Imaging after radiation therapy of thoracic tumors

Imaging Manifestations Following Radiation Therapy for Lung Cancer

Radiation therapy (RT) using conventional or newer high precision techniques, including 3-dimensional conformal radiotherapy, intensity-modulated RT, stereotactic body RT, and proton therapy, is an important component in the treatment of patients with lung cancer. Interpreting images for these patients requires knowledge of the radiation technique used, the expected temporal evolution of radiation-induced lung injury (RILI), and patient-specific parameters such as previous radiotherapy and concurrent chemoradiotherapy or immunotherapy. This review discusses factors that affect the development and severity of RILI and its radiologic manifestations, differences between conventional and high-precision dose radiotherapy techniques, and common complications following RT.

Analysis of radiological lung changes after stereotactic body radiation therapy

PURPOSE

Stereotactic body radiation therapy is indicated in cases of early inoperable lung cancer and surgical rejection, and it is also an option for oligometastatic, recurrent, and/or relapsing tumours. The aim of this study was to analyse the incidence of different patterns of radiological changes on CT scans, correlate their occurrence with risk factors, and analyse the usefulness of imaging information to predict treatment outcome in terms of local progression-free survival.

MATERIALS AND METHODS

A retrospective review was carried out on the data from 104 patients who received lung stereotactic body radiation therapy between 2014 and 2022. A first check-up visit was carried out a month after treatment. Visits were then performed every 3 to 4months during the first year, with imaging tests (CT or PET), and every 4 to 6months after the first year. Acute radiological changes were defined as those occurring in the first 6months and chronic radiological changes as those occurring starting from 6months onwards following treatment.

RESULTS

Acute radiological changes were detected in 44.44 % of the patients, with up to 86 % of them appearing chronically. The modified conventional fibrosis pattern was the most prevalent. Having received lung thoracic radiotherapy and irradiation of tumours located in peripheral regions significantly increases the likelihood of chronic radiological changes appearing. Fifteen patients underwent further tests such as a PET scan for suspected local progression after the appearance of chronic changes, of which 11 were positive. No association was identified between the occurrence of either acute or chronic radiological changes with worsened survival or a higher percentage of local progression.

CONCLUSIONS

Proper knowledge of the different patterns of radiological changes secondary to lung stereotactic body radiation therapy and their dynamics over time is necessary to discern between a benign pathology and progression.

Case Report: Grade 4 pneumonitis occurred after thoracic radiotherapy and dacomitinib in a patient with lung adenocarcinoma

Osimertinib combined with chest radiotherapy has a high incidence of pneumonia, dacomitinib is widely used in clinical practice, but there are no studies reporting the pulmonary safety of dacomitinib in combinating with radiotherapy. Here we report a case of radiation pneumonitis occurring by dacomitinib and thoracic radiotherapy (TRT). The patient was a 55-year-old woman with lung adenocarcinoma. She had received surgery and adjuvant chemotherapy. The patient presented with bilateral intramammary and para-aortic metastatic lymphadenopathy, which was confirmed as metastasis, and subsequently received treatment with dacomitinib. Radiotherapy started after 4 months of dacomitinib. The Clinical Target Volume (CTV) was metastatic lymph nodes area. The prescription dose was 60 Gy/30F. The mean lung dose (MLD), V20, and V5 were 8.16Gy, 16%, and 34.5%. Despite the lung V20 and mean lung dose being exceptionally low, the patient exhibited respiratory symptoms, and a CT chest scan revealed grade 4 radiation pneumonitis two weeks following the conclusion of radiotherapy. The radiotherapy and dacomitinib were discontinued, and immediate initiation of pulmonary anti-inflammatory treatment ensued. The concurrent administration of dacomitinib and RT carries the risk of inducing serious pneumonia. This case highlights the potential risk of severe pneumonia associated with this combination therapy, emphasizing the need for further research to clarify its safety and develop effective management strategies.

Longitudinal registration of thoracic CT images with radiation-induced lung diseases: A divide-and-conquer approach based on component structure wise registration using coherent point drift

BACKGROUND AND OBJECTIVE

Registration of pulmonary computed tomography (CT) images with radiation-induced lung diseases (RILD) was essential to investigate the voxel-wise relationship between the formation of RILD and the radiation dose received by different tissues. Although various approaches had been developed for the registration of lung CTs, their performances remained clinically unsatisfactory for registration of lung CT images with RILD. The main difficulties arose from the longitudinal change in lung parenchyma, including RILD and volumetric change of lung cancers, after radiation therapy, leading to inaccurate registration and artifacts caused by erroneous matching of the RILD tissues.

METHODS

To overcome the influence of the parenchymal changes, a divide-and-conquer approach rooted in the coherent point drift (CPD) paradigm was proposed. The proposed method was based on two kernel ideas. One was the idea of component structure wise registration. Specifically, the proposed method relaxed the intrinsic assumption of equal isotropic covariances in CPD by decomposing a lung and its surrounding tissues into component structures and independently registering the component structures pairwise by CPD. The other was the idea of defining a vascular subtree centered at a matched branch point as a component structure. This idea could not only provide a sufficient number of matched feature points within a parenchyma, but avoid being corrupted by the false feature points resided in the RILD tissues due to globally and indiscriminately sampling using mathematical operators. The overall deformation model was built by using the Thin Plate Spline based on all matched points.

RESULTS

This study recruited 30 pairs of lung CT images with RILD, 15 of which were used for internal validation (leave-one-out cross-validation) and the other 15 for external validation. The experimental results showed that the proposed algorithm achieved a mean and a mean of maximum 1 % of average surface distances <2 and 8 mm, respectively, and a mean and a maximum target registration error <2 mm and 5 mm on both internal and external validation datasets. The paired two-sample t-tests corroborated that the proposed algorithm outperformed a recent method, the Stavropoulou's method, on the external validation dataset (p < 0.05).

CONCLUSIONS

The proposed algorithm effectively reduced the influence of parenchymal changes, resulting in a reasonably accurate and artifact-free registration.

Lung cancer reirradiation: Exploring modifications to utilization, treatment modalities and factors associated with outcomes

BACKGROUND

Patients treated for lung cancer (LC) often experience locoregional failure after initial treatment. Due to technological advances, thoracic reirradiation (re-RT) has become a viable treatment option. We sought to investigate the use of thoracic re-RT in LC patients over a time period characterized by technological advances in a large, multi-center cohort.

METHODS AND MATERIALS

LC patients treated with thoracic re-RT in two University Hospitals from 2010-2020 were identified. Clinical variables and RT data were extracted from the medical records and treatment planning systems. Overall survival (OS) was calculated from the last day of re-RT until death or last follow up.

RESULTS

296 patients (small cell LC n=30, non-small cell LC n=266) were included. Three-dimensional conformal radiation therapy was the RT technique used most frequently (63%), and 86% of all patients were referred for re-RT with palliative treatment intent. During the second half of the study period, the use of thoracic re-RT increased in general, more patients received curative re-RT, and there was an increased use of stereotactic body radiation therapy (SBRT). Median time between initial RT and re-RT was 18 months (range 1-213 months). Only 83/296 patients had combined treatment plans that allowed for registration of combined doses to organs at risk (OAR). Most of the combined doses to OAR were below recommendations from guidelines. Multivariate analysis showed superior OS (p<0.05) in patients treated with curative intent, SBRT or intensity modulated radiation therapy or had excellent performance status prior to re-RT.

CONCLUSIONS

The use of re-RT increased in the second half of the study period, although 2020 did not follow the trend. The use of SBRT and IMRT became more frequent over the years, yet the majority received palliative re-RT. Combined dose plans were only created for one third of the patients.

Spectrum of Imaging Patterns of Lung Cancer following Radiation Therapy

Radiation therapy using conventional or newer high-precision dose techniques, including three-dimensional conformal radiotherapy, intensity-modulated radiation therapy, stereotactic body radiation therapy, four-dimensional conformational radiotherapy, and proton therapy, is an important component of treating patients with lung cancer. Knowledge of the radiation technique used and the expected temporal evolution of radiation-induced lung injury, as well as patient-specific parameters such as previous radiotherapy, concurrent chemoradiotherapy, or immunotherapy, is important in image interpretation. This review discusses factors that affect the development and severity of radiation-induced lung injury and its radiological manifestations, as well as the differences between conventional and high-precision dose radiotherapy techniques.

Pirfenidone for the prevention of radiation-induced lung injury in patients with locally advanced oesophageal squamous cell carcinoma: a protocol for a randomised controlled trial

INTRODUCTION

Radiation-induced lung injury (RILI) is one of the most clinically-challenging toxicities and dose-limiting factors during and/or after thoracic radiation therapy for oesophageal squamous cell carcinoma (ESCC). With limited effective protective drugs against RILI, the main strategy to reduce the injury is strict adherence to dose-volume restrictions of normal lungs. RILI can manifest as acute radiation pneumonitis with cellular injury, cytokine release and cytokine recruitment to inflammatory infiltrate, and subsequent chronic radiation pulmonary fibrosis. Pirfenidone inhibits the production of inflammatory cytokines, scavenges-free radicals and reduces hydroxyproline and collagen formation. Hence, pirfenidone might be a promising drug for RILI prevention. This study aims to evaluate the efficacy and safety of pirfenidone in preventing RILI in patients with locally advanced ESCC receiving chemoradiotherapy.

METHODS AND ANALYSIS

This study is designed as a randomised, placebo-controlled, double-blinded, single-centre phase 2 trial and will explore whether the addition of pirfenidone during concurrent chemoradiation therapy (CCRT) could prevent RILI in patients with locally advanced ESCC unsuitable for surgery. Eligible participants will be randomised at 1:1 to pirfenidone and placebo groups. The primary endpoint is the incidence of grade >2 RILI. Secondary endpoints include the incidence of any grade other than grade >2 RILI, time to RILI occurrence, changes in pulmonary function after CCRT, completion rate of CCRT, disease-free survival and overall survival. The follow-up period will be 1 year. In case the results meet the primary endpoint of this trial, a phase 3 multicentre trial with a larger sample size will be required to substantiate the evidence of the benefit of pirfenidone in RILI prevention.

ETHICS AND DISSEMINATION

This study was approved by the Ethics Committee of Fujian Union Hospital (No. 2021YF001-02). The findings of the trial will be disseminated through peer-reviewed journals, and national and international conference presentations.

TRIAL REGISTRATION NUMBER

ChiCTR2100043032.

Immune checkpoint inhibitor-related pneumonitis in non-small cell lung cancer: A review

Immune checkpoint inhibitors (ICIs) have shown definite therapeutic effects in various types of cancers, especially non-small cell lung cancer (NSCLC). However, ICIs have unique side effects, called immune-related adverse events (irAEs), which can occur in various systems throughout the body. Among such irAEs, immune checkpoint inhibitor-related pneumonitis (ICI-P) is a fatal adverse reaction. In this review, we discussed the risk factors, pathogenesis, clinical characteristics, radiological manifestations, pathological features, diagnosis, grading, and management of ICI-P in NSCLC and the relationship between ICI-P and the efficacy of ICI therapy. In addition, we discussed the predictive factors for ICI-P. This review will play a crucial role in the prediction, evaluation, and management of ICI-P for widespread application of immunotherapy.

Group and Basis Restricted Non-Negative Matrix Factorization and Random Forest for Molecular Histotype Classification and Raman Biomarker Monitoring in Breast Cancer

Raman spectroscopy is a non-invasive optical technique that can be used to investigate biochemical information embedded in cells and tissues exposed to ionizing radiation used in cancer therapy. Raman spectroscopy could potentially be incorporated in personalized radiation treatment design as a tool to monitor radiation response in at the metabolic level. However, tracking biochemical dynamics remains challenging for Raman spectroscopy. Here we developed a novel analytical framework by combining group and basis restricted non-negative matrix factorization and random forest (GBR-NMF-RF). This framework can monitor radiation response profiles in different molecular histotypes and biochemical dynamics in irradiated breast cancer cells. Five subtypes of; human breast cancer (MCF-7, BT-474, MDA-MB-230, and SK-BR-3) and normal cells derived from human breast tissue (MCF10A) which had been exposed to ionizing radiation were tested in this framework. Reference Raman spectra of 20 biochemicals were collected and used as the constrained Raman biomarkers in the GBR-NMF-RF framework. We obtained scores for individual biochemicals corresponding to the contribution of each Raman reference spectrum to each spectrum obtained from the five cell types. A random forest classifier was then fitted to the chemical scores for performing molecular histotype classifications (HER2, PR, ER, Ki67, and cancer versus non-cancer) and assessing the importance of the Raman biochemical basis spectra for each classification test. Overall, the GBR-NMF-RF framework yields classification results with high accuracy (>97%), high sensitivity (>97%), and high specificity (>97%). Variable importance calculated in the random forest model indicated high contributions from glycogen and lipids (cholesterol, phosphatidylserine, and stearic acid) in molecular histotype classifications.

Imaging and its Impact on Defining the Oligometastatic State

Successful treatment of oligometastatic disease (OMD) is facilitated through timely detection and localization of disease, both at the time of initial diagnosis (synchronous OMD) and following the initial therapy (metachronous OMD). Hence, imaging plays an indispensable role in management of patients with OMD. However, the challenges and complexities of OMD management are also reflected in the imaging of this entity. While innovations and advances in imaging technology have made a tremendous impact in disease detection and management, there remain substantial and unaddressed challenges for earlier and more accurate establishment of OMD state. This review will provide an overview of the available imaging modalities and their inherent strengths and weaknesses, with a focus on their role and potential in detection and evaluation of OMD in different organ systems. Furthermore, we will review the role of imaging in evaluation of OMD for malignancies of various primary organs, such as the lung, prostate, colon/rectum, breast, kidney, as well as neuroendocrine tumors and gynecologic malignancies. We aim to provide a practical overview about the utilization of imaging for clinicians who play a role in the care of those with, or at risk for OMD.

Radiation-induced lung injury: current evidence

Chemo-radiotherapy and systemic therapies have proven satisfactory outcomes as standard treatments for various thoracic malignancies; however, adverse pulmonary effects, like pneumonitis, can be life-threatening. Pneumonitis is caused by direct cytotoxic effect, oxidative stress, and immune-mediated injury. Radiotherapy Induced Lung Injury (RILI) encompasses two phases: an early phase known as Radiation Pneumonitis (RP), characterized by acute lung tissue inflammation as a result of exposure to radiation; and a late phase called Radiation Fibrosis (RF), a clinical syndrome that results from chronic pulmonary tissue damage. Currently, diagnoses are made by exclusion using clinical assessment and radiological findings. Pulmonary function tests have constituted a significant step in evaluating lung function status during radiotherapy and useful predictive tools to avoid complications or limit toxicity. Systemic corticosteroids are widely used to treat pneumonitis complications, but its use must be standardized, and consider in the prophylaxis setting given the fatal outcome of this adverse event. This review aims to discuss the clinicopathological features of pneumonitis and provide practical clinical recommendations for prevention, diagnosis, and management.

Impact of prior chemoradiotherapy-related variables on outcomes with durvalumab in unresectable Stage III NSCLC (PACIFIC)

INTRODUCTION

The PACIFIC trial demonstrated that durvalumab significantly improved progression-free and overall survival (PFS/OS), versus placebo, in patients with Stage III NSCLC and stable or responding disease following concurrent, platinum-based chemoradiotherapy (CRT). A range of CT and RT regimens were permitted, and used, in the trial. We report post-hoc, exploratory analyses of clinical outcomes from PACIFIC according to CRT-related variables.

METHODS

Patients were randomized 2:1 (1-42 days post-CRT) to up to 12 months durvalumab (10 mg/kg intravenously every 2 weeks) or placebo. Efficacy and safety were analyzed in patient subgroups defined by the following baseline variables: platinum-based CT (cisplatin/carboplatin); vinorelbine, etoposide, or taxane-based CT (all yes/no); total RT dose (<60 Gy/60-66 Gy/>66 Gy); time from last RT dose to randomization (<14 days/≥14 days); and use of pre-CRT induction CT (yes/no). Treatment effects for time-to-event endpoints were estimated by hazard ratios (HRs) from unstratified Cox-proportional-hazards models.

RESULTS

Overall, 713 patients were randomized, of whom 709 received treatment in either the durvalumab (n/N = 473/476) or placebo arms (n/N = 236/237). Durvalumab improved PFS, versus placebo, across all subgroups (median follow up, 14.5 months; HR range, 0.34-0.63). Durvalumab improved OS across most subgroups (median follow up, 25.2 months; HR range, 0.35-0.86); however, the 95 % confidence interval (CI) of the estimated treatment effect crossed one for the subgroups of patients who received induction CT (HR, 0.78 [95 % CI, 0.51-1.20]); carboplatin (0.86 [0.60-1.23]); vinorelbine (0.79 [0.49-1.27]); and taxane-based CT (0.73 [0.51-1.04]); and patients who were randomized ≥14 days post-RT (0.81 [0.62-1.06]). Safety was broadly similar across the CRT subgroups.

CONCLUSION

Durvalumab prolonged PFS and OS irrespective of treatment variables related to prior CRT to which patients with Stage III NSCLC had previously stabilized or responded. Limited patient numbers and imbalances in baseline factors in each subgroup preclude robust conclusions.

Bayesian Information-Theoretic Calibration of Radiotherapy Sensitivity Parameters for Informing Effective Scanning Protocols in Cancer

With new advancements in technology, it is now possible to collect data for a variety of different metrics describing tumor growth, including tumor volume, composition, and vascularity, among others. For any proposed model of tumor growth and treatment, we observe large variability among individual patients’ parameter values, particularly those relating to treatment response; thus, exploiting the use of these various metrics for model calibration can be helpful to infer such patient-specific parameters both accurately and early, so that treatment protocols can be adjusted mid-course for maximum efficacy. However, taking measurements can be costly and invasive, limiting clinicians to a sparse collection schedule. As such, the determination of optimal times and metrics for which to collect data in order to best inform proper treatment protocols could be of great assistance to clinicians. In this investigation, we employ a Bayesian information-theoretic calibration protocol for experimental design in order to identify the optimal times at which to collect data for informing treatment parameters. Within this procedure, data collection times are chosen sequentially to maximize the reduction in parameter uncertainty with each added measurement, ensuring that a budget of n high-fidelity experimental measurements results in maximum information gain about the low-fidelity model parameter values. In addition to investigating the optimal temporal pattern for data collection, we also develop a framework for deciding which metrics should be utilized at each data collection point. We illustrate this framework with a variety of toy examples, each utilizing a radiotherapy treatment regimen. For each scenario, we analyze the dependence of the predictive power of the low-fidelity model upon the measurement budget.

Real-world outcomes of chemoradiotherapy for unresectable Stage III non-small cell lung cancer: The SOLUTION study

There are limited real‐world data on the treatment practices, outcomes, and safety of chemoradiotherapy (CRT) alone in potential candidates for immune checkpoint inhibitors (ICI) for unresectable non‐small cell lung cancer (NSCLC). In this study, we analyzed the safety and efficacy of CRT in patients who underwent CRT and would satisfy the key eligibility criteria for maintenance therapy with durvalumab (eg, no progression after CRT) in real‐world settings (m‐sub) for unresectable Stage III NSCLC between 1 January 2013 and 31 December 2015 at 12 sites in Japan. The m‐sub comprised 214 patients with a median follow‐up of 31.6 months (range 1.9‐65.8 months). Median overall survival (OS) and progression‐free survival (PFS) from completing CRT were 36.4 months (95% confidence interval [CI] 28.1 months to not reached) and 9.5 months (95% CI 7.7‐11.7 months), respectively. Consolidation chemotherapy did not influence OS or PFS. Median PFS was 16.9 vs 9.1 months in patients with vs without epidermal growth factor receptor (EGFR) mutations, with PFS rates of ~20% at 3‐4 years. Pneumonitis was the most common adverse event (according to MedDRA version 21.0J), and about half of events were grade 1. Pneumonitis mostly occurred 10‐24 weeks after starting CRT, peaking at 18‐20 weeks. Esophagitis and dermatitis generally occurred from 0 to 4 weeks, peaking at 2‐4 weeks after starting CRT. Pericarditis was rare and occurred sporadically. In conclusion, the results of the m‐sub provide real‐world insight into the outcomes of CRT, and will be useful for future evaluations of ICI maintenance therapy after CRT.

Radiological assessment after stereotactic body radiation of lung tumours

The increasing use of stereotactic body radiation therapy for lung tumours comes along with new post-therapeutic imaging findings that should be known by physicians involved in patient follow-up. Radiation-induced lung injury is much more frequent than after conventional radiation therapy, it can also be delayed and has a different radiological presentation. Radiation-induced lung injury after stereotactic body radiation therapy involves the lung parenchyma surrounding the target tumour and appears as a dynamic process continuing for years after completion of the treatment. Thus, the radiological pattern and the severity of radiation-induced lung injury are prone to changes during follow-up, which can make it difficult to differentiate from local recurrence. Contrary to radiation-induced lung injury, local recurrence after stereotactic body radiation therapy is rare. Other complications mainly depend on tumour location and include airway complications, rib fractures and organizing pneumonia. The aim of this article is to provide a wide overview of radiological changes occurring after SBRT for lung tumours. Awareness of changes following stereotactic body radiation therapy should help avoiding unnecessary interventions for pseudo tumoral presentations.

Monitor Ionizing Radiation-Induced Cellular Responses with Raman Spectroscopy, Non-Negative Matrix Factorization, and Non-Negative Least Squares

Radiation therapy (RT) is one of the most commonly prescribed cancer treatments. New tools that can accurately monitor and evaluate individual patient responses would be a major advantage and lend to the implementation of personalized treatment plans. In this study, Raman spectroscopy (RS) was applied to examine radiation-induced cellular responses in H460, MCF7, and LNCaP cancer cell lines across different dose levels and times post-irradiation. Previous Raman data analysis was conducted using principal component analysis (PCA), which showed the ability to extract biological information of glycogen. In the current studies, the use of non-negative matrix factorization (NMF) allowed for the discovery of multiplexed biological information, specifically uncovering glycogen-like and lipid-like component bases. The corresponding scores of glycogen and previously unidentified lipids revealed the content variations of these two chemicals in the cellular data. The NMF decomposed glycogen and lipid-like bases were able to separate the cancer cell lines into radiosensitive and radioresistant groups. A further lipid phenotype investigation was also attempted by applying non-negative least squares (NNLS) to the lipid-like bases decomposed individually from three cell lines. Qualitative differences found in lipid weights for each lipid-like basis suggest the lipid phenotype differences in the three tested cancer cell lines. Collectively, this study demonstrates that the application of NMF and NNLS on RS data analysis to monitor ionizing radiation-induced cellular responses can yield multiplexed biological information on bio-response to RT not revealed by conventional chemometric approaches.

Staple Line Thickening After Sublobar Resection: Reaction or Recurrence?

BACKGROUND

Stapling across lung parenchyma may lead to tissue granulation, which could be confused radiographically with recurrence. We sought to define the time course and radiographic characteristics of such thickening and to determine their association with recurrence.

METHODS

Patients who underwent limited resection for non-small cell lung cancer were included. Surveillance computed tomography scans were reviewed to characterize the morphology and size of staple line granulation tissue. Radiological and clinical findings were analyzed and univariate predictors of recurrence were examined.

RESULTS

We characterized 78 patients for tissue granulation a total of 314 times in serial scans. On initial postoperative scans, 3.8% (n = 3) of staple lines showed no thickening and 17.9% (n = 14) showed thickening less than 2 mm, whereas 78.2% (n = 61) showed thickening 2 mm or greater. Of the 75 staple lines with thickening, soft tissue was characterized as linear in 32.0% (n = 24), focal along the pleura, hilum, or parenchyma in 24.0% (n = 18), and nodular in 44.0% (n = 33). Subsequent scans revealed that 25.3% of these areas (n = 19) did not change in shape or size over time, 58.7% (n = 44) showed regressive changes, and 16.0% (n = 12) showed progressive changes, the thickening of which in all 12 of these patients showed an increase in the largest dimension by 2 mm or greater. Among the 78 patients, 7.7% (n = 6) had biopsy-proven recurrence along the staple line. An increase in the largest dimension by 2 mm or greater (83.3% versus 9.7%; P = .001) and radiologic concern for malignancy (66.7% versus 11.1%; P = .001) predicted staple line recurrence.

CONCLUSIONS

Staple line thickening is a frequent occurrence after pulmonary limited resection, but rarely indicative of recurrence. The characteristics and initial size of granulation tissue do not predict recurrence. Increases in tissue 2 mm or greater at the staple line over time predict local recurrence, which typically occurs after a prolonged time interval.

Differential Diagnosis of COVID-19 Pneumonia in Cancer Patients Received Radiotherapy

Background: During the outbreak period of COVID-19 pneumonia, cancer patients have been neglected and in greater danger. Furthermore, the differential diagnosis between COVID-19 pneumonia and radiation pneumonitis in cancer patients remains a challenge. This study determined their clinical presentations and radiological features in order to early diagnose and separate COVID-19 pneumonia from radiation pneumonitis patients promptly. Methods and Findings: From January 21, 2020 to February 18, 2020, 112 patients diagnosed with suspected COVID-19 were selected consecutively. A retrospective analysis including all patients' presenting was performed. Four patients from 112 suspected individals were selected, including 2 males and 2 females with a median age of 54 years (range 39-64 years). After repeated pharyngeal swab nucleic acid tests, 1 case was confirmed and 3 cases were excluded from COVID-19 pneumonia. Despite the comparable morphologic characteristics of lung CT imaging, the location, extent, and distribution of lung lesions between COVID-19 pneumonia and radiation pneumonitis differed significantly. Conclusions: Lung CT imaging combined with clinical and laboratory findings can facilitate early diagnosis and appropriate management of COVID-19 pneumonia with a history of malignancy and radiation therapy.

Utility of Molecular Imaging with 2-Deoxy-2-[Fluorine-18] Fluoro-DGlucose Positron Emission Tomography (18F-FDG PET) for Small Cell Lung Cancer (SCLC): A Radiation Oncology Perspective

BACKGROUND AND OBJECTIVE

Although accounting for a relatively small proportion of all lung cancers, small cell lung cancer (SCLC) remains to be a global health concern with grim prognosis. Radiotherapy (RT) plays a central role in SCLC management either as a curative or palliative therapeutic strategy. There has been considerable progress in RT of SCLC, thanks to improved imaging techniques leading to accurate target localization for precise delivery of RT. Positron emission tomography (PET) is increasingly used in oncology practice as a non-invasive molecular imaging modality.

METHODS

Herein, we review the utility of molecular imaging with 2-deoxy-2-[fluorine-18] fluoro-Dglucose PET (18F-FDG PET) for SCLC from a radiation oncology perspective.

RESULTS

There has been extensive research on the utility of PET for SCLC in terms of improved staging, restaging, treatment designation, patient selection for curative/palliative intent, target localization, response assessment, detection of residual/recurrent disease, and prediction of treatment outcomes.

CONCLUSION

PET provides useful functional information as a non-invasive molecular imaging modality and may be exploited to improve the management of patients with SCLC. Incorporation of PET/CT in staging of patients with SCLC may aid in optimal treatment allocation for an improved therapeutic ratio. From a radiation oncology perspective, combination of functional and anatomical data provided by integrated PET/CT improves discrimination between atelectasis and tumor, and assists in the designation of RT portals with its high accuracy to detect intrathoracic tumor and nodal disease. Utility of molecular imaging for SCLC should be further investigated in prospective randomized trials to acquire a higher level of evidence for future potential applications of PET.