A Review of Immunotherapy for Stage III and Metastatic Non-Small Cell Lung Cancer and the Rationale for the ECOG-ACRIN EA5181 Study.

ECOG-ACRIN EA5181 is a phase III prospective, randomized trial that randomizes patients undergoing chemo/radiation for locally advanced non-small cell lung cancer (LA-NSCLC) to concomitant durvalumab or no additional therapy, with both arms receiving 1 year of consolidative durvalumab. Radiation dose escalation failed to improve overall survival in RTOG 0617. However, conventionally fractionated radiation to 60 Gy with concomitant chemotherapy is associated with a high risk of local failure (38%-46%). It is hoped that concomitant immunotherapy during chemo/radiation can help decrease the risk of local failure, thereby improving overall survival and progression-free survival with acceptable toxicity. In this article, we review conventional chemo/radiation therapy for LA-NSCLC, as well as the quickly evolving world of immunotherapy in the treatment of non-small cell lung cancer and discuss the rationale and study design of EA5181. IMPLICATIONS FOR PRACTICE: This article provides an up-to-date assessment of how immunotherapy is reshaping the landscape of metastatic non-small cell lung cancer (NSCLC) and how the impact of this therapy is now rapidly moving into the treatment of patients with locally advanced NSCLC who are presenting for curative treatment. This article reviews the recent publications of chemo/radiation as well as those combining immunotherapy with chemotherapy and chemo/radiation, and provides a strategy for improving overall survival of patients with locally advanced NSCLC by using concomitant immunotherapy with standard concurrent chemo/radiation.

Phase I Study of Intrapleural Gene-Mediated Cytotoxic Immunotherapy in Patients with Malignant Pleural Effusion.

Gene-mediated cytotoxic immunotherapy (GMCI) is an immune strategy implemented through local delivery of an adenovirus-based vector expressing the thymidine kinase gene (aglatimagene besadenovec, AdV-tk) followed by anti-herpetic prodrug valacyclovir. A phase I dose escalation trial of GMCI followed by chemotherapy was conducted in patients with malignant pleural effusion (MPE). AdV-tk was administered intrapleurally (IP) in three cohorts at a dose of 1 × 1012 to 1013 vector particles. Primary endpoint was safety; secondary endpoints included response rate, progression-free survival, and overall survival. Nineteen patients were enrolled: median age 67 years; 14 with malignant mesothelioma, 4 non-small-cell lung cancer (NSCLC), and 1 breast cancer. There were no dose limiting toxicities. All 3 patients in cohort 2 experienced transient cytokine release syndrome (CRS). Addition of celecoxib in cohort 3 reduced the incidence and severity of CRS (none > grade 2). Three patients are alive (23-33 months after GMCI), and 3 of 4 NSCLC patients had prolonged disease stabilization; one is alive 29 months after GMCI, 3.6 years after initial diagnosis. GMCI was safe and well tolerated in combination with chemotherapy in patients with MPE and showed encouraging response. Further studies are warranted to determine efficacy.

PET imaging for assessing tumor response to therapy.

Positron emission tomography (PET) is a radioisotope imaging technique capable of quantifying the regional distribution of molecular imaging probes targeted to biochemical pathways and processes allowing direct measurement of biochemical changes induced by cancer therapy, including the activity of targeted growth pathways and cellular populations. In this manuscript, we review the underlying principles of PET imaging, choices for PET radiopharmaceuticals, methods for tumor analysis and PET applications for cancer therapy response assessment including potential future directions.

Pulmonary Tuberculosis: Role of Radiology in Diagnosis and Management.

Tuberculosis is a public health problem worldwide, including in the United States-particularly among immunocompromised patients and other high-risk groups. Tuberculosis manifests in active and latent forms. Active disease can occur as primary tuberculosis, developing shortly after infection, or postprimary tuberculosis, developing after a long period of latent infection. Primary tuberculosis occurs most commonly in children and immunocompromised patients, who present with lymphadenopathy, pulmonary consolidation, and pleural effusion. Postprimary tuberculosis may manifest with cavities, consolidations, and centrilobular nodules. Miliary tuberculosis refers to hematogenously disseminated disease that is more commonly seen in immunocompromised patients, who present with miliary lung nodules and multiorgan involvement. The principal means of testing for active tuberculosis is sputum analysis, including smear, culture, and nucleic acid amplification testing. Imaging findings, particularly the presence of cavitation, can affect treatment decisions, such as the duration of therapy. Latent tuberculosis is an asymptomatic infection that can lead to postprimary tuberculosis in the future. Patients who are suspected of having latent tuberculosis may undergo targeted testing with a tuberculin skin test or interferon-γ release assay. Chest radiographs are used to stratify for risk and to assess for asymptomatic active disease. Sequelae of previous tuberculosis that is now inactive manifest characteristically as fibronodular opacities in the apical and upper lung zones. Stability of radiographic findings for 6 months distinguishes inactive from active disease. Nontuberculous mycobacterial disease can sometimes mimic the findings of active tuberculosis, and laboratory confirmation is required to make the distinction. Familiarity with the imaging, clinical, and laboratory features of tuberculosis is important for diagnosis and management. ©RSNA, 2017.

Radiomics Analysis for the Identification of Invasive Pulmonary Subsolid Nodules From Longitudinal Presurgical CT Scans.

PURPOSE: Effective identification of malignant part-solid lung nodules is crucial to eliminate risks due to therapeutic intervention or lack thereof. We aimed to develop delta radiomics and volumetric signatures, characterize changes in nodule properties over three presurgical time points, and assess the accuracy of nodule invasiveness identification when combined with immediate presurgical time point radiomics signature and clinical biomarkers. MATERIALS AND METHODS: Cohort included 156 part-solid lung nodules with immediate presurgical CT scans and a subset of 122 nodules with scans at 3 presurgical time points. Region of interest segmentation was performed using ITK-SNAP, and feature extraction using CaPTk. Image parameter heterogeneity was mitigated at each time point using nested ComBat harmonization. For 122 nodules, delta radiomics features (ΔRAB= (RB-RA)/RA) and delta volumes (ΔVAB= (VB-VA)/VA) were computed between the time points. Principal Component Analysis was performed to construct immediate presurgical radiomics (Rs1) and delta radiomics signatures (ΔRs31+ ΔRs21+ ΔRs32). Identification of nodule pathology was performed using logistic regression on delta radiomics and immediate presurgical time point signatures, delta volumes (ΔV31+ ΔV21+ ΔV32), and clinical variable (smoking status, BMI) models (train test split (2:1)). RESULTS: In delta radiomics analysis (n= 122 nodules), the best-performing model combined immediate pre-surgical time point and delta radiomics signatures, delta volumes, and clinical factors (classification accuracy [AUC]): (77.5% [0.73]) (train); (71.6% [0.69]) (test). CONCLUSIONS: Delta radiomics and volumes can detect changes in nodule properties over time, which are predictive of nodule invasiveness. These tools could improve conventional radiologic assessment, allow for earlier intervention for aggressive nodules, and decrease unnecessary intervention-related morbidity.

Imaging in pleural Mesothelioma: A review of the 16th International Conference of the International Mesothelioma Interest Group.

Imaging continues to gain a greater role in the assessment and clinical management of patients with mesothelioma. This communication summarizes the oral presentations from the imaging session at the 2023 International Conference of the International Mesothelioma Interest Group (iMig), which was held in Lille, France from June 26 to 28, 2023. Topics at this session included an overview of best practices for clinical imaging of mesothelioma as reported by an iMig consensus panel, emerging imaging techniques for surgical planning, radiologic assessment of malignant pleural effusion, a radiomics-based transfer learning model to predict patient response to treatment, automated assessment of early contrast enhancement, and tumor thickness for response assessment in peritoneal mesothelioma.

KLF5 and p53 comprise an incoherent feed-forward loop directing cell-fate decisions following stress.

In response to stress, cells make a critical decision to arrest or undergo apoptosis, mediated in large part by the tumor suppressor p53. Yet the mechanisms of these cell fate decisions remain largely unknown, particularly in normal cells. Here, we define an incoherent feed-forward loop in non-transformed human squamous epithelial cells involving p53 and the zinc-finger transcription factor KLF5 that dictates responses to differing levels of cellular stress from UV irradiation or oxidative stress. In normal unstressed human squamous epithelial cells, KLF5 complexes with SIN3A and HDAC2 repress TP53, allowing cells to proliferate. With moderate stress, this complex is disrupted, and TP53 is induced; KLF5 then acts as a molecular switch for p53 function by transactivating AKT1 and AKT3, which direct cells toward survival. By contrast, severe stress results in KLF5 loss, such that AKT1 and AKT3 are not induced, and cells preferentially undergo apoptosis. Thus, in human squamous epithelial cells, KLF5 gates the response to UV or oxidative stress to determine the p53 output of growth arrest or apoptosis.

Considerations for Imaging of Malignant Pleural Mesothelioma: A Consensus Statement from the International Mesothelioma Interest Group.

Malignant pleural mesothelioma (MPM) is an aggressive primary malignancy of the pleura that presents unique radiologic challenges with regard to accurate and reproducible assessment of disease extent at staging and follow-up imaging. By optimizing and harmonizing technical approaches to imaging MPM, the best quality imaging can be achieved for individual patient care, clinical trials, and imaging research. This consensus statement represents agreement on harmonized, standard practices for routine multimodality imaging of MPM, including radiography, computed tomography, 18F-2-deoxy-D-glucose positron emission tomography, and magnetic resonance imaging, by an international panel of experts in the field of pleural imaging assembled by the International Mesothelioma Interest Group. In addition, modality-specific technical considerations and future directions are discussed. A bulleted summary of all technical recommendations is provided.

Clinical Outcomes Associated With Pembrolizumab Monotherapy Among Adults With Diffuse Malignant Peritoneal Mesothelioma.

Importance: Diffuse malignant peritoneal mesothelioma (DMPM) represents a rare and clinically distinct entity among malignant mesotheliomas. Pembrolizumab has activity in diffuse pleural mesothelioma but limited data are available for DMPM; thus, DMPM-specific outcome data are needed. Objective: To evaluate outcomes after the initiation of pembrolizumab monotherapy in the treatment of adults with DMPM. Design, Setting, and Participants: This retrospective cohort study was conducted in 2 tertiary care academic cancer centers (University of Pennsylvania Hospital Abramson Cancer Center and Memorial Sloan Kettering Cancer Center). All patients with DMPM treated between January 1, 2015, and September 1, 2019, were retrospectively identified and followed until January 1, 2021. Statistical analysis was performed between September 2021 and February 2022. Exposures: Pembrolizumab (200 mg or 2 mg/kg every 21 days). Main Outcomes and Measures: Median progression-free survival (PFS) and median overall survival (OS) were assessed using Kaplan-Meier estimates. The best overall response was determined using RECIST (Response Evaluation Criteria in Solid Tumors) criteria, version 1.1. The association of disease characteristics with partial response was evaluated using the Fisher exact test. Results: This study included 24 patients with DMPM who received pembrolizumab monotherapy. Patients had a median age of 62 years (IQR, 52.4-70.6 years); 14 (58.3%) were women, 18 (75.0%) had epithelioid histology, and most (19 [79.2%]) were White. A total of 23 patients (95.8%) received systemic chemotherapy prior to pembrolizumab, and the median number of lines of prior therapy was 2 (range, 0-6 lines). Of the 17 patients who underwent programmed death ligand 1 (PD-L1) testing, 6 (35.3%) had positive tumor PD-L1 expression (range, 1.0%-80.0%). Of the 19 evaluable patients, 4 (21.0%) had a partial response (overall response rate, 21.1% [95% CI, 6.1%-46.6%]), 10 (52.6%) had stable disease, and 5 (26.3%) had progressive disease (5 of 24 patients [20.8%] were lost to follow-up). There was no association between a partial response and the presence of a BAP1 alteration, PD-L1 positivity, or nonepithelioid histology. With a median follow-up of 29.2 (95% CI, 19.3 to not available [NA]) months, the median PFS was 4.9 (95% CI, 2.8-13.3) months and the median OS was 20.9 (95% CI, 10.0 to NA) months from pembrolizumab initiation. Three patients (12.5%) experienced PFS of more than 2 years. Among patients with nonepithelioid vs epithelioid histology, there was a numeric advantage in median PFS (11.5 [95% CI, 2.8 to NA] vs 4.0 [95% CI, 2.8-8.8] months) and median OS (31.8 [95% CI, 8.3 to NA] vs 17.5 [95% CI, 10.0 to NA] months); however, this did not reach statistical significance. Conclusions and Relevance: The results of this retrospective dual-center cohort study of patients with DMPM suggest that pembrolizumab had clinical activity regardless of PD-L1 status or histology, although patients with nonepithelioid histology may have experienced additional clinical benefit. The partial response rate of 21.0% and median OS of 20.9 months in this cohort with 75.0% epithelioid histology warrants further investigation to identify those most likely to respond to immunotherapy.

A trial of intrapleural adenoviral-mediated Interferon-α2b gene transfer for malignant pleural mesothelioma.

New therapeutic strategies are needed for malignant pleural mesothelioma (MPM). We conducted a single-center, open-label, nonrandomized, pilot and feasibility trial using two intrapleural doses of an adenoviral vector encoding human IFN-α (Ad.IFN-α2b). Nine subjects were enrolled at two dose levels. The first three subjects had very high pleural and systemic IFN-α concentrations resulting in severe "flu-like" symptoms necessitating dose de-escalation. The next six patients had reduced (but still significant) pleural and serum IFN-α levels, but with tolerable symptoms. Repeated vector administration appeared to prolong IFN-α expression levels. Anti-tumor humoral immune responses against mesothelioma cell lines were seen in seven of the eight subjects evaluated. No clinical responses were seen in the four subjects with advanced disease. However, evidence of disease stability or tumor regression was seen in the remaining five patients, including one dramatic example of partial tumor regression at sites not in contiguity with vector infusion. These data show that Ad.IFN-α2b has potential therapeutic benefit in MPM and that it generates anti-tumor immune responses that may induce anatomic and/or metabolic reductions in distant tumor. Clinical trial registered with www.clinicaltrials.gov (NCT 01212367).

Resampling and harmonization for mitigation of heterogeneity in image parameters of baseline scans.

Our study investigates the effects of heterogeneity in image parameters on the reproducibility of prognostic performance of models built using radiomic biomarkers. We compare the prognostic performance of models derived from the heterogeneity-mitigated features with that of models obtained from raw features, to assess whether reproducibility of prognostic scores improves upon application of our methods. We used two datasets: The Breast I-SPY1 dataset-Baseline DCE-MRI scans of 156 women with locally advanced breast cancer, treated with neoadjuvant chemotherapy, publicly available via The Cancer Imaging Archive (TCIA); The NSCLC IO dataset-Baseline CT scans of 107 patients with stage 4 non-small cell lung cancer (NSCLC), treated with pembrolizumab immunotherapy at our institution. Radiomic features (n = 102) are extracted from the tumor ROIs. We use a variety of resampling and harmonization scenarios to mitigate the heterogeneity in image parameters. The patients were divided into groups based on batch variables. For each group, the radiomic phenotypes are combined with the clinical covariates into a prognostic model. The performance of the groups is assessed using the c-statistic, derived from a Cox proportional hazards model fitted on all patients within a group. The heterogeneity-mitigation scenario (radiomic features, derived from images that have been resampled to minimum voxel spacing, are harmonized using the image acquisition parameters as batch variables) gave models with highest prognostic scores (for e.g., IO dataset; batch variable: high kernel resolution-c-score: 0.66). The prognostic performance of patient groups is not comparable in case of models built using non-heterogeneity mitigated features (for e.g., I-SPY1 dataset; batch variable: small pixel spacing-c-score: 0.54, large pixel spacing-c-score: 0.65). The prognostic performance of patient groups is closer in case of heterogeneity-mitigated scenarios (for e.g., scenario-harmonize by voxel spacing parameters: IO dataset; thin slice-c-score: 0.62, thick slice-c-score: 0.60). Our results indicate that accounting for heterogeneity in image parameters is important to obtain more reproducible prognostic scores, irrespective of image site or modality. For non-heterogeneity mitigated models, the prognostic scores are not comparable across patient groups divided based on batch variables. This study can be a step in the direction of constructing reproducible radiomic biomarkers, thus increasing their application in clinical decision making.

Imaging in pleural mesothelioma: A review of the 15th International Conference of the International Mesothelioma Interest Group.

Imaging of mesothelioma plays a role in all aspects of patient management, including disease detection, staging, evaluation of treatment options, response assessment, pre-surgical evaluation, and surveillance. Imaging in this disease impacts a wide range of disciplines throughout the healthcare enterprise. Researchers and clinician-scientists are developing state-of-the-art techniques to extract more of the information contained within these medical images and to utilize it for more sophisticated tasks; moreover, image-acquisition technology is advancing the inherent capabilities of these images. This paper summarizes the imaging-based topics presented orally at the 2021 International Conference of the International Mesothelioma Interest Group (iMig), which was held virtually from May 7-9, 2021. These topics include an update on the mesothelioma staging system, novel molecular targets to guide therapy in mesothelioma, special considerations and potential pitfalls in imaging mesothelioma in the immunotherapy setting, tumor measurement strategies and their correlation with patient survival, tumor volume measurement in MRI and CT, CT-based texture analysis for differentiation of histologic subtype, diffusion-weighted MRI for the assessment of biphasic mesothelioma, and the prognostic significance of skeletal muscle loss with chemotherapy.

Comparative Evaluation of Choose Your Own Adventure and Traditional Linear Case Formats in Radiology Small Group Teaching.

RATIONALE AND OBJECTIVES: We aim to compare Choose Your Own Adventure (CYOA) presentation format with linear case format as educational methods for teaching a radiology small group session to medical students. MATERIALS AND METHODS: A radiology small group session was held for preclinical second-year medical students in the pulmonary course, whereby eight classrooms of students and eight radiology facilitators were each randomized to do either the linear case format or the nonlinear CYOA presentation format. All students in attendance were administered a survey at the end of the session, which assessed students' perceptions using five-point Likert-type questions. The survey also contained a four-question knowledge quiz on chest radiology. The facilitators were administered a qualitative survey as well. Between-group analyses were performed using Student's t-test. RESULTS: Of the 144 students who attended the small group sessions, 143 students completed the survey (99.3%). The CYOA format group reported significantly greater engagement in the cases (4.5 ± 0.7 vs. 3.8 ± 0.7, p < 0.001), satisfaction with the format (4.6 ± 0.6 vs. 3.7 ± 0.9, p < 0.001), and enhancement of clinical decision making skills (4.5 ± 0.6 vs. 3.5 ± 0.9, p < 0.001). The linear format group reported a greater role for the facilitator to add value (4.6 ± 0.5 vs. 4.3 ± 1.1, p = 0.033). There was no significant difference between groups in performance on the knowledge quiz. CONCLUSION: Medical students reported higher satisfaction, engagement, and enhanced clinical decision making skills with the CYOA presentation method compared to linear case format for radiology small group learning.

Development of a robust radiomic biomarker of progression-free survival in advanced non-small cell lung cancer patients treated with first-line immunotherapy.

We aim to determine the feasibility of a novel radiomic biomarker that can integrate with other established clinical prognostic factors to predict progression-free survival (PFS) in patients with non-small cell lung cancer (NSCLC) undergoing first-line immunotherapy. Our study includes 107 patients with stage 4 NSCLC treated with pembrolizumab-based therapy (monotherapy: 30%, combination chemotherapy: 70%). The ITK-SNAP software was used for 3D tumor volume segmentation from pre-therapy CT scans. Radiomic features (n = 102) were extracted using the CaPTk software. Impact of heterogeneity introduced by image physical dimensions (voxel spacing parameters) and acquisition parameters (contrast enhancement and CT reconstruction kernel) was mitigated by resampling the images to the minimum voxel spacing parameters and harmonization by a nested ComBat technique. This technique was initialized with radiomic features, clinical factors of age, sex, race, PD-L1 expression, ECOG status, body mass index (BMI), smoking status, recurrence event and months of progression-free survival, and image acquisition parameters as batch variables. Two phenotypes were identified using unsupervised hierarchical clustering of harmonized features. Prognostic factors, including PDL1 expression, ECOG status, BMI and smoking status, were combined with radiomic phenotypes in Cox regression models of PFS and Kaplan Meier (KM) curve-fitting. Cox model based on clinical factors had a c-statistic of 0.57, which increased to 0.63 upon addition of phenotypes derived from harmonized features. There were statistically significant differences in survival outcomes stratified by clinical covariates, as measured by the log-rank test (p = 0.034), which improved upon addition of phenotypes (p = 0.00022). We found that mitigation of heterogeneity by image resampling and nested ComBat harmonization improves prognostic value of phenotypes, resulting in better prediction of PFS when added to other prognostic variables.

A phase I trial of repeated intrapleural adenoviral-mediated interferon-beta gene transfer for mesothelioma and metastatic pleural effusions.

We previously showed that a single intrapleural dose of an adenoviral vector expressing interferon-beta (Ad.IFN-beta) in patients with malignant pleural mesothelioma (MPM) or malignant pleural effusions (MPE) resulted in gene transfer, humoral antitumor immune responses, and anecdotal clinical responses manifested by modified Response Evaluation Criteria in Solid Tumors (RECIST) disease stability in 3 of 10 patients at 2 months and an additional patient with significant metabolic response on positron emission tomography (PET) imaging. This phase I trial was conducted to determine whether using two doses of Ad.IFN-beta vector would be superior. Ten patients with MPM and seven with MPE received two doses of Ad.IFN-beta through an indwelling pleural catheter. Repeated doses were generally well tolerated. High levels of IFN-beta were detected in pleural fluid after the first dose; however, only minimal levels were seen after the second dose of vector. Lack of expression correlated with the rapid induction of neutralizing Ad antibodies (Nabs). Antibody responses against tumor antigens were induced in most patients. At 2 months, modified RECIST responses were as follows: one partial response, two stable disease, nine progressive disease, and two nonmeasurable disease. One patient died after 1 month. By PET scanning, 2 patients had mixed responses and 11 had stable disease. There were seven patients with survival times longer than 18 months. This approach was safe, induced immune responses and disease stability. However, rapid development of Nabs prevented effective gene transfer after the second dose, even with a dose interval as short as 7 days.

Multimodality imaging of Surgicel®, an important mimic of post-operative complication in the thorax.

Absorbable hemostatic agents such as Surgicel are hemostatic materials composed of an oxidized cellulose polymer used to control post-surgical bleeding and cause coagulation. This material is sometimes purposefully left in situ where it slowly degrades over time and can produce an imaging appearance that mimics serious post-operative complications such as gangrenous infections and anastomotic leaks as well as potentially mimicking disease recurrence in later stages. In this article, we review the multimodality imaging appearance of this material in situ longitudinally in the range of post-operative settings, in order to promote awareness of this entity when interpreting post-operative imaging. We present this as a pictorial review focusing primarily but not exclusively on the chest noting that the thoracic imaging appearance of Surgicel® is less well reported in the published literature. An understanding of this entity may help to minimize erroneous diagnosis of a postoperative complication leading to unnecessary interventions.

A 53-Year-Old Man Presents to the ED With Shortness of Breath, Cough, and Fever.

CASE PRESENTATION: A 53-year-old man presented to the ED at a time of low severe acute respiratory syndrome coronavirus 2, also known as coronavirus disease 2019 (COVID-19), prevalence and reported 2 weeks of progressive shortness of breath, dry cough, headache, myalgias, diarrhea, and recurrent low-grade fevers to 39°C for 1 week with several days of recorded peripheral capillary oxygen saturation of 80% to 90% (room air) on home pulse oximeter. Five days earlier, he had visited an urgent care center where a routine respiratory viral panel was reportedly negative. A COVID-19 reverse transcriptase polymerase chain reaction test result was pending at the time of ED visit. He reported a past medical history of gastroesophageal reflux disease that was treated with famotidine. Travel history included an out-of-state trip 3 weeks earlier, but no recent international travel.

CT for detection of malignant posterior intercostal lymph nodes in patients undergoing pre-operative staging for malignant pleural mesothelioma.

INTRODUCTION: Recent evidence suggests that patients with malignant pleural mesothelioma (MPM) undergoing extended pleurectomy/decortication (eP/D) with metastasis to the posterior intercostal lymph nodes (PILN) have a worse prognosis. In this study, we determine if MPM PILN metastasis can be reliably detected on computed tomography (CT). MATERIALS AND METHODS: Preoperative staging CT exams were reviewed for the presence of PILN in MPM patients undergoing eP/D between 2007-2013 with surgical sampling of their PILN. CT images were reviewed by two thoracic radiologists blinded to clinical records, including operative pathology reports. The number and short axis size of PILN were recorded and correlated with surgical pathology. Statistical analysis examined the value of preoperative CT to detect metastatic PILN. RESULTS: Of 36 patients that underwent eP/D with PILN sampling had preoperative CT images for review. At surgery, 22 of these patients had metastatic PILN and 14 had benign PILN. The positive and negative predictive values for one or more nodes seen on preoperative CT were 60 % and 38 % respectively. The number of PILN on preoperative CT did not predict metastasis (p = 0.40) with an average of 2 PILN seen, regardless of PILN pathology. The average nodal short axis size was 4.6 mm and 4.8 mm for benign and malignant PILN, respectively, and PILN short axis size did not predict metastasis (p = 0.39). There was little inter-observer variability between the size and number of nodes detected by each radiologist. CONCLUSIONS: CT does not reliably identify metastatic PILN on preoperative CT for patients with MPM undergoing extended pleurectomy/decortication.

Impact of Interobserver Variability in Manual Segmentation of Non-Small Cell Lung Cancer (NSCLC) Applying Low-Rank Radiomic Representation on Computed Tomography.

This study tackles interobserver variability with respect to specialty training in manual segmentation of non-small cell lung cancer (NSCLC). Four readers included for segmentation are: a data scientist (BY), a medical student (LS), a radiology trainee (MH), and a specialty-trained radiologist (SK) for a total of 293 patients from two publicly available databases. Sørensen-Dice (SD) coefficients and low rank Pearson correlation coefficients (CC) of 429 radiomics were calculated to assess interobserver variability. Cox proportional hazard (CPH) models and Kaplan-Meier (KM) curves of overall survival (OS) prediction for each dataset were also generated. SD and CC for segmentations demonstrated high similarities, yielding, SD: 0.79 and CC: 0.92 (BY-SK), SD: 0.81 and CC: 0.83 (LS-SK), and SD: 0.84 and CC: 0.91 (MH-SK) in average for both databases, respectively. OS through the maximal CPH model for the two datasets yielded c-statistics of 0.7 (95% CI) and 0.69 (95% CI), while adding radiomic and clinical variables (sex, stage/morphological status, and histology) together. KM curves also showed significant discrimination between high- and low-risk patients (p-value < 0.005). This supports that readers' level of training and clinical experience may not significantly influence the ability to extract accurate radiomic features for NSCLC on CT. This potentially allows flexibility in the training required to produce robust prognostic imaging biomarkers for potential clinical translation.