SARS-CoV-2 infection of African green monkeys results in mild respiratory disease discernible by PET/CT imaging and shedding of infectious virus from both respiratory and gastrointestinal tracts.

Vaccines are urgently needed to combat the global coronavirus disease 2019 (COVID-19) pandemic, and testing of candidate vaccines in an appropriate non-human primate (NHP) model is a critical step in the process. Infection of African green monkeys (AGM) with a low passage human isolate of SARS-CoV-2 by aerosol or mucosal exposure resulted in mild clinical infection with a transient decrease in lung tidal volume. Imaging with human clinical-grade 18F-fluoro-2-deoxy-D-glucose positron emission tomography (18F-FDG PET) co-registered with computed tomography (CT) revealed pulmonary lesions at 4 days post-infection (dpi) that resolved over time. Infectious virus was shed from both respiratory and gastrointestinal (GI) tracts in all animals in a biphasic manner, first between 2-7 dpi followed by a recrudescence at 14-21 dpi. Viral RNA (vRNA) was found throughout both respiratory and gastrointestinal systems at necropsy with higher levels of vRNA found within the GI tract tissues. All animals seroconverted simultaneously for IgM and IgG, which has also been documented in human COVID-19 cases. Young AGM represent an species to study mild/subclinical COVID-19 disease and with possible insights into live virus shedding. Future vaccine evaluation can be performed in AGM with correlates of efficacy being lung lesions by PET/CT, virus shedding, and tissue viral load.

Microbiology for Radiologists: How to Minimize Infection Transmission in the Radiology Department.

The implementation of standardized infection control and prevention practices is increasingly relevant as modern radiology practice evolves into its more clinical role. Current Centers for Disease Control and Prevention, National Institutes of Health, and World Health Organization guidelines for the proper use of personal protective equipment, decontamination of reusable medical equipment, and appropriate management of bloodborne pathogen exposures will be reviewed. Standard precautions apply to all patients at all times and are the mainstay of infection control. Proper hand hygiene includes washing hands with soap and water when exposed to certain infectious particles, such as Clostridium difficile spores, which are not inactivated by alcohol-based hand rubs. The appropriate use of personal protective equipment in accordance with recommendations from the Centers for Disease Control and Prevention includes wearing a surgical mask during lumbar puncture. Because radiologists may perform lumbar punctures for patients with prion disease, it is important to appreciate that incineration is the most effective method of inactivating prion proteins. However, there is currently no consensus recommendation on the decontamination of prion-contaminated reusable items associated with lumbar puncture, and institutional policies should be consulted for directed management. In the event of a needlestick injury, radiology staff must be able to quickly provide appropriate initial management and seek medical attention, including laboratory testing for bloodborne pathogens.

Traumatic Injury to the Portal Vein With Shock Bowel.

A portal vein aneurysm is the dilatation of the portal vein due to a defect in the vein wall. This rare disease manifestation is difficult to predict and has the potential for severe complications. We describe the case of a 68-year-old man involved in a motor vehicle collision who presented with abdominal hemorrhage found on ultrasound, hypotension, and vague abdominal pain. The patient underwent an exploratory laparotomy to control bleeding. Surgery and a subsequent abdominal computed tomography revealed the presence of a portal vein pseudoaneurysm and shock bowel. This case highlights the importance of radiologists to consider the prospect of portal vein aneurysm in the differential diagnosis of hypotension following abdominal trauma.

Sorting the Alphabet Soup of Renal Pathology: A Review.

Diseases of the kidney often have their names shortened, creating an arcane set of acronyms which can be confusing to both radiologists and clinicians. This review of renal pathology aims to explain some of the most commonly used acronyms within the field. For each entity, a summary of the clinical features, pathophysiology, and radiological findings is included to aid in the understanding and differentiation of these entities. Discussed topics include acute cortical necrosis, autosomal dominant polycystic kidney disease, angiomyolipoma, autosomal recessive polycystic kidney disease, acute tubular necrosis, localized cystic renal disease, multicystic dysplastic kidney, multilocular cystic nephroma, multilocular cystic renal cell carcinoma, medullary sponge kidney, paroxysmal nocturnal hemoglobinuria, renal papillary necrosis, transitional cell carcinoma, and xanthogranulomatous pyelonephritis.

Photo Rounds: Chronic diarrhea in a 64-year-old woman.

Our patient presented with abdominal pain and worsening diarrhea. She had no significant medical history, but imaging studies helped us make the Dx.

Richter Transformation: An Unexpected Diffuse Large B-Cell Lymphoma Within a Fatty Mesenteric Mass in a Patient With Refractory Chronic Lymphocytic Leukemia.

Richter transformation is the development of a high-grade lymphoma from chronic lymphocytic leukemia. This rare disease manifestation is difficult to predict and carries a poor prognosis. We describe the case of a 75-year-old man with refractory chronic lymphocytic leukemia who presented with multiple growing fatty abdominal masses on computed tomography and vague abdominal distension. The patient underwent exploratory laparotomy with mass resection due to the nonspecific imaging findings. A mesenteric mass was found to contain nodules of diffuse large B-cell lymphoma. This case highlights the importance of radiologists to consider the prospect tumor transformation in the differential diagnosis of enlarging abdominal masses.

Epipericardial fat necrosis: Uncommon cause of acute pleuritic chest pain.

Epipericardial fat necrosis (EPFN) is a rare cause for acute chest. We describe the case of a previously healthy 25-year-old man who presented with sudden onset of left-sided chest pain. Laboratory values showed only mildly elevated d-dimer and electrocardiogram was normal. However, subsequent CT angiogram of the chest revealed fat necrosis in the epipericardial fat, characteristic for EPFN, for which the patient was treated with nonsteroidal anti-inflammatory drug. This case highlights the importance of radiologists to consider the prospect of EPFN in the differential diagnosis of acute chest pain as correct diagnosis allows for conservative management and avoidance of more aggressive techniques in symptomatic patients.

Pancreatic Carcinosarcoma: A Case Report Highlighting Computed Tomography Characteristics.

Primary pancreatic carcinosarcoma is a rare and malignant neoplasm arising within the pancreas. With fewer than a dozen cases ever reported, the recognition and treatment of this rare phenomenon can be difficult. We describe the case of an 85-year-old man who presented with vague right upper quadrant and epigastric abdominal pain and was found to have a pancreatic mass on ultrasound and computed tomography. The patient underwent open pancreaticoduodenectomy and was found to have pancreatic carcinosarcoma on microscopic evaluation. Although specific radiologic diagnosis of this entity is not possible, bringing the possibility of primary pancreatic carcinosarcoma to the ordering clinician׳s attention has the potential to hasten treatment and improve patient outcomes. We review the current literature on this rare type of neoplasia, considering histopathologic and clinical features. This case highlights the importance of radiologist awareness of this rare neoplasm and to consider carcinosarcoma in the differential when presented with a mixed solid and cystic pancreatic mass.

Congenital and Acquired Disorders of Ureteral Course.

A wide variety of entities can alter the course of the ureter in the abdomen and pelvis. These include conditions both intrinsic and extrinsic to the ureter leading to a number of different ureteral abnormalities including thickening, displacement, dilatation, etc. An understanding of ureteral pathology, as with any organ, first requires understanding of the normal anatomic appearance. The ureter can be evaluated in a number of ways, including radiographs, such as intravenous pyelogram and retrograde pyelogram, as well as computed tomography or magnetic resonance urography. The unopacified ureter can also be evaluated on examinations tailored for evaluation of other pathologic entities. Although the full spectrum of ureteral pathology is rather broad, this article serves as a review of the normal embryology and anatomy of the ureter, methods of evaluating the ureter at imaging, and entities that can alter the course of the ureter. These potential disorders of ureteral course include embryologic causes; surgical procedures; and displacement by inflammatory, neoplastic, and anatomic abnormalities.

ACR Appropriateness Criteria® Hematospermia.

Most men with hematospermia or hemospermia (HS) are young (<40 years of age), presenting with transient or episodic HS without other signs or symptoms of disease. The condition is self-limiting in most cases and idiopathic in nature. When a cause can be identified, infections of the urogenital tract are the most common. Imaging does not play a role in this patient population. In older men (>40 years of age), clinical screening for prostate cancer is advised. Furthermore, when HS is persistent or has symptoms, causes include obstruction or stricture at the level of the verumontanum, calcifications or calculi in the prostate, ejaculatory ducts or seminal vesicles, and cysts arising within these structures. Noninvasive imaging, predominantly transrectal ultrasound (TRUS) and MRI, can be used in men of any age with persistent or refractory HS, or other associated symptoms or signs. TRUS is considered as the first-line imaging with MRI used when TRUS is inconclusive or negative. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer-reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Thymic Epidermoid Cyst: Clinical and Imaging Manifestations of This Rare Anterior Mediastinal Mass.

Thymic epidermoid cysts are an extremely rare entity. These arise from epidermal cells that migrate to the thymus. The radiologic diagnosis of this rare lesion is challenging. We describe a case of an otherwise healthy 35-year-old woman who presented with an acute onset of chest pain and shortness of breath. She was found to have an anterior mediastinal mass. The imaging findings were, however, not characteristic for any single diagnostic entity. Since the imaging was inconclusive, surgical resection was performed for definitive diagnosis. The mass was found to be a thymic epidermoid cyst. This case underlines the significance for radiologists to be aware that epidermoid cysts can occur in the thymus and should be considered in the differential diagnosis for a heterogeneous anterior mediastinal mass.

Primary Splenic Angiosarcoma: Clinical and Imaging Manifestations of This Rare Aggressive Neoplasm.

Primary splenic angiosarcoma is a rare and fatal neoplasm arising from vascular endothelial cells within the spleen. With an incidence of 2 cases per 10 million people worldwide, the diagnosis and treatment of this rare entity is unfamiliar and challenging. We describe the case of a previously healthy 45-year-old woman who presented with vague upper-abdominal pain and was found to have a splenic mass on computed tomography. The patient underwent laparoscopic splenectomy and was found to have splenic angiosarcoma on microscopic evaluation. Although specific radiologic diagnosis is not possible, bringing the possibility of primary splenic angiosarcoma to the ordering clinician's attention has the potential to hasten treatment and improve patient outcomes. This case highlights the importance for radiologists to be aware of this rare neoplasm and to consider it in the differential when encountering a heterogeneously enhancing splenic mass.

ACR Appropriateness Criteria Staging of Testicular Malignancy.

Testicular cancer represents only 1% of all malignancies occurring in men. However, it is the most frequent malignancy in men between the ages of 20 and 34 years, accounting for 10% to 14% of cancer incidence in that age group. In most instances, the diagnosis of testicular tumors is established with a carefully performed physical examination and scrotal ultrasonography. Tumor markers are useful for determining the presence of residual disease. Cross-sectional imaging studies (CT, MRI) are useful in determining the location of metastases. Chest radiography and CT are used to assess pulmonary disease. Fluorine-18-2-fluoro-2-deoxy-d-glucose (FDG) PET scans have slightly higher sensitivity than CT, but their role in staging testicular cancer has not been determined in a large study. FDG PET may play a role in the follow-up of higher stage seminoma after chemotherapy. Bone scans are useful in the absence of FDG PET scans and should be used when bone metastases are suspected. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (the RAND/UCLA Appropriateness Method and the Grading of Recommendations Assessment, Development, and Evaluation) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances in which evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

From the RSNA refresher courses: a practical approach to the cystic renal mass.

The pathologic and imaging features of the renal cyst have been well described. A fluid-filled lesion is considered a cystic mass (ie, not a simple cyst) when it has any of the following features: calcification, high attenuation (>20 HU) at computed tomography, signal intensity not typical of water at magnetic resonance imaging, septations, multiple locules, enhancement, wall thickening, or nodularity. There are two important causes of a cystic renal mass: a complicated simple cyst (eg, one with hemorrhage, infection, or ischemia) and cystic renal cell carcinoma. At radiologic evaluation of such masses, it is imperative that optimal imaging techniques be used. Masses with calcification, high attenuation or high signal intensity, or septations can be categorized as benign (no further evaluation required), as requiring follow-up (probably benign), or as requiring surgery. Lesions requiring surgery can be benign or malignant at microscopic examination. Lesions that are multiloculated or demonstrate enhancement, wall thickening, or nodularity usually require surgery. When multiple features are present (eg, calcification and enhancement), the mass should be managed according to its most aggressive feature. Likewise, when there are conflicting findings at evaluation with different imaging modalities, the mass should be managed according to the most aggressive finding.

Radiology medical student education: an outcome-based survey of PGY-1 residents.

RATIONALE AND OBJECTIVES: Postgraduate year (PGY)-1 residents are frequently required to order imaging studies and make preliminary interpretations on them. This study determines whether PGY-1 residents feel their radiology education in medical school sufficiently trained them for the clinical responsibilities of internship. MATERIALS AND METHODS: This multicenter, institutional review board-approved survey asked PGY-1 trainees three categories of questions: 1) extent of medical school training for ordering and interpreting imaging studies, 2) confidence levels in ordering appropriate imaging studies and making common/emergent diagnoses, and 3) rating the importance of radiologic interpretation by interns. Respondents also submitted ideas for medical school teaching topics deemed most useful for interns. RESULTS: A total of 175 questionnaires were returned with good representation across specialties. Although 63.7% of interns were frequently asked to independently preview radiology studies, 12.6% received no formal radiology training in medical school. Participants rated chest radiographs as the most important study for interns to competently interpret (93.4% reporting very or extremely important). However, only 60.2% of interns reported high confidence in recognizing common/emergent pulmonary findings, and 56.3% for evaluating line and tube position. With regard to ordering imaging studies, 81.0% had never used or never heard of the American College of Radiology Appropriateness Criteria®. Only 33.1% had high confidence in knowing when to order oral/intravenous contrast. Similar low percentages had high confidence identifying and premedicating contrast allergies (36.4%) and knowing risk factors of nephrogenic systemic fibrosis (13.2%). CONCLUSIONS: PGY-1 residents feel that medical school curriculum emphasizing interpretation of chest radiographs and ordering appropriate imaging studies would better prepare students for the responsibilities of internship.

Understanding the US medical school requirements and medical students' attitudes about radiology rotations.

RATIONALE AND OBJECTIVES: To learn what percentage of US medical schools require their students to complete rotations in radiology during the clinical years. A secondary goal was to survey students' opinions about radiology rotations. MATERIALS AND METHODS: Data were collected from 159 US medical schools from the Association of American Medical Colleges (AAMC) for allopathic medical schools, the American Association of Colleges of Osteopathic Medicine (AACOM) for osteopathic medical schools, and by e-mailing curriculum directors at US medical schools with a survey. The secondary goal was achieved by e-mailing curriculum directors for voluntary medical student participation with an institutional review board-approved online survey. RESULTS: Data from the 2009-2010 academic year from AAMC and AACOM showed that 25% of US medical schools required radiology as a clinical rotation. Our survey of curriculum directors corroborated the AAMC and AACOM data. Data from our medical student survey showed that 87% of students from institutions requiring radiology thought radiology should be required. From institutions not requiring radiology, 45% of students thought that radiology should be required as a standalone course. Of students not required to take radiology, 63% planned to take radiology as an elective. CONCLUSIONS: Students, regardless of requirements, think there is value in having radiology as a regular aspect of a medical school curriculum. Medical schools should consider ways of incorporating radiology into their clinical curriculum.

A case of primary intrahepatic gastrinoma.

Gastrinoma is an uncommon but important cause of peptic ulcer disease. These tumors are most commonly located in the duodenum or pancreas. We present a case of a primary intrahepatic gastrinoma. Only 20 such cases have been previously reported in the literature. Metastatic hepatic gastrinomas are much more common, but it is important to differentiate between a primary and metastatic lesion because of the worse prognosis associated with a metastatic lesion.

Multifocal Renal Carcinoid Tumor Arising in Horseshoe Kidney with Metastases to the Thyroid.

Primary renal carcinoid tumor is a rare tumor of the kidney. Less than 40 cases of primary and metastatic renal carcinoids have been reported. There is a strong association of renal carcinoid tumors with horseshoe kidneys [1, 2]. The radiographic appearance is non-specific and overlaps that of renal cell carcinoma. Histopathologic differentiation between these two entities is essential because the treatment and prognosis are entirely different. We report a unique case of multifocal carcinoid tumor within a horseshoe kidney with metastases to the thyroid gland. It has been postulated that the renal carcinoid horseshoe subtype carried a more favorable prognosis; however, our case with multifocal involvement and distant metastases suggests the possibility for a more aggressive course.

Alveolar adenoma.

Alveolar adenoma of the lung is a rare benign neoplasm with proliferation of alveolar epithelium and septal mesenchyme. This unusual neoplasm presents as a solitary mass on chest roentgenograms, especially in older, asymptomatic patients. We report a case of this unusual neoplasm and describe the histologic and radiographic features of this tumor, which should be included in the differential diagnosis of a solitary pulmonary mass.