-processing of DECT data can lead to an improved characterisation and delineation of benign post-ablation changes from LTP. Radiologists need to be familiar with typical post-ablation image interpretations when using DECT techniques. Here, we review the spectrum of changes after RF ablation of liver, kidney, and lung lesions using single-source DECT imaging, with the emphasis on the additional information obtained and pitfalls encountered with this relatively new technique. Teaching Points •Technical success of RF ablation means complete destruction of the tumour. •Assessment of residual tumour on contrast-enhanced CT is hindered by post-ablative changes. •DECT improves material differentiation and may improve focal lesion characterisation. •Iodine maps delineate the treated area from the surrounding parenchyma well.