The Role of Nuclear Medicine in Benign Thyroid Disease.

Since the mid-twentieth century, the radionuclide thyroid scan has been utilized in the management of benign thyroid disorders. In current medical practice, patients with hyperthyroidism are referred for thyroid scintigraphy, while patients with goiters and thyroid nodules are most often evaluated by ultrasound or computed tomography. Since thyroid scintigraphy reflects the functional state of the gland, it provides information that anatomical imaging lacks. Therefore, radionuclide imaging of the thyroid is the imaging modality of choice in the evaluation of the hyperthyroid patient. In addition, patients with so-called subclinical hyperthyroidism often present a diagnostic dilemma to the clinician since the causative factor must be determined for proper patient management. The aim of this manuscript is to illustrate the imaging characteristics of thyroid disorders commonly seen in clinical practice resulting in thyrotoxicosis or pending thyrotoxicosis, so that correlation with clinical presentation and pertinent laboratory data will lead to the correct diagnosis.

Comparison of Gray-scale Inversion to Improve Detection of Pulmonary Nodules on Chest X-rays Between Radiologists and a Deep Convolutional Neural Network.

Detection of pulmonary nodules on chest x-rays is an important task for radiologists. Previous studies have shown improved detection rates using gray-scale inversion. The purpose of our study was to compare the efficacy of gray-scale inversion in improving the detection of pulmonary nodules on chest x-rays for radiologists and machine learning models (ML). We created a mixed dataset consisting of 60, 2-view (posteroanterior view - PA and lateral view) chest x-rays with computed tomography confirmed nodule(s) and 62 normal chest x-rays. Twenty percent of the cases were separated for a testing dataset (24 total images). Data augmentation through mirroring and transfer learning was used for the remaining cases (784 total images) for supervised training of 4 ML models (grayscale PA, grayscale lateral, gray-scale inversion PA, and gray-scale inversion lateral) on Google's cloud-based AutoML platform. Three cardiothoracic radiologists analyzed the complete 2-view dataset (n=120) and, for comparison to the ML, the single-view testing subsets (12 images each). Gray-scale inversion (area under the curve (AUC) 0.80, 95% confidence interval (CI) 0.75-0.85) did not improve diagnostic performance for radiologists compared to grayscale (AUC 0.84, 95% CI 0.79-0.88). Gray-scale inversion also did not improve diagnostic performance for the ML. The ML did demonstrate higher sensitivity and negative predictive value for grayscale PA (72.7% and 75.0%), grayscale lateral (63.6% and 66.6%), and gray-scale inversion lateral views (72.7% and 76.9%), comparing favorably to the radiologists (63.9% and 72.3%, 27.8% and 58.3%, 19.5% and 50.5% respectively). In the limited testing dataset, the ML did demonstrate higher sensitivity and negative predictive value for grayscale PA (72.7% and 75.0%), grayscale lateral (63.6% and 66.6%), and gray-scale inversion lateral views (72.7% and 76.9%), comparing favorably to the radiologists (63.9% and 72.3%, 27.8% and 58.3%, 19.5% and 50.5%, respectively). Further investigation of other post-processing algorithms to improve diagnostic performance of ML is warranted.

Comprehensive Imaging Review of Pleural Fistulas from Diagnosis to Management.

Pleural fistula is an abnormal communication between the pleural cavity and an adjacent structure. The interplay of anatomic and physiologic factors including proximity to various intrathoracic structures, deep pleural recesses, and negative pleural pressures makes the pleura an easy victim of fistulization. Iatrogenic creation followed by necrotizing infections and malignancies are the most common causes. While the overall incidence and size of postsurgical pleural fistulas are decreasing with increased adoption of vascularized flaps for high-risk resections, the smaller fistulas that develop in the setting of post-radiation therapy changes, with necrotizing infections in immunosuppressed patients, and with use of newer antiangiogenic chemotherapies can be challenging to visualize directly. Imaging signs in clinical practice are often subtle and indirect. Multimodality imaging and biochemical pleural fluid analysis can offer important adjunctive information when a diagnosis is only suggested with the first imaging study. Certain pleural fistulas are inconsequential, some spontaneously close with or without diversion of flow or use of positive-pressure ventilation, while others carry a higher risk of complications or recurrence. Estimated fistula size, factors that impair healing, and the possibility of diversion are important considerations when deciding between endoscopic or surgical closure. The authors have tailored this article for a general imager or clinical practitioner and review 10 types of pleural fistulas, ranging from routine to rare, with regard to their etiology, pathophysiology, clinical cues, imaging features, nuances of pleural fluid analysis, and management options available today. ©RSNA, 2022.

Multimodality Imaging of Pleuropulmonary Blastoma: Pearls, Pitfalls, and Differential Diagnosis.

Pleuropulmonary blastomas are rare, potentially aggressive embryonal cancers of the lung parenchyma and pleural surfaces that account for 0.25%-0.5% of primary pulmonary malignancies in children. Pleuropulmonary blastomas are classified as cystic (type I), mixed cystic and solid (type II), and solid (type III). Pleuropulmonary blastoma occurs in the same age group (0-6 years) as other more common solid tumors such as neuroblastoma and Wilms tumor. Differential diagnosis includes metastasis from Wilms tumor and macrocystic congenital pulmonary airway malformation (CPAM). A key pathologic and genetic discriminator is the DICER1 germline mutation found in patients with pleuropulmonary blastoma. Imaging, histopathologic, and clinical data are important to use in conjunction in order to determine the diagnosis and risk stratification of pleuropulmonary blastomas. Survival varies from poor to good, depending on type. However, the spectrum of pleuropulmonary blastoma is insufficiently understood due to the variable presentation of this rare disease. We present a current review of the literature regarding pleuropulmonary blastomas in this article.

Aortic Fistulas: Pathophysiologic Features, Imaging Findings, and Diagnostic Pitfalls.

Fistulas between the aorta and surrounding organs are extremely rare but can be fatal if they are not identified and treated promptly. Most of these fistulas are associated with a history of trauma or vascular intervention. However, spontaneous aortic fistulas (AoFs) can develop in patients with weakened vasculature, which can be due to advanced atherosclerotic disease, collagen-vascular disease, vasculitides, and/or hematogenous infections. The clinical features of AoFs are often nonspecific, with patients presenting with bleeding manifestations, back or abdominal pain, fever, and shock. Confirmation with invasive endoscopy is often impractical in the acute setting. Imaging plays an important role in the management of AoFs, and multiphasic multidetector CT angiography is the initial imaging examination of choice. Obvious signs of AoF include intravenous contrast material extravasation into the fistulizing hollow organ, tract visualization, and aortic graft migration into the adjacent structure. However, nonspecific indirect signs such as loss of fat planes and ectopic foci of gas are seen more commonly. These indirect signs can be confused with other entities such as infection and postoperative changes. Management may involve complex and staged surgical procedures, depending on the patient's clinical status, site of the fistula, presence of infection, and anticipated tissue friability. As endovascular interventions become more common, radiologists will need to have a high index of suspicion for this entity in patients who have a history of aneurysms, vascular repair, or trauma and present with bleeding. Online supplemental material and the slide presentation from the RSNA Annual Meeting are available for this article. ©RSNA, 2021.

Gunshot-Related Pediatric Left Ventricular Apical Aneurysm.

Penetrating injuries of the thorax and abdomen, such as gunshot and stabbing, are rare in children. We present the case of a pediatric patient with a history of remote gunshot injury presenting with a late aneurysm in the left ventricle. (Level of Difficulty: Intermediate.).

Change of heart: Reverse takotsubo's cardiomyopathy - A case report.

Reverse takotsubo's cardiomyopathy is a rare and relatively unknown variant of takotsubo's cardiomyopathy, also known as stress cardiomyopathy or broken heart syndrome. There are significant differences in the patient age and clinical profiles between classic and reverse takotsubo's cardiomyopathy. Classic takotsubo's cardiomyopathy has been extensively described. However, the little described literature related to reverse takotsubo's cardiomyopathy is limited to the cardiology speciality, with a relative paucity described in radiology. We describe a case report of a 73 year-old female who was diagnosed with reverse takotsubo's cardiomyopathy on the basis of Cardiac MRI. Herein, we hope to bring more awareness of this condition and describe its features on MRI.

Performance of a Severity Score on Admission Chest Radiography in Predicting Clinical Outcomes in Hospitalized Patients With Coronavirus Disease (COVID-19).

BACKGROUND. Chest radiographs (CXRs) are typically obtained early in patients admitted with coronavirus disease (COVID-19) and may help guide prognosis and initial management decisions. OBJECTIVE. The purpose of this study was to assess the performance of an admission CXR severity scoring system in predicting hospital outcomes in patients admitted with COVID-19. METHODS. This retrospective study included 240 patients (142 men, 98 women; median age, 65 [range, 50-80] years) admitted to the hospital from March 16 to April 13, 2020, with COVID-19 confirmed by real-time reverse-transcriptase polymerase chain reaction who underwent chest radiography within 24 hours of admission. Three attending chest radiologists and three radiology residents independently scored patients' admission CXRs using a 0- to 24-point composite scale (sum of scores that range from 0 to 3 for extent and severity of disease in upper and lower zones of left and right lungs). Interrater reliability of the score was assessed using the Kendall W coefficient. The mean score was obtained from the six readers' scores for further analyses. Demographic variables, clinical characteristics, and admission laboratory values were collected from electronic medical records. ROC analysis was performed to assess the association between CXR severity and mortality. Additional univariable and multivariable logistic regression models incorporating patient characteristics and laboratory values were tested for associations between CXR severity and clinical outcomes. RESULTS. Interrater reliability of CXR scores ranged from 0.687 to 0.737 for attending radiologists, from 0.653 to 0.762 for residents, and from 0.575 to 0.666 for all readers. A composite CXR score of 10 or higher on admission achieved 53.0% (35/66) sensitivity and 75.3% (131/174) specificity for predicting hospital mortality. Hospital mortality occurred in 44.9% (35/78) of patients with a high-risk admission CXR score (≥ 10) versus 19.1% (31/162) of patients with a low-risk CXR score (< 10) (p < .001). Admission composite CXR score was an independent predictor of death (odds ratio [OR], 1.17; 95% CI, 1.10-1.24; p < .001). composite CXR score was a univariable predictor of intubation (OR, 1.23; 95% CI, 1.12-1.34; p < .001) and continuous renal replacement therapy (CRRT) (OR, 1.15; 95% CI, 1.04-1.27; p = .007) but was not associated with these in multivariable models (p > .05). CONCLUSION. For patients admitted with COVID-19, an admission CXR severity score may help predict hospital mortality, intubation, and CRRT. CLINICAL IMPACT. CXR may assist risk assessment and clinical decision-making early in the course of COVID-19.

Coronary artery aneurysm in Kawasaki disease.

A 3-year-old male presents to the emergency department with chief complaints of fever and vomiting. He had a positive rapid streptococcus throat test with cervical lymphadenopathy. The patient was started on antibiotics. On examination, there was diffuse erythematous macular rash on the chest. Laboratory tests revealed elevated white cell count and C-reactive protein. Electrocardiogram was notable for prolonged PR interval indicating 1st degree atrioventricular block. Echocardiogram revealed ectasia of the right coronary artery (RCA). A presumptive diagnosis of Kawasaki disease was made and the patient was started on high-dose aspirin and intravenous immunoglobulins. Cardiac computed tomography angiography (CTA) showed an aneurysm of the proximal RCA measuring up to 7.4 mm. The RCA immediately proximal to the aneurysm measured 3 mm in diameter. The Z score was 13.4. Oblique coronal image from cardiac CTA and volume rendered images demonstrated an aneurysm of the proximal RCA. The patient improved with treatment.

Review of the Chest CT Differential Diagnosis of Ground-Glass Opacities in the COVID Era.

Coronavirus disease 2019 (COVID-19), a recently emerged lower respiratory tract illness, has quickly become a pandemic. The purpose of this review is to discuss and differentiate typical imaging findings of COVID-19 from those of other diseases, which can appear similar in the first instance. The typical CT findings of COVID-19 are bilateral and peripheral predominant ground-glass opacities. As per the Fleischner Society consensus statement, CT is appropriate in certain scenarios, including for patients who are at risk for and/or develop clinical worsening. The probability that CT findings represent COVID-19, however, depends largely on the pretest probability of infection, which is in turn defined by community prevalence of infection. When the community prevalence of COVID-19 is low, a large gap exists between positive predictive values of chest CT versus those of reverse transcriptase polymerase chain reaction. This implies that with use of chest CT there are a large number of false-positive results. Imaging differentiation is important for management and isolation purposes and for appropriate disposition of patients with false-positive CT findings. Herein the authors discuss differential pathology with close imaging resemblance to typical CT imaging features of COVID-19 and highlight CT features that may help differentiate COVID-19 from other conditions.

Review of Thoracic Causes of Systemic Arterial Air Embolism on Computed Tomography.

Systemic arterial air embolism (SAAE) is a rare but potentially life-threatening condition that may occur when air enters into pulmonary veins or directly into the systemic circulation after pulmonary procedures (biopsy or resection) or penetrating trauma to the lung. While venous air embolism is commonly reported, arterial air embolism is rare. Even a minor injury to the chest along with positive-pressure ventilation can cause SAAE. Small amounts of air may cause neurological or cardiac symptoms depending on the affected arteries, while massive embolism can result in fatal cardiovascular collapse. We discuss the various causes of SAAE, including trauma, computed tomography-guided lung biopsy, and various intervention procedures such as mechanical circulatory support device implantation, coronary catheterization, and atrial fibrillation repair. SAAE diagnosis can be overlooked because its symptoms are not specific, and confirmation of the presence of air in the arterial system is difficult. Although computed tomography is the optimal imaging tool for diagnosis, patient instability and resuscitation often precludes its use. When imaging is performed, awareness of the causes of SAAE allows the radiologist to promptly diagnose the condition and relay findings to the clinicians so that treatment, namely hyperbaric oxygen therapy, may be started promptly.

Crowdsourcing pneumothorax annotations using machine learning annotations on the NIH chest X-ray dataset.

Pneumothorax is a potentially life-threatening condition that requires prompt recognition and often urgent intervention. In the ICU setting, large numbers of chest radiographs are performed and must be interpreted on a daily basis which may delay diagnosis of this entity. Development of artificial intelligence (AI) techniques to detect pneumothorax could help expedite detection as well as localize and potentially quantify pneumothorax. Open image analysis competitions are useful in advancing state-of-the art AI algorithms but generally require large expert annotated datasets. We have annotated and adjudicated a large dataset of chest radiographs to be made public with the goal of sparking innovation in this space. Because of the cumbersome and time-consuming nature of image labeling, we explored the value of using AI models to generate annotations for review. Utilization of this machine learning annotation (MLA) technique appeared to expedite our annotation process with relatively high sensitivity at the expense of specificity. Further research is required to confirm and better characterize the value of MLAs. Our adjudicated dataset is now available for public consumption in the form of a challenge.

Regenerative liver surgeries: the alphabet soup of emerging techniques.

New surgical procedures taking advantage of the regenerative abilities of the liver are being introduced as potential curative therapies to these patients either to provide auxiliary support while the native liver recovers or undergoes hypertrophy. For patients with hepatocellular carcinoma outside of the Milan criteria or bilobar colorectal metastases liver transplantation is not an option. Fulminant hepatic failure can be treated but requires life-long immunosuppression. These complex surgical procedures require high quality and directed imaging.

Value of coronary computed tomography as a prognostic tool.

Coronary computed tomography angiography (CCTA) has become an important part of our armamentarium for noninvasive diagnosis of coronary artery disease (CAD). Emerging technologies have produced lower radiation dose, improved spatial and temporal resolution, as well as information about coronary physiology. Although the prognostic role of coronary artery calcium scoring is known, similar evidence for CCTA has only recently emerged. Initial, small studies in various patient populations have indicated that CCTA-identified CAD may have a prognostic value. These findings were confirmed in a recent analysis of the international, prospective Coronary CT Angiography Evaluation For Clinical Outcomes: An International Multicenter (CONFIRM) registry. An incremental increase in mortality was found with a worse severity of CAD on a per-patient, per-vessel, and per-segment basis. In addition, age-, sex-, and ethnicity-based differences in mortality were also found. Whether changing our management algorithms based on these findings will affect outcomes is unclear. Large prospective studies utilizing targeted management strategies for obstructive and nonobstructive CAD are required to incorporate these recent findings into our daily practice.