[18F]Fluorodeoxyglucose positron emission tomography (FDG-PET) and computed tomography (CT) are indispensable components in modern medicine. Although PET can provide additional diagnostic value, it is costly and not universally accessible, particularly in low-income countries. To bridge this gap, we have developed a conditional generative adversarial network pipeline that can produce FDG-PET from diagnostic CT scans based on multi-center multi-modal lung cancer datasets (n = 1,478). Synthetic PET images are validated across imaging, biological, and clinical aspects. Radiologists confirm comparable imaging quality and tumor contrast between synthetic and actual PET scans. Radiogenomics analysis further proves that the dysregulated cancer hallmark pathways of synthetic PET are consistent with actual PET. We also demonstrate the clinical values of synthetic PET in improving lung cancer diagnosis, staging, risk prediction, and prognosis. Taken together, this proof-of-concept study testifies to the feasibility of applying deep learning to obtain high-fidelity PET translated from CT.

Malignant mesothelioma is a rare tumor arising from the mesothelial cells that line the pleura, pericardium, peritoneum, and tunica vaginalis. Imaging plays a primary role in the diagnosis, staging, and management of malignant mesothelioma. Multimodality imaging, including radiography, computed tomography (CT), magnetic resonance imaging (MRI), and F-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT), is used in a variety of scenarios, including diagnosis, guidance for tissue sampling, staging, and reassessment of disease after therapy. CT is the primary imaging modality used in staging. MRI has superior contrast resolution compared with CT and can add value in terms of determining surgical resectability in equivocal cases. MRI can further assess the degree of local invasion, particularly into the mediastinum, chest wall, and diaphragm, for malignant pleural and pericardial mesotheliomas. FDG PET/CT plays a role in the diagnosis and staging of malignant pleural mesothelioma (MPM) and has been shown to be more accurate than CT, MRI, and PET alone in the staging of malignant pleural mesothelioma. PET/CT can also be used to target lesions for biopsy and to assess prognosis, treatment response, and tumor recurrence.

A wide variety of neoplastic and nonneoplastic conditions occur in the mediastinum. Imaging plays a central role in the evaluation of mediastinal pathologies and their mimics. Localization of a mediastinal lesion to a compartment and characterization of morphology, density/signal intensity, enhancement, and mass effect on neighboring structures can help narrow the differentials. The International Thymic Malignancy Interest Group (ITMIG) established a cross-sectional imaging-derived and anatomy-based classification system for mediastinal compartments, comprising the prevascular (anterior), visceral (middle), and paravertebral (posterior) compartments. Cross-sectional imaging is integral in the evaluation of mediastinal lesions. Computed tomography (CT) and magnetic resonance imaging (MRI) are useful to characterize mediastinal lesions detected on radiography. Advantages of CT include its widespread availability, fast acquisition time, relatively low cost, and ability to detect calcium. Advantages of MRI include the lack of radiation exposure, superior soft tissue contrast resolution to detect invasion of the mass across tissue planes, including the chest wall and diaphragm, involvement of neurovascular structures, and the potential for dynamic sequences during free-breathing or cinematic cardiac gating to assess motion of the mass relative to adjacent structures. MRI is superior to CT in the differentiation of cystic from solid lesions and in the detection of fat to differentiate thymic hyperplasia from thymic malignancy.

OBJECTIVES:Cancer patients have worse outcomes from the COVID-19 infection and greater need for ventilator support and elevated mortality rates than the general population. However, previous artificial intelligence (AI) studies focused on patients without cancer to develop diagnosis and severity prediction models. Little is known about how the AI models perform in cancer patients. In this study, we aim to develop a computational framework for COVID-19 diagnosis and severity prediction particularly in a cancer population and further compare it head-to-head to a general population. METHODS:We have enrolled multi-center international cohorts with 531 CT scans from 502 general patients and 420 CT scans from 414 cancer patients. In particular, the habitat imaging pipeline was developed to quantify the complex infection patterns by partitioning the whole lung regions into phenotypically different subregions. Subsequently, various machine learning models nested with feature selection were built for COVID-19 detection and severity prediction. RESULTS:These models showed almost perfect performance in COVID-19 infection diagnosis and predicting its severity during cross validation. Our analysis revealed that models built separately on the cancer population performed significantly better than those built on the general population and locked to test on the cancer population. This may be because of the significant difference among the habitat features across the two different cohorts. CONCLUSIONS:Taken together, our habitat imaging analysis as a proof-of-concept study has highlighted the unique radiologic features of cancer patients and demonstrated effectiveness of CT-based machine learning model in informing COVID-19 management in the cancer population.

In imaging of the mediastinum, advances in computed tomography (CT), and magnetic resonance imaging (MRI) technology enable improved characterization of mediastinal masses. Knowledge of the boundaries of the mediastinal compartments is key to accurate localization. Awareness of distinguishing imaging characteristics allows radiologists to suggest a specific diagnosis or narrow the differential. In certain situations, MRI adds value to further characterize mediastinal lesions.

Introduction: Patients with systemic AL amyloidosis (AL) should be evaluated for cardiac amyloidosis (CA), as prognosis is strongly related to cardiac involvement. We assessed the characteristics of patients referred to cardiac magnetic resonance (CMR) with suspected CA from a cancer center and determine predictors of mortality/heart failure hospitalizations (HFH). Methods: Forty-four consecutive patients referred for CMR with suspected CA were retrospectively included. Variables collected included cardiac biomarkers, in addition to echocardiographic and CMR variables. Survival analyses were performed to determine which variables were more predictive of mortality and HFH. Results: Of the 44 patients included, 55% were females. 73% of patients were diagnosed with CA by CMR; 56% of them had an established diagnosis of AL. Patients with CA by CMR had higher native T1, higher extracellular volume (ECV) fraction, higher T2, less negative GLS by Echo, and higher troponin I and B-type natriuretic peptide (BNP). Kaplan-Meier survival analysis revealed that the following were predictive of mortality: an ECV ≥ 0.50 ( p = 0.0098), CMR LVEF < 50% ( p = 0.0010), T2/ECV ≤ 100 ( p = 0.0001), and troponin I > 0.03 ( p = 0.0025). In a stepwise conditional Cox logistic regression model, the only variable predictive of a composite of mortality and HFH was ECV (HR: 1.17, 95% CI = 1.02–1.34 p = 0.030). Conclusion: ECV seems to be an important biomarker that could be a predictor of outcomes in cardiac AL amyloidosis. In combination, CMR and serum cardiac biomarkers might help to establish prognosis in patients with CA.

Introduction: Late cardiotoxicity related to radiotherapy (RT) in breast cancer and Hodgkin's lymphoma has been well-reported. However, the relatively higher cardiac dose exposure for esophageal cancer (EC) may result in the earlier onset of cardiac diseases. In this report, we examined the incidence, onset, and long-term survival outcomes of high-grade cardiac events after RT in a large cohort of patients with EC. Methods: Between March 2005 and August 2017, a total of 479 patients with EC from a prospectively maintained institutional database at The University of Texas MD Anderson Cancer Center were analyzed. All patients were treated with either intensity-modulated RT or proton beam therapy, either preoperatively or definitively. We focused on any grade 3 or higher (G3+) cardiac events according to the Common Terminology Criteria for Adverse Events, version 5.0. Results: G3+ cardiac events occurred in 18% of patients at a median of 7 months with a median follow-up time of 76 months. Preexisting cardiac disease (p = 0.001) and radiation modality (intensity-modulated RT versus proton beam therapy) (p = 0.027) were significantly associated with G3+ cardiac events. Under multivariable analysis, the mean heart dose, particularly of less than 15 Gy, was associated with reduced G3+ events. Furthermore, G3+ cardiac events were associated with worse overall survival (p = 0.041). Conclusions: Severe cardiac events were relatively common in patients with early onset EC after RT, especially those with preexisting cardiac disease and higher radiation doses to the heart. Optimal treatment approaches should be taken to reduce cumulative doses to the heart, especially for patients with preexisting cardiac disease. (C) 2020 International Association for the Study of Lung Cancer. Published by Elsevier Inc. All rights reserved.

BACKGROUND:Radiation exposure increases the risk of coronary artery disease (CAD). We explored the association of CAD with coronary artery dose-volume parameters in patients treated with 3D-planned radiation therapy (RT).METHODS:Patients who received thoracic RT and were evaluated by cardiac computed tomography ≥ 1 year later were included. Demographic data and cardiac risk factors were retrospectively collected. Dosimetric data (mean heart dose, dmax, dmean, V50 - V₅) were collected for the whole heart and for each coronary artery. A coronary artery calcium (CAC) Agatston score was calculated on a per-coronary basis and as a total score. Multivariable generalized linear mixed models were generated. The predicted probabilities were used for receiver operating characteristic analyses.RESULTS:Twenty patients with a median age of 53 years at the time of RT were included. Nine patients (45%) had ≥ 3/6 conventional cardiac risk factors. Patients received RT for breast cancer (10, 50%), lung cancer (6, 30%), or lymphoma/myeloma (4, 20%) with a median dose of 60 Gy. CAC scans were performed a median of 32 months after RT. CAC score was significantly associated with radiation dose and presence of diabetes. In a multivariable model adjusted for diabetes, segmental coronary artery dosimetric parameters (dmax, dmean, V₅₀, V₄₀ V₃₀, V₂₀, V₁₀, and V₅) were significantly associated with CAC score > 0. V₅₀ had the highest area under the ROC curve (0.89, 95% confidence interval, 0.80-0.97).CONCLUSIONS:Coronary artery radiation exposure is strongly correlated with subsequent segmental CAC score. Coronary calcification may occur soon after RT and in individuals with conventional cardiac risk factors.

From detailed characterization of cardiac abnormalities to the assessment of cancer treatment‐related cardiac dysfunction, cardiac MRI is playing a growing role in the evaluation of cardiac pathology in oncology patients. Current guidelines are now incorporating the use of MRI for the comprehensive multidisciplinary approach to cancer management, and innovative applications of MRI in research are expanding its potential to provide a powerful noninvasive tool in the arsenal against cancer. This review focuses on the application of cardiac MRI to diagnose and manage cardiovascular complications related to cancer and its treatment. Following an introduction to current cardiac MRI methods and principles, this review is divided into two sections: functional cardiovascular analysis and anatomical or tissue characterization related to cancer and cancer therapeutics. Level of Evidence: 5 Technical Efficacy Stage: 1 J. Magn. Reson. Imaging 2019;50:1349–1366.

Continuous bed motion (CBM) was recently introduced as an alternative to step-and-shoot (SS) mode for PET/CT data acquisition. In CBM, the patient is continuously advanced into the scanner at a preset speed, whereas in SS, the patient is imaged in overlapping bed positions. Previous investigations have shown that patients preferred CBM over SS for PET data acquisition. In this study, we investigated the effect of CBM versus SS on patient breathing and respiratory motion correction. One hundred patients referred for PET/CT were scanned using a Siemens mCT scanner. Patient respiratory waveforms were recorded using an Anzai system and analyzed using four methods: Methods 1 and 2 measured the coefficient of variation (COV) of the respiratory cycle duration (RCD) and amplitude (RCA). Method 3 measured the respiratory frequency signal prominence (RSP) and method 4 measured the width of the HDChest optimal gate (OG) window when using a 35% duty cycle. Waveform analysis was performed over the abdominothoracic region which exhibited the greatest respiratory motion and the results were compared between CBM and SS. Respiratory motion correction was assessed by comparing the ratios of SUVmax, SUVpeak, and CNR of focal FDG uptake, as well as Radiologists' visual assessment of corresponding image quality of motion corrected and uncorrected images for both acquisition modes. The respiratory waveforms analysis showed that the RCD and RCA COV were 3.7% and 33.3% lower for CBM compared to SS, respectively, while the RSP and OG were 30.5% and 2.0% higher, respectively. Image analysis on the other hand showed that SUVmax, SUVpeak, and CNR were 8.5%, 4.5%, and 3.4% higher for SS compared to CBM, respectively, while the Radiologists' visual comparison showed similar image quality between acquisition modes. However, none of the results showed statistically significant differences between SS and CBM, suggesting that motion correction is not impacted by acquisition mode.

Our purpose is to discuss the importance of multimodality imaging in the assessment of cardiac tumors and management. We have compiled a recent review of the scientific literature and embedded our clinical pathways and recommendations based on data and clinical experience.

Response assessment in mesothelioma using the Response Evaluation Criteria in Solid Tumors (RECIST) continues to be challenging, with higher disagreement between investigators that with other solid tumors. The modified RECIST1Byrne M.J. Nowak A.K. Modified RECIST criteria for assessment of response in malignant pleural mesothelioma.Ann Oncol. 2004; 15: 257-260Crossref PubMed Scopus (529) Google Scholar system that was published in 2004 enabled more accurate measurements of the pleural rind by implementing six perpendicular chest wall measurements from three separate sections of the pleural tumor. Even though this was an improvement over RECIST, high variability and imprecision in measurements and adherence to the correct methodology continues to affect response assessment. The article by Armato and Nowak in this issue of the Journal of Thoracic Oncology proposes amendments to modified RECIST version 1.0 with the new RECIST version 1.1.2Armato 3rd, S.G. Nowak A.K. Revised modified response evaluation criteria in solid tumors for assessment of response in malignant pleural mesothelioma (version 1.1).J Thorac Oncol. 2018; 13: 1012-1021Abstract Full Text Full Text PDF PubMed Scopus (56) Google Scholar The authors should be complimented for undertaking this important task and suggesting necessary updates. The article provides clarification of the methodology and proposes novel changes to disease quantification. We agree with the authors on several points but have concerns about others. We agree that the minimum baseline measurable pleural disease should be redefined from 10 mm to 7 mm and that in treatment responders, the minimum default size should be adjusted from 5 mm to 2 mm. However, we acknowledge that there may be concern over measurement consistency at this small size given a potential 10% to 15% variability. Also, classifying the default size as 2 mm will be inconsistent with RECIST version 1.1, according to which the minimum default size is specified as 5 mm. This may cause confusion among investigators who treat mesothelioma infrequently. For improvements in measurement consistency, we agree with the authors' recommendations to maintain the orientation, keep the same observer, utilize the same image display parameters, and store the reference baseline measurement graphics. This is especially important for trials that have independent central radiographic review. We also agree with updating nonpleural and lymph node measurements to be consistent with RECIST 1.1, notating nonmeasurable pleural disease with statements such as “extensive pleural nodularity”2Armato 3rd, S.G. Nowak A.K. Revised modified response evaluation criteria in solid tumors for assessment of response in malignant pleural mesothelioma (version 1.1).J Thorac Oncol. 2018; 13: 1012-1021Abstract Full Text Full Text PDF PubMed Scopus (56) Google Scholar and utilizing immune-related RECIST parameters for immune-modified Response Evaluation Criteria in Solid Tumors 1.1. We differ in opinion with the authors on four main issues. First, in defining measurable disease, the authors propose a “selection of up to six pleural measurements at baseline (with no more than two sites per computed tomography [CT] section) and sites selected across no more than three sections each separated by at least 1 cm.”2Armato 3rd, S.G. Nowak A.K. Revised modified response evaluation criteria in solid tumors for assessment of response in malignant pleural mesothelioma (version 1.1).J Thorac Oncol. 2018; 13: 1012-1021Abstract Full Text Full Text PDF PubMed Scopus (56) Google Scholar We agree that the emphasis on “up to six pleural measurements at baseline” is reasonable and can provide a good representation of the overall tumor burden.2Armato 3rd, S.G. Nowak A.K. Revised modified response evaluation criteria in solid tumors for assessment of response in malignant pleural mesothelioma (version 1.1).J Thorac Oncol. 2018; 13: 1012-1021Abstract Full Text Full Text PDF PubMed Scopus (56) Google Scholar We also agree with the need to separate the selected levels by at least 1 cm to ensure that the measurements are obtained from different components of the tumor. However, we believe that more flexibility is needed with regard to the requirement that these pleural measurements be on the same three sections, especially in tumors that present as irregular and discontinuous areas of pleural thickening. Flexibility in choosing a site that may not be on one of the three sections but a slice higher or lower than the designated three sections will allow for more reproducible measurements and reduce partial volume averaging. We recommend clearly indicating that although the three selected levels should be separated by at least 1 cm, the tumor can be measured on the image that allows an optimally reproducible measurement of that site. Second, we do not agree with the recommendations for “preferred location of measurable disease” and advise broader guidelines owing to the limited recommended measurable area superior to the left atrium and below the aortic arch.2Armato 3rd, S.G. Nowak A.K. Revised modified response evaluation criteria in solid tumors for assessment of response in malignant pleural mesothelioma (version 1.1).J Thorac Oncol. 2018; 13: 1012-1021Abstract Full Text Full Text PDF PubMed Scopus (56) Google Scholar Indeed, in many patients, there is only about 3 to 4 cm separating the aortic arch and left atrium. The concern is that these narrow limits would push inexperienced investigators to obtain tightly clustered measurements rather than optimally sampling a broad coverage of the tumor. The area of significant vertical curvature of the apical thoracic cavity usually begins 1 or 2 cm above the aortic arch, so any measurement not above the aortic arch should not be affected significantly. Conversely, respiratory motion is rarely a significant issue in patients with mesothelioma and measurements obtained above the diaphragm are unlikely to be affected. Using the carina and the superior pulmonary veins allows for a more uniform division of the hemithorax into three equal quadrants, allows for a broad area of the tumor to be sampled, and could be reliably used in noncontrast scans as well. Third, we believe that in cases of bilateral disease, combining both hemithorax measurements as a single organ is highly problematic. The authors propose including up to six pleural measurements from both involved hemithoraces (up to three pleural measurements each). Contralateral pleural disease is considered a site of metastases except in cases of bilateral synchronous involvement; hence, considering it as the same organ will cause confusion. Moreover, in cases of mixed response with the metastatic sites in the contralateral lung and pleura responding differently from the primary tumor, the current proposal would not enable capturing a differential response to therapy. Thus, combining the bilateral hemithorax measurements as one organ could lead to highly inaccurate quantification of disease clinical staging and response to therapy. Moreover, there is no precedent in any of the universally accepted tumor metrics that combine a metastatic site with the primary tumor as one organ system. We would recommend against consolidating bilateral pleural disease measurements as a single organ and continue to identify the contralateral pleura as a metastatic site. The investigator would choose the primary tumor site to measure up to six pleural measurements, and the opposite metastatic pleural disease would be measured similarly but independently, considering it as a different organ. Lastly, the proposed definition of progressive disease remains unclear and subject to variable interpretation. In particular, the transition of nontarget pleural disease from nonmeasurable to unequivocally measurable might amount to only a few millimeters' difference and not represent significant change in light of overall tumor volume. We advise simplifying the language to state that any new ipsilateral focus must not have been previously present and should not have been connected to or a part of the prior pleural thickening. Also, the new focus of pleural thickening must exceed the minimum baseline measurable size of 7 mm. A minimum increase of 5 mm would probably also be appropriate. In conclusion, the authors have written an elegant article that has clarified some aspects of modified RECIST 1.0. However, we believe that there are significant areas of controversy that should be addressed before these proposed updates can be accepted into clinical practice. In the clinical trial setting, not all users of this system will be experienced radiologists, especially in the cooperative group settings in which, in many centers, mesothelioma is a rare entity. Any proposed measurement update will need validation and comparison with modified RECIST version 1.0 in an independent data set. Perhaps most importantly, a consensus panel guideline with multiple centers represented is needed to enact formal updates. The National Cancer Institute–International Association for the Study of Lung Cancer–Mesothelioma Applied Research Foundation Mesothelioma Clinical Trials Planning Meeting will be putting forward a consensus article addressing radiographic measurements and end points for clinical trials. Although the focus of this article is on optimizing modified RECIST version 1.0, we agree that the future for mesothelioma measurements lies in volumetric quantification.3Plathow C. Klopp M. Thieke C. et al.Therapy response in malignant pleural mesothelioma-role of MRI using RECIST, modified RECIST and volumetric approaches in comparison with CT.Eur Radiol. 2008; 18: 1635-1643Crossref PubMed Scopus (65) Google Scholar There are new data emerging on utilization of positron emission tomography/CT4Francis R.J. Byrne M.J. van der Schaaf A.A. et al.Early prediction of response to chemotherapy and survival in malignant pleural mesothelioma using a novel semiautomated 3-dimensional volume-based analysis of serial 18F-FDG PET scans.J Nucl Med. 2007; 48: 1449-1458Crossref PubMed Scopus (165) Google Scholar that may ultimately be adopted in prospective trials. Positron emission tomography/CT scans can provide metabolic information in addition to anatomical detail and can help identify new distant sites of disease. Novel magnetic resonance techniques, including diffusion-weighted imaging and dynamic contrast-enhanced pharmacokinetics can offer complementary information in addition to improving more accurate tumor measurements. Additional resources and research should be dedicated to technological advances. Revised Modified Response Evaluation Criteria in Solid Tumors for Assessment of Response in Malignant Pleural Mesothelioma (Version 1.1)Journal of Thoracic OncologyVol. 13Issue 7PreviewMalignant pleural mesothelioma poses unique difficulties in tumor measurement and response assessment; however, robust and reproducible assessment of response is critically important in the conduct, interpretation, and reporting of clinical trials. Full-Text PDF Open Archive

Purpose: Precision radiation therapy such as stereotactic body radiation therapy and limited resection are being used more frequently to treat intrathoracic malignancies. Effective local control requires precise radiation target delineation or complete resection. Lung biopsy tracts (LBT) on computed tomography (CT) scans after the use of tract sealants can mimic malignant tract seeding (MTS) and it is unclear whether these LBTs should be included in the calculated tumor volume or resected. This study evaluates the incidence, appearance, evolution, and malignant seeding of LBTs. Methods and materials: A total of 406 lung biopsies were performed in oncology patients using a tract sealant over 19 months. Of these patients, 326 had follow-up CT scans and were included in the study group. Four thoracic radiologists retrospectively analyzed the imaging, and a pathologist examined 10 resected LBTs. Results: A total of 234 of 326 biopsies (72%, including primary lung cancer [n = 98]; metastases [n = 81]; benign [n = 50]; and nondiagnostic [n = 5]) showed an LBT on CT. LBTs were identified on imaging 0 to 3 months after biopsy. LBTs were typically straight or serpiginous with a thickness of 2 to 5 mm. Most LBTs were unchanged (92%) or decreased (6.3%) over time. An increase in LBT thickness/nodularity that was suspicious for MTS occurred in 4 of 234 biopsies (1.7%). MTS only occurred after biopsy of metastases from extrathoracic malignancies, and none occurred in patients with lung cancer. Conclusions: LBTs are common on CT after lung biopsy using a tract sealant. MTS is uncommon and only occurred in patients with extrathoracic malignancies. No MTS was found in patients with primary lung cancer. Accordingly, potential alteration in planned therapy should be considered only in patients with LBTs and extrathoracic malignancies being considered for stereotactic body radiation therapy or wedge resection. (C) 2017 The Author(s). Published by Elsevier Inc. on behalf of the American Society for Radiation Oncology.

Positron emission tomography (PET) computed tomography (CT) with 2-[fluorine-18] fluoro-2-deoxy-d-glucose (FDG) has been established as an effective modality for evaluation of cancer. Interpretations of patterns of physiologic 18F-FDG uptake by the heart is particularly difficult given the wide normal variations of 18F-FDG metabolic activity observed. Atypical patterns of focal or diffuse physiologic cardiac 18F-FDG uptake and post-therapeutic effects after radiation therapy, systemic diseases, or cardiomyopathy may also be confused with malignant disease on 18F-FDG PET/CT. In this article, we review the variations of normal cardiac 18F-FDG uptake observed in oncology patients and the appearances of other patterns of pathologic metabolic activity, related or not related to the malignancy being investigated, that may lead to false-negative and false-positive results.

This clinical practice parameter has been developed collaboratively by the American College of Radiology (ACR), the Society for Pediatric Radiology (SPR), and the Society of Thoracic Radiology (STR). This document is intended to act as a guide for physicians performing and interpreting positron emission tomography-computed tomography (PET/CT) of cardiac diseases in adults and children. The primary value of cardiac PET/CT imaging include evaluation of perfusion, function, viability, inflammation, anatomy, and risk stratification for cardiac-related events such as myocardial infarction and death. Optimum utility of cardiac PET/CT is achieved when images are interpreted in conjunction with clinical information and laboratory data. Measurement of myocardial blood flow, coronary flow reserve and detection of balanced ischemia are significant advantages of cardiac PET perfusion studies. Increasingly cardiac PET/CT is used in diagnosis and treatment response assessment for cardiac sarcoidosis.

Venous thromboembolism (VTE) is a major complication of cancer with recent increasing reports of incidental VTE. The objectives are to estimate the prevalence of incidental VTE in cancer patients on staging CT scans, identify common symptoms, and determine VTE recurrence in a prospective study.

Tract sealants are being used more frequently to reduce pneumothoraces and chest tube placement in patients undergoing lung biopsy. Use of a sealant plug can produce visible biopsy tracts on follow-up imaging and can mimic the appearance of malignant tract seeding. The purpose of our study was to characterize these tracts and determine the likelihood of malignant seeding to inform further management including localized radiation therapy and/or surgical planning. Over a 15 month period 407 lung biopsies were performed in patients with known or suspected thoracic and extrathoracic malignancies using a BioSentry Tract Sealant System; 321 cases had follow up CT studies. 4 chest radiologists retrospectively analyzed subsequent imaging to determine the incidence, appearance, temporal relationship and evolution of biopsy tracts. Tracts that decreased or did not change on follow-up were considered benign. 10 surgically resected cases were retrospectively examined by a pathologist for malignant tract seeding. 321 cases were analyzed. 237 (74%) had a visible biopsy tract on CT (95%CI 0.69, 0.78) (primary lung cancer n=90, metastases n=81, benign nodule n=66). All tracts were identified on 1st follow-up imaging at 1-3 months post-biopsy. Tracts were typically serpiginous and smooth or lobulated with a thickness of 2-5 mm. 218/237 (92%) tracts were unchanged over time (mean follow up, 12 months). 15/237 (6.3%) decreased in thickness. Unchanged or decreasing tracts were considered negative for malignant seeding. Increase in tract thickness or nodularity occurred in 4/237 (1.8%), suspicious for malignant tract seeding. 0/90 (0%) biopsy tracts in primary lung cancer showed progressive increase. 4/81 (4.9%) tracts in patients with metastases showed increase (mean, 99 days post-biopsy). 10 resected nodules (5 primary NSCLCs, 5 metastases) had no malignant tract seeding at histology. An observable biopsy tract on CT is common after lung biopsy using the BioSentryTM device. Tracts from biopsy of primary lung cancers using the BioSentry device had no malignant seeding and they should have no impact on surgical resection or localized radiation therapy. In the study population, patients who underwent lung biopsy for metastasis had a higher than expected rate of malignant seeding manifested by increased track thickness over time, requiring further investigation.