Hemodialysis Access: US for Preprocedural Mapping and Evaluation of Maturity and Access Dysfunction.

Patients with kidney failure require kidney replacement therapy. While renal transplantation remains the treatment of choice for kidney failure, renal replacement therapy with hemodialysis may be required owing to the limited availability and length of time patients may wait for allografts or for patients ineligible for transplant owing to advanced age or comorbidities. The ideal hemodialysis access should provide complication-free dialysis by creating a direct connection between an artery and vein with adequate blood flow that can be reliably and easily accessed percutaneously several times a week. Surgical arteriovenous fistulas and grafts are commonly created for hemodialysis access, with newer techniques that involve the use of minimally invasive endovascular approaches. The emphasis on proactive planning for the placement, protection, and preservation of the next vascular access before the current one fails has increased the use of US for preoperative mapping and monitoring of complications for potential interventions. Preoperative US of the extremity vasculature helps assess anatomic suitability before vascular access creation, increasing the rates of successful maturation. A US mapping protocol ensures reliable measurements and clear communication of anatomic variants that may alter surgical planning. Postoperative imaging helps assess fistula maturation before cannulation for dialysis and evaluates for early and late complications associated with arteriovenous access. Clinical and US findings can suggest developing stenosis that may progress to thrombosis and loss of access function, which can be treated with percutaneous vascular interventions to preserve access patency. Vascular access steal, aneurysms and pseudoaneurysms, and fluid collections are other complications amenable to US evaluation. ©RSNA, 2023 Supplemental material is available for this article. Test Your Knowledge questions for this article are available through the Online Learning Center.

Imaging Update for Hereditary Abdominopelvic Neuroendocrine Neoplasms.

ABSTRACT: Neuroendocrine neoplasms have shown a linear increase in incidence and prevalence in recent decades, primarily due to improved cross-sectional imaging, expanded use of endoscopic procedures, and advanced genetic analysis. However, diagnosis of hereditary neuroendocrine tumors is still challenging because of heterogeneity in their presentation, the variety of tumor locations, and multiple associated syndromes. Radiologists should be familiar with the spectrum of these tumors and associated hereditary syndromes. Furthermore, as the assessment of multiple tumor elements such as morphology, biochemical markers, and presence of metastatic disease are essential for the treatment plan, conventional anatomic and functional imaging methods are fundamental in managing and surveilling these cases. Our article illustrates the role of different cross-sectional imaging modalities in diagnosing and managing various hereditary abdominopelvic neuroendocrine tumors.

Adrenal Neoplasms: Lessons from Adrenal Multidisciplinary Tumor Boards.

The radiologic diagnosis of adrenal disease can be challenging in settings of atypical presentations, mimics of benign and malignant adrenal masses, and rare adrenal anomalies. Misdiagnosis may lead to suboptimal management and adverse outcomes. Adrenal adenoma is the most common benign adrenal tumor that arises from the cortex, whereas adrenocortical carcinoma (ACC) is a rare malignant tumor of the cortex. Adrenal cyst and myelolipoma are other benign adrenal lesions and are characterized by their fluid and fat content, respectively. Pheochromocytoma is a rare neuroendocrine tumor of the adrenal medulla. Metastases to the adrenal glands are the most common malignant adrenal tumors. While many of these masses have classic imaging appearances, considerable overlap exists between benign and malignant lesions and can pose a diagnostic challenge. Atypical adrenal adenomas include those that are lipid poor; contain macroscopic fat, hemorrhage, and/or iron; are heterogeneous and/or large; and demonstrate growth. Heterogeneous adrenal adenomas may mimic ACC, metastasis, or pheochromocytoma, particularly when they are 4 cm or larger, whereas smaller versions of ACC, metastasis, and pheochromocytoma and those with washout greater than 60% may mimic adenoma. Because of its nonenhanced CT attenuation of less than or equal to 10 HU, a lipid-rich adrenal adenoma may be mimicked by a benign adrenal cyst, or it may be mimicked by a tumor with central cystic and/or necrotic change such as ACC, pheochromocytoma, or metastasis. Rare adrenal tumors such as hemangioma, ganglioneuroma, and oncocytoma also may mimic adrenal adenoma, ACC, metastasis, and pheochromocytoma. The authors describe cases of adrenal neoplasms that they have encountered in clinical practice and presented to adrenal multidisciplinary tumor boards. Key lessons to aid in diagnosis and further guide appropriate management are provided. © RSNA, 2023 Online supplemental material is available for this article. Quiz questions for this article are available through the Online Learning Center.

Secondary sclerosing cholangitis: mimics of primary sclerosing cholangitis.

Sclerosing cholangitis is a chronic cholestatic disease characterized by stricturing, beading, and obliterative fibrosis of the bile ducts. Sclerosing cholangitis is considered primary (PSC) if no underlying etiology is identified or secondary (SSC) if related to another identifiable cause. In this article, we will review the clinical features, pathogenesis, diagnosis, and imaging findings of PSC and SSC, with an emphasis on features that may aid in the distinction of these entities. We will also discuss various etiologies of SSC including recurrent pyogenic cholangitis, other infectious etiologies, ischemic damage, toxic insults, and immunologic, congenital, and miscellaneous causes, highlighting the unique imaging findings and clinical context of each diagnosis.

Imaging of neuroendocrine neoplasms of the male GU tract.

Male genitourinary neuroendocrine neoplasms (GU-NENs) are rare, without any definite imaging characteristics. The WHO classified neuroendocrine neoplasms in the 2016 classification of the tumors of the urinary tract and genital organs along with other GU tumors; however, no pathologic grading system is available as published for gastroenteropancreatic neuroendocrine neoplasms. Often a multimodality approach using cross-sectional imaging techniques, such as molecular imaging and histopathology are implemented to arrive at the diagnosis. This article provides a review of the pathology and imaging features of the male GU-NENs.

Multi-Center Follow-up Study to Develop a Classification System Which Differentiates Mucinous Cystic Neoplasm of the Liver and Benign Hepatic Cyst Using Machine Learning.

RATIONALE AND OBJECTIVES: To date, no clinically useful classification system has been developed for reliably differentiating mucinous cystic neoplasm (MCN) from a benign hepatic cyst (BHC) in the liver. The objective was to use machine learning and a multi-center study design to develop and assess the performance of a novel classification system for predicting whether a hepatic cystic lesion represents MCN or BHC. MATERIALS AND METHODS: A multi-center cohort study identified 154 surgically resected hepatic cystic lesions in 154 subjects which were pathologic confirmed as MCN (43) or BHC (111). Readers at each institution recorded seven pre-determined imaging features previously identified as potential differentiating features from prior publications. The contribution of each of these features to differentiating MCN from BHC was assessed by machine learning to develop an optimal classification system. RESULTS: Although several of the assessed imaging features demonstrated statistical significance, only 3 imaging features were found by machine learning to significantly contribute to a potential classification system: (1) solid enhancing nodule (2) all septations arising from an external macro-lobulation (3) whether the lesion was solitary or one of multiple cystic liver lesions. The optimal classification system had only four categories and correctly identified 144/154 lesion (93.5%). CONCLUSION: This multi-center follow-up study was able to use machine learning to develop a highly accurate classification system for differentiation of hepatic MCN from BHC, which could be readily applied to clinical practice.

Incidental Thyroid Nodules on Imaging: Relevance and Management.

Incidental thyroid nodules (ITNs) are commonly detected on imaging examinations performed for other reasons, particularly computed tomography (CT) (and now PET-CT and even PET-MR imaging), MR imaging, and sonography, primarily a consequence of the increasing sensitivity of these diagnostic modalities. Appropriate management of ITNs is crucial to avoid the cost and medical consequences of unnecessary workups.

Update on the Role of Imaging in Clinical Staging and Restaging of Renal Cell Carcinoma Based on the AJCC 8th Edition, From the AJR Special Series on Cancer Staging.

This article reviews the essential role of imaging in clinical staging and restaging of renal cell carcinoma (RCC). To completely characterize and stage an indeterminate renal mass, renal CT or MRI without and with IV contrast administration is recommended. The critical items for initial clinical staging of an indeterminate renal mass or of a known RCC according to the TNM staging system are tumor size, renal sinus fat invasion, urinary collecting system invasion, perinephric fat invasion, venous invasion, adrenal gland invasion, invasion of the perirenal (Gerota) fascia, invasion into other adjacent organs, the presence of enlarged or pathologic regional (retroperitoneal) lymph nodes, and the presence of distant metastatic disease. Larger tumor size is associated with higher stage disease and invasiveness, lymph node spread, and distant metastatic disease. Imaging practice guidelines for clinical staging of RCC, as well as the role of renal mass biopsy, are highlighted. Specific findings associated with response of advanced cancer to antiangiogenic therapy and immunotherapy are discussed, as well as limitations of changes in tumor size after targeted therapy. The accurate clinical staging and restaging of RCC using renal CT or MRI provides important prognostic information and helps guide the optimal management of patients with RCC.

Contrast-Enhanced Ultrasound for the Evaluation of Renal Transplants.

Contrast-enhanced ultrasound has emerged as a useful imaging modality for the evaluation of the transplant kidney. Advantages over traditional imaging modalities such as computed tomography and magnetic resonance imaging include the ability to visualize a lesion's enhancement pattern in real time, the lack of nephrotoxicity, and relatively low cost. Potential uses of contrast-enhanced ultrasound include characterization of solid and cystic transplant renal masses, assessment for pyelonephritis and identification of its complications, and evaluation of transplant complications in immediate and delayed settings. Contrast-enhanced ultrasound will likely play an increasing role for evaluating the transplant kidney, as an accurate diagnosis based on imaging can direct treatment and prevent unnecessary interventions.

Imaging of scrotal masses.

Testicular cancer is responsible for approximately 0.1% of all cancer deaths in the USA, and seminoma is the most common type of testicular tumor. Ultrasonography is the primary imaging modality for accessing testicular and extratesticular lesions, while magnetic resonance imaging can be used for problem solving in lesion characterization in certain cases. CT imaging is usually performed for retroperitoneal staging of testicular cancer metastasis and follow-up after treatment. Extratesticular masses are common, yet rarely malignant. Imaging plays an important role in primary diagnosis of testicular cancer and differentiating it from common non-neoplastic findings. The purpose of this article is to review various imaging findings in testicular and extratesticular masses.

Traumatic pancreatitis.

Post-traumatic pancreatitis can develop secondary to blunt or penetrating abdominal trauma, post-endoscopic retrograde cholangiopancreatography, or following pancreatic surgery. Clinical findings are often nonspecific, and imaging findings can be subtle on presentation. Early diagnosis of pancreatic duct injury is critical and informs management strategy; imaging plays important role in diagnosis of ductal injury and identification of delayed complications such as retroperitoneal fluid collections, pancreatic fistula, ductal strictures, and recurrent pancreatitis. Delayed diagnosis of pancreatic injury is associated with high mortality and morbidity, and therefore, heightened clinical suspicion is important in order for the radiologist to effectively impact patient care. There are accepted scoring systems for classification of post-traumatic pancreatic injuries and these should be included in radiology reports. Pancreatitis following ERCP appears similar on imaging to other causes of acute pancreatitis unless concomitant perforation occurs. Postoperative pancreatitis may be difficult to diagnose given associated or overlapping expected postoperative findings. Postoperative pancreatic fistulas typically arise from either a leaking pancreatic resection surface or the pancreatoenteric anastomosis and are more common in patients with a "soft" pancreas. Preoperative imaging biomarkers like duct diameter, pancreatic glandular steatosis and parenchymal fibrosis can help predict risk of development of postoperative pancreatic fistula. This review will illustrate the imaging features and the most important imaging findings in patients with post-traumatic pancreatitis.

MR Imaging of the Fetal Face: Comprehensive Review.

The human face is a complex anatomic structure with an equally complex embryologic development. Derangement of the developmental process can result in various structural anomalies, which range from a mainly cosmetic deformity, such as cleft lip, to potentially life-threatening conditions such as arhinia. These anomalies (a) can occur as isolated anomalies; (b) can be associated with intracranial, spinal, or dental anomalies; or (c) can be a part of various syndromes, thus serving as diagnostic clues in such cases. Proper evaluation of fetal facial deformities can help in prognostication, family counseling, and prenatal or early postnatal intervention. Ultrasonography (US) is the first line of investigation in these cases. However, when US does not allow complete evaluation of these anomalies owing to its inherent limitations, magnetic resonance (MR) imaging allows comprehensive evaluation of the anomaly itself and also evaluation of various associations and the treatment approach. The embryology of the fetal facial structures is considered with regard to the MR imaging technique and the MR imaging anatomy. The MR imaging features of various structural anomalies are described and classified into six groups, namely, orofacial clefts, orbital anomalies, nasal anomalies, facial masses, external ear anomalies, and abnormal face shape or profile. Also, the key associations and relevant treatment implications are reviewed. The article provides a "one-stop shop" review of these unique disorders-from basic understanding of the embryology to applying the knowledge in clinical practice, helping the interprofessional team and the patients alike. ©RSNA, 2018.

A Case of Bilateral Atrophy of the Inferior Vestibular Nerves.

: We report a case of a 62-year-old woman who was found to have bilateral atrophy of the inferior vestibular nerves on magnetic resonance imaging (MRI) after presenting to our clinic with 6 years of intermittent vertigo and residual unsteadiness. The nerve atrophy may be associated with an episode of vestibular neuritis, a common cause of vertigo that exclusively involves the inferior vestibular nerve in less than 3% of cases. While MRI may demonstrate vestibular nerve enhancement in cases of acute vestibular neuritis, no single MRI finding has been demonstrated consistently among cases of acute or chronic vestibular neuritis. Physical therapy is likely an effective long-term treatment for this patient to achieve central compensation for symptomatic relief.

Current Techniques and Clinical Applications of Computed Tomography Urography.

From conventional radiograph to magnetic resonance urography, imaging of urinary system has evolved with variety of investigations over the past several decades with each of them having advantages and limitations of their own. In the current era, computed tomography (CT) has emerged as a preferred investigations for evaluation of the urinary tract. There are various techniques involved in performing CT urography (CTU) with triple bolus technique (TB-CTU) currently drawing a special attention because of its low radiation exposure. This article aims to discuss the current techniques, indications, and clinical applications of CTU with illustrations.

Partial hydatidiform mole in septate uterus.

Partial mole is a form of gestational trophoblastic disease that may be associated with serious medical complications and occasionally progresses to the second trimester of pregnancy. We present a case report of a partial mole diagnosed at 18 weeks of gestation in a septate uterus with molar placenta in one horn and a dead fetus in the other.

Diagnosis of short rib polydactyly syndrome type IV (Beemer-Langer syndrome) with cystic hygroma: A case report.

Short rib polydactyly syndrome (SRPS) is a very rare congenital autosomal recessive inherited disease, classified into four subtypes. It has distinct imaging findings on prenatal sonography (US) and ancillary findings on both pre- and postnatal examinations may help classify individual cases into one of four subtypes. We report the US findings in a case of SRPS type IV (Beemer-Langer dysplasia) in a male fetus with multiple congenital anomalies, including cystic hygroma. The postnatal ultrasound, radiographic, and postmortem examinations helped to classify the SRPS as type IV. We believe this is the first documented case associating cystic hygroma and polydactyly.