Generative Adversarial Network-Based Image Conversion Among Different Computed Tomography Protocols and Vendors: Effects on Accuracy and Variability in Quantifying Regional Disease Patterns of Interstitial Lung Disease.

OBJECTIVE: To assess whether computed tomography (CT) conversion across different scan parameters and manufacturers using a routable generative adversarial network (RouteGAN) can improve the accuracy and variability in quantifying interstitial lung disease (ILD) using a deep learning-based automated software. MATERIALS AND METHODS: This study included patients with ILD who underwent thin-section CT. Unmatched CT images obtained using scanners from four manufacturers (vendors A-D), standard- or low-radiation doses, and sharp or medium kernels were classified into groups 1-7 according to acquisition conditions. CT images in groups 2-7 were converted into the target CT style (Group 1: vendor A, standard dose, and sharp kernel) using a RouteGAN. ILD was quantified on original and converted CT images using a deep learning-based software (Aview, Coreline Soft). The accuracy of quantification was analyzed using the dice similarity coefficient (DSC) and pixel-wise overlap accuracy metrics against manual quantification by a radiologist. Five radiologists evaluated quantification accuracy using a 10-point visual scoring system. RESULTS: Three hundred and fifty CT slices from 150 patients (mean age: 67.6 ± 10.7 years; 56 females) were included. The overlap accuracies for quantifying total abnormalities in groups 2-7 improved after CT conversion (original vs. converted: 0.63 vs. 0.68 for DSC, 0.66 vs. 0.70 for pixel-wise recall, and 0.68 vs. 0.73 for pixel-wise precision; P < 0.002 for all). The DSCs of fibrosis score, honeycombing, and reticulation significantly increased after CT conversion (0.32 vs. 0.64, 0.19 vs. 0.47, and 0.23 vs. 0.54, P < 0.002 for all), whereas those of ground-glass opacity, consolidation, and emphysema did not change significantly or decreased slightly. The radiologists' scores were significantly higher (P < 0.001) and less variable on converted CT. CONCLUSION: CT conversion using a RouteGAN can improve the accuracy and variability of CT images obtained using different scan parameters and manufacturers in deep learning-based quantification of ILD.

Generative adversarial network for automatic quantification of Coronavirus disease 2019 pneumonia on chest radiographs.

PURPOSE: To develop a generative adversarial network (GAN) to quantify COVID-19 pneumonia on chest radiographs automatically. MATERIALS AND METHODS: This retrospective study included 50,000 consecutive non-COVID-19 chest CT scans in 2015-2017 for training. Anteroposterior virtual chest, lung, and pneumonia radiographs were generated from whole, segmented lung, and pneumonia pixels from each CT scan. Two GANs were sequentially trained to generate lung images from radiographs and to generate pneumonia images from lung images. GAN-driven pneumonia extent (pneumonia area/lung area) was expressed from 0% to 100%. We examined the correlation of GAN-driven pneumonia extent with semi-quantitative Brixia X-ray severity score (one dataset, n = 4707) and quantitative CT-driven pneumonia extent (four datasets, n = 54-375), along with analyzing a measurement difference between the GAN and CT extents. Three datasets (n = 243-1481), where unfavorable outcomes (respiratory failure, intensive care unit admission, and death) occurred in 10%, 38%, and 78%, respectively, were used to examine the predictive power of GAN-driven pneumonia extent. RESULTS: GAN-driven radiographic pneumonia was correlated with the severity score (0.611) and CT-driven extent (0.640). 95% limits of agreements between GAN and CT-driven extents were -27.1% to 17.4%. GAN-driven pneumonia extent provided odds ratios of 1.05-1.18 per percent for unfavorable outcomes in the three datasets, with areas under the receiver operating characteristic curve (AUCs) of 0.614-0.842. When combined with demographic information only and with both demographic and laboratory information, the prediction models yielded AUCs of 0.643-0.841 and 0.688-0.877, respectively. CONCLUSION: The generative adversarial network automatically quantified COVID-19 pneumonia on chest radiographs and identified patients with unfavorable outcomes.

Clinical characteristics of rheumatoid arthritis patients with interstitial lung disease: baseline data of a single-center prospective cohort.

BACKGROUND: To introduce a prospective cohort for rheumatoid arthritis (RA) patients with interstitial lung disease (ILD) and to identify their clinical features in comparison with RA patients without ILD. METHODS: Using a multidisciplinary collaborative approach, a single-center cohort for RA patients with ILD (RA-ILD) was established in May 2017, and enrolment data from May 2017 to March 2021 were used to compare the clinical features of RA patients without ILD (RA-non ILD). Multivariable logistic regression analysis was used to identify factors associated with ILD in RA patients. RESULTS: Among 148 RA-ILD and 410 RA-non ILD patients, participants in the RA-ILD group were older (65.8 ± 9.9 vs. 58.0 ± 10.4 years, P < 0.001) and included more males (35.8% vs. 14.6%, P < 0.001) than in the RA-non ILD group. The RA-ILD group had a higher proportion of late-onset RA patients (age ≥ 60 years) than in the comparator group (43.9% vs. 14.2%, P < 0.001). Multivariable logistic regression analysis showed that higher age at RA onset (OR 1.056, 95% CI 1.021-1.091), higher body mass index (BMI; OR 1.65, 95% CI 1.036-2.629), smoking history (OR 2.484, 95% CI 1.071-5.764), and oral glucocorticoid use (OR 3.562, 95% CI 2.160-5.874) were associated with ILD in RA patients, whereas methotrexate use was less likely to be associated with ILD (OR 0.253, 95% CI 0.155-0.412). CONCLUSIONS: Higher age at RA onset, smoking history, and higher BMI were associated with the presence of ILD among RA patients. Oral glucocorticoids were more frequently used whereas methotrexate was less likely to be used in RA-ILD patients.

Diagnosis of Scoliosis Using Chest Radiographs with a Semi-Supervised Generative Adversarial Network.

Purpose: To develop and validate a deep learning-based screening tool for the early diagnosis of scoliosis using chest radiographs with a semi-supervised generative adversarial network (GAN). Materials and Methods: Using a semi-supervised learning framework with a GAN, a screening tool for diagnosing scoliosis was developed and validated through the chest PA radiographs of patients at two different tertiary hospitals. Our proposed method used training GAN with mild to severe scoliosis only in a semi-supervised manner, as an upstream task to learn scoliosis representations and a downstream task to perform simple classification for differentiating between normal and scoliosis states sensitively. Results: The area under the receiver operating characteristic curve, negative predictive value (NPV), positive predictive value, sensitivity, and specificity were 0.856, 0.950, 0.579, 0.985, and 0.285, respectively. Conclusion: Our deep learning-based artificial intelligence software in a semi-supervised manner achieved excellent performance in diagnosing scoliosis using the chest PA radiographs of young individuals; thus, it could be used as a screening tool with high NPV and sensitivity and reduce the burden on radiologists for diagnosing scoliosis through health screening chest radiographs.

Erratum: Systemic Manifestations of Immunoglobulin G4-Related Disease: A Pictorial Essay.

[This corrects the article on p. 575 in vol. 82.].

Systemic Manifestations of Immunoglobulin G4-Related Disease: A Pictorial Essay.

Immunoglobulin G4 (IgG4)-related disease is a systemic fibro-inflammatory disease characterized by pathologic findings in various organs. Imaging is critical for the diagnosis and treatment assessment of patients with IgG4-related disease. In this pictorial essay, we review the key features of multiple imaging modalities, typical pathologic findings, and differential diagnosis of IgG4-related disease. This systematic pictorial review can further our understanding of the broad-spectrum manifestations of this disease.

Giant Infrascapular Rheumatoid Nodules Mimicking Elastofibroma Dorsi: A Case Report.

Rheumatoid nodules are the most common extra-articular presentations of rheumatoid arthritis. Although rheumatoid nodules can develop anywhere in the body, they develop most commonly in the subcutaneous region, where they are easily exposed to repetitive trauma or pressure. However, an infrascapular presentation has not yet been reported. We report a case of giant bilateral rheumatoid nodules that developed in the infrascapular area, complicating its distinction from elastofibroma dorsi on radiological examination.

Endobronchial squamous cell carcinoma presenting as localized, long, continuous bronchial thickening on CT.

OBJECTIVE: To report pulmonary squamous cell carcinomas presenting as localized, long, continuous, bronchial thickening on computed tomography (CT). MATERIALS AND METHODS: This study comprised five men (mean age, 66 years; range, 60-79 years) with pulmonary squamous cell carcinoma, including two (0.6%) selected from 310 consecutive patients with the diagnosis. Inclusion criteria were as follows: histological diagnosis obtained from thickened bronchi; continuous bronchial thickening >5cm in longitudinal extension on CT. CT scans were retrospectively reviewed, focusing on bronchial abnormalities. They were correlated with histopathological findings in four patients who underwent lobectomy. RESULTS: On initial CT, bronchial thickening was continuous without skip area (n=5), measured 56-114mm in maximum longitudinal length, involved lobar (n=3) or segmental and distal bronchi (n=5) of the right upper (n=4) or lower (n=1) lobe, and was focally bulbous (n=2). Follow-up CT before treatment, available in two, showed progression of bronchial thickening in its thickness and longitudinal length (n=2) and a new bulbous portion (n=1) and peribronchial nodules (n=1) along the thickened bronchi. Cancer recurred after lobectomy in two, one of which manifested as continuous bronchial thickening extending from the bronchial stump on CT. On CT-histopathological correlation, bronchial thickening was mostly due to tumor spreading along the bronchus. A focal or short segmental tumor outgrowth from the thickened bronchi corresponded to a nodule or bulbous portion along thickened bronchi on CT, respectively. CONCLUSION: Pulmonary squamous cell carcinoma may present as localized, long, continuous, bronchial thickening on CT, simulating benign infectious or inflammatory diseases.

Characteristics of Coronary Artery to Pulmonary Artery Fistula on Coronary Computed Tomography Angiography.

OBJECTIVE: The aim of the study was to evaluate the characteristics of coronary artery-to-pulmonary artery fistula (CPAF) found by coronary computed tomography (CT) angiography. METHODS: Among 10,121 cases of coronary CT angiography performed for 7 years, we found 32 cases of CPAF. We retrospectively evaluated the demographics, clinical symptoms, and anatomical characteristics such as the origin, number of origins, course, opening site of the fistula, and the presence of aneurysmal changes (defined as dilatation 1.5 times the diameter of the origin). We also categorized the fistula openings according to size compared with that of the proximal left anterior descending coronary artery. RESULTS: The patients were 14 men and 18 women with a mean (range) age of 56.5 (34-86) years. Nineteen patients had no related symptoms, and the other 13 patients had symptoms such as angina, chest discomfort, palpitations, or shoulder pain. Among these patients, 2 patients were diagnosed with coronary artery disease. The origins of CPAF were single (n = 15, 46.9%) or multiple (n = 17, 53.1%). The CPAFs arose most commonly from the conus branch of the right coronary artery (n = 20, 62.5%) and proximal left anterior descending (n = 17, 53.1%). All CPAFs coursed anteriorly to the main pulmonary artery and drained into the anterolateral aspect. Twenty-five patients (78.1%) exhibited aneurysmal changes. The openings were small in 13 (40.6%), medium in 13 (40.6%), and large in 6 (18.8%) patients. CONCLUSIONS: More than half of patients with CPAF had no related symptoms. Coronary artery-to-pulmonary artery fistula may have a single origin or multiple origins. All of the CPAFs coursed anteriorly to the main pulmonary artery and drained into the anterolateral aspect; the CPAFs identified here frequently exhibited aneurysmal changes.

Radiogenomic correlation in lung adenocarcinoma with epidermal growth factor receptor mutations: Imaging features and histological subtypes.

OBJECTIVES: To correlate imaging features of resected lung adenocarcinoma with epidermal growth factor receptor (EGFR) mutation and the IASLC/ATS/ERS classification histological subtypes. METHODS: In 250 consecutive patients with resected lung adenocarcinoma, EGFR mutation status was correlated with demographics, imaging features including ground-glass opacity (GGO) proportion and the IASLC/ATS/ERS classification histological subtypes. RESULTS: EGFR mutations were significantly more frequent in women (54.5 % vs. 38.1 %, p = 0.011) and in never-smokers (54.7 % vs. 35.3 %, p = 0.003). GGO proportion was significantly higher in tumours with EGFR mutation than in those without (30.3 ± 33.8 % vs. 19.0 ± 29.3 %, p = 0.005). EGFR mutation was significantly more frequent in tumours with GGO ≥ 50 % and tumours with any GGO (p = 0.026 and 0.008, respectively). Adenocarcinomas with exon 19 or 21 mutation showed significantly higher GGO proportion than that in EGFR wild-type tumours (p = 0.009 and 0.029, respectively). Absence of GGO was an independent predictor of negative EGFR mutation (odds ratio, 1.81; 95 % confidence interval, 1.16-3.04; p = 0.018). CONCLUSIONS: GGO proportion in adenocarcinomas with EGFR mutation was significantly higher than that in EGFR wild-type tumours, and the absence of GGO on CT was an independent predictor of negative EGFR mutation. KEY POINTS: • Ground-glass opacity (GGO) proportion is significantly higher in EGFR-mutated adenocarcinomas • Exon 19 or 21 mutated adenocarcinomas shows significantly higher GGO proportion • GGO absence is an independent predictor of negative EGFR mutation in lung adenocarcinomas.

Near fatal desquamative interstitial pneumonia with bilateral recurrent tension pneumothorax.

Desquamative interstitial pneumonia (DIP) is an uncommon form of interstitial lung disease demonstrating good response to corticosteroid therapy and favorable prognosis. In rare cases, patients with DIP fail to respond to corticosteroid therapy, and may progress to end-stage fibrotic lung disease with respiratory failure. For such patients, well defined treatment regimen does not exist until now. We report a rare case of near fatal DIP with recurrent bilateral tension pneumothorax despite of corticosteroid maintenance therapy. Clinical and radiological findings improved with surgical intervention in addition to combination therapy with prednisolone and clarithromycin. The patient has remained in an improved state and has been receiving prednisolone and clarithromycin for 9 months.

Low attenuation areas in normal costal cartilages on CT: clinical implication and correlation with histology.

While normal costal cartilages are known to be homogenous in attenuation on computed tomography (CT), they frequently show internal low attenuation. This study was performed to assess CT features of the low attenuation and to correlate them with histological features. Chest CT scans of 80 patients without chest wall abnormalities in the first eight decades of age with ten consecutive patients in each decade were reviewed. Histological examinations and CT of three costal cartilage specimens, one each from three cadavers, were done. Of the 80 patients, low attenuation areas were noted in 32% of the upper seven costal cartilages and in 64 patients (80%) without significant sexual difference (P = 0.503 and 0.786, respectively). The areas appeared more frequently in the lower costal cartilages than the upper ones, and were mostly symmetrical in distribution (82%). They were usually ill defined (74%) and similar in attenuation to the chest wall muscle (94%), located centrally (100%), and at most a half of the cartilage diameter. In all three cartilage specimens, central areas were grossly distinct from surrounding areas, and were corresponded to low attenuation areas on CT. At histological exam, the central areas showed multiple foci of vascularized loose connective tissue and fat on myxoid background, generally agreeing with the previous description of cartilage canals, a kind of nutrient channel. In conclusion, normal costal cartilages can show central low attenuation areas, which are typically symmetrical in distribution and at most a half of the cartilage diameter.

Comparison between transauricular and transfemoral arterial access for hepatic artery angiography in a rabbit model.

PURPOSE: To evaluate the feasibility of transauricular arterial access and compare the procedure time needed for hepatic artery angiography via transfemoral versus transauricular arterial access in a rabbit model. MATERIALS AND METHODS: This study was approved by the research animal care and use committee. Twenty rabbits were divided into transfemoral (n = 10) and transauricular access groups (n = 10). The procedure consisted of shaving the hair, obtaining intraarterial access, performing hepatic artery angiography, and repairing the access site. A Mann-Whitney U test was used to compare the two groups in terms of the total procedure time and the time needed for each step. RESULTS: Hepatic artery angiography was technically feasible in all animals in both groups. The time required for shaving was 55 seconds ± 9.9 in the transfemoral access group; shaving was unnecessary in the transauricular access group. The times needed to obtain intraarterial access, perform hepatic artery angiography, repair the access site, and perform the entire procedure in the transfemoral and transauricular access groups were as follows: 503.3 s ± 211.8 and 97 s ± 83.3 (P < .001), 229.6 s ± 90 and 310.7 s ± 211 (P = .705), 305.5 s ± 80.6 and 90 s ± 0 (P < .001), and 1,038 s ± 265.9 and 497.7 s ± 256.9 (P = 0.001), respectively. CONCLUSIONS: Hepatic artery angiography is technically feasible via transauricular arterial access. The major advantages of transauricular arterial access versus transfemoral arterial access include a procedure time reduced by the omission of shaving and surgical cutdown.

Left costomediastinal recess of the pleura, the potential pleural space anterior to the heart.

OBJECTIVE: To investigate clinical implications of the left costomediastinal recess of the pleura. METHODS: The left anterior pleural anatomy was studied in 12 cadavers. Chest computed tomography (CT) scans of 68 healthy/near-healthy patients were reviewed for the recess. Twenty pleural lesions in the recess were analyzed on CT. Eight cases of left paracardiac pericardiocentesis were analyzed for pleural complications. RESULTS: Two fresh cadavers showed the recess to be wider downward, measuring 75 and 55 mm in width at the sixth intercostal space. None of the 68 healthy/near- healthy CT scans displayed the recess. Twenty recess lesions were connected to similar pleural lesions surrounding the left lung (n = 19) or showed an isolated lesion therein only partly facing the left lung (n = 1). Ipsilateral pleural effusion complicated 3 of 7, successful left paracardiac pericardiocentesis. CONCLUSION: Regardless of their contiguity with the lung, the differential diagnosis of precordial lesions should include pleural diseases in the recess. Left anterior pericardiocentesis unavoidably violates the intervening recess, sometimes causing pleural effusion.

Omental mesothelial cyst herniated to the thorax through the esophageal hiatus: a case report.

Both mesothelial cyst in the omentum and omental herniation through the esophageal hiatus without abdominal visceral involvement are rare. We report a case of omental mesothelial cyst herniated to the thorax through the esophageal hiatus.

High prevalence of bronchiectasis in adults: analysis of CT findings in a health screening program.

Bronchiectasis is one of the common chronic respiratory diseases and associated with respiratory morbidity and mortality. However, neither its prevalence nor its etiology is well-defined. We aimed to estimate the prevalence and risk factors of bronchiectasis in adults. In a retrospective study, we analyzed radiologic findings on chest computed tomography (CT) images performed as part of a health-screening program. From January to December 2008, 1,409 (24.6%) of 5,727 participants in the screening program of a health promotion center at a university hospital underwent chest CT scans based on the subject's decision. Bronchiectasis was diagnosed, if there was abnormal bronchial dilatation in any area of both lungs on chest CT. Respiratory symptoms, smoking status, and past medical history were also analyzed to define clinical characteristics and risk factors of bronchiectasis. Of 1,409 patients (aged 23-86 years), who were screened for respiratory diseases using chest CT for one year in a health promotion center, 129 patients (9.1%) were diagnosed with bronchiectasis. The prevalence of bronchiectasis was higher in females than in males (11.5% vs. 7.9%, p = 0.022) and increased with age. Respiratory symptoms were reported in 53.7% of subjects. Previous history of tuberculosis (TB) (OR 4.61, 95% CI 2.39-8.88, p = 0.001) and age (OR 2.49, 95% CI 1.56-3.98, p = 0.001) were significantly associated with bronchiectasis. This retrospective analysis of chest CT findings in health screening examinees revealed a very high prevalence of bronchiectasis in adults. Previous TB infection is one of the major causes of bronchiectasis.

Benign tumors of the tracheobronchial tree: CT-pathologic correlation.

OBJECTIVE: The purpose of this essay is to illustrate the CT findings of variable benign tumors of the tracheobronchial tree and to correlate the CT and pathologic findings in 17 patients. CONCLUSION: The tracheal tumors were eccentric, well-defined, polypoid masses in all cases. The endobronchial tumors were masses confined within the bronchus in all cases, and atelectasis or pneumonia of the distal parenchyma was frequently associated. Of the six hamartomas, one was a fatty mass, and two were nodules with calcification. The others were soft-tissue-density nodules. The lipomas manifested as fat density on CT scans in both cases. The other benign tumors were low-attenuating, soft-tissue-density masses without characteristic findings on CT scans.

Low-dose and standard-dose unenhanced helical computed tomography for the assessment of acute renal colic: prospective comparative study.

PURPOSE: To compare the efficacy of low-dose and standard-dose computed tomography (CT) for the diagnosis of ureteral stones. MATERIAL AND METHODS: Unenhanced helical CT was performed with both a standard dose (260 mAs, pitch 1.5) and a low dose (50 mAs, pitch 1.5) in 121 patients suspected of having acute renal colic. The two studies were prospectively and independently interpreted for the presence and location of ureteral stones, abnormalities unrelated to stone disease, identification of secondary signs, i.e. hydronephrosis and perinephric stranding, and tissue rim sign. The standard-dose CT images were interpreted by one reviewer and the low-dose CT images independently by two reviewers unaware of the standard-dose CT findings. The findings of the standard and low-dose CT scans were compared with the exact McNemar test. Interobserver agreements were assessed with kappa analysis. The effective radiation doses resulting from two different protocols were calculated by means of commercially available software to which the Monte-Carlo phantom model was given. RESULTS: The sensitivity, specificity, and accuracy of standard-dose CT for detecting ureteral stones were 99%, 93%, and 98%, respectively, whereas for the two reviewers the sensitivity of low-dose CT was 93% and 95%, specificity 86%, and accuracy 92% and 94%. We found no significant differences between standard-dose and low-dose CT in the sensitivity and specificity for diagnosing ureter stones (P >0.05 for both). However, the sensitivity of low-dose CT for detection of 19 stones less than or equal to 2 mm in diameter was 79% and 68%, respectively, for the two reviewers. Low-dose CT was comparable to standard-dose CT in visualizing hydronephrosis and the tissue rim sign. Perinephric stranding was far less clear on low-dose CT. Low-dose CT had the same diagnostic performance as standard-dose CT in diagnosing alternative diseases. Interobserver agreement between the two low-dose CT reviewers in the diagnosis of ureter stones and alternative diseases, the identification of secondary signs, and tissue rim sign were high, with kappa values ranging from 0.769 to 0.968. On standard-dose CT scans, the calculated mean effective radiation dose was 7.30 mSv for males and 10.00 mSv for females. On low-dose CT scans, the calculated mean effective radiation dose was 1.40 mSv for males and 1.97 mSv for females. CONCLUSION: Compared with standard scans using 260 mAs, low-dose unenhanced helical CT using a reduced tube current of 50 mAs results in a concomitant decrease in the radiation dose of 81%. Although low-dose CT was limited in its ability to depict small-sized calculi less than or equal to 2 mm, it is still comparable to standard-dose CT for the diagnosis of ureter stones and alternative disease.

Pulmonary tuberculosis: another disease showing clusters of small nodules.

OBJECTIVE: Pulmonary sarcoidosis was recently reported to show the "sarcoid galaxy" sign, indicating large pulmonary nodules composed of coalescent small nodules. The purpose of this study was to review cases of pulmonary tuberculosis showing CT features indistinguishable from the sarcoid galaxy sign. CONCLUSION: Large nodules arising from the coalescence of small nodules may be seen in active tuberculosis and in sarcoidosis. The CT finding was termed "clusters of small nodules" instead of the "sarcoid galaxy sign" in this article. A single cluster of small nodules, clusters of small nodules in the superior segment of the lower lobe, or clusters of small nodules not associated with lymphadenopathy or associated with tree-in-bud lesions would favor the diagnosis of active pulmonary tuberculosis rather than pulmonary sarcoidosis.