Imaging after Pancreatic Surgery: Expected Findings and Postoperative Complications

Pancreatic surgery is considered one of the most technically challenging surgical procedures, despite the evolution of modern techniques. Neoplasms remain the most common indication for pancreatic surgery, although inflammatory conditions may also prompt surgical evaluation. The choice of surgical procedure depends on the type and location of the pathologic finding because different parts of the pancreas have separate vascular supplies that may be shared by adjacent organs. The surgical approach could be conventional or minimally invasive (laparoscopic, endoscopic, or robotic assisted). Because of the anatomic complexity of the pancreatic bed, perioperative complications may be frequently encountered and commonly involve the pancreatic-biliary, vascular, lymphatic, or bowel systems, irrespective of the surgical technique used. Imaging plays an important role in the assessment of suspected postoperative complications, with CT considered the primary imaging modality, while MRI, digital subtraction angiography, and molecular imaging are considered ancillary diagnostic tools. Accurate diagnosis of postoperative complications requires a solid understanding of pancreatic anatomy, surgical indications, normal postoperative appearance, and expected postsurgical changes. The practicing radiologist should be familiar with the most common perioperative complications, such as anastomotic leak, abscess, and hemorrhage, and be able to differentiate these entities from normal anticipated postoperative changes such as seroma, edema and fat stranding at the surgical site, and perivascular soft-tissue thickening. In addition to evaluation of the primary operative fossa, imaging plays a fundamental role in assessment of the adjacent organ systems secondarily affected after pancreatic surgery, such as vascular, biliary, and enteric complications. Published under a CC BY 4.0 license. Test Your Knowledge questions are available in the supplemental material. See the invited commentary by Winslow in this issue.

Paraneoplastic Syndromes from Head to Toe: Pathophysiology, Imaging Features, and Workup

Patients often have symptoms due to the mass effect of a neoplasm on surrounding tissues or the development of distant metastases. However, some patients may present with clinical symptoms that are not attributable to direct tumor invasion. In particular, certain tumors may release substances such as hormones or cytokines or trigger an immune cross-reactivity between malignant and normal body cells, resulting in characteristic clinical features that are broadly referred to as paraneoplastic syndromes (PNSs). Recent advances in medicine have improved the understanding of the pathogenesis of PNSs and enhanced their diagnosis and treatment. It is estimated that 8% of patients with cancer develop a PNS. Diverse organ systems may be involved, most notably the neurologic, musculoskeletal, endocrinologic, dermatologic, gastrointestinal, and cardiovascular systems. Knowledge of various PNSs is necessary, as these syndromes may precede tumor development, complicate the patient's clinical presentation, indicate tumor prognosis, or be mistaken for metastatic spread. Radiologists should be familiar with the clinical presentations of common PNSs and the selection of appropriate imaging examinations. Many of these PNSs have imaging features that can assist with arriving at the correct diagnosis. Therefore, the key radiographic findings associated with these PNSs and the diagnostic pitfalls that can be encountered during imaging are important, as their detection can facilitate early identification of the underlying tumor, reveal early recurrence, and enable monitoring of the patient's response to therapy. ^© RSNA, 2023 Quiz questions for this article are available in the supplemental material.

Multimodality imaging findings of infection-induced tumors

Several infections can predispose to certain malignancies in different body parts. These infections include viral, bacterial, and fungal pathogens. Imaging plays a vital role in the diagnosis, staging, and management of these neoplastic conditions. Furthermore, it can help in differentiating infection-related non-neoplastic processes that can mimic malignancies. Both radiologists and clinicians should be familiar with these conditions. This review discusses the epidemiology, pathogenesis, and imaging features of infection-related tumors.

Non-Alcoholic Fatty Pancreas Disease: The Unsung Disease

Non-alcoholic fatty pancreas disease (NAFPD) is a relatively new and emerging disease definition that is increasingly diagnosed every year, like non-alcoholic fatty liver disease (NAFLD). It is associated especially with metabolic syndrome and obesity. As awareness of pancreatic steatosis and its clinical implications increase, it is diagnosed more frequently. The researchers have explained the clinical importance of NAFPD and the diseases it causes, such as pancreatitis, pancreatic insufficiency, and pancreatic cancer. Although the definitive treatment is not yet established, the primary treatment approach is weight loss since NAFPD is associated with metabolic syndrome as well as obesity. Although pharmacological agents such as oral hypoglycemic agents have been investigated in animal experiments, studies on humans have not been conducted. Since the research on NAFPD is still insufficient, it is a subject that needs to be investigated, and further studies are needed to explore its pathophysiology, clinical impact and its management.

Primary splenic lymphoma on top of intrahepatic splenosis: A unique case report

Solid organ splenosis is a challenging diagnosis with many atypical imaging features that can overlap with neoplastic masses of the affected organ. We present a sporadic case of intrahepatic splenosis in a 68-year-old woman with transformation into a low-grade B cell lymphoma. Initial cross-sectional imaging suggested focal nodular hyperplasia (FNH) ruled out on contrast-enhanced Magnetic Resonance Imaging (MRI) using a hepatobiliary-specific contrast agent. A Tc-99m sulfur colloid scan was negative. The final diagnosis was confirmed by a needle-guided biopsy revealing intrahepatic splenosis with transformation into a low-grade B cell lymphoma.

Shear wave elastography of the common fibular nerve at the fibular head

ABSTRACT

The aim of this work is to study the sonoelastographic features of the common fibular nerve in healthy adult subjects.This is an observational cross-sectional study. Shear wave elastography was used to evaluate the common fibular nerve. Crosssectional area and stiffness were measured in kilopascal (kPa) and meters/second (m/s).The study included 82 common fibular nerves in 41 healthy adult subjects. The mean cross-sectional area of the common fibular nerve at the fibular head was 8.7 mm2. Positive correlation was noted between stiffness measurements between short and long axes by both methods. The mean stiffness of the common fibular nerve in the short axis was 22.5 kPa, and in the long axis (LA) was 35.4 kPa. Positive correlation was noted between height and stiffness measured by both methods in both axes by kPa. In m/s, the mean stiffness of the common fibular in the short axis was 2.6 m/s, and while in the LA was 3.4 m/s. Height showed positive correlation with both axes for stiff measurements in m\s. Weight showed positive correlation with stiffness measurements by m/s in the LA.The results obtained in our study could be a reference point for evaluating stiffness of the common fibular nerve in research involving different pathologies.

Abdominal and pelvic splenosis: atypical findings, pitfalls, and mimics

Splenosis is an acquired form of ectopic splenic tissue that typically arises after trauma or splenectomy. It is often an incidental image finding in an otherwise asymptomatic patient, but the spectrum of symptoms varies based on the site of implantation. Radiologists should be familiar with the imaging features of splenosis to avoid mistaking it for malignancy. Splenosis has identical imaging features to that of the native spleen on US, CT, MRI, and nuclear medicine examinations. Therefore, when the radiologic findings support the diagnosis of splenosis, the patient can be spared invasive procedures for tissue sampling.

Superior mesenteric artery thrombosis and small bowel necrosis: An uncommon thromboembolic manifestation in COVID-19 pneumonia

Thromboembolism is a recognized complication in patients with COVID-19 infection. It is believed that coagulopathy results secondary to severe inflammatory response syndrome with release of cytokines, viral activation of coagulation cascade or viral related vasculitis. Both arterial and venous thromboembolic complications have been described, however venous thromboembolic complications are much far common. We present an uncommon thromboembolic complication of the superior mesenteric artery in a 49-year-old male with COVID-19 pneumonia. The patient also developed segmental infarct of his renal transplant. Patients with SARS-COV-2 infection should be closely evaluated and monitored for the development of thromboembolic complications. Prompt evaluation with CT angiography of suspected thromboembolism could help early diagnosis and treatment which can reflect better patients' outcomes.

Fat-containing pelvic lesions in females

Pelvic tumors are common in females and have a broad differential diagnosis. The clinical management of pelvic tumors varies widely-from observation to surgical resection-and imaging plays a pivotal role in diagnosis and clinical decision-making in these cases. In particular, imaging can help determine the organ of origin and tissue content of these tumors, which are the most important steps to narrowing the differential diagnosis. Fat has a characteristic appearance and is often easily identified on ultrasonography (US), computed tomography (CT), and magnetic resonance imaging (MRI). The amount and distribution of intralesional fat varies in different types of tumors. Macroscopic intralesional fat is often easily recognized by its hyperechoic appearance on US and low attenuation on CT similar to subcutaneous fat. On MRI, macroscopic fat is hyperintense on T1-weighted (T1W) images, with characteristic signal loss on fat-saturated sequences and India-ink artifact on opposed-phase T1W images. Macroscopic fat is the hallmark of teratomas, which are the most common ovarian neoplasms. Uterine lipoleiomyomas, peritoneal loose bodies, intraperitoneal and extraperitoneal primary lipomatous tumors such as lipoma and liposarcomas, and extra-adrenal myelolipomas are other pelvic masses distinguished by the presence of macroscopic fat. However, the imaging diagnosis of pelvic masses containing minimal or microscopic fat, such as immature ovarian teratomas, steroid cell ovarian neoplasms, and extramedullary hematopoiesis, can present a diagnostic challenge owing to their nonspecific appearance on US or CT. Obtaining MRI with in-phase and opposed-phase dual-echo T1W sequences and depicting chemical shift artifacts can be helpful in distinguishing these lesions.

Atypical pulmonary presentation of Strongyloides stercoralis hyperinfection in a patient with philadelphia chromosome-positive acute lymphoblastic leukemia: Case report

Strongyloides stercoralis is a soil-transmitted helminth endemic to tropical and subtropical regions and can be acquired due to parasite penetration through the skin. It can remain dormant in the gastrointestinal system for decades after the primary infection. In immunocompromised patients, this parasite can cause autoinfection with progression to hyperinfection syndrome. Here we report a unique case of pulmonary strongyloidiasis in a 32-year-old female, originally from Guatemala, with a significant clinical history of Philadelphia chromosome-positive B-cell acute lymphoblastic leukemia diagnosed in 2019. The patient is status post chemotherapy with tyrosine kinase inhibitor plus hyper-CVAD regimen (Cyclophosphamide, Vincristine sulfate, Doxorubicin hydrochloride (Adriamycin), and Dexamethasone). History of drug-induced hyperglycemia and obesity was also noted. Her current chief complaint included dyspnea, tachycardia, and chest pain. Chest computerized tomography (CT) scan showed diffuse interstitial pulmonary edema with septal thickening, scattered ground-glass opacities, and small pericardial effusion. Due to normal ejection fraction, the differential diagnosis included non-cardiogenic pulmonary edema, pneumonitis secondary to chemotoxicity, and infection. She rapidly progressed to acute hypoxic respiratory failure, and a bronchoalveolar lavage study revealed numerous larvae consistent with Strongyloides hyperinfection. Further workup revealed eosinophilia with negative Strongyloides IgG antibody. Given the rarity of this infection in the United States and the patient's place of birth, acquired latent Strongyloides infection is favored as the initial source of infection. The reactivation of the infection process was most likely secondary to her chemotherapy treatment. Strongyloides hyperinfection diagnosis can be challenging to establish and entails a high level of suspicion. Cytology evaluation is an essential factor for diagnosis.

Solitary fibrous tumors: Clinical and imaging features from head to toe

Solitary fibrous tumors (SFTs) are rare fibroblastic mesenchymal tumors that are usually benign with variable malignant potential. They can develop in any organ due to their spindle cell origin. The exact etiology of solitary fibrous tumors is unknown. The majority of SFTs are benign with 10-30% of them exhibiting aggressive and malignant features. The aggressiveness of this type of tumor is not associated with its histological features, which makes surgical resection the treatment of choice. We will review the clinical and radiological features and possible differential diagnoses of SFTs according to their anatomical sites following the World Health Organization 2020 classification.

Adrenal hemorrhage and hemorrhagic masses; diagnostic workup and imaging findings

Adrenal hemorrhage (AH) is a rare condition. It can be traumatic or non-traumatic. Most common causes are septicemia, coagulopathy or bleeding diathesis, and underlying neoplasms. Other reported less common causes of AH are COVID-19 and neonatal stress. Clinical diagnosis of AH is challenging due to its non-specific presentation and occurrence in the setting of acute medical illness. Therefore, most cases are diagnosed incidentally on imaging. Having high clinical suspicion in the proper clinical setting for AH is crucial to avoid life-threatening adrenal insufficiency that occurs in 16-50% of patients with bilateral AH. We discuss the clinical situations that predispose to AH, review the imaging features on different imaging modalities, highlight a variety of clinical cases, imaging features that should be concerning for an underlying neoplasm, and outline the potential role of interventional radiology in management of AH.

Shear wave elastography of the scalene muscles in healthy adults: A preliminary study

The aim of the study is to evaluate the reliability of shear wave elastography to assess the anterior and middle scalene muscles in healthy adult subjects.The study included 60 scalene muscles in 15 healthy subjects. High-resolution ultrasound and shear wave elastography were used to evaluate the anterior scalene and the middle scalene muscles. Stiffness values were measured.The mean shear elastic modulus showed the following values, right anterior scalene muscle 18.83 ± 5.32 kPa, left anterior scalene muscle 21.71 ± 4.8 kPa, right middle scalene muscle 12.84 ± 5.2 kPa, left middle scalene muscle 19.76 ± 5.30 kPa. Positive correlation was noted between the left middle scalene muscle and body mass index (P = .004). No difference in elasticity was noted between the right and left anterior scalene muscles; however, significant difference was noted between the right and left middle scalene muscles (P = .002).The results obtained in our study could be a reference point for future research considering different scalene muscle pathologies.

The Tailgate Study: Differing metabolic effects of a bout of excessive eating and drinking

INTRODUCTION

Excess energy intake by spectators at a sporting event (i.e., a tailgate) might cause acute negative health effects. However, limited data exist regarding the effects of overeating and alcohol consumption on lipid metabolism and the potential to gain intrahepatic triacylglycerols (IHTG). We tested the hypothesis that overconsumption of food and alcohol would significantly increase both hepatic de novo lipogenesis (DNL) and IHTG.

METHODS

Eighteen males (mean ± SD, age: 31.4 ± 7.3 years, BMI: 32.1 ± 5.9 kg/m²) were given alcoholic drinks to elevate blood alcohol for 5 h, while highly palatable food was presented. Blood samples were collected and DNL in TG-rich lipoproteins (TRL) was measured by GC/MS, IHTG was measured via MRS (n = 15), and substrate oxidation was measured via indirect calorimetry.

RESULTS

Subjects consumed 5087 ± 149 kcal (191 ± 25% excess of total daily energy needs including 171 ± 24 g alcohol), which increased plasma insulin, glucose, TG, and decreased NEFA (ANOVA p ≤ 0.003 for all). Both DNL and TRL-TG increased (p < 0.001), while IHTG did not change in the group as a whole (p = 0.229). Individual subject data revealed remarkably differing responses for IHTG (nine increased, five decreased, one did not change). Despite maintaining equal breath alcohol levels, subjects with IHTG elevations exhibited higher DNL, consumed 90% less alcohol (p = 0.048), tended to consume more carbohydrates, and exhibited lower whole-body fat oxidation (not significant) compared to those whose IHTG was reduced.

DISCUSSION

This study demonstrates that acute excess energy intake may have differing effects on an individual's DNL and IHTG, and dietary carbohydrate may influence DNL more than alcohol.

Morison's pouch: anatomical review and evaluation of pathologies and disease spread on cross-sectional imaging

The peritoneum is a complex structure. Having a better understanding of this complex anatomy will enable the radiologist to accurately assess and diagnose the wide range of intra-abdominal pathologies. In this article, we review the anatomy, boundaries, and connections of Morison's pouch. In addition, we discuss the incidence and development of common pathological conditions within Morison's pouch and the role of multiple imaging modalities in assessment and diagnosis of these conditions.

Trans-diaphragmatic Pathologies: Anatomical Background and Spread of Disease on Cross-sectional Imaging

The diaphragm is not only a sheet of muscle separating the abdominal and thoracic cavities: it plays an essential role in ventilation and can act as a gateway for the spread of different disease processes between the abdominal and the thoracic cavity. Careful attention to the appearance of the diaphragm on various imaging modalities is essential to ensure the accurate diagnosis of diaphragmatic disorders, which may be secondary to functional or anatomical derangements.

Fatty Acid Synthase Inhibitor TVB-2640 Reduces Hepatic de Novo Lipogenesis in Males With Metabolic Abnormalities

BACKGROUND AND AIMS

Elevated hepatic de novo lipogenesis (DNL) is a key distinguishing characteristic of nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis. In rodent models of NAFLD, treatment with a surrogate of TVB-2640, a pharmacological fatty acid synthase inhibitor, has been shown to reduce hepatic fat and other biomarkers of DNL. The purpose of this phase I clinical study was to test the effect of the TVB-2640 in obese men with certain metabolic abnormalities that put them at risk for NAFLD.

APPROACH AND RESULTS

Twelve subjects (mean ± SEM, 42 ± 2 years, body mass index 37.4 ± 1.2 kg/m² , glucose 103 ± 2 mg/dL, triacylglycerols 196 ± 27 mg/dL, and elevated liver enzymes) underwent 10 days of treatment with TVB-2640 at doses ranging from 50-150 mg/day. Food intake was controlled throughout the study. Hepatic DNL was measured before and after an oral fructose/glucose bolus using isotopic labeling with 1-¹³ C₁ -acetate intravenous infusion, followed by measurement of labeled very low-density lipoprotein palmitate via gas chromatography mass spectometry. Substrate oxidation was measured by indirect calorimetry. Across the range of doses, fasting DNL was reduced by up to 90% (P = 0.003). Increasing plasma concentrations of TVB-2640 were associated with progressive reductions in the percent of fructose-stimulated peak fractional DNL (R²  = -0.749, P = 0.0003) and absolute DNL area under the curve 6 hours following fructose/glucose bolus (R²  = -0.554, P = 0.005). For all subjects combined, alanine aminotransferase was reduced by 15.8 ± 8.4% (P = 0.05). Substrate oxidation was unchanged, and safety monitoring revealed that the drug was well tolerated, without an increase in plasma triglycerides. Alopecia occurred in 2 subjects (reversed after stopping the drug), but otherwise no changes were observed in fasting glucose, insulin, ketones, and renal function.

CONCLUSION

These data support the therapeutic potential of a fatty acid synthase inhibitor, TVB-2640 in particular, in patients with NAFLD and nonalcoholic steatohepatitis.

Spontaneous hemorrhage of an adrenal myelolipoma treated with transarterial embolization: A case report

Adrenal myelolipoma is a benign tumor of the adrenal cortex composed predominantly of fat and hematopoietic tissue. These lesions are usually asymptomatic, and most often incidentally detected on imaging. Uncommonly, they present with retroperitoneal hemorrhage, and these have been traditionally treated with emergent surgery. Although, transarterial embolization has been effectively and safely used in patients presenting with active hemorrhage from acute traumatic and nontraumatic causes, literature specifically pertaining to adrenal artery embolization is scant, perhaps due to smaller size and variability of adrenal arteries. With recent advances in endovascular techniques and imaging, there are emerging case reports and series of adrenal artery embolization in acute and nonacute settings. We report a case of spontaneous hemorrhage within an adrenal myelolipoma in a 43-year-old male patient, successfully treated with transarterial embolization, thereby avoiding major surgery. Our report adds to the growing body of literature pertaining to adrenal artery embolization.

Primary Pulmonary Chondrosarcoma: A Case Report and Literature Review

Chondrosarcomas are tumors consisting of osseous or cartilaginous stroma. They are not an uncommon pathology; however, primary pulmonary chondrosarcomas arising in lung parenchyma are extremely rare, with few cases published in literature. Herein, we present a case with biopsy-proven primary pulmonary chondrosarcoma after exclusion of primary origin elsewhere. In the case presented in this report, we demonstrate the clinical presentations, pulmonary function tests, and the radiological findings of this rare tumor in a young male patient. Further, we present a brief review of existing literature for patients with similar pathology.

Lumbosacral plexiform neurofibroma: a rare case in an adult without neurofibromatosis type I

Plexiform neurofibromas are an uncommon variant of neurofibromas that are described as being essentially pathognomonic of neurofibromatosis type 1 (NF1). Plexiform neurofibromas in the absence of NF1 are extremely rare. We present the case of a 38-year-old woman with a large multilobulated lumbosacral mass extending into the pelvis and proximal thigh. Histopathology of a CT-guided biopsy of the mass revealed it to be a neurofibroma. The imaging findings were consistent with a plexiform subtype. Further imaging and clinical workup showed that the patient had no other identifiable neurofibromas and did not meet criteria for the diagnosis of NF1.

HIV-related Malignancies and Mimics: Imaging Findings and Management

The risk of developing malignancy is higher in patients with human immunodeficiency virus (HIV) infection than in non-HIV-infected patients. Several factors including immunosuppression, viral coinfection, and high-risk lifestyle choices lead to higher rates of cancer in the HIV-infected population. A subset of HIV-related malignancies are considered to be acquired immunodeficiency syndrome (AIDS)-defining malignancies, as their presence confirms the diagnosis of AIDS in an HIV-infected patient. The introduction of highly active antiretroviral therapy (HAART) has led to a significant drop in the rate of AIDS-defining malignancies, including Kaposi sarcoma, non-Hodgkin lymphoma, and invasive cervical carcinoma. However, non-AIDS-defining malignancies (eg, Hodgkin lymphoma, lung cancer, hepatocellular carcinoma, and head and neck cancers) now account for an increasing number of cancer cases diagnosed in HIV-infected patients. Although the number has decreased, AIDS-defining malignancies account for 15%-19% of all deaths in HIV-infected patients in the post-HAART era. Most HIV-related malignancies in HIV-infected patients manifest at an earlier age with a more aggressive course than that of non-HIV-related malignancies. Understanding common HIV-related malignancies and their specific imaging features is crucial for making an accurate and early diagnosis, which impacts management. Owing to the weakened immune system of HIV-infected patients, other entities such as various infections, particularly opportunistic infections, are prevalent in these patients. These processes can have confounding clinical and imaging manifestations that mimic malignancy. This article reviews the most common AIDS-defining and non-AIDS-defining malignancies, the role of imaging in their diagnosis, and the imaging mimics of malignancies in HIV-infected patients. ^©RSNA, 2018.

Villous Gastrointestinal Tumors: Multimodality Imaging with Histopathologic Correlation

Villous lesions are advanced adenomas that manifest most commonly in the colon; however, they can develop throughout the gastrointestinal tract. The duodenum is the most common small-bowel site of these lesions. Although in most cases these are isolated lesions that occur sporadically, patients with certain specific colorectal cancer syndromes, including familial adenomatous polyposis and hereditary nonpolyposis colorectal cancer, may develop multiple advanced adenomas. Villous lesions are important because although they are histologically benign, they may harbor dysplasia and have potential for malignancy. These characteristics make them a primary target for colorectal cancer screening with optical and virtual colonoscopy. However, these lesions can also be symptomatic and detected at diagnostic imaging when patients present for examination. They have characteristic features at a variety of imaging examinations, including barium fluoroscopy, CT, MRI, and endoscopic US. It is important for radiologists to be aware of these lesions, their potential morphologies, and their typical appearances at multimodality imaging. Although villous tumors can be detected at imaging and confirmed with biopsy, owing to limitations in identifying dysplasia and foci of malignancy with the above modalities alone and the potential for malignancy, referral for surgical resection of these lesions ultimately is required. ^©RSNA, 2018.

Solitary fibrous tumor of the ischioanal fossa-a multidisciplinary approach to management with radiologic-pathologic correlation

Solitary fibrous tumors are primary mesenchymal tumors, which may occur in any part of the body. Overall, these tumors are considered to have intermediate malignant potential with 5- and 10-year metastasis-free and overall disease-specific survival rates of 74% and 55%, and 89% and 73%, respectively (Demicco et al, 2012). Herein we present an unusual case of solitary fibrous tumors involving the ischioanal fossa in a 19-year-old woman with radiologic-pathologic correlation. This case was complicated by extensive tumor vascularity and was thus managed with preoperative embolization followed by en bloc surgical resection.

Nongynecologic Findings Seen at Pelvic US

Ultrasonography (US) is frequently the first imaging modality used to examine women with symptoms involving the pelvis. It is widely available and involves no exposure to ionizing radiation. Images can be acquired with a transabdominal, endovaginal, or translabial approach, and the use of video clips and three-dimensional reconstructions can be helpful. US is excellent for assessment of the uterus, ovaries, and adnexa. Occasionally, nongynecologic pelvic diseases arising from the gastrointestinal, genitourinary, and musculoskeletal systems and the pelvic peritoneal and extraperitoneal spaces may be detected and can be a source of diagnostic dilemma. US can be helpful not only in the detection but also occasionally in the characterization of such entities. Computed tomography and magnetic resonance imaging are useful in complicated cases. In this article, the normal US appearance of the bowel and US signs of bowel disease and specific entities, including appendicitis, diverticular disease, bowel obstruction, appendiceal mucocele, and intestinal tumors, are reviewed. The lower urinary tract is included in the field of view in every pelvic US examination; commonly encountered entities related to the urinary bladder, distal ureter, and urethra are illustrated. In addition to arising in the gastrointestinal and genitourinary tracts, pathologic conditions in the pelvis can arise in the peritoneal or extraperitoneal space. Although conditions of the pelvic peritoneal and extraperitoneal spaces are rare, it is important to recognize these entities and distinguish them from the more common gynecologic diseases. Owing to the implications for diagnosis and management, radiologists and other physicians who perform pelvic US should be aware of the spectrum of nongynecologic pathologic entities that can be detected. ©RSNA, 2017.

Angiosarcoma: clinical and imaging features from head to toe

Angiosarcoma is a rare, aggressive subtype of soft-tissue sarcoma with a propensity for local recurrence and metastasis associated with a generally poor prognosis, unless diagnosed early. Given the vascular endothelial cell origin of angiosarcoma, tumours may develop in essentially any organ; however, there is a predilection for the skin where half of all tumours arise, increasing in prevalence with age. The most common risk factors are chronic lymphoedema and history of radiation. We review the most important radiological findings along the spectrum of angiosarcoma from head to toe throughout the body, including uncommon and rare locations. Key imaging features of angiosarcoma across multiple organ systems will be described, as well as the impact on management and prognosis.

Beyond the GIST: mesenchymal tumors of the stomach

Intramural gastric masses arise in the wall of the stomach (generally within the submucosa or muscularis propria), often with intact overlying mucosa. These tumors are typically mesenchymal in origin and have overlapping radiologic appearances. A combination of features such as location, attenuation, enhancement, and growth pattern may suggest one diagnosis over another. Gastrointestinal stromal tumors (GISTs) account for the majority of intramural tumors and can vary widely in appearance, from small intraluminal lesions to exophytic masses that protrude into the peritoneal cavity, commonly with areas of hemorrhage or necrosis. A well-circumscribed mass measuring -70 to -120 HU is a lipoma. Leiomyomas usually manifest as low-attenuation masses at the gastric cardia. Homogeneous attenuation is a noteworthy characteristic of schwannomas, particularly for larger lesions that might otherwise be mistaken for GISTs. A hypervascular mass in the antrum is a common manifestation of glomus tumors. Hemangiomas are also hypervascular but often manifest in childhood. Inflammatory fibroid polyps usually arise as a polypoid mass in the antrum. Inflammatory myofibroblastic tumors are infiltrative neoplasms with a propensity for local recurrence. Plexiform fibromyxomas are rare, usually antral tumors. Carcinoid tumors are epithelial in origin, but often submucosal in location, and therefore should be distinguished from other intramural lesions. Multiple carcinoid tumors are associated with hypergastrinemia, either in the setting of chronic atrophic gastritis or Zollinger-Ellison syndrome. Sporadic solitary carcinoid tumors not associated with hypergastrinemia have a higher rate of metastasis. Histopathologic analysis, including immunohistochemistry, is usually required for diagnosis of intramural masses.