Deep Learning With Chest Radiographs for Making Prognoses in Patients With COVID-19: Retrospective Cohort Study.

BACKGROUND: An artificial intelligence (AI) model using chest radiography (CXR) may provide good performance in making prognoses for COVID-19. OBJECTIVE: We aimed to develop and validate a prediction model using CXR based on an AI model and clinical variables to predict clinical outcomes in patients with COVID-19. METHODS: This retrospective longitudinal study included patients hospitalized for COVID-19 at multiple COVID-19 medical centers between February 2020 and October 2020. Patients at Boramae Medical Center were randomly classified into training, validation, and internal testing sets (at a ratio of 8:1:1, respectively). An AI model using initial CXR images as input, a logistic regression model using clinical information, and a combined model using the output of the AI model (as CXR score) and clinical information were developed and trained to predict hospital length of stay (LOS) ≤2 weeks, need for oxygen supplementation, and acute respiratory distress syndrome (ARDS). The models were externally validated in the Korean Imaging Cohort of COVID-19 data set for discrimination and calibration. RESULTS: The AI model using CXR and the logistic regression model using clinical variables were suboptimal to predict hospital LOS ≤2 weeks or the need for oxygen supplementation but performed acceptably in the prediction of ARDS (AI model area under the curve [AUC] 0.782, 95% CI 0.720-0.845; logistic regression model AUC 0.878, 95% CI 0.838-0.919). The combined model performed better in predicting the need for oxygen supplementation (AUC 0.704, 95% CI 0.646-0.762) and ARDS (AUC 0.890, 95% CI 0.853-0.928) compared to the CXR score alone. Both the AI and combined models showed good calibration for predicting ARDS (P=.079 and P=.859). CONCLUSIONS: The combined prediction model, comprising the CXR score and clinical information, was externally validated as having acceptable performance in predicting severe illness and excellent performance in predicting ARDS in patients with COVID-19.

Correction: Deep Learning With Chest Radiographs for Making Prognoses in Patients With COVID-19: Retrospective Cohort Study.

[This corrects the article DOI: 10.2196/42717.].

Erratum: Correction of Affiliations in the Article "Establishment of a Nationwide Korean Imaging Cohort of Coronavirus Disease 2019".

This corrects the article on p. e413 in vol. 35, PMID: 33258333.

Low Tube Voltage Chest Computed Tomography With Enhancement Using Low-Concentration Iodinated Contrast Media: Comparison of 240 mg/mL Versus 300 mg/mL Iodinated Contrast Media.

Purpose: To evaluate the image quality of low voltage chest computed tomography with enhancement (CECT) using low-concentration-iodine contrast media (LCCM). Method: From 9 December to 19 December 2019, three different protocols were used for 263 patients undergoing chest CECT. Chest CECT was done using routine (300 mgI/ml contrast media with 100 kVp) protocol (group 1), LCCM (240 mgI/ml contrast media)-100 kVp protocol (group 2) and LCCM-80 kVp protocol (group 3) in 91, 97 and 75 patients, respectively. The overall diagnostic acceptability, anatomical depiction, noise and contrast-related artifacts were assessed. Additionally, the mean attenuation, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and figure of merit (FOM) in the aorta and the main pulmonary trunk were measured. Results: The overall diagnostic acceptability scores were not significantly different between groups 1 and 2 (P = .261); group 3 demonstrated significantly lower overall diagnostic acceptability score compared with group 1 (P = .011) or group 2 (P < .001). However, in CECT with iterative reconstruction (IR), the overall diagnostic acceptability scores did not show significant difference among 3 groups. Group 3 showed significantly lower effective radiation dose compared with group 1 (2.33 vs 1.22 mSv, P < .001) or group 2 (2.28 vs .22 mSv, P < .001). Conclusions: In 100 kVp chest CECT, the image quality of using 240 mg/mL iodinated contrast media is comparable to that using 300 mg/mL iodine contrast media, regardless of application of IR; with IR, chest CECT using 80 kVp and 240 mg/mL iodinated contrast media results in acceptable image quality and lower radiation dose.

Computed Tomography Findings for Predicting Invasiveness of Lung Adenocarcinomas Manifesting as Pure Ground-Glass Nodules.

Purpose: To comprehensively evaluate qualitative and quantitative features for predicting invasiveness of pure ground-glass nodules (pGGNs) using multiplanar computed tomography. Methods: Ninety-three resected pGGNs (16 atypical adenomatous hyperplasia [AAH], 18 adenocarcinoma in situ [AIS], 31 minimally invasive adenocarcinoma [MIA], and 28 invasive adenocarcinoma [IA]) were retrospectively included. Two radiologists analyzed qualitative and quantitative features on three standard planes. Univariable and multivariable logistic regression analyses were performed to identify features to distinguish the pre-invasive (AAH/AIS) from the invasive (MIA/IA) group. Results: Tumor size showed high area under the curve (AUC) for predicting invasiveness (.860, .863, .874, and .893, for axial long diameter [AXLD], multiplanar long diameter, mean diameter, and volume, respectively). The AUC for AXLD (cutoff, 11 mm) was comparable to that of the volume (P = .202). The invasive group had a significantly higher number of qualitative features than the pre-invasive group, regardless of tumor size. Six out of 59 invasive nodules (10.2%) were smaller than 11 mm, and all had at least one qualitative feature. pGGNs smaller than 11 mm without any qualitative features (n = 16) were all pre-invasive. In multivariable analysis, AXLD, vessel change, and the presence or number of qualitative features were independent predictors for invasiveness. The model with AXLD and the number of qualitative features achieved the highest AUC (.902, 95% confidence interval .833-.971). Conclusion: In adenocarcinomas manifesting as pGGNs on computed tomography, AXLD and the number of qualitative features are independent risk factors for invasiveness; small pGGNs (<11 mm) without qualitative features have low probability of invasiveness.

T1 and T2 Mapping for Characterization of Mediastinal Masses: A Feasibility study.

Purpose: To evaluate the feasibility and usefulness of T1 and T2 mapping in characterization of mediastinal masses. Methods: From August 2019 through December 2021, 47 patients underwent 3.0-T chest MRI with T1 and post-contrast T1 mapping using modified look-locker inversion recovery sequences and T2 mapping using a T2-prepared single-shot shot steady-state free precession technique. Mean native T1, native T2, and post-contrast T1 values were measured by drawing the region of interest in the mediastinal masses, and enhancement index (EI) was calculated using these values. Results: All mapping images were acquired successfully, without significant artifact. There were 25 thymic epithelial tumors (TETs), 3 schwannomas, 6 lymphomas, and 9 thymic cysts, and 4 other cystic tumors. TET, schwannoma, and lymphoma were grouped together as "solid tumor," to be compared with thymic cysts and other tumors ("cystic tumors"). The mean post-contrast T1 mapping (P < .001), native T2 mapping (P < .001), and EI (P < .001) values showed significant difference between these two groups. Among TETs, high risk TETs (thymoma types B2, B3, and thymic carcinoma) showed significantly higher native T2 mapping values (P = .002) than low risk TETs (thymoma types A, B1, and AB). For all measured variables, interrater reliability was good to excellent (intraclass coefficient [ICC]: .869∼.990) and intrarater reliability was excellent (ICC: .911∼.995). Conclusion: The use of T1 and T2 mapping in MRI of mediastinal masses is feasible and may provide additional information in the evaluation of mediastinal masses.

Phantom-based correction for standardization of myocardial native T1 and extracellular volume fraction in healthy subjects at 3-Tesla cardiac magnetic resonance imaging.

OBJECTIVES: To investigate the effect of the phantom-based correction method for standardizing myocardial native T1 and extracellular volume fraction (ECV) in healthy subjects. METHODS: Seventy-one healthy asymptomatic adult (≥ 20 years) volunteers of five different age groups (34 men and 37 women, 45.5 ± 15.5 years) were prospectively enrolled in three academic hospitals. Cardiac MRI including Modified Look - Locker Inversion recovery T1 mapping sequence was performed using a 3-Tesla system with a different type of scanner for each hospital. Native T1 and ECV were measured in the short-axis T1 map and analyzed for mean values of the 16 entire segments. The myocardial T1 value of each subject was corrected based on the site-specific equation derived from the T1 Mapping and ECV Standardization phantom. The global native T1 and ECV were compared between institutions before and after phantom-based correction, and the variation in native T1 and ECV among institutions was assessed using a coefficient of variation (CoV). RESULTS: The global native T1 value significantly differed between the institutions (1198.7 ± 32.1 ms, institution A; 1217.7 ± 39.9 ms, institution B; 1232.7 ± 31.1 ms, institution C; p = 0.002), but the mean ECV did not (26.6-27.5%, p = 0.355). After phantom-based correction, the global native T1 and ECV were 1289.7 ± 32.4 ms and 25.0 ± 2.7%, respectively, and CoV for native T1 between the three institutions decreased from 3.0 to 2.5%. The corrected native T1 value did not significantly differ between institutions (1284.5 ± 31.5 ms, institution A; 1296.5 ± 39.1 ms, institution B; 1291.3 ± 29.3 ms, institution C; p = 0.440), and neither did the ECV (24.4-25.9%, p = 0.078). CONCLUSIONS: The phantom-based correction method can provide standardized reference T1 values in healthy subjects. KEY POINTS: • After phantom-based correction, the global native T1 of 16 entire myocardial segments on 3-T cardiac MRI is 1289.4 ± 32.4 ms, and the extracellular volume fraction was 25.0 ± 2.7% for healthy subjects. • After phantom - based correction was applied, the differences in the global native T1 among institutions became insignificant, and the CoV also decreased from 3.0 to 2.5%.

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.

Effectiveness of radiologist training in improving reader agreement for Lung-RADS 4X categorization.

OBJECTIVES: To identify the agreement on Lung CT Screening Reporting and Data System 4X categorization between radiologists and an expert-adjudicated reference standard and to investigate whether training led to improvement of the agreement measures and diagnostic potential for lung cancer. METHODS: Category 4 nodules in the Korean Lung Cancer Screening Project were identified retrospectively, and each 4X nodule was matched with one 4A or 4B nodule. An expert panel re-evaluated the categories and determined the reference standard. Nineteen radiologists were asked to determine the presence of CT features of malignancy and 4X categorization for each nodule. A review was performed in two sessions, and training material was given after session 1. Agreement on 4X categorization between radiologists and the expert-adjudicated reference standard and agreement between radiologist-assessed 4X categorization and lung cancer diagnosis were evaluated. RESULTS: The 48 expert-adjudicated 4X nodules and 64 non-4X nodules were evenly distributed in each session. The proportion of category 4X decreased after training (56.4% ± 16.9% vs. 33.4% ± 8.0%; p < 0.001). Cohen's κ indicated poor agreement (0.39 ± 0.16) in session 1, but agreement improved in session 2 (0.47 ± 0.09; p = 0.03). The increase in agreement in session 2 was observed among inexperienced radiologists (p < 0.05), and experienced and inexperienced reviewers exhibited comparable agreement performance in session 2 (p > 0.05). All agreement measures between radiologist-assessed 4X categorization and lung cancer diagnosis increased in session 2 (p < 0.05). CONCLUSION: Radiologist training can improve reader agreement on 4X categorization, leading to enhanced diagnostic performance for lung cancer. KEY POINTS: • Agreement on 4X categorization between radiologists and an expert-adjudicated reference standard was initially poor, but improved significantly after training. • The mean proportion of 4X categorization by 19 radiologists decreased from 56.4% ± 16.9% in session 1 to 33.4% ± 8.0% in session 2. • All agreement measures between the 4X categorization and lung cancer diagnosis increased significantly in session 2, implying that appropriate training and guidance increased the diagnostic potential of category 4X.

Establishment of a Nationwide Korean Imaging Cohort of Coronavirus Disease 2019.

BACKGROUND: The Korean Society of Thoracic Radiology (KSTR) recently constructed a nation-wide coronavirus disease 2019 (COVID-19) database and imaging repository, referred to the Korean imaging cohort of COVID-19 (KICC-19) based on the collaborative efforts of its members. The purpose of this study was to provide a summary of the clinico-epidemiological data and imaging data of the KICC-19. METHODS: The KSTR members at 17 COVID-19 referral centers retrospectively collected imaging data and clinical information of consecutive patients with reverse transcription polymerase chain reaction-proven COVID-19 in respiratory specimens from February 2020 through May 2020 who underwent diagnostic chest computed tomography (CT) or radiograph in each participating hospital. RESULTS: The cohort consisted of 239 men and 283 women (mean age, 52.3 years; age range, 11-97 years). Of the 522 subjects, 201 (38.5%) had an underlying disease. The most common symptoms were fever (n = 292) and cough (n = 245). The 151 patients (28.9%) had lymphocytopenia, 86 had (16.5%) thrombocytopenia, and 227 patients (43.5%) had an elevated CRP at admission. The 121 (23.4%) needed nasal oxygen therapy or mechanical ventilation (n = 38; 7.3%), and 49 patients (9.4%) were admitted to an intensive care unit. Although most patients had cured, 21 patients (4.0%) died. The 465 (89.1%) subjects underwent a low to standard-dose chest CT scan at least once during hospitalization, resulting in a total of 658 CT scans. The 497 subjects (95.2%) underwent chest radiography at least once during hospitalization, which resulted in a total of 1,475 chest radiographs. CONCLUSION: The KICC-19 was successfully established and comprised of 658 CT scans and 1,475 chest radiographs of 522 hospitalized Korean COVID-19 patients. The KICC-19 will provide a more comprehensive understanding of the clinical, epidemiological, and radiologic characteristics of patients with COVID-19.

A case of early diagnosis of pulmonary capillary hemangiomatosis in a worker with exposure to silica.

BACKGROUND: Pulmonary capillary hemangiomatosis (PCH) is a progressive and refractory vascular disease in the lung. Pulmonary hypertension is frequently combined with PCH when capillary proliferation invades to nearby pulmonary vascular systems. It is difficult to differentiate PCH from other diseases such as pulmonary venoocclusive disease and pulmonary arterial hypertension that cause pulmonary hypertension as they frequently overlap. CASE PRESENTATION: A 29-year-old female who had worked at a bathtub factory presented with progressive exertional dyspnea for the past 2 years. Computed tomography revealed centrilobular, diffusely spreading ground-glass opacities sparing subpleural parenchyma with some cystic lesions and air-trapping in both lungs, suggesting a peculiar pattern of interstitial lung disease with airway involvement. There was not any evidence of right heart failure or pulmonary hypertension on echocardiogram, as well as radiography. Microscopic examination of the lung by thoracoscopic resection showed atypical proliferation of capillary channels within alveolar walls and interlobar septa, without invasion of large vessels. CONCLUSION: We experienced a pathologically diagnosed PCH in a young female complaining progressive dyspnea with prior exposure to occupational silica or organic solvent without elevated right ventricular systolic pressure (RVSP) who showed atypical pattern of radiologic findings.

Incidental Pulmonary Embolism After Coronary Artery Bypass Surgery: Long-Term Clinical Follow-Up.

OBJECTIVE: The purpose of this study was to investigate the incidence and natural history of incidentally found and untreated pulmonary embolism (PE) at coronary CT angiography after coronary artery bypass grafting. MATERIALS AND METHODS: We retrospectively reviewed the records of 353 patients consecutively registered between January 1, 2010, and November 11, 2015, who underwent coronary artery bypass grafting followed within 2 weeks by coronary CT angiography. All patients received 100 mg of aspirin and 75 mg of clopidogrel after surgery. We collected relevant clinical and CT data, including total follow-up duration after coronary artery bypass grafting, follow-up CT findings, mortality, and incidence of any recurrent PE. RESULTS: PE was diagnosed in 22 of the 353 patients (6.2%) who remained in the study after the exclusion criteria were applied. Most of the PEs occurred at the segmental or subsegmental level. All patients were in hemodynamically stable condition, had no symptoms, and underwent follow-up for a median of 53 months (range 19-74 months). Twenty of the 22 patients did not receive anticoagulation, and all but one of these patients had complete resolution of PE at second follow-up coronary CT angiography (median, 149 days after surgery). There was no associated mortality or recurrent PE. CONCLUSION: Incidental PE after coronary artery bypass grafting is found in approximately 6% of patients undergoing postoperative coronary CT angiography, and most PEs resolve spontaneously without anticoagulation. No patient in this study died or had recurrent PE during a median follow-up period of 53 months.

Coronary artery calcium score plays an important role for cardiovascular risk stratification in the statin benefit groups of asymptomatic individuals.

BACKGROUND: The purpose of this study was to describe and analyze the relationship between statin benefit groups based on statin-intensity class of drugs and coronary artery calcium score (CACS) using multidetector computed tomography (MDCT) in an asymptomatic Korean population. METHODS: A total of 3914 asymptomatic individuals (mean age: 55 ± 10 years; male: female = 2649: 1265) who underwent MDCT for health examination between January 2009 and December 2012 were retrospectively enrolled. They were categorized into three groups based on statin-intensity class of drugs (high-intensity (n = 1284, 32.8%); moderate-intensity (n = 1602, 40.9%) and low-intensity (n = 931, 23.8%) statin therapy groups) according to the American College of Cardiology (ACC)/American heart Association (AHA) 2013 guideline and the relationship between CACS and statin benefit group was analyzed. The statin benefit group was defined as individuals who should be considered moderate- and high-intensity statin therapy. RESULTS: Ten-year atherosclerotic cardiovascular disease (ASCVD; 12.6 ± 5.3% vs. 2.9 ± 1.9%, p < 0.001) and CACS (98 ± 270 vs. 3 ± 2, p < 0.001) were significantly higher in the high-intensity group compared to the moderate-intensity statin therapy group. In the high-intensity statin therapy group, age [odds ratio: 1.299 (1.137-1.483), p < 0.001], male gender [odds ratio: 44.252 (1.959-999.784), p = 0.001], and fasting blood glucose [odds ratio: 1.046 (1.007-1.087), p = 0.021] were independent risk factors associated with CACS ≥300 on multivariate logistic regression analysis. CONCLUSIONS: CACS on MDCT might be an important complementary tool for cardiovascular disease risk stratification. This study indicates that individualization of statin therapy as well as lifestyle modification will be useful in asymptomatic individuals, especially those in whom high-intensity statin therapy is required.

Interstitial lung disorders in the indium workers of Korea: an update study for the relationship with biological exposure indices.

BACKGROUND: Korea is one of the highest indium-consuming countries worldwide. The present study aims to determine the relationship between interstitial lung disorders and indium exposure in Korea. METHODS: In 50 indium workers from seven plants, the effect of serum indium on the lungs was determined using laboratory tests, spirometry, and high-resolution computed tomography (HRCT). RESULTS: Higher serum indium and Krebs von den Lungen-6 (KL-6) levels were associated with HRCT-detected interstitial lung changes. Workers with high serum indium levels (≥3 µg/L) had longer exposure durations and a higher prevalence of HRCT-detected interstitial lung changes. KL-6 and surfactant protein-D (SP-D) levels were significantly higher in the highest serum indium quartile than the lowest quartile. Significant dose-effect relationships existed between serum indium levels and KL-6, SP-D levels and the prevalence of HRCT-detected interstitial lung changes. CONCLUSIONS: Workforce medical surveillance should be established to prevent indium-induced interstitial lung disease in Korea.

Arteria praebronchialis found on MDCT: potentially dangerous aberrant artery supplying the left lower lobe.

PURPOSE: To describe the incidence and CT features of a rare branching pattern of the pulmonary artery, the Arteria praebronchialis (AP): According to the initial description, the AP originates as the first branch of the left pulmonary artery, crosses the front of the left mainstem bronchus and then runs along the mediastinal margin as it gives off branches to one or more of the basal segments. MATERIALS AND METHODS: Since the incidental discovery of the first patient, contrast-enhanced CT was screened by one radiologist for the presence of AP, until three more cases were identified. In those four patients, segmental and lobar branching patterns of the AP were assessed. RESULTS: The estimated incidence of the AP was 0.03%. All four patients were men. Compared to the normal interlobar artery, the AP was smaller (n = 2), larger (n = 1), or of an equal size (n = 1). The segmental branches of the AP to the upper lobe (present in three patients) were A3 and A4 (n = 1), A3 and A5 (n = 1) and A4+5 (n = 1), respectively. Regarding the supply of the left lower lobe, AP gave off A7+8 and A9 (n = 2), A7+8 (n = 1), and A7 and A10 (n = 1), respectively. In two patients, a contralateral variant of pulmonary arterial branching was found, with (right) A7 arising as the first branch of right pulmonary artery. CONCLUSION: The AP is extremely rare, but has a strong male predilection and highly diverse branching patterns in both the current study and the literature. Radiologists should familiarize themselves with the CT features of this surgically important variation, and be able to describe its lobar and segmental blood supply.

Prevalence and types of coronary artery fistulas detected with coronary CT angiography.

OBJECTIVE: The prevalence of coronary artery fistula (CAF) based on coronary angiographic findings has been reported. However, the number of incidentally found CAFs is increasing as coronary CT angiography (CTA) has become popular. The purpose of this study was to determine the prevalence and types of CAFs detected with coronary CTA. MATERIALS AND METHODS: Between March 2009 and November 2011, 6341 patients underwent coronary CTA at one institution. The prevalence of CAF was retrospectively evaluated, and the morphologic features were analyzed, including vessel of origin, drainage site, size, and presence of an aneurysmal sac. We also analyzed cardiac and pulmonary findings. RESULTS: Among 6341 patients, 56 (0.9%) patients had CAF. The types of CAF detected, in decreasing frequency, were coronary to pulmonary artery fistula (43 cases [76.8%]), coronary to bronchial artery fistula (five cases [8.9%]), coronary artery to cardiac chamber fistula (five cases [8.9%]), combined coronary to pulmonary and coronary to bronchial artery fistula (two cases [3.6%]), and coronary artery to superior vena cava fistula (one case [1.8%]). Lung parenchymal or vascular anomaly was more frequently noted in coronary to bronchial artery fistulas, combined coronary to pulmonary and coronary to bronchial artery fistulas, and coronary artery to superior vena cava fistulas than in coronary to pulmonary artery and coronary artery to cardiac chamber fistulas. CONCLUSION: The prevalence of CAF at coronary CTA was 0.9%, which is higher than the known prevalence based on conventional angiographic findings (0.05-0.25%). Furthermore, the most common type of CAF in this study was coronary to pulmonary artery, whereas coronary artery to ventricle fistula was previously considered the most common type in studies conducted with conventional angiography. Coronary CTA is a useful, noninvasive imaging modality for the detection of CAF.

Acute pulmonary complications in patients with hematologic malignancies.

Various acute pulmonary complications may occur in patients with hematologic malignancies because they are in an immunocompromised state due to systemic disease or to chemotherapy or hematopoietic stem cell transplantation. Pulmonary complications may arise from other treatment regimens, as well, or from direct pulmonary involvement in the malignant disease process. The differential diagnosis of pulmonary opacities in patients with hematologic malignancies is broad and includes both infectious and noninfectious causes. Pulmonary hemorrhage, edema, leukostasis, and pneumonia are well-known and common acute pulmonary complications. Less common complications are now encountered with increasing frequency because of the increasing complexity of therapeutic regimens for hematologic malignancies, which may include various drugs that are in clinical trials or were recently released to market. These once uncommon acute pulmonary complications include retinoic acid syndrome, tyrosine kinase inhibitor-induced pulmonary complications, engraftment syndrome, and hemophagocytic lymphohistiocytosis. It is often difficult to differentiate between these entities. However, the clinical setting and radiologic imaging findings may provide clues for interpreting imaging findings of abnormal pulmonary opacity in patients with a hematologic malignancy. Pulmonary hemorrhage is characterized by a sudden onset of symptoms and rapid progression of pulmonary imaging abnormalities and usually occurs in patients with impaired coagulation or a predisposition to bleed. Pulmonary edema should be considered when typical findings of hydrostatic pulmonary edema are seen. Pulmonary leukostasis develops in patients with hyperleukocytosis and leads to symptoms such as a cough, fever, and dyspnea. Various types of pneumonia may develop, depending on the degree and duration of immunosuppression in the patient. Retinoic acid syndrome, tyrosine kinase inhibitor-induced pulmonary complications, and engraftment syndrome occur after specific treatments, so a detailed medical history including recent or current treatments may be helpful for diagnosis. Accurate differentiation of these entities allows their appropriate management, with resultant decreases in morbidity and mortality.

Post-RFA Pulmonary Vein Stenosis Mimicking Lymphangitic Carcinomatosis in a Patient With History of Liposarcoma.

ABSTRACT: A 58-year-old man with resected liposarcoma exhibited persistent irregular interlobular septal thickening of lung on CT concerning lymphangitic metastasis. FDG PET/CT was positive in these foci. There was a narrowing of the pulmonary veins, which had not been seen on the imaging conducted prior to radiofrequency ablation therapy for atrial fibrillation. Lung perfusion scanning demonstrated more extensive hypoperfusion. This case highlights the diagnostic pitfalls of interstitial thickening of the lung in cancer patients. Meticulous history review and nuclear imaging helped distinguish the postablation pulmonary venous stenosis from metastatic spread to the lung interstitium.

Diagnostic Efficacy and Safety of Low-Contrast-Dose Dual-Energy CT in Patients With Renal Impairment Undergoing Transcatheter Aortic Valve Replacement.

OBJECTIVE: This study aimed to evaluate the diagnostic efficacy and safety of low-contrast-dose, dual-source dual-energy CT before transcatheter aortic valve replacement (TAVR) in patients with compromised renal function. MATERIALS AND METHODS: A total of 54 consecutive patients (female:male, 26:38; 81.9 ± 7.3 years) with reduced renal function underwent pre-TAVR dual-energy CT with a 30-mL contrast agent between June 2022 and March 2023. Monochromatic (40- and 50-keV) and conventional (120-kVp) images were reconstructed and analyzed. The subjective quality score, vascular attenuation, contrast-to-noise ratio (CNR), and signal-to-noise ratio (SNR) were compared among the imaging techniques using the Friedman test and post-hoc analysis. Interobserver reliability for aortic annular measurement was assessed using the intraclass correlation coefficient (ICC) and Bland-Altman analysis. The procedural outcomes and incidence of post-contrast acute kidney injury (AKI) were assessed. RESULTS: Monochromatic images achieved diagnostic quality in all patients. The 50-keV images achieved superior vascular attenuation and CNR (P < 0.001 in all) while maintaining a similar SNR compared to conventional CT. For aortic annular measurement, the 50-keV images showed higher interobserver reliability compared to conventional CT: ICC, 0.98 vs. 0.90 for area and 0.97 vs. 0.95 for perimeter; 95% limits of agreement width, 0.63 cm² vs. 0.92 cm² for area and 5.78 mm vs. 8.50 mm for perimeter. The size of the implanted device matched CT-measured values in all patients, achieving a procedural success rate of 92.6%. No patient experienced a serum creatinine increase of ≥ 1.5 times baseline in the 48-72 hours following CT. However, one patient had a procedural delay due to gradual renal function deterioration. CONCLUSION: Low-contrast-dose imaging with 50-keV reconstruction enables precise pre-TAVR evaluation with improved image quality and minimal risk of post-contrast AKI. This approach may be an effective and safe option for pre-TAVR evaluation in patients with compromised renal function.