Fetal Gas Gangrene: A Rare and Critical Case.

Gas gangrene is a lethal necrotic infection resulting in gas production within tissue. It is typically associated with trauma and is especially lethal during pregnancy, resulting in severe maternal infection and fetal death. We report the case of a 31-year-old G3P2 female who presented to the emergency department with abdominal bloating, vaginal cramping, and brown vaginal discharge. Physical examination showed that the patient was hypertensive, tachycardic, and tachypneic, and laboratory examination showed a downtrending beta-human chorionic gonadotropin and leukocytosis, with elevated inflammatory markers. Ultrasound showed copious gas located within the lower abdomen and the fetus was not visualized. Computed tomography (CT) of the abdomen and pelvis showed a gravid uterus with a single fetus and extensive air locules in the fetus, amniotic cavity, and placenta. The findings were consistent with gas gangrene of a mature fetus in the third trimester. Fetal gas gangrene is a potentially lethal condition during pregnancy, and early diagnosis is imperative in management. CT was utilized in this case to outline the increased gas production within the amniotic cavity and fetal organs and proved crucial in determining the next steps of management.

Imaging of Biliary Tree Abnormalities.

Pathologic conditions of the biliary system, although common, can be difficult to diagnose clinically. Challenges in biliary imaging include anatomic variants and the dynamic nature of the biliary tract, which can change with age and intervention, blurring the boundaries of normal and abnormal. Choledochal cysts can have numerous appearances and are important to diagnose given the risk of cholangiocarcinoma potentially requiring surgical resection. Choledocholithiasis, the most common cause of biliary dilatation, can be difficult to detect at US and CT, with MRI having the highest sensitivity. However, knowledge of the imaging pitfalls of MRI and MR cholangiopancreatography is crucial to avoid misinterpretation. Newer concepts in biliary tract malignancy include intraductal papillary biliary neoplasms that may develop into cholangiocarcinoma. New paradigms in the classification of cholangiocarcinoma correspond to the wide range of imaging appearances of the disease and have implications for prognosis. Accurately staging cholangiocarcinoma is imperative, given expanding curative options including transplant and more aggressive surgical options. Infections of the biliary tree include acute cholangitis or recurrent pyogenic cholangitis, characterized by obstruction, strictures, and central biliary dilatation. Inflammatory conditions include primary sclerosing cholangitis, which features strictures and fibrosis but can be difficult to differentiate from secondary causes of sclerosing cholangitis, including more recently described entities such as immunoglobulin G4-related sclerosing cholangitis and COVID-19 secondary sclerosing cholangitis. The authors describe a wide variety of benign and malignant biliary tract abnormalities, highlight differentiating features of the cholangitides, provide an approach to interpretation based on the pattern of imaging findings, and discuss pearls and pitfalls of imaging to facilitate accurate diagnosis. ©RSNA, 2024 Supplemental material is available for this article.

Imaging of pancreatic serous cystadenoma and common imitators.

Pancreatic cystic neoplasms are lesions comprised of cystic components that show different biological behaviors, epidemiology, clinical manifestations, imaging features, and malignant potential and management. Benign cystic neoplasms include serous cystic neoplasms (SCAs). Other pancreatic cystic lesions have malignant potential, such as intraductal papillary mucinous neoplasms and mucinous cystic neoplasms. SCAs can be divided into microcystic (classic appearance), honeycomb, oligocystic/macrocystic, and solid patterns based on imaging appearance. They are usually solitary but may be multiple in von Hippel-Lindau disease, which may depict disseminated involvement. The variable appearances of SCAs can mimic other types of pancreatic cystic lesions, and cross-sectional imaging plays an important role in their differential diagnosis. Endoscopic ultrasonography has helped in improving diagnostic accuracy of pancreatic cystic lesions by guiding tissue sampling (biopsy) or cyst fluid analysis. Immunohistochemistry and newer techniques such as radiomics have shown improved performance for preoperatively discriminating SCAs and their mimickers.

Pancreatic Cancer and Its Mimics.

Pancreatic ductal adenocarcinoma (PDAC) is the most common primary pancreatic malignancy, ranking fourth in cancer-related mortality in the United States. Typically, PDAC appears on images as a hypovascular mass with upstream pancreatic duct dilatation and abrupt duct cutoff, distal pancreatic atrophy, and vascular encasement, with metastatic involvement including lymphadenopathy. However, atypical manifestations that may limit detection of the underlying PDAC may also occur. Atypical PDAC features include findings related to associated conditions such as acute or chronic pancreatitis, a mass that is isointense to the parenchyma, multiplicity, diffuse tumor infiltration, associated calcifications, and cystic components. Several neoplastic and inflammatory conditions can mimic PDAC, such as paraduodenal "groove" pancreatitis, autoimmune pancreatitis, focal acute and chronic pancreatitis, neuroendocrine tumors, solid pseudopapillary neoplasms, metastases, and lymphoma. Differentiation of these conditions from PDAC can be challenging due to overlapping CT and MRI features; however, certain findings can help in differentiation. Diffusion-weighted MRI can be helpful but also can be nonspecific. Accurate diagnosis is pivotal for guiding therapeutic planning and potential outcomes in PDAC and avoiding biopsy or surgical treatment of some of these mimics. Biopsy may still be required for diagnosis in some cases. The authors describe the typical and atypical imaging findings of PDAC and features that may help to differentiate PDAC from its mimics. ©RSNA, 2023 Online supplemental material is available for this article. Quiz questions for this article are available through the Online Learning Center. See the invited commentary by Zins in this issue.

Primary sclerosing cholangitis: review for radiologists.

Primary sclerosing cholangitis is a rare chronic inflammatory disease affecting the bile ducts, which can eventually result in bile duct strictures, cholestasis and cirrhosis. Patients are often asymptomatic but may present with clinical features of cholestasis. Imaging plays an important role in the diagnosis and management. This review covers the pathophysiology, clinical features, imaging findings as well as methods of surveillance and post-transplant appearance.

Abdominal Manifestations of Sickle Cell Disease.

Sickle cell disease is a debilitating hematologic process that affects the entire body. Disease manifestations in the abdomen most commonly result from vaso-occlusion, hemolysis, or infection due to functional asplenia. Organ specific manifestations include those involving the liver (eg, hepatopathy, iron deposition), gallbladder (eg, stone formation), spleen (eg, infarction, abscess formation, sequestration), kidneys (eg, papillary necrosis, infarction), pancreas (eg, pancreatitis), gastrointestinal tract (eg, infarction), reproductive organs (eg, priapism, testicular atrophy), bone (eg, marrow changes, avascular necrosis), vasculature (eg, vasculopathy), and lung bases (eg, acute chest syndrome, infarction). Imaging provides an important clinical tool for evaluation of acute and chronic disease manifestations and complications. In summary, there are multifold abdominal manifestations of sickle cell disease. Recognition of these sequela helps guide management and improves outcomes. The purpose of this article is to review abdominal manifestations of sickle cell disease and discuss common and rare complications of the disease within the abdomen.

Gallbladder Carcinoma and Its Differential Diagnosis at MRI: What Radiologists Should Know.

Gallbladder carcinoma is the most common cancer of the biliary system. It is challenging to diagnose because patients are often asymptomatic or present with nonspecific symptoms that mimic common benign diseases. Surgical excision is the only curative therapy and is best accomplished at early non-locally advanced stages. Unfortunately, gallbladder cancer often manifests at late locally advanced stages, precluding cure. Early tumors are often incidentally detected at imaging or at cholecystectomy performed for another indication. Typical imaging features of localized disease include asymmetric gallbladder wall thickening, polyps larger than 1.0 cm, and a solid mass replacing the gallbladder lumen. Advanced tumors are often infiltrative and can be confusing at CT and MRI owing to their large size. Determination of the origin of the lesion is paramount to narrow the differential diagnosis but is often challenging. It is important to identify gallbladder cancer and distinguish it from other benign and malignant hepatobiliary processes. Since surgical resection is the only curative treatment option, radiologist understanding and interpretation of pathways of nodal and infiltrative tumor spread can direct surgery or preclude patients who may not benefit from surgery. While both CT and MRI are effective, MRI provides superior soft-tissue characterization of the gallbladder and biliary tree and is a useful imaging tool for diagnosis, staging, and evaluation of treatment response. ©RSNA, 2020.

A 73-gene proliferative transcriptomic signature predicts uterine serous carcinoma patient survival and response to primary therapy.

OBJECTIVES: To develop a transcriptomic signature capable of predicting overall survival (OS) for uterine serous carcinoma (USC). METHODS: RNAseq data for 58 USC patients were obtained from TCGA. Expression of 73 candidate genes was measured for 67 Augusta University (AU) samples using NanoString technology. RESULTS: Analysis of the TCGA RNAseq data identified 73 genes that individually predict prognosis for USC patients and an elastic net model with all 73 genes (USC73) distinguishes a good OS group with low USC73 score from a poor OS group with high USC73 score (5-year OS = 83.3% and 13.3% respectively, HR = 40.1; p = 3 × 10-8). This finding was validated in the independent AU cohort (HR = 4.3; p = 0.0004). The poor prognosis group with high USC73 score consists of 37.9% and 32.8% of patients in the TCGA and AU cohort respectively. USC73 score and pathologic stage independently contribute to OS and together provide the best prognostic value. Early stage, low USC73 patients have the best prognosis (5-year OS = 85.1% in the combined dataset), while advanced stage, high USC73 patients have the worst prognosis (5-year OS = 6.4%, HR = 30.5, p = 1.2 × 10-12). Consistent with the observed poor survival, primary cell cultures from high USC73 patients had higher proliferation rate and cell cycle progression; and high USC73 patients had lower rates of complete response to standard therapy. CONCLUSIONS: The USC73 transcriptomic signature and stage independently predict OS of USC patients and the best prediction is achieved using USC73 and stage. USC73 may also serve as a therapeutic biomarker to guide patient care.

Nonfetal Imaging During Pregnancy: Acute Abdomen/Pelvis.

Abdominal pain is a common occurrence in pregnant women and may have a variety of causes, including those that are specific to pregnancy (eg, round ligament pain in the first trimester) and the wide range of causes of abdominal pain that affect men and women who are not pregnant (eg, appendicitis, acute cholecystitis). Noncontrast magnetic resonance (MR) imaging is increasingly performed to evaluate pregnant women with abdominal pain, either as the first-line test or as a second test following ultrasonography. The imaging appearance of causes of abdominal pain in pregnant women are reviewed with an emphasis on noncontrast MR imaging.

Differentiation of focal autoimmune pancreatitis from pancreatic ductal adenocarcinoma.

Autoimmune pancreatitis (AIP) is an inflammatory process of the pancreas that occurs most commonly in elderly males and clinically can mimic pancreatic adenocarcinoma and present with jaundice, weight loss, and abdominal pain. Mass-forming lesions in the pancreas are seen in the focal form of AIP and both clinical and imaging findings can overlap those of pancreatic cancer. The accurate distinction of AIP from pancreatic cancer is of utmost importance as it means avoiding unnecessary surgery in AIP cases or inaccurate steroid treatment in patients with pancreatic cancer. Imaging concomitantly with serological examinations (IgG4 and Ca 19-9) plays an important role in the distinction between these entities. Characteristic extra-pancreatic manifestations as well as favorable good response to treatment with steroids are characteristic of AIP. This paper will review current diagnostic parameters useful in differentiating between focal AIP and pancreatic adenocarcinoma.

Impact of Overlying Personal Items on CT Dose with Use of Automated Tube Current Modulation-Pilot Investigation.

PURPOSE: To determine the incidence and impact of overlying radiopaque personal items (e.g., cellular phones, zippers) on CT dose and image quality with use of automated tube current modulation. METHODS: Topogram images from 100 consecutive adult outpatient CT abdomen pelvis studies were retrospectively reviewed, and the number and type of overlying radiopaque personal items were recorded. Additionally, an anthropomorphic phantom was imaged with overlying personal items 1) present in topogram and axial images; 2) present in topogram but removed prior to axial acquisition; and 3) present in topogram positioned outside the field of view of the axial acquisition. dose length product (DLP) and CT dose index volume (CTDIvol) were compared to acquisitions performed without overlying personal items. Image noise was evaluated by assessing the standard deviation of Hounsfield units at the level of the overlying personal item. RESULTS: Overlying personal items were visible in topogram images for 55% of CT exams and included underwires (38% of exams), zippers (7%), and cellular phones (1%). DLP increased when a cellular phone was present in the topogram whether or not it was removed before axial image acquisition (3.7% p = 0.002, combined AutomA and SmartmA), and image noise increased (144%, p = 0.002; AutomA). No increase in dose or image noise was observed with overlying zippers or underwires or when any object was visible in the topogram outside the field of view of the axial images. CONCLUSIONS: Overlying personal items were observed in the majority of abdominopelvic CT scans. Large overlying radiopaque personal items resulted in increased dose and increased image noise. Removal of all overlying personal items will result in optimized dose and image quality.

MRI of the penis.

This article reviews the anatomy and magnetic resonance imaging (MRI) appearance of the penis. The recommended technique for MRI of the penis is outlined, with discussion of the benefits and drawbacks to imaging the penis after artificial erection. Common penile pathologies are reviewed, with a summary of their clinical features, MRI appearance, and treatment. The ability to demonstrate the erectile bodies and vasculature helps to evaluate vascular pathologies such as priapism, Mondor disease, and cavernosal thrombosis. MRI is also a useful tool to assess for traumatic abnormalities of the penis, with the depiction of soft tissue anatomy and fascial layers allowing for evaluation of penile fracture and penile contusion. Malignant disease of the penis is also reviewed, including squamous cell carcinoma, urethral carcinoma, metastases, and rare neoplasms. Staging of these neoplasms is addressed, with discussion of how MRI can be used to assess the extent of tumor involvement. MRI also clearly demonstrates the tunica albuginea, which allows for evaluation of Peyronie's disease.

Pancreatitis in the developmentally anomalous pancreas.

Developmental anomalies of the pancreas include more common entities such as pancreas divisum and annular pancreas, and unusual entities such as heterotopic pancreas. While these anomalies can present a diagnostic challenge to the radiologist, when the pancreatic tissue involved in these processes develops pancreatitis, the radiographic appearance can present a diagnostic dilemma. Awareness of these pancreatic anomalies and familiarity with their appearance when inflamed is necessary to distinguish pancreatitis in the developmentally anomalous pancreas from other inflammatory or neoplastic processes.

Multidetector CT Findings in the Abdomen and Pelvis after Damage Control Surgery for Acute Traumatic Injuries.

After experiencing blunt or penetrating trauma, patients in unstable condition who are more likely to die of uncorrected shock than of incomplete injury repairs undergo emergency limited exploratory laparotomy, which is also known as damage control surgery (DCS). This surgery is part of a series of resuscitation steps, with the goal of stabilizing the patient's condition, with rapid surgical control of hemorrhage followed by supportive measures in the intensive care unit before definitive repair of injuries. These patients often are imaged with multidetector CT within 24-48 hours of the initial surgery. Knowledge of this treatment plan is critical to CT interpretation, because there are anatomic derangements and foreign bodies that would not be present in patients undergoing surgery for other reasons. Patients may have injuries beyond the surgical field that are only identified at imaging, which can alter the care plan. Abnormalities related to the resuscitation period such as the CT hypoperfusion complex and ongoing hemorrhage can be recognized at CT. Familiarity with these imaging and clinical findings is important, because they can be seen not only in trauma patients after DCS but also in other patients in the critical care setting. The interpretation of imaging studies can be helped by an understanding of the diagnostic challenges of grading organ injuries with surgical materials in place and the awareness of potential artifacts on images in these patients. Online supplemental material is available for this article. ©RSNA, 2019 See discussion on this article by LeBedis .

Secondary Hypertension and Complications: Diagnosis and Role of Imaging.

Hypertension is a common problem; if left untreated, it can result in significant complications, including those involving the cardiovascular system and end organs. Approximately 10% of patients with hypertension are classified as having secondary hypertension, defined as hypertension attributable to a specific and potentially remediable cause. The evaluation for secondary hypertension typically begins with acquiring the patient history and performing a physical examination and screening laboratory tests. Directed imaging may be performed, on the basis of laboratory test results, to assess for potential causes of secondary hypertension. The causes can be broadly classified as endocrine (eg, hyperaldosteronism, pheochromocytoma, hyperparathyroidism) and nonendocrine (eg, aortic coarctation, renal vascular hypertension). In addition, patients with hypertension can develop significant complications that also are diagnosed with imaging, including conditions involving the cardiovascular system (eg, aortic aneurysm, acute aortic syndrome) and central nervous system (eg, stroke, subarachnoid hemorrhage, and posterior reversible encephalopathy syndrome). The imaging workup and imaging appearances of some of the causes of secondary hypertension are reviewed, treatment options are discussed, and the imaging appearances of hypertension-related complications are described. It is important for radiologists to accurately diagnose the secondary causes of hypertension, as many of them are treatable, and treatment may result in improved symptoms or resolution of hypertension. ©RSNA, 2019.

Uncommon Intraluminal Tumors of the Gallbladder and Biliary Tract: Spectrum of Imaging Appearances.

Intraluminal pathologic conditions of the bile ducts and gallbladder are common, most frequently consisting of calculi and adenocarcinoma. In recent years, intraductal papillary neoplasm of the bile ducts (IPN-B), which is analogous to intraductal papillary mucinous neoplasm of the pancreas, has been recognized as a distinct pathologic entity and a precursor lesion to adenocarcinoma of the bile ducts. Intraductal tubulopapillary neoplasm (ITPN) of the bile duct was subsequently described as a distinct pathologic entity. With increased awareness and advances in imaging techniques, these lesions are diagnosed with increased frequency at preoperative imaging. A similar neoplasm in the gallbladder is referred to as intracholecystic papillary neoplasm. These lesions are often diagnosed at a preinvasive stage and have a better prognosis than invasive cholangiocarcinoma when treated with curative resection, underscoring the importance of an accurate imaging diagnosis. The most common causes of polypoid lesions of the gallbladder are cholesterol polyps and adenomyomatosis. These lesions need to be differentiated from the less common but clinically important adenocarcinoma of the gallbladder. Imaging is crucial to identify polyps that are at high risk for malignancy so that the appropriate management choice between imaging follow-up and cholecystectomy can be made by the treating physicians. Other less common gallbladder tumors, such as gallbladder adenomas, lymphoma, and metastases to the gallbladder, can manifest as intraluminal tumors; and awareness of these lesions is also important. In this article, the recent literature is reviewed; and the imaging appearances, histopathologic findings, and management of uncommon intraluminal tumors of the bile ducts and gallbladder and their mimics are discussed. ©RSNA, 2019.

Patient Knowledge Regarding Colorectal Cancer Risk, Opinion of Screening, and Preferences for a Screening Test.

AIMS: To assess patient knowledge about colorectal cancer incidence and prognosis as well as willingness to undergo screening with various tests (eg, optical colonoscopy, stool-based tests, computed tomographic colonography (CTC)). MATERIALS AND METHODS: A survey was administered to consecutive patients of a general academic-based internal medicine clinic. RESULTS: Survey response rate was 86.3%. A majority of respondents (55%) reported being aware of general information about colorectal cancer, and 99% indicated a belief that colorectal cancer screening was a good idea. A majority of respondents (73%) were willing to undergo optical colonoscopy, and some were willing to undergo stool-based tests (48%), or CT colonography CTC (40%). A majority reported being more willing to undergo a colorectal cancer screening test if the test did not involve radiation (86%), did not involve insertion of a tube or device into the rectum (78%), did not involve a pre-proceduralpreprocedural bowel cleansing regimen (73%), or did not involve sedation (60%). CONCLUSION: Improved patient education about the negligible radiation risk associated with CTC or development of a non-invasive imaging test that did not involve a preprocedural bowel cleansing regimen may increase rates of colorectal cancer screening.

Prevalence and Severity of Off-Centering During Diagnostic CT: Observations From 57,621 CT scans of the Chest, Abdomen, and/or Pelvis.

PURPOSE: To determine distances between patient centroid and gantry isocenter during CT imaging of the chest, abdomen, and/or pelvis, and to evaluate differences based on patient gender, scan region, patient position, and gantry aperture. MATERIALS AND METHODS: A water phantom and an anthropomorphic phantom were imaged in the centered position in the CT gantry and at several off-centered positions. Additionally, data from 57,621 adult chest, abdomen, and/or pelvic CT acquisitions were evaluated. Data were analyzed with an analysis of variance using the centroid-to-isocenter data as the dependent variable and the other parameters as independent variables. RESULTS: The majority of patient acquisitions (83.7% (48271/57621)) were performed with the patient's centroid positioned below isocenter (mean 1.7 cm below isocenter (SD 1.8 cm); range 12.1 cm below to 7.8 cm above isocenter). Off-centering in the x-axis was less severe (mean 0.01 cm left of isocenter (SD 1.6 cm)). Distance between centroid and isocenter in the y-axis did not differ as a function of sex but did differ based on scan region, patient position, and gantry aperture. CONCLUSION: Off-centering is common during CT imaging and has been previously demonstrated to impact dose and image quality.

Rectal MRI for Cancer Staging and Surveillance.

MRI is an integral part of the multidisciplinary treatment of rectal adenocarcinoma. Staging MRI is performed to establish TNM stage and assess for prognostic factors, including circumferential resection margin status and presence of extramural vascular invasion. The results of staging MRI determine which patients will undergo preoperative neoadjuvant chemoradiation before resection. Restaging MRI is performed to evaluate for treatment response and may identify patients with no residual visible tumor who are candidates for a "watch and wait" strategy in lieu of resection. In addition, the results of MRI in conjunction with endoscopy determine the surgical technique used to remove the tumor.