Multimodality Imaging Findings in Carcinoid Tumors: A Head-to-Toe Spectrum.

Carcinoid tumors are a rare biologically heterogeneous group of neuroendocrine tumors with a spectrum ranging from benign indolent to aggressive metastatic tumors. They belong to the category of amine precursor uptake and decarboxylase tumors, or apudomas. The most common sites for primary locations are the gastrointestinal and respiratory tracts; however, any organ can be involved. The clinical presentation depends on location, aggressiveness, production of biologically active amines and peptides, paraneoplastic syndromes, and tendency for metastasis. Their reported age-adjusted incidence has increased in recent years, partly due to improved detection at radiologic imaging and endoscopy. Not a ll neuroendocrine cell tumors are carcinoids. Numerous systems have been proposed regarding their nomenclature and classification. Cross-sectional and functional imaging plays an important role in diagnosis, lesion characterization, and staging. Awareness of nomenclature, classification, common sites of involvement, and imaging presentation are pivotal for making the diagnosis. Knowledge of the diverse clinical, pathologic, and radiologic spectrum of carcinoid tumors involving various organs of the body is important for diagnosis and patient management. ©RSNA, 2017.

Extrauterine Pelvic Serous Carcinomas: Current Update on Pathology and Cross-sectional Imaging Findings.

The spectrum of extrauterine pelvic serous carcinomas includes ovarian serous carcinoma, primary peritoneal serous carcinoma, and primary fallopian tube carcinoma. Ovarian serous carcinoma, the most common ovarian malignant epithelial neoplasm, consists of two distinct entities: high-grade and low-grade serous carcinomas. Primary peritoneal serous carcinoma and primary fallopian tube carcinoma are rare malignancies that share many characteristics of high-grade serous carcinomas. Recent advances in the genetics and molecular biology of gynecologic cancers have suggested a common origin of many extrauterine pelvic serous carcinomas from fallopian tube epithelium. With the exception of low-grade serous carcinomas, which arise from cortical inclusion cysts lined by tubal epithelium, most extrauterine pelvic serous carcinomas are believed to originate from serous tubal intraepithelial carcinomas and show similar clinical-biologic behaviors and natural histories. Indeed, the International Federation of Gynecology and Obstetrics Committee on Gynecologic Oncology recently recognized that these cancers should be considered collectively, with a common system of staging and management strategies for ovarian, primary peritoneal, and fallopian tube cancers. A paradigm shift has occurred in our understanding of the pathogenesis of extrauterine pelvic serous carcinomas that has the potential to change current strategies for screening, prevention, diagnosis, and management. Ultrasonography (US), computed tomography (CT), magnetic resonance imaging, and combined positron emission tomography and CT are pivotal in screening, initial diagnosis, and treatment follow-up; however, because of this paradigm shift, new radiologic techniques, such as contrast material-enhanced US and molecular US imaging, and various optical imaging techniques are being investigated as important screening and diagnostic tools. Because of evolving knowledge of genetic and molecular changes underlying the pathogenesis of extrauterine pelvic serous carcinomas, new targeted therapies are being developed to improve patient prognosis. (©)RSNA, 2016.

Clinical value of liver ultrasound for the diagnosis of nonalcoholic fatty liver disease in overweight and obese patients.

BACKGROUND & AIMS: Liver ultrasound (US) is usually used in the clinical setting for the diagnosis and follow-up of patients with nonalcoholic fatty liver disease (NAFLD). However, no large study has carefully assessed its performance using a semiquantitative ultrasonographic scoring system in overweight/obese patients, in comparison to magnetic resonance spectroscopy ((1) H-MRS) and histology. METHODS: We recruited 146 patients and performed: a liver US using a 5-parameter scoring system, a liver (1) H-MRS to quantify liver fat content, and a liver biopsy to assess histology. All measurements were repeated in a subgroup of patients (n = 62) after 18 months of follow-up. RESULTS: The performance of liver US (parenchymal echo alone) was rather modest, and significantly worse than (1) H-MRS (AUROC: 0.82 [0.69-0.94] vs. 0.96 [0.90-1.00]; P = 0.04). However, the AUROC improved when different echographic parameters were taken into account (AUROC: 0.89 [0.83-0.96], P = 0.15 against (1) H-MRS). Optimum sensitivity for liver US was achieved at a liver fat content ≥12.5%, suggesting that below this threshold, liver US is less sensitive. Liver (1) H-MRS showed a high accuracy for the diagnosis of NAFLD, and correlated strongly with histological steatosis (r = 0.73, P < 0.0001). None of the imaging tests was adequate enough to predict changes over time in histology. CONCLUSIONS: Despite its widespread use, liver US has several important limitations that healthcare providers should recognize, particularly because of its low sensitivity. Using a combination of echographic parameters, liver US showed a significant improvement in its diagnostic performance, but still was of limited value for monitoring treatment over time.

Imaging of tuberculosis of the abdominal viscera: beyond the intestines.

There is an increasing incidence of both intra- and extra-thoracic manifestations of tuberculosis, in part due to the AIDS epidemic. Isolated tubercular involvement of the solid abdominal viscera is relatively unusual. Cross-sectional imaging with ultrasound, multidetector computed tomography (CT), and magnetic resonance imaging (MRI) plays an important role in the diagnosis and post treatment follow-up of tuberculosis. Specific imaging features of tuberculosis are frequently related to caseous necrosis, which is the hallmark of this disease. However, depending on the type of solid organ involvement, tubercular lesions can mimic a variety of neoplastic and nonneoplastic conditions. Often, cross-sectional imaging alone is insufficient in reaching a conclusive diagnosis, and image-guided tissue sampling is needed. In this article, we review the pathology and cross-sectional imaging features of tubercular involvement of solid abdominopelvic organs with a special emphasis on appropriate differential diagnoses.

MDCT of abdominopelvic oncologic emergencies.

Acute complications arising in abdominopelvic malignancies represent a unique subset of patients presenting to the emergency room. The acute presentation can be due to complications occurring in the tumor itself or visceral or vascular structures harboring the tumor. Multidetector computed tomography (MDCT) is the investigation of choice in the workup of these patients and enables appropriate and timely management. Management of the complication depends primarily on the extent of the underlying malignancy and the involvement of other viscera. The purpose of this article is to depict the imaging features of these complications on MDCT.

Non-invasive diagnosis of abdomino-pelvic masses: role of multimodality imaging.

Recent advances in radiology have greatly increased the ability to make highly accurate diagnosis. Biopsy of many commonly seen lesions is no longer performed as the radiological findings are pathognomonic. This gives rise to the concept of 'virtual biopsy', a term coined on the lines of other imaging techniques such as virtual colonoscopy. Virtual biopsy is not a new imaging technique but a new concept which refers to the use of existing imaging modalities to evaluate the morphological features of tumors and arriving at a non-invasive diagnosis with a high degree of confidence obviating the need for true biopsy. Elements of virtual biopsy have already been incorporated into some evidence-based guidelines, and it is expected that with further technological advancements, an increasing number of tumors may be diagnosed and managed accordingly. A wider acceptance of virtual biopsy could further reduce the need for invasive biopsies and its attendant costs and risks. In this review article, we use index cases to further emphasize this concept.

Abdominal hemangiomas: a pictorial review of unusual, atypical, and rare types.

Hemangiomas are a radiologist's dream lesions because they allow a confident diagnosis most of the time. However, within the abdomen, hemangiomas may occur in such atypical locations and can have such unusual features that they cause significant diagnostic dilemma and may end up being excised surgically. The literature is replete with isolated case reports of atypical hemangiomas in the abdominal cavity, and, to our knowledge, so far, there is no comprehensive review. We present, in this article, a pictorial review of a gamut of uncommon hemangiomas and hemangiomatosis syndromes. Knowledge of these rare types can help in limiting diagnostic errors and increase the confidence of radiologists, thus avoiding unnecessary surgeries.

Adrenal collision tumors and their mimics: multimodality imaging findings.

Adrenal collision tumors (ACTs) refer to coexistence of two adjacent, but histologically distinct neoplasms involving the adrenal gland without histologic admixture at interface. ACTs include adenoma with myelolipoma, adenoma with metastases, hemangioma with adenoma, and adrenocortical carcinoma with myelolipoma. In addition, hemorrhage into a pre-existing adrenal mass can mimic an ACT, and it is important to differentiate these two pathologies. Accurate characterization of ACTs is difficult, but critical, for correct staging of patients with malignancies and to guide percutaneous biopsy. Magnetic resonance imaging (MRI) and multidetector computed tomography imaging techniques may depict different tumor components separately; however, biopsy may be required in selected patients for confirmation. [(18)F]Fluorodeoxyglucose-positron emission tomography (PET) shows increased uptake in the malignant component of ACTs, and guides percutaneous biopsy. Even in patients requiring percutaneous biopsy for a definite diagnosis, imaging findings can help in guiding the appropriate component to be biopsied. Knowledge of imaging findings of different ACTs and their mimics on MRI, computed tomography, and PET help in optimal patient management.

Spectrum of multidetector computed tomography/magnetic resonance imaging findings in intrahepatic vascular shunts: classification, characterization, and management.

With the increasing use of multidetector computed tomography and dynamic magnetic resonance imaging in evaluation of liver pathologies, a variety of vascular shunts are detected in the liver. These shunts can be related to tumors or they can be nonneoplastic. Identification of these shunts can help in diagnosing an underlying condition. We classify and describe a wide spectrum of intrahepatic vascular shunts with their key imaging features. After reviewing this article, the reader should have improved ability to detect and characterize intrahepatic vascular shunts, which will help in diagnosing an underlying condition and facilitate optimal patient care.

Radiation dose management: part 1, minimizing radiation dose in CT-guided procedures.

OBJECTIVE: The purpose of this article is to discuss radiation dose during CT-guided interventions and to explain how radiologists can modify technical factors to minimize radiation doses. Scanner-displayed indexes of radiation exposure that are available during the procedure will be defined to increase awareness about CT radiation dose reduction during interventional procedures. CONCLUSION: CT-guided fluoroscopic procedures are safe and effective methods of directed intervention; however, the increasing use of medical radiation is an important consideration. The appropriate use of imaging with an acceptable risk must be considered in every case. During CT-guided interventions, scanner parameters that can be used as a guide for effective dose management, including the CT dose index and dose-length product, are readily displayed. These parameters can be adjusted by modifying the longitudinal scan length, number of scans, and tube current-exposure time product (milliampere × second [mAs]). A team approach to radiation dose reduction will work the best.

Current update on primary and secondary sclerosing cholangitis.

Sclerosing cholangitis can be idiopathic (primary) or secondary to an identifiable cause. Irrespective of cause, sclerosing cholangitis usually progresses to end-stage liver disease and warrants orthotopic liver transplantation. Recent studies provide new insights into the etiopathogenesis, natural history, diagnosis, and management of these different entities.

Taxonomy and imaging spectrum of small bowel obstruction after Roux-en-Y gastric bypass surgery.

OBJECTIVE: For most patients with morbid obesity, bariatric surgery is the only effective method to achieve sustainable weight loss. Small bowel obstruction (SBO) after bariatric surgery is a major complication that affects postoperative course and management. Knowledge of the types of and imaging findings for SBO is essential to prompt diagnosis. CONCLUSION: We discuss different types of SBO and a taxonomic schemata of bowel obstruction (ABC classification) and present a review of imaging findings that facilitates optimal patient management.

Mimics of cholangiocarcinoma: spectrum of disease.

Cholangiocarcinoma is the second most common primary malignant hepatobiliary neoplasm, accounting for approximately 15% of liver cancers. Diagnosis of cholangiocarcinoma is challenging and the prognosis is uniformly poor, with recurrence rates of 60%-90% after surgical resection. A wide spectrum of neoplastic and nonneoplastic conditions of the biliary tract may masquerade as cholangiocarcinoma, adding to the complexity of management in patients suspected to have cholangiocarcinoma. Mimics of cholangiocarcinoma constitute a heterogeneous group of entities that includes primary sclerosing cholangitis, recurrent pyogenic cholangitis, acquired immunodeficiency syndrome cholangiopathy, autoimmune pancreatitis, inflammatory pseudotumor, Mirizzi syndrome, xanthogranulomatous cholangitis, sarcoidosis, chemotherapy-induced sclerosis, hepatocellular carcinoma, metastases, melanoma, lymphoma, leukemia, and carcinoid tumors. These entities demonstrate characteristic histomorphology and variable clinicobiologic behaviors. The imaging findings of these disparate entities are protean and may be indistinguishable from those of cholangiocarcinoma. In most cases, a definitive diagnosis can be established only with histopathologic examination of a biopsy specimen.

Benign hepatic neoplasms: an update on cross-sectional imaging spectrum.

Benign hepatic neoplasms constitute a heterogeneous group of neoplasms with characteristic histology and variable tumor biology. Based on the cell of origin, benign hepatic neoplasms are classified into epithelial, nonepithelial, and miscellaneous categories according to the 2000 World Health Organization classification system. Benign hepatic neoplasms demonstrate a wide spectrum of imaging findings that reflect the histomorphologic changes. Some neoplasms show pathognomic imaging findings that permit accurate characterization and optimal management.

Imaging in bariatric surgery: a guide to postsurgical anatomy and common complications.

OBJECTIVE: This article reviews the various bariatric surgical techniques and the associated imaging findings of normal postoperative anatomy and of common complications. CONCLUSION: Bariatric surgery is increasingly performed to control morbid obesity secondary to failed medical approaches. As a result, imaging plays an important role in postoperative evaluation and management. Practical knowledge of postsurgical anatomy allows accurate interpretation of imaging findings related to normal postsurgical anatomy and common postsurgical complications.

Benign renal neoplasms in adults: cross-sectional imaging findings.

OBJECTIVE: A broad spectrum of benign renal neoplasms in adults shows characteristic ontogeny, histology, and tumor biology. Benign renal tumors are classified into renal cell tumors, metanephric tumors, mesenchymal tumors, and mixed epithelial and mesenchymal tumors. Select benign tumors show characteristic anatomic distribution and imaging features. However, because of overlapping of findings between benign and malignant renal tumors, histologic evaluation may be required to establish a definitive diagnosis. Accurate preoperative characterization facilitates optimal patient management. CONCLUSION: We attempt to provide a comprehensive, contemporary review of benign renal neoplasms that occur in adults, focusing on cross-sectional imaging characteristics.

Neoplasms of the perivascular epithelioid cell involving the abdomen and the pelvis: cross-sectional imaging findings.

Neoplasms of the perivascular epithelioid cell (PEComas) represent a recently described heterogeneous group of mesenchymal tumors characterized by the presence of specific histological, immunohistochemical, and ultrastructural findings. The PEComas encompass a family of neoplasms that include angiomyolipomas, clear cell sugar tumors, and lymphangioleiomyomatosis. The PEComas demonstrate a wide spectrum of clinicobiological behavior and imaging findings. Perivascular epithelioid cell, as the name implies, is a unique cell that is characterized by perivascular distribution and epithelioid morphology. Perivascular epithelioid cell consistently shows immunoreactivity to melanocytic and smooth muscle markers including HMB-45 and actin. Abdominopelvic PEComas are found at a variety of somatic and visceral locations including kidney, liver, pancreas, gastrointestinal tract, genitourinary tract, peritoneum, and retroperitoneum. A subset of patients with abdominopelvic PEComas manifests tuberous sclerosis complex. In this paper, we review the histological spectrum and discuss the imaging findings of the PEComas that involve the abdomen and pelvis.

Price of isotropy in multidetector CT.

Recent advances in multidetector computed tomography (CT) have made isotropic data acquisition feasible for nearly every application. The benefits of routine use of isotropic data for image display and interpretation have been described in the literature and at educational conferences. However, there is usually a trade-off in the form of an increased radiation dose to the patient. The parameters that affect the radiation dose vary considerably in accordance with the CT scanner design, and those variations determine the cost in dose increase relative to the voxel size. The detector configuration and beam collimation (narrow or wide) used for a particular acquisition also affect the voxel size and the relationship between spatial resolution and the radiation dose. By closely comparing the quality of multidetector CT images obtained with different detector configurations on scanners with four, 16, 40, and 64 channels and the estimated radiation exposure incurred with each option, radiologists may achieve an understanding of the relationship between radiation dose and voxel size. This understanding, in turn, may help balance the need for diagnostic image quality against the concern for patient safety.

Common and uncommon histologic subtypes of renal cell carcinoma: imaging spectrum with pathologic correlation.

Renal cell carcinoma (RCC) is a cause of significant morbidity and mortality, with an estimated 35,000 new cases and 12,480 deaths in the United States in 2003. Recent advances in imaging technology, pathology, urology, and oncology permit early diagnosis of RCC and facilitate optimal management. The 2004 World Health Organization classification for renal neoplasms recognizes several distinct histologic subtypes of RCC. These subtypes include clear cell RCC, papillary RCC, chromophobe RCC, hereditary cancer syndromes, multilocular cystic RCC, collecting duct carcinoma, medullary carcinoma, mucinous tubular and spindle cell carcinoma, neuroblastoma-associated RCC, Xp11.2 translocation-TFE3 carcinoma, and unclassified lesions. Different histologic subtypes of RCC have characteristic histomorphologic and biologic profiles. Clear cell RCC is the most common subtype and has a less favorable prognosis (stage for stage) than do papillary RCC and chromophobe RCC. Collecting duct carcinoma and renal medullary carcinoma are associated with aggressive clinical behavior and a poor prognosis.

Informatics in radiology (infoRAD): introduction to the language of three-dimensional imaging with multidetector CT.

The recent proliferation of multi-detector row computed tomography (CT) has led to an increase in the creation and interpretation of images in planes other than the traditional axial plane. Powerful three-dimensional (3D) applications improve the utility of detailed CT data but also create confusion among radiologists, technologists, and referring clinicians when trying to describe a particular method or type of image. Designing examination protocols that optimize data quality and radiation dose to the patient requires familiarity with the concepts of beam collimation and section collimation as they apply to multi-detector row CT. A basic understanding of the time-limited nature of projection data and the need for thin-section axial reconstruction for 3D applications is necessary to use the available data effectively in clinical practice. The axial reconstruction data can be used to create nonaxial two-dimensional images by means of multiplanar reformation. Multiplanar images can be thickened into slabs with projectional techniques such as average, maximum, and minimum intensity projection; ray sum; and volume rendering. By assigning a full spectrum of opacity values and applying color to the tissue classification system, volume rendering provides a robust and versatile data set for advanced imaging applications.