Radiologic Abnormalities in Prolonged SARS-CoV-2 Infection: A Systematic Review.

We systematically reviewed radiological abnormalities in patients with prolonged SARS-CoV-2 infection, defined as persistently positive polymerase chain reaction (PCR) results for SARS-CoV-2 for > 21 days, with either persistent or relapsed symptoms. We extracted data from 24 patients (median age, 54.5 [interquartile range, 44-64 years]) reported in the literature and analyzed their representative CT images based on the timing of the CT scan relative to the initial PCR positivity. Our analysis focused on the patterns and distribution of CT findings, severity scores of lung involvement on a scale of 0-4, and the presence of migration. All patients were immunocompromised, including 62.5% (15/24) with underlying lymphoma and 83.3% (20/24) who had received anti-CD20 therapy within one year. Median duration of infection was 90 days. Most patients exhibited typical CT appearance of coronavirus disease 19 (COVID-19), including ground-glass opacities with or without consolidation, throughout the follow-up period. Notably, CT severity scores were significantly lower during ≤ 21 days than during > 21 days (P < 0.001). Migration was observed on CT in 22.7% (5/22) of patients at ≤ 21 days and in 68.2% (15/22) to 87.5% (14/16) of patients at > 21 days, with rare instances of parenchymal bands in previously affected areas. Prolonged SARS-CoV-2 infection usually presents as migrating typical COVID-19 pneumonia in immunocompromised patients, especially those with impaired B-cell immunity.

Arteria Praebronchialis (AP) Found on MDCT: An Updated Incidence and Branching Patterns.

Preoperative detection of the arteria praebronchialis (AP), a rare variant mediastinal branch of the left pulmonary artery, can be crucial to a successful left-lung surgery; if the AP is overlooked and ligated during surgery, the blood supply to the remaining lobe may be compromised. The purpose of this study was to update the incidence and branching patterns of the AP. From 18 April 2012 to 31 December 2022, contrast-enhanced CT was screened by one radiologist for the presence of AP. Branching patterns of the AP were analyzed by three thoracic radiologists. The incidence of AP was updated to 0.068% (18/26,310) from the previously reported 0.03%; the incidence of AP for male and female patients was 0.110% and 0.017%, respectively. AP supplied only the LLL in 10 cases and both the lingular division of LUL and LLL in nine cases. Dual segmental supply by both the AP and the normal left descending pulmonary artery existed in 15 cases; exclusive segmental supply by either artery existed in four cases. The AP supplies either the LLL alone or both LLL and the lingular division of LUL, and its incidence is not negligible in the male population, necessitating routine surveillance prior to pulmonary resection.

Migratory Pneumonia in Prolonged SARS-CoV-2 Infection in Patients Treated With B-cell Depletion Therapies for B-cell Lymphoma.

OBJECTIVE: To report the clinical and radiological characteristics of patients with underlying B-cell lymphoma and coronavirus disease 2019 (COVID-19) showing migratory airspace opacities on serial chest computed tomography (CT) with persistent COVID-19 symptoms. MATERIALS AND METHODS: From January 2020 to June 2022, of the 56 patients with underlying hematologic malignancy who had undergone chest CT more than once at our hospital after acquiring COVID-19, seven adult patients (5 female; age range, 37-71 years; median age, 45 years) who showed migratory airspace opacities on chest CT were selected for the analysis of clinical and CT features. RESULTS: All patients had been diagnosed with B-cell lymphoma (three diffuse large B-cell lymphoma and four follicular lymphoma) and had received B-cell depleting chemotherapy, including rituximab, within three months prior to COVID-19 diagnosis. The patients underwent a median of 3 CT scans during the follow-up period (median 124 days). All patients showed multifocal patchy peripheral ground glass opacities (GGOs) with basal predominance in the baseline CTs. In all patients, follow-up CTs demonstrated clearing of previous airspace opacities with the development of new peripheral and peribronchial GGO and consolidation in different locations. Throughout the follow-up period, all patients demonstrated prolonged COVID-19 symptoms accompanied by positive polymerase chain reaction results from nasopharyngeal swabs, with cycle threshold values of less than 25. CONCLUSION: COVID-19 patients with B-cell lymphoma who had received B-cell depleting therapy and are experiencing prolonged SARS-CoV-2 infection and persistent symptoms may demonstrate migratory airspace opacities on serial CT, which could be interpreted as ongoing COVID-19 pneumonia.

Five-Year Overall Survival and Prognostic Factors in Patients with Lung Cancer: Results from the Korean Association of Lung Cancer Registry (KALC-R) 2015.

PURPOSE: This study aimed to provide the clinical characteristics, prognostic factors, and 5-year relative survival rates of lung cancer diagnosed in 2015. MATERIALS AND METHODS: The demographic risk factors of lung cancer were calculated using the KALC-R (Korean Association of Lung Cancer Registry) cohort in 2015, with survival follow-up until December 31, 2020. The 5-year relative survival rates were estimated using Ederer II methods, and the general population data used the death rate adjusted for sex and age published by the Korea Statistical Information Service from 2015 to 2020. RESULTS: We enrolled 2,657 patients with lung cancer who were diagnosed in South Korea in 2015. Of all patients, 2,098 (79.0%) were diagnosed with non-small cell lung cancer (NSCLC) and 345 (13.0%) were diagnosed with small cell lung cancer (SCLC), respectively. Old age, poor performance status, and advanced clinical stage were independent risk factors for both NSCLC and SCLC. In addition, the 5-year relative survival rate declined with advanced stage in both NSCLC (82%, 59%, 16%, 10% as the stage progressed) and SCLC (16%, 4% as the stage progressed). In patients with stage IV adenocarcinoma, the 5-year relative survival rate was higher in the presence of epidermal growth factor receptor (EGFR) mutation (19% vs. 11%) or anaplastic lymphoma kinase (ALK) translocation (38% vs. 11%). CONCLUSION: In this Korean nationwide survey, the 5-year relative survival rates of NSCLC were 82% at stage I, 59% at stage II, 16% at stage III, and 10% at stage IV, and the 5-year relative survival rates of SCLC were 16% in cases with limited disease, and 4% in cases with extensive disease.

Myocardial T2* Imaging at 3T and 1.5T: A Pilot Study with Phantom and Normal Myocardium.

BACKGROUND: Myocardial T2* mapping at 1.5T remains the gold standard, but the use of 3T scanners is increasing. We aimed to determine the conversion equations in different scanners with clinically available, vendor-provided T2* mapping sequences using a phantom and evaluated the feasibility of the phantom-based conversion method. METHODS: T2* of a phantom with FeCl3 (five samples, 3.53-20.09 mM) were measured with 1.5T (MR-A1) and 3T scanners (MR-A2, A3, B), and the site-specific equation was determined. T2* was measured in the interventricular septum of three healthy volunteers at 1.5T (T2*1.5T, MR-A1) and 3T (T2*3.0T, MR-B). T2*3.0T was converted based on the equation derived from the phantom (T2*eq). RESULTS: R2* at 1.5T and 3T showed linear association, but a different relationship was observed according to the scanners (MR-A2, R2*1.5T = 0.76 × R2*3.0T - 2.23, R2 = 0.999; MR-A3, R2*1.5T = 0.95 × R2*3.0T - 34.28, R2 = 0.973; MR-B, R2*1.5T = 0.76 × R2*3.0T - 3.02, R2 = 0.999). In the normal myocardium, T2*eq and T2*1.5T showed no significant difference (35.5 ± 3.5 vs. 34.5 ± 1.2, p = 0.340). The mean squared error between T2*eq and T2*1.5T was 16.33, and Bland-Altman plots revealed a small bias (-0.94, 95% limits of agreement: -8.86-6.99). CONCLUSIONS: a phantom-based, site-specific equation can be utilized to estimate T2* values at 1.5T in centers where only 3T scanners are available.

DeepCUBIT: Predicting Lymphovascular Invasion or Pathological Lymph Node Involvement of Clinical T1 Stage Non-Small Cell Lung Cancer on Chest CT Scan Using Deep Cubical Nodule Transfer Learning Algorithm.

The prediction of lymphovascular invasion (LVI) or pathological nodal involvement of tumor cells is critical for successful treatment in early stage non-small cell lung cancer (NSCLC). We developed and validated a Deep Cubical Nodule Transfer Learning Algorithm (DeepCUBIT) using transfer learning and 3D Convolutional Neural Network (CNN) to predict LVI or pathological nodal involvement on chest CT images. A total of 695 preoperative CT images of resected NSCLC with tumor size of less than or equal to 3 cm from 2008 to 2015 were used to train and validate the DeepCUBIT model using five-fold cross-validation method. We also used tumor size and consolidation to tumor ratio (C/T ratio) to build a support vector machine (SVM) classifier. Two-hundred and fifty-four out of 695 samples (36.5%) had LVI or nodal involvement. An integrated model (3D CNN + Tumor size + C/T ratio) showed sensitivity of 31.8%, specificity of 89.8%, accuracy of 76.4%, and AUC of 0.759 on external validation cohort. Three single SVM models, using 3D CNN (DeepCUBIT), tumor size or C/T ratio, showed AUCs of 0.717, 0.630 and 0.683, respectively on external validation cohort. DeepCUBIT showed the best single model compared to the models using only C/T ratio or tumor size. In addition, the DeepCUBIT model could significantly identify the prognosis of resected NSCLC patients even in stage I. DeepCUBIT using transfer learning and 3D CNN can accurately predict LVI or nodal involvement in cT1 size NSCLC on CT images. Thus, it can provide a more accurate selection of candidates who will benefit from limited surgery without increasing the risk of recurrence.

The effectiveness and safety of local pleural anesthesia for pain control in patients undergoing CT-guided transthoracic needle biopsy.

OBJECTIVES: To evaluate the effectiveness and safety of pleural anesthesia for CT-guided transthoracic needle biopsy (TNB). METHODS: This retrospective study was performed between March 2019 and August 2019 in a tertiary care hospital. Patients undergoing CT-guided TNB received either (a) pleural and skin anesthesia (pleural anesthesia group) or (b) skin anesthesia only (skin anesthesia group). Pain score was reported on a 0-5 numeric rating scale, and pain scores 3-5 were classified as significant pain. The relationship between pleural anesthesia and pain score, significant pain, and pneumothorax was assessed by using multivariable linear and logistic regression models. RESULTS: A total of 111 patients (67 men, 66.0 ± 11.4 years) were included (pleural anesthesia group, 38; skin anesthesia group, 73). Pleural anesthesia group reported lower pain score (1.4 ± 1.0 vs. 2.3 ± 1.1, p < 0.001) and less frequent significant pain (18.4% [7/38] vs. 42.5% [31/73], p = 0.020) than skin anesthesia group. Pain score was negatively associated with pleural anesthesia (ß = -0.93, p < 0.001) and positively associated with procedure time (ß = 0.06, p < 0.001). Significant pain was negatively associated with pleural anesthesia (p = 0.004, adjusted odds ratio [OR] = 0.21 [95% confidence interval: 0.07, 0.61]) and positively associated with procedure time (p < 0.001, adjusted OR = 1.15 [95% confidence interval: 1.07, 1.24]). Pleural anesthesia was not associated with pneumothorax or chest tube placement (p = 0.806 and 0.291, respectively). CONCLUSION: Pleural anesthesia reduces subjective pain without increasing the risk of pneumothorax. KEY POINTS: • Local pleural anesthesia is a simple method that can be added to the conventional skin anesthesia for CT-guided transthoracic needle biopsy. • The addition of local pleural anesthesia can effectively reduce pain compared to the conventional skin anesthesia method. • This procedure is not associated with an increased risk of pneumothorax or chest tube placement.

A Highly Sensitive Next-Generation Sequencing-Based Genotyping Platform for EGFR Mutations in Plasma from Non-Small Cell Lung Cancer Patients.

Sel-CapTM, a digital enrichment next-generation sequencing (NGS)-based cancer panel, was assessed for detection of epidermal growth factor receptor (EGFR) gene mutations in plasma for non-small cell lung cancer (NSCLC), and for application in monitoring EGFR resistance mutation T790M in plasma following first-line EGFR-tyrosine kinase inhibitor (EGFR-TKI) treatment. Using Sel-Cap, we genotyped plasma samples collected from 185 patients for mutations Ex19del, L858R, and T790M, and compared results to those of PNAclampTM tumor biopsy (reference method, a peptide nucleic acid-mediated polymerase chain reaction clamping) and two other NGS liquid biopsies. Over two-thirds of activating mutations (Ex19del and L858R), previously confirmed by PNAclamp, were detected by Sel-Cap, which is 4-5 times more sensitive than NGS liquid biopsy. Sel-Cap showed particularly high sensitivity for T790M (88%) and for early-stage plasma samples. The relationship between initial T790M detection in plasma and progression-free survival (PFS) following first-line EGFR-TKIs was evaluated in 34 patients. Patients with T790M detected at treatment initiation (±3 months) had significantly shorter PFS than patients where T790M was first detected >3 months post treatment initiation (median PFS: 5.9 vs. 26.5 months; p < 0.0001). However, time from T790M detection to disease progression was not significantly different between the two groups (median around 5 months). In conclusion, Sel-Cap is a highly sensitive platform for EGFR mutations in plasma, and the timing of the first appearance of T790M in plasma, determined via highly sensitive liquid biopsies, may be useful for prediction of disease progression of NSCLC, around 5 months in advance.

Invasive mucinous adenocarcinoma of the lung: Serial CT findings, clinical features, and treatment and survival outcomes.

BACKGROUND: Invasive mucinous adenocarcinoma (IMA) of the lung is a rare and distinct subtype of adenocarcinoma that can appear as airspace opacities on computed tomography (CT). In daily practice, we have occasionally encountered spontaneous regression of airspace opacities (SRAs) without treatment on serial CTs in patients with IMAs, which has not previously been described in the literature. Here, we describe serial CT findings with emphasis on SRAs in relation to clinicopathological features and treatment outcomes in patients with IMAs. METHODS: A total of 46 patients with pathologically-confirmed IMAs of the lung from January 2013 to June 2018 were included. Serial CT scans were reviewed and the patients were classified into SRA and no-SRA groups according to the presence of SRA. Radiological features, clinicopathological characteristics, and treatment outcomes were compared between the SRA and no-SRA groups. RESULTS: A total of 32 patients were included in the no-SRA group and 14 patients in the SRA group. IMAs in the SRA group were mostly pneumonic (P < 0.001), larger (P < 0.001), multifocal (P = 0.001), and showed higher stage (P < 0.001) on initial CT. Of seven patients who died during follow-up, six were from the SRA group (P < 0.001). Mean overall survival for all IMAs was 86.6 months (range, 0-110 months), and the SRA group showed significantly worse overall survival (P < 0.001). CONCLUSIONS: IMAs of the lung showing SRAs on serial CTs are larger and multifocal, and tend to be pneumonic in type on initial CT. Patients present at a higher stage of disease, with higher mortality rate and reduced overall survival. KEY POINTS: SIGNIFICANT FINDINGS OF THE STUDY: Invasive mucinous adenocarcinomas (IMAs) of the lung can show spontaneous regression of airspace opacities (SRAs) on serial CTs, without being correlated to the administration of anticancer drugs. IMAs that showed SRAs demonstrated reduced overall survival in patients. WHAT THIS STUDY ADDS: When airspace opacities show regression on CT, IMA should still be included in the differential diagnosis. A more careful application of RECIST 1.1 is needed in the assessment of tumor response of IMAs.

DeepBTS: Prediction of Recurrence-free Survival of Non-small Cell Lung Cancer Using a Time-binned Deep Neural Network.

Accurate prediction of non-small cell lung cancer (NSCLC) prognosis after surgery remains challenging. The Cox proportional hazard (PH) model is widely used, however, there are some limitations associated with it. In this study, we developed novel neural network models called binned time survival analysis (DeepBTS) models using 30 clinico-pathological features of surgically resected NSCLC patients (training cohort, n = 1,022; external validation cohort, n = 298). We employed the root-mean-square error (in the supervised learning model, s- DeepBTS) or negative log-likelihood (in the semi-unsupervised learning model, su-DeepBTS) as the loss function. The su-DeepBTS algorithm achieved better performance (C-index = 0.7306; AUC = 0.7677) than the other models (Cox PH: C-index = 0.7048 and AUC = 0.7390; s-DeepBTS: C-index = 0.7126 and AUC = 0.7420). The top 14 features were selected using su-DeepBTS model as a selector and could distinguish the low- and high-risk groups in the training cohort (p = 1.86 × 10-11) and validation cohort (p = 1.04 × 10-10). When trained with the optimal feature set for each model, the su-DeepBTS model could predict the prognoses of NSCLC better than the traditional model, especially in stage I patients. Follow-up studies using combined radiological, pathological imaging, and genomic data to enhance the performance of our model are ongoing.

Asian Oceanian Radiology Forum 2018: International Education of Radiology in Asian Oceanian Countries.

According to the reports presented at the Fourth Asian Oceanian Radiology Forum (AORF) 2018, organized by the Korean Society of Radiology during the Korean Congress of Radiology in September 2018 in Seoul, there is an increasing demand for the Asian Oceanian Society of Radiology and its member societies for international education in radiology in the Asian Oceanian region. In AORF 2018, the national delegates of the Asian Oceanian radiological partner societies primarily discussed their societies' activities and current status of international education in radiology.

KSR/KSTR Guidelines for the Use of Diagnostic Imaging for COVID-19.

The Korean Society of Radiology and the Korean Society of Thoracic Radiology have prepared recommendations for the use of diagnostic imaging for COVID-19 in various clinical scenarios. We have tried to grasp the situation in the real world, aggregated opinions from the chest radiologists, and reviewed available references, in order to suggest the most reasonable recommendations possible at this moment. As circumstances change and new evidences emerge, the recommendations should immediately be modified accordingly.

Coronary-to-Pulmonary Artery Fistula in Adults: Natural History and Management Strategies.

OBJECTIVE: To evaluate the natural course of coronary-to-pulmonary artery fistula (CPAF) detected on coronary computed tomography angiography (CCTA) and to propose potential treatment strategies. MATERIALS AND METHODS: In this retrospective multicenter study, we assessed the CCTA reports of 188 CPAF patients evaluated between March 2009 and June 2016. Fifty-seven patients were excluded because their follow-up (FU) periods were less than 2 years. Information regarding demographic characteristics, past history, treatment method, and the occurrence of major adverse cardiac events (MACE) during the FU period was collected. We analyzed the morphologic features of CPAF and the various factors associated with surgical treatment. Patients who had undergone FU CCTA after being diagnosed with CPAF were assessed for the presence of morphological changes on FU imaging. RESULTS: The median age of the study population was 63.0 years (range, 57.0-72.0 years), and the median FU period was 5.72 years (range, 4.08-6.96 years). The most common origin of the CPAF was both coronary arteries in 76 (58.0%) cases. An aneurysm or aneurysms was/were present in 41 (31.3%) cases. Fifty-four (41.2%) fistulas were less than 2 mm in size. Eight patients underwent surgery, and 123 (93.9%) patients received optimal medical treatment (OMT). The fistula size was significantly different between the two treatment groups (p = 0.013) and was the only factor associated with surgical treatment (odds ratio = 1.14, p = 0.021). Only one patient in the OMT group reported MACE during the FU period due to preexisting coronary artery disease. Twenty-nine patients (22.1%) underwent FU CCTA after CPAF diagnosis, with a median FU period of 3.81 years. None of the patients in the OMT group demonstrated morphological changes in the CPAF on FU imaging. CONCLUSION: Most CPAFs identified on CCTA have a favorable prognosis. Observation with OMT is usually an appropriate strategy. Fistula size is a possible determinant for surgical treatment.

Role of CT-guided transthoracic biopsy in the diagnosis of mycobacterial infection.

Mycobacterial infection(MI) is sometimes diagnosed using CT-guided transthoracic needle biopsy (TNB). However, the exact role of CT-guided TNB in this diagnostic process is not clearly known. The purpose of this study is to analyze the role of CT-guided TNB in patients with MI who present with a focal lung lesion. Of 1233 patients who underwent CT-guided TNB from January 2010 through February 2016 at our institution, patients with a final diagnosis of MI were included for analysis. Clinical characteristics and biopsy-related factors were compared between patients whose diagnosis could be established using TNB samples alone (group 1) and those whose samples from additional tests were necessary for diagnosis (group 2). We also analyzed the possible benefit of CT-guided TNB as compared with bronchoscopy in a subgroup who underwent both procedures. 47 patients with MI were included in the study, with 37 patients (78.7%) in group 1 and 10 patients (21.2%) in group 2. There was no statistically significant difference in clinical characteristics or biopsy-related factors between the two groups. Of 41 patients with MI who underwent both bronchoscopy and TNB, success in diagnosis was solely attributable to TNB in 16 (39.0%) patients; in 19 (46.0%) patients, diagnosis could be made based on bronchoscopy results alone. MI can be successfully diagnosed by CT-guided TNB in about 80% of patients with MI who underwent TNB, but 46% of the patients could have been diagnosed with bronchoscopy results alone. CT-guided TNB is inferior to bronchoscopy in the differentiation of Mycobacterium species even in peripheral lung lesions.

Simple quantification of paracardial and epicardial fat dimensions at low-dose chest CT: correlation with metabolic risk factors and usefulness in predicting metabolic syndrome.

PURPOSE: To assess the usefulness of simple axial bi-dimensional diameters of pericardial fat tissues at low-dose chest CT, in correlation with metabolic parameters in predicting metabolic syndrome. MATERIALS AND METHODS: Subjects were 373 asymptomatic individuals who performed both low-dose chest CT and abdominal fat CT for medical check-up. Maximum bi-dimensional axial diameters of paracardial fats at right (RPF) and left (LPF) cardiophrenic angle portions, and epicardial fats around right (REF) and left (LEF) coronary arteries, and coronary sinus (SEF) were measured. Correlation between pericardial fat diameters and metabolic parameters were statistically analyzed. RESULTS: RPF, LPF, REF, LEF, and SEF diameters were moderately correlated with abdominal visceral fat (AVF) area (R = 0.74, 0.70, 0.48, 0.41, and 0.53, respectively, p < 0.01) in Pearson's correlation analysis. In multiple linear regression analysis, coefficient of RPF for AVF showed highest value. Means of each PF and EF diameters in subjects with metabolic syndrome were significantly larger than those without metabolic syndrome (p < 0.001). All PF and EF diameters were well-discriminated for prediction of metabolic syndrome in ROC analysis (AUC values, from 0.696 to 0.795). CONCLUSION: RPF diameter at low-dose chest CT would be a simple method for prediction of metabolic syndrome.