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Large Publicly Available Datasets of Chest Radiographs for Deep Learning

PURPOSE. Deep learning is currently the most popular approach for building artificial intelligence systems for chest radiograph interpretation. However, collecting a sufficient number of images to satisfy the requirement for learning is difficult. Data annotation is also time- and labor-intensive. Large publicly available datasets of chest radiographs may provide alternative learning resources. MATERIALS AND METHODS. We searched the PubMed and Google Scholar databases for papers associated with publicly available datasets of chest radiographs containing more than 100,000 images. We compared the datasets in terms of four dimensions: size, image quality, annotation quality, and licensing. RESULTS. Four data sources with six versions (ChestX-ray8, ChestX-ray14, PadChest, CheXpert, MIMIC-CXR 1.0, and MIMICCXR 2.0) were obtained and reviewed. CONCLUSION. Public datasets provide an alternative resource to quickly initiate deep learning projects for chest radiograph interpretation. Understanding the characteristics, limits, and differences across these datasets can facilitate artificial intelligence research on chest radiograph interpretation.

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Intraprocedural Cerebral Hyperperfusion Syndrome after Carotid Angioplasty and Stenting

Cerebral hyperperfusion syndrome (CHS) is a rare but serious complication that may develop after carotid artery revascularization. The clinical triad of CHS comprises ipsilateral pulsatile headaches, seizures, and focal neurologic deficits, which usually occur within 36 hours postoperatively. If left untreated, CHS may eventually result in intracranial hemorrhage. Blood pressure control is recommended for preventing CHS. In this case report, the patient presented signs of CHS while undergoing carotid angioplasty and stenting, and the symptoms were resolved after immediate treatment with an antihypertensive drug. The patient did not experience any other complications and was discharged. This case report indicates that CHS can occur as soon as carotid angioplasty and stenting begins and manifests as pulsatile headaches; therefore, early-onset CHS should not be overlooked, and antihypertensive drugs should always be prepared for such emergencies.

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Radiofrequency Ablation for Locally Recurrent Papillary Thyroid Cancer Refractory to Radioiodine Therapy

PURPOSE. Radiofrequency ablation (RFA) is a well-tolerated alternative to surgery for metastatic papillary thyroid carcinoma (PTC). However, its efficacy for lymph node metastasis refractory to radioactive iodine (RAI) and whether it can be guided by imaging modalities other than ultrasonography (US) remain unclear. This study investigated using computed tomography (CT)- and US-guided RFA for recurrent PTC. MATERIALS AND METHODS. Between January 2018 and April 2019, we recruited 4 middle-aged patients with recurrent, inoperable thyroid cancer who were treated with RFA. All patients previously underwent completion thyroidectomy and neck dissection for PTC and initially had a high postoperative American Thyroid Association risk stratification. All patients received thyroid hormone suppression therapy. Cases 1-3 had lesions next to vital organs, with loss of RAI avidity on whole-body scintigraphy. Case 4 had recurrent PTC with mass effect symptoms; the patient refused to undergo a reoperation. CT-guided RFA was used for Case 1 for a recurrent lesion not visible with US guidance. RESULTS. Two patients received RFA for recurrent tumors per current guidelines, and 2 with more complicated conditions underwent RFA after traditional treatment failure. Decreased serum thyroglobulin concentration or structural remission through RFA was noted. CONCLUSION. In patients with recurrent or difficult-to-reach thyroid tumors and those who refuse to undergo surgery, RFA is a safe and effective option, with a low incidence of complications. CT-guided RFA can be useful for lesions that are difficult to visualize under US guidance.

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Mediastinal Thymoma with Remote Endobronchial Metastasis

Thymoma with endobronchial polypoid growth is extremely rare, and only 21 cases have thus far been reported, with most of the cases involving obstruction of the left upper bronchus. Furthermore, an endobronchial lesion as a form of distal metastasis is extremely rare, and only 2 cases have been documented. Herein, we report an exceedingly rare case of anterior mediastinal thymoma with remote endobronchial metastasis involving the left lower bronchi without contiguous pleural dissemination. This case appears to be evidence against the previously proposed mechanism-that endobronchial metastatic thymoma spreads through pleural involvement.

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Cryptococcal Meningitis Mimicking Leptomeningeal Metastasis: A Case Report

Cryptococcal infection of the central nervous system is a critical concern in immunocompromised patients. However, differentiating between cryptococcus infection and other meningeal processes, such as leptomeningeal metastasis, is occasionally challenging both clinically and radiologically. Herein, we report the case of a 64-year-old man with underlying stage IV lung adenocarcinoma with cryptococcal meningitis mimicking leptomeningeal metastasis.

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Signet Ring Cell Carcinoma of the Terminal Ileum and Ascending Colon Mimicking Lymphoma: A Rare Case Report

We report a case of a mass involving the proximal ascending colon, cecum, and terminal ileum with conglomerate lymphadenopathy. These signs mimic that of lymphoma, but surgical pathology confirmed a diagnosis of colorectal signet ring cell carcinoma (SRCC), a rare subtype of poorly differentiated adenocarcinoma most commonly located in the stomach. Few reports have described the radiological features of this rare condition. Colorectal SRCC and lymphoma both have similar radiological appearances of concentric bowel wall thickening and enlarged lymph nodes. This case report describes the target appearance of SRCC, facilitating the diagnose of colorectal SRCC.

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Right Ventricular Volume Reduction after Different Types of Pulmonary Valve Replacement in Repaired Tetralogy of Fallot

PURPOSE. Right ventricular (RV) dilatation due to pulmonary regurgitation (PR) is common in repaired tetralogy of Fallot (rTOF). Pulmonary valve replacement (PVR) surgery eliminates PR and can reverse RV dilatation. This study analyzed the types of PVR and other factors related to RV reduction. MATERIALS AND METHODS. We retrospectively reviewed data on patients with rTOF who underwent PVR between 2009 and 2019 and received magnetic resonance imaging (MRI) before and after the operation. Three types of valves were employed for PVR, namely bioprosthetic, polytetrafluoroethylene tricuspid, and polytetrafluoroethylene monocuspid valves. The type of PVR, duration after PVR, and indices of the right ventricle measured through MRI before and after the operation were analyzed. RESULTS. We analyzed 36 patients and 72 examinations. PVR with a bioprosthetic valve significantly reduced the RV end-diastolic volume index, RV end-systolic volume index, and PR after the operation. However, this improvement was not observed in patients in the polytetrafluoroethylene monocuspid group, who exhibited a smaller reduction in the postoperative RV end-diastolic volume index (median 158.5 mL/m^2, range 139.3-200.3 mL/m^2) than did those in the bioprosthetic group (median 121.1 mL/m^2, range 82.2-177.4 mL/m^2, p = 0.006) and the polytetrafluoroethylene tricuspid group (median 123.6 mL/ m^2, range 105.7-182.9 mL/m^2, p = 0.109). The polytetrafluoroethylene monocuspid group exhibited the smallest improvement in postoperative PR of all the groups (median 38.9%, range 20.6%-67.7%). CONCLUSION. A handmade polytetrafluoroethylene monocuspid valve is less effective for surgical PVR than polytetrafluoroethylene tricuspid and bioprosthetic valves in reducing both RV dilatation and PR in rTOF. Hence, bioprosthetic valves rather than polytetrafluoroethylene valves are the optimal choice for PVR in patients with rTOF.

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Impact of an Occluder on Cardiovascular Structures After Transcatheter Closure of an Atrial Septal Defect: Computed Tomography and Echocardiography

PURPOSE. Our purpose in this study was to demonstrate the usefulness of computed tomography (CT) to assess the impact of occluders on cardiovascular structures in patients after transcatheter closure of secundum atrial septal defects (ASDs). MATERIALS AND METHODS. Cardiac CT was performed on 131 patients who had undergone transcatheter ASD closure at one institution over a 6-year period. The interval between ASD closure and CT study ranged from 3 to 13 months. Transverse sections, multiplanar reformatted images, and three-dimensional reconstructed images were retrospectively reviewed to disclose the effects of these implanted occluders on the systemic/pulmonary veins and the intracardiac structures. Echocardiography was used to follow the effects shown on CT, and the interval ranged from 4.1 months to 8.5 years. Descriptive statistics were used for data analysis. RESULTS. No major complications requiring intervention were noted. The presence of significant structural impingement by the occluder was noted in CT on the aortic locus (12.2%), on the tricuspid annulus (2.3%), on the tricuspid valve (1.5%), on the dorsal wall of the right atrium (0.8%), on the mitral annulus (9.2%), on the mitral valve (2.3%), and on the dorsal wall of the left atrium (2.3%). Echocardiography showed mild and moderate regurgitation of the tricuspid, mitral, pulmonary, and aortic valves in 40.5%, 22.9%, 12.2%, and 0.8% of patients, respectively. The sensitivity, specificity, and accuracy of mitral impingement on CT in predicting the occurrence of significant mitral regurgitation in echocardiography were 83.3%, 83.2%, and 83.2%, respectively. The sensitivity, specificity, and accuracy of tricuspid impingement on CT in predicting the occurrence of significant tricuspid regurgitation in echocardiography were 100.0%, 60.9%, and 61.8%, respectively. Significant ostial impingement by the occluder appeared in the right lower pulmonary vein (11.5%), in the right upper pulmonary vein (9.2%), in the right middle pulmonary vein (7.6%), in the inferior vena cava (3.8%), in the superior vena cava (2.3%), and in none of the coronary sinuses. Follow-up echocardiographic studies of all patients showed that none had significantly accelerated flow from pulmonary or systemic veins into the atria. Four patients (3.1%) had arrhythmia after occluder implantation, and all had prominent structural impingement on the CT images. Mild residual shunt appeared in 9.2% of patients. CONCLUSION. Cardiac CT imaging can be useful for assessing the relationship between the occluder and intracardiac structures in ASD patients following transcatheter closure. Pulmonary or systemic venous orifice impingement by the occluder observed in CT imaging had no effect on inflow pattern. Mitral or tricuspid impingement may predict their regurgitation. Arrhythmia after occluder implantation occurred in the case of severe device impingement on the central part of the fibrous skeleton of the heart. Thus, this study suggests that the deployment of the ASD occluder is safer over the long term in more dorsal positions.

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Radiographic Clues to Retroperitoneal Liposarcoma

Retroperitoneal liposarcomas are rare tumors and difficult to diagnose. We demonstrate one case diagnosed in the emergency room from some radiographic clues in an abdomen standing radiograph.

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Four-Dimensional Computed Tomography for Diagnosis of Double-Chambered Right Ventricle: A Case Report

Double-chambered right ventricle (DCRV) is an uncommon heart defect. We describe a case of tetralogy of Fallot combined with DCRV, persistent left superior vena cava, and a perimembranous ventricular septal defect. DCRV was inconspicuous by echocardiography and could only be detected on electrocardiogram-gated cardiac four-dimensional computer tomography (4DCT) with RV separated by hypertrophic anomalous muscle. 4DCT is an effective method for detecting DCRV and highlights other extra-cardiac anatomy for surgical planning.