Long-term outcome and prognosis of mixed histiocytosis (Erdheim-Chester disease and Langerhans Cell Histiocytosis).

Background: Erdheim-Chester disease (ECD) is a rare histiocytosis that may overlap with Langerhans Cell Histiocytosis (LCH). This "mixed" entity is poorly characterized. We here investigated the clinical phenotype, outcome, and prognostic factors of a large cohort of patients with mixed ECD-LCH. Methods: This retrospective study was performed at two referral centers in France and Italy (Pitié-Salpêtrière Hospital, Paris; Meyer Children's Hospital, Florence). We included children and adults with ECD diagnosed in 2000-2022 who had biopsy-proven LCH, available data on clinical presentation, treatment and outcome, and a minimum follow-up of one year. Outcomes included differences in clinical presentation and survival between mixed ECD-LCH and isolated ECD; we also investigated response to treatments and predictors of survival in the mixed cohort. Survival was analyzed using the Kaplan-Maier method and differences in survival with the long-rank test. Cox regression models were used to evaluate the potential impact of age and gender on survival and to identify predictors of non-response and survival. Findings: Out of a cohort of 502 ECD patients, 69 (14%) had mixed ECD-LCH. Compared to isolated ECD, mixed ECD-LCH occurred more frequently in females (51 vs. 26%, p < 0.001) and in patients with multisystem disease (≥4 sites). Mixed ECD-LCH more frequently involved long bones (91 vs. 79%, p = 0.014), central nervous system (51 vs. 34%, p = 0.007), facial/orbit (52 vs. 38%, p = 0.031), lungs (43 vs. 28%, p = 0.009), hypothalamic/pituitary axis (51 vs. 26%, p < 0.001), skin (61 vs. 29%, p < 0.001), and lymph nodes (15 vs. 7%, p = 0.028); the BRAFV600E mutation was also more frequent in mixed ECD-LCH (81 vs. 59%, p < 0.001). Targeted treatments (BRAF and/or MEK inhibitors) induced response more frequently than conventional therapies (interferon-α, chemotherapy), either as first-line (77 vs. 29%, p < 0.001) or as any line (75 vs. 24%, p < 0.001). After a median follow-up of 71 months, 24 patients (35%) died. Survival probability was comparable between ECD alone and mixed ECD-LCH (log-rank p = 0.948). At multivariable analysis, age at diagnosis (HR 1.052, 95% CI 1.008-1.096), associated hematologic conditions (HR 3.030, 95% CI 1.040-8.827), and treatment failure (HR 9.736, 95% CI 2.919-32.481) were associated with an increased risk of death, while lytic bone lesions with a lower risk (HR 0.116, 95% CI 0.031-0.432). Interpretation: Mixed ECD-LCH is a multisystem disease driven by the BRAFV600E mutation and targeted treatments are effective. Age at diagnosis, bone lesion patterns, associated hematologic conditions, and treatment failure are the main predictors of death in mixed ECD-LCH. Funding: None.

Assessing respiratory epidemic potential in French hospitals through collection of close contact data (April-June 2020).

The transmission risk of SARS-CoV-2 within hospitals can exceed that in the general community because of more frequent close proximity interactions (CPIs). However, epidemic risk across wards is still poorly described. We measured CPIs directly using wearable sensors given to all present in a clinical ward over a 36-h period, across 15 wards in three hospitals in April-June 2020. Data were collected from 2114 participants and combined with a simple transmission model describing the arrival of a single index case to the ward to estimate the risk of an outbreak. Estimated epidemic risk ranged four-fold, from 0.12 secondary infections per day in an adult emergency to 0.49 per day in general paediatrics. The risk presented by an index case in a patient varied 20-fold across wards. Using simulation, we assessed the potential impact on outbreak risk of targeting the most connected individuals for prevention. We found that targeting those with the highest cumulative contact hours was most impactful (20% reduction for 5% of the population targeted), and on average resources were better spent targeting patients. This study reveals patterns of interactions between individuals in hospital during a pandemic and opens new routes for research into airborne nosocomial risk.

Outcomes and risk assessment in pulmonary veno-occlusive disease.

Introduction: Pulmonary veno-occlusive disease (PVOD) is a rare and severe subtype of pulmonary arterial hypertension (PAH). Although European Society of Cardiology/European Respiratory Society (ESC/ERS) guidelines advise assessing PAH severity at baseline and during follow-up, no existing risk assessment methods have been validated for PVOD. This study aimed to identify prognostic factors, examine the impact of treatment strategies and evaluate risk assessment methods for PVOD patients. Methods: The study analysed all incident PVOD patients included in the French Pulmonary Hypertension Registry between 2006 and 2021. Survival was assessed based on initial treatment strategy and risk status and compared to a matched (age, sex, pulmonary vascular resistance) PAH group. Six risk assessment methods (number of four low-risk and three noninvasive low-risk variables, ESC/ERS guidelines three-strata and four-strata models, REVEAL 2.0 and Lite 2) were applied at baseline and early follow-up, and their accuracy was compared using Harrell's c-statistic. Results: Among the 327 included PVOD patients, survival rates at 1, 3 and 5 years were 86%, 50% and 27%, respectively. Multivariate analysis showed that only 6-min walk distance was associated with survival, with no significant difference based on initial treatment strategy. All six risk assessment methods could discriminate mortality risk, and the ESC/ERS four-strata model was the most accurate at both baseline and follow-up (C-index 0.64 and 0.74). PVOD survival rates were consistently lower than PAH when comparing baseline risk status using the ESC/ERS four-strata model. Conclusion: PVOD is associated with poor outcomes, and initial treatment strategies do not significantly affect survival. Risk assessment methods can be useful in predicting survival for PVOD patients.

Radiological pulmonary sequelae after COVID-19 and correlation with clinical and functional pulmonary evaluation: results of a prospective cohort.

OBJECTIVES: Whether COVID-19 leads to long-term pulmonary sequelae or not remains unknown. The aim of this study was to assess the prevalence of persisting radiological pulmonary fibrotic lesions in patients hospitalized for COVID-19. MATERIALS AND METHODS: We conducted a prospective single-center study among patients hospitalized for COVID-19 between March and May 2020. Patients with residual symptoms or admitted into intensive care units were investigated 4 months after discharge by a chest CT (CCT) and pulmonary function tests (PFTs). The primary endpoint was the rate of persistent radiological fibrotic lesions after 4 months. Secondary endpoints included further CCT evaluation at 9 and 16 months, correlation of fibrotic lesions with clinical and PFT evaluation, and assessment of predictive factors. RESULTS: Among the 1151 patients hospitalized for COVID-19, 169 patients performed a CCT at 4 months. CCTs showed pulmonary fibrotic lesions in 19% of the patients (32/169). These lesions were persistent at 9 months and 16 months in 97% (29/30) and 95% of patients (18/19) respectively. There was no significant clinical difference based on dyspnea scale in patients with pulmonary fibrosis. However, PFT evaluation showed significantly decreased diffusing lung capacity for carbon monoxide (p < 0.001) and total lung capacity (p < 0.001) in patients with radiological lesions. In multivariate analysis, the predictive factors of radiological pulmonary fibrotic lesions were pulmonary embolism (OR = 9.0), high-flow oxygen (OR = 6.37), and mechanical ventilation (OR = 3.49). CONCLUSION: At 4 months, 19% of patients investigated after hospitalization for COVID-19 had radiological pulmonary fibrotic lesions; they persisted up to 16 months. CLINICAL RELEVANCE STATEMENT: Whether COVID-19 leads to long-term pulmonary sequelae or not remains unknown. The aim of this study was to assess the prevalence of persisting radiological pulmonary fibrotic lesions in patients hospitalized for COVID-19. The prevalence of persisting lesions after COVID-19 remains unclear. We assessed this prevalence and predictive factors leading to fibrotic lesions in a large cohort. The respiratory clinical impact of these lesions was also assessed. KEY POINTS: • Nineteen percent of patients hospitalized for COVID-19 had radiological fibrotic lesions at 4 months, remaining stable at 16 months. • COVID-19 fibrotic lesions did not match any infiltrative lung disease pattern. • COVID-19 fibrotic lesions were associated with pulmonary function test abnormalities but did not lead to clinical respiratory manifestation.

Functional respiratory complaints among COVID-19 survivors: a prospective cohort study.

Background: Dyspnoea is a common persistent symptom after COVID-19. Whether it is associated with functional respiratory disorders remains unclear. Methods: We assessed the proportion and characteristics of patients with "functional respiratory complaints" (FRCs) (as defined by Nijmegen Questionnaire >22) among 177 post-COVID-19 individuals who benefited from outclinic evaluation in the COMEBAC study (i.e., symptomatic and/or intensive care unit (ICU) survivors at 4 months). In a distinct explanatory cohort of 21 consecutive individuals with unexplained post-COVID-19 dyspnoea after routine tests, we also analysed the physiological responses to incremental cardiopulmonary exercise testing (CPET). Findings: In the COMEBAC cohort, 37 patients had significant FRCs (20.9%, IC95: 14.9-26.9). The prevalence of FRCs ranged from 7.2% (ICU patients) to 37.5% (non-ICU patients). The presence of FRCs was significantly associated with more severe dyspnoea, lower 6-min walk distance, more frequent psychological and neurological symptoms (cognitive complaint, anxiety, depression, insomnia and post-traumatic stress disorders) and poorer quality of life (all p<0.01). In the explanatory cohort, seven out of 21 patients had significant FRCs. Based on CPET, dysfunctional breathing was identified in 12 out of 21 patients, five out of 21 had normal CPET, three out of 21 had deconditioning and one out of 21 had evidence of uncontrolled cardiovascular disease. Interpretation: FRCs are common during post-COVID-19 follow-up, especially among patients with unexplained dyspnoea. Diagnosis of dysfunctional breathing should be considered in those cases.

Clinical Added Value of SARS-CoV-2 Antigen Detection in Blood Samples.

This study evaluated the performances of immunoassays (LFIA and ELISA) designed for SARS-CoV-2 Antigen (Ag)-detection in nasopharyngeal (NP) and serum samples in comparison to RT-PCR. NP samples from patients with respiratory symptoms (183 RT-PCR-positive and 74 RT-PCR-negative samples) were collected from March to April and November to December 2020. Seroconversion and antigen dynamics were assessed by symptom onset and day of RT-PCR diagnosis. Serum samples from 87 COVID-19 patients were used to investigate the added value of Ag quantification, at diagnosis and during follow-up. The sensitivity of COVID-VIRO-LFIA on samples with Ct ≤ 33, considered as the contagious threshold, was 86% on NPs (CI 95%: 79-90.5) and 76% on serum samples (CI 95%: 59.4-88), with a specificity of 100%. Serum N-Ag was detected during active infection as early as day two from symptom onset, with a diagnostic sensitivity of 81.5%. Within one week of symptom onset, diagnostic sensitivity and specificity reached 90.9% (95% CI, 85.1%-94.6%) and 98.3% (95% CI, 91.1%-99.9%), respectively. Serum N-Ag concentration closely correlated with disease severity. Longitudinal analysis revealed the simultaneous increase of antibodies and decrease of N-Ag. Sensitivities of COVID-VIRO-LFIA and COV-QUANTO-ELISA tests on NP and serum samples were close to 80%. They are suitable COVID-19-laboratory diagnostic tests, particularly when blood samples are available, thus reducing the requirement for NP sampling, and subsequent PCR analysis. ELISA titers may help to identify patients at risk of poor outcomes.

COVID-19 in Patients with Pulmonary Hypertension: A National Prospective Cohort Study.

Rationale: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is associated with pulmonary endothelial dysfunction. There are limited data available on the outcomes of coronavirus disease (COVID-19) in patients with pulmonary hypertension (PH), a disease characterized by pulmonary endothelial dysfunction. Objectives: To describe characteristics and outcomes of patients with precapillary PH and COVID-19. Methods: We prospectively collected characteristics, management, and outcomes of adult patients with precapillary PH in the French PH network who had COVID-19 between February 1, 2020, and April 30, 2021. Clinical, functional, and hemodynamic characteristics of PH before COVID-19 were collected from the French PH registry. Measurements and Main Results: A total of 211 patients with PH (including 123 with pulmonary arterial hypertension, 47 with chronic thromboembolic PH, and 41 with other types of PH) experienced COVID-19, and 40.3% of them were outpatients, 32.2% were hospitalized in a conventional ward, and 27.5% were in an ICU. Among hospitalized patients (n = 126), 54.0% received corticosteroids, 37.3% high-flow oxygen, and 11.1% invasive ventilation. Right ventricular and acute renal failure occurred in 30.2% and 19.8% of patients, respectively. Fifty-two patients (all hospitalized) died from COVID-19. Overall mortality was 24.6% (95% CI [confidence interval], 18.8-30.5) and in-hospital mortality 41.3% (95% CI, 32.7-49.9). Nonsurvivors were significantly older, more frequently male and suffering comorbidities (diabetes, chronic respiratory diseases, systemic hypertension, chronic cardiac diseases, and/or chronic renal failure), and had more severe PH at their most recent evaluation preceding COVID-19 diagnosis (in terms of functional class and 6-minute-walk distance; all P < 0.05). Use of pulmonary arterial hypertension therapy was similar between survivors and nonsurvivors. Conclusions: COVID-19 in patients with precapillary PH was associated with a high in-hospital mortality. The typical risk factors for severe COVID-19 and severity of PH were associated with mortality in this population.

Respiratory symptoms and radiological findings in post-acute COVID-19 syndrome.

Rationale: The characteristics of patients with respiratory complaints and/or lung radiologic abnormalities after hospitalisation for coronavirus disease 2019 (COVID-19) are unknown. The objectives were to determine their characteristics and the relationships between dyspnoea, radiologic abnormalities and functional impairment. Methods: In the COMEBAC (Consultation Multi-Expertise de Bicêtre Après COVID-19) cohort study, 478 hospital survivors were evaluated by telephone 4 months after hospital discharge, and 177 who had been hospitalised in an intensive care unit (ICU) or presented relevant symptoms underwent an ambulatory evaluation. New-onset dyspnoea and cough were evaluated, and the results of pulmonary function tests and high-resolution computed tomography of the chest were collected. Results: Among the 478 patients, 78 (16.3%) reported new-onset dyspnoea, and 23 (4.8%) new-onset cough. The patients with new-onset dyspnoea were younger (56.1±12.3 versus 61.9±16.6 years), had more severe COVID-19 (ICU admission 56.4% versus 24.5%) and more frequent pulmonary embolism (18.0% versus 6.8%) (all p≤0.001) than patients without dyspnoea. Among the patients reassessed at the ambulatory care visit, the prevalence of fibrotic lung lesions was 19.3%, with extent <25% in 97% of the patients. The patients with fibrotic lesions were older (61±11 versus 56±14 years, p=0.03), more frequently managed in an ICU (87.9 versus 47.4%, p<0.001), had lower total lung capacity (74.1±13.7 versus 84.9±14.8% pred, p<0.001) and diffusing capacity of the lung for carbon monoxide (D LCO) (73.3±17.9 versus 89.7±22.8% pred, p<0.001). The combination of new-onset dyspnoea, fibrotic lesions and D LCO <70% pred was observed in eight out of 478 patients. Conclusions: New-onset dyspnoea and mild fibrotic lesions were frequent at 4 months, but the association of new-onset dyspnoea, fibrotic lesions and low D LCO was rare.

Fully Integrated Quantitative Multiparametric Analysis of Non-Small Cell Lung Cancer at 3-T PET/MRI: Toward One-Stop-Shop Tumor Biological Characterization at the Supervoxel Level.

INTRODUCTION: The aim of this study was to study the feasibility of a fully integrated multiparametric imaging framework to characterize non-small cell lung cancer (NSCLC) at 3-T PET/MRI. PATIENTS AND METHODS: An 18F-FDG PET/MRI multiparametric imaging framework was developed and prospectively applied to 11 biopsy-proven NSCLC patients. For each tumor, 12 parametric maps were generated, including PET full kinetic modeling, apparent diffusion coefficient, T1/T2 relaxation times, and DCE full kinetic modeling. Gaussian mixture model-based clustering was applied at the whole data set level to define supervoxels of similar multidimensional PET/MRI behaviors. Taking the multidimensional voxel behaviors as input and the supervoxel class as output, machine learning procedure was finally trained and validated voxelwise to reveal the dominant PET/MRI characteristics of these supervoxels at the whole data set and individual tumor levels. RESULTS: The Gaussian mixture model-based clustering clustering applied at the whole data set level (17,316 voxels) found 3 main multidimensional behaviors underpinned by the 12 PET/MRI quantitative parameters. Four dominant PET/MRI parameters of clinical relevance (PET: k2, k3 and DCE: ve, vp) predicted the overall supervoxel behavior with 97% of accuracy (SD, 0.7; 10-fold cross-validation). At the individual tumor level, these dimensionality-reduced supervoxel maps showed mean discrepancy of 16.7% compared with the original ones. CONCLUSIONS: One-stop-shop PET/MRI multiparametric quantitative analysis of NSCLC is clinically feasible. Both PET and MRI parameters are useful to characterize the behavior of tumors at the supervoxel level. In the era of precision medicine, the full capabilities of PET/MRI would give further insight of the characterization of NSCLC behavior, opening new avenues toward image-based personalized medicine in this field.

Association between Initial Treatment Strategy and Long-Term Survival in Pulmonary Arterial Hypertension.

Rationale: The relationship between the initial treatment strategy and survival in pulmonary arterial hypertension (PAH) remains uncertain. Objectives: To evaluate the long-term survival of patients with PAH categorized according to the initial treatment strategy. Methods: A retrospective analysis of incident patients with idiopathic, heritable, or anorexigen-induced PAH enrolled in the French Pulmonary Hypertension Registry (January 2006 to December 2018) was conducted. Survival was assessed according to the initial strategy: monotherapy, dual therapy, or triple-combination therapy (two oral medications and a parenteral prostacyclin). Measurements and Main Results: Among 1,611 enrolled patients, 984 were initiated on monotherapy, 551 were initiated on dual therapy, and 76 were initiated on triple therapy. The triple-combination group was younger and had fewer comorbidities but had a higher mortality risk. The survival rate was higher with the use of triple therapy (91% at 5 yr) as compared with dual therapy or monotherapy (both 61% at 5 yr) (P < 0.001). Propensity score matching of age, sex, and pulmonary vascular resistance also showed significant differences between triple therapy and dual therapy (10-yr survival, 85% vs. 65%). In high-risk patients (n = 243), the survival rate was higher with triple therapy than with monotherapy or dual therapy, whereas there was no difference between monotherapy and double therapy. In intermediate-risk patients (n = 1,134), survival improved with an increasing number of therapies. In multivariable Cox regression, triple therapy was independently associated with a lower risk of death (hazard ratio, 0.29; 95% confidence interval, 0.11-0.80; P = 0.017). Among the 148 patients initiated on a parenteral prostacyclin, those on triple therapy had a higher survival rate than those on monotherapy or dual therapy. Conclusions: Initial triple-combination therapy that includes parenteral prostacyclin seems to be associated with a higher survival rate in PAH, particularly in the youngest high-risk patients.

Association between Leflunomide and Pulmonary Hypertension.

Rationale: Pulmonary hypertension (PH) has been described in patients treated with leflunomide. Objectives: To assess the association between leflunomide and PH. Methods: We identified incident cases of PH in patients treated with leflunomide from the French PH Registry and through the pharmacoVIGIlAnce in Pulmonary ArTerial Hypertension (VIGIAPATH) program between September 1999 to December 2019. PH etiology, clinical, functional, radiologic, and hemodynamic characteristics were reviewed at baseline and follow-up. A pharmacovigilance disproportionality analysis using the World Health Organization's global database was conducted. We then investigated the effect of leflunomide on human pulmonary endothelial cells. Data are expressed as median (min-max). Results: Twenty-eight patients treated with leflunomide before PH diagnosis was identified. A total of 21 (75%) had another risk factor for PH and 2 had two risk factors. The median time between leflunomide initiation and PH diagnosis was 32 months (1-120). Right heart catheterization confirmed precapillary PH with a cardiac index of 2.37 L⋅min-1 ⋅m-2 (1.19-3.1) and elevated pulmonary vascular resistance at 9.63 Wood Units (3.6-22.1) without nitric oxide reversibility. Five patients (17.9%) had no other risk factor for PH besides exposure to leflunomide. No significant hemodynamic improvement was observed after leflunomide withdrawal. The pharmacovigilance disproportionality analysis using the World Health Organization's database revealed a significant overrepresentation of leflunomide among reported pulmonary arterial hypertension-adverse drug reactions. In vitro studies showed the dose-dependent toxicity of leflunomide on human pulmonary endothelial cells. Conclusions: PH associated with leflunomide is rare and usually associated with other risk factors. The pharmacovigilance analysis suggests an association reinforced by experimental data.

18F-FDG PET and DCE kinetic modeling and their correlations in primary NSCLC: first voxel-wise correlative analysis of human simultaneous [18F]FDG PET-MRI data.

OBJECTIVES: To decipher the correlations between PET and DCE kinetic parameters in non-small-cell lung cancer (NSCLC), by using voxel-wise analysis of dynamic simultaneous [18F]FDG PET-MRI. MATERIAL AND METHODS: Fourteen treatment-naïve patients with biopsy-proven NSCLC prospectively underwent a 1-h dynamic [18F]FDG thoracic PET-MRI scan including DCE. The PET and DCE data were normalized to their corresponding T1-weighted MR morphological space, and tumors were masked semi-automatically. Voxel-wise parametric maps of PET and DCE kinetic parameters were computed by fitting the dynamic PET and DCE tumor data to the Sokoloff and Extended Tofts models respectively, by using in-house developed procedures. Curve-fitting errors were assessed by computing the relative root mean square error (rRMSE) of the estimated PET and DCE signals at the voxel level. For each tumor, Spearman correlation coefficients (rs) between all the pairs of PET and DCE kinetic parameters were estimated on a voxel-wise basis, along with their respective bootstrapped 95% confidence intervals (n = 1000 iterations). RESULTS: Curve-fitting metrics provided fit errors under 20% for almost 90% of the PET voxels (median rRMSE = 10.3, interquartile ranges IQR = 8.1; 14.3), whereas 73.3% of the DCE voxels showed fit errors under 45% (median rRMSE = 31.8%, IQR = 22.4; 46.6). The PET-PET, DCE-DCE, and PET-DCE voxel-wise correlations varied according to individual tumor behaviors. Beyond this wide variability, the PET-PET and DCE-DCE correlations were mainly high (absolute rs values > 0.7), whereas the PET-DCE correlations were mainly low to moderate (absolute rs values < 0.7). Half the tumors showed a hypometabolism with low perfused/vascularized profile, a hallmark of hypoxia, and tumor aggressiveness. CONCLUSION: A dynamic "one-stop shop" procedure applied to NSCLC is technically feasible in clinical practice. PET and DCE kinetic parameters assessed simultaneously are not highly correlated in NSCLC, and these correlations showed a wide variability among tumors and patients. These results tend to suggest that PET and DCE kinetic parameters might provide complementary information. In the future, this might make PET-MRI a unique tool to characterize the individual tumor biological behavior in NSCLC.

Characteristics and outcomes of asthmatic patients with COVID-19 pneumonia who require hospitalisation.

BACKGROUND: Viral respiratory infections are the main causes of asthma exacerbation. The susceptibility of patients with asthma to develop an exacerbation when they present with severe pneumonia due to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is unknown. The objective of this study was to investigate the characteristics and outcomes of asthmatic patients with coronavirus disease 2019 (COVID-19) pneumonia who required hospitalisation during the spring 2020 outbreak in Paris, France. METHODS: A prospective cohort follow-up was carried out from 15 March to 15 April 2020 in Bicêtre Hospital, University Paris-Saclay, France. All hospitalised patients with a SARS-CoV-2 infection who reported a history of asthma were included. RESULTS: Among 768 hospitalised patients, 37 (4.8%) reported a history of asthma, which had been previously confirmed by a pulmonologist in 85% of cases. These asthmatic patients were mainly female (70%) and nonsmokers (85%), with a median age of 54 years (interquartile range (IQR) 42-67 years). None of them presented with an asthma exacerbation. 22 (59%) had major comorbidities and 31 (84%) had a body mass index ≥25 kg·m-2. The most common comorbidities were obesity (36%), hypertension (27%) and diabetes (19%). All patients had a confirmed diagnosis of COVID-19 pneumonia on computed tomography of the chest. Eosinopenia was a typical biological feature with a median count of 0 cells·mm-3 (IQR 0-0 cells·mm-3). 11 patients (30%) were admitted into the intensive care unit, with three deaths (8.1%) occurring in the context of comorbidities. CONCLUSION: Asthma patients were not overrepresented among those with severe pneumonia due to SARS-CoV-2 infection who required hospitalisation. The worst outcomes were observed mainly in patients with major comorbidities.

Diffusion-weighted Imaging Voxelwise-matched Analyses of Lung Cancer at 3.0-T PET/MRI: Reverse Phase Encoding Approach for Echo-planar Imaging Distortion Correction.

Background PET/MRI has drawn increasing interest in thoracic oncology due to the simultaneous acquisition of PET and MRI data. Geometric distortions related to diffusion-weighted imaging (DWI) limit the evaluation of voxelwise multimodal analyses. Purpose To assess the effectiveness of reverse phase encoding in correcting DWI geometric distortion for multimodal PET/MRI voxelwise lung tumor analyses. Materials and Methods In this prospective study, reverse phase encoding method was implemented with 3.0-T PET/MRI to correct geometric distortions related to DWI. The method was validated in dedicated phantom and then applied to 12 consecutive patients (mean age, 66 years ± 13 [standard deviation]; 10 men) suspected of having lung cancer who underwent fluorodeoxyglucose PET/MRI between October 2018 and April 2019. The effects on DWI-related image matching and apparent diffusion coefficient (ADC) regional map computation were assessed. Consequences on multimodal PET/MRI voxelwise lung tumor analyses were evaluated. Spearman correlation coefficients (rs) between the standardized uptake value (SUV) and ADC data corrected for distortion were computed from optimal realigned DWI PET data, along with bootstrap confidence intervals. Results Phantom results showed that in highly distorted areas, correcting the distortion significantly reduced the mean error against the ground truth (-25% ± 10.6 to -18.4% ± 12.6; P < .001) and the number of voxels with more than 20% error (from 85.3% to 31.4%). In the 12 patients, the coregistration of multimodal PET/MRI tumor data was improved by using the reverse phase encoding method (0.4%-44%). In all tumors, voxelwise correlations (rs) between ADC and SUV revealed null or weak monotonic relationships (mean rs of 0.016 ± 0.24 with none above 0.5). Conclusion Reverse phase encoding is a simple-to-implement method for improved diffusion-weighted multimodal PET/MRI voxelwise-matched analyses in lung cancer. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Colletti in this issue.

Rapid Contour-based Segmentation for 18F-FDG PET Imaging of Lung Tumors by Using ITK-SNAP: Comparison to Expert-based Segmentation.

Purpose To assess the performance of the ITK-SNAP software for fluorodeoxyglucose (FDG) positron emission tomography (PET) segmentation of complex-shaped lung tumors compared with an optimized, expert-based manual reference standard. Materials and Methods Seventy-six FDG PET images of thoracic lesions were retrospectively segmented by using ITK-SNAP software. Each tumor was manually segmented by six raters to generate an optimized reference standard by using the simultaneous truth and performance level estimate algorithm. Four raters segmented 76 FDG PET images of lung tumors twice by using ITK-SNAP active contour algorithm. Accuracy of ITK-SNAP procedure was assessed by using Dice coefficient and Hausdorff metric. Interrater and intrarater reliability were estimated by using intraclass correlation coefficients of output volumes. Finally, the ITK-SNAP procedure was compared with currently recommended PET tumor delineation methods on the basis of thresholding at 41% volume of interest (VOI; VOI41) and 50% VOI (VOI50) of the tumor's maximal metabolism intensity. Results Accuracy estimates for the ITK-SNAP procedure indicated a Dice coefficient of 0.83 (95% confidence interval: 0.77, 0.89) and a Hausdorff distance of 12.6 mm (95% confidence interval: 9.82, 15.32). Interrater reliability was an intraclass correlation coefficient of 0.94 (95% confidence interval: 0.91, 0.96). The intrarater reliabilities were intraclass correlation coefficients above 0.97. Finally, VOI41 and VOI50 accuracy metrics were as follows: Dice coefficient, 0.48 (95% confidence interval: 0.44, 0.51) and 0.34 (95% confidence interval: 0.30, 0.38), respectively, and Hausdorff distance, 25.6 mm (95% confidence interval: 21.7, 31.4) and 31.3 mm (95% confidence interval: 26.8, 38.4), respectively. Conclusion ITK-SNAP is accurate and reliable for active-contour-based segmentation of heterogeneous thoracic PET tumors. ITK-SNAP surpassed the recommended PET methods compared with ground truth manual segmentation.

Adenosine deaminase is a useful biomarker to diagnose pleural tuberculosis in low to medium prevalence settings.

Adenosine deaminase (ADA) activity measurement in pleural fluid is a relevant test to diagnose pleural tuberculosis (pTB) in high tuberculosis prevalence settings. We investigated the diagnostic utility of pleural ADA using a retrospective analysis of patients admitted with newly diagnosed pleural effusion without identified etiology between 2001 and 2008 in Paris suburb, a low to medium tuberculosis prevalence area. 104 adults (mean age 55 years; 34 with pTB, 70 with other diagnoses) were analyzed. Median follow-up was 15.6 months. Mean [interquartile range] pleural ADA was 119 U/L [IQR: 83-143] in pTB and 24 U/L [IQR: 15-31] in non-tuberculous effusions (P<0.001). With an optimal pleural ADA cut-off value of 41.5 U/L for pTB diagnosis, sensitivity and specificity were 97.1% and 92.9%, while positive and negative predictive values were 86.8% and 98.5%, respectively. We conclude that pleural ADA activity could be integrated in the diagnostic procedures of pTB in low to medium tuberculosis prevalence settings.