Mesenchymal neoplasms of the urinary bladder: a comprehensive review with focus on cross-sectional imaging findings.

Mesenchymal neoplasms of the urinary bladder are exceedingly rare and display remarkable diversity. These tumors demonstrate distinct pathological features as well as variable biological behavior and cross-sectional imaging findings. The rarity of tumors, nonspecific symptoms and seemingly normal cystoscopic findings (particularly with small and exophytic tumors) frequently lead to misdiagnosis or missed diagnosis. While some tumors display characteristic cross-sectional imaging findings that may suggest a diagnosis, imaging findings are mostly nonspecific. Histopathological examination is required for accurate diagnosis, management and prognostication. The purpose of this article is to review the cross-sectional imaging findings of a diverse spectrum of mesenchymal tumors of the urinary bladder.

Utility of diffusion-weighted MRI for differentiating acute from chronic cholecystitis.

PURPOSE: To assess the use of diffusion-weighted imaging (DWI) for differentiating acute from chronic cholecystitis, in comparison with conventional magnetic resonance imaging (MRI) features. MATERIALS AND METHODS: Liver MRI including DWI (b-values 0/500/1000s/mm(2) ) was performed at 1.5T ≤30 days before cholecystectomy in 83 patients with abdominal pain. Two radiologists assessed cases for conventional (gallstones, wall thickening, pericholecystic fluid, pericholecystic fat changes, gallbladder distension, pericholecystic liver enhancement, mural T2 -hyperintensity, mural hyperenhancement, mural striations, abscess, intraluminal membranes, and mural defect) and DWI (increased mural signal on high b-value images, visually low apparent diffusion coefficient [ADC], and ADC values) features. RESULTS: Acute cholecystitis was present in 43%; chronic cholecystitis was present in 57%. Nine of 12 conventional features were more frequent in acute cholecystitis for both readers (P ≤ 0.003). Increased mural signal on high b-value images was more frequent (P < 0.001) in acute than chronic cholecystitis for R1 (92% vs. 32%) and R2 (83% vs. 30%). Sensitivity and specificity of increased signal on high b-value images were: R1, 92%/68%; R2, 83%/70%. Visually low ADC was more frequent in acute cholecystitis for R2 (P < 0.001) but not R1 (P = 0.406); ADC values were not different between groups for either reader (P = 0.104-0.139). Among conventional and DWI features, only increased signal on high b-value DWI was independently associated with acute cholecystitis for both readers (P = 0.006-0.012). CONCLUSION: Visually increased mural signal on high b-value DWI was highly sensitive and moderately specific for acute cholecystitis, being an independent predictor relative to conventional features for both readers. Although requiring larger studies, DWI (particularly the high b-value images) may have additive value relative to conventional MRI-suspected acute cholecystitis. J. Magn. Reson. Imaging 2016;44:89-97.

Length of capsular contact for diagnosing extraprostatic extension on prostate MRI: Assessment at an optimal threshold.

PURPOSE: To evaluate the length of capsular contact of dominant lesions on multiparametric prostate magnetic resonance imaging (MRI) for predicting extraprostatic extension (EPE) and to determine a threshold value to apply in clinical practice. MATERIALS AND METHODS: Ninety patients undergoing 3T prostate MRI before prostatectomy were included. Two independent readers (R1, R2) recorded for each lobe the presence or absence of capsular irregularity on T2 -weighted imaging (T2 WI) and of overt measurable EPE. Readers also recorded the length of capsular contact of each lobe's dominant lesion for T2 WI and the apparent diffusion coefficient (ADC) map. Based on prostatectomy specimens, EPE was recorded for each lobe and classified as focal (single focus ≤0.5 mm in depth) vs. established. Receiver operating characteristic analysis, logistic regression, and kappa coefficients were used to assess interpretive approaches on a side-specific basis. RESULTS: The optimal thresholds were 6 mm and 7 mm of contact using T2 WI and ADC for any EPE, and 10 mm and 7 mm using T2 WI and ADC for nonfocal EPE (AUCs 81.0-82.5%). Capsular contact had higher sensitivity, yet lower specificity, than subjective interpretations for any EPE and for nonfocal EPE (all P ≤ 0.018, aside from any EPE for R2 using ADC). Length of contact exhibited more substantial gains in sensitivity (9-20% for any EPE; 34-41% for nonfocal EPE) than losses in specificity (6-13% for any EPE; 17-27% for nonfocal EPE) compared with subjective interpretations. Interreader agreement: 0.70 for assessments based on length of contact; 0.49-0.59 for subjective assessments. CONCLUSION: Length of capsular contact of dominant lesions can improve interreader agreement and sensitivity for EPE compared with subjective features, with relatively mild specificity loss.

Three-dimensional conformal radiation therapy in the liver: MRI findings along a time continuum.

Recent development of 3-dimensional conformal radiation therapies provides a concentrated radiation dose to the tumor. To achieve this goal, a complex design of multiple narrow beamlets is used to shape the radiation exposure to conform to the shape of the tumor. Imaging findings after novel radiation therapy techniques differ from those of conventional radiation therapy. This article discusses changes in the liver parenchyma and tumor after conformal radiation therapy focusing on magnetic resonance imaging.

Uncommon pancreatic tumors and pseudotumors.

A heterogeneous group of uncommon neoplastic and non-neoplastic pancreatic pathologies exists that can mimic pancreatic adenocarcinoma. These "imitators" are unique and may demonstrate characteristic clinical and imaging features. Imaging characteristics of some of these diverse lesions are not well described in the literature, and erroneous diagnoses of these entities as pancreatic carcinoma may be responsible for unnecessary surgeries. Knowledge of these selected pancreatic pathologies is essential to facilitate optimal patient management.

Current update on combined hepatocellular-cholangiocarcinoma.

Combined hepatocellular-cholangiocarcinoma is a rare but unique primary hepatic tumor with characteristic histology and tumor biology. Recent development in genetics and molecular biology support the fact that combined hepatocellular-cholangiocarcinoma is closely linked with cholangiocarcinoma, rather than hepatocellular carcinoma. Combined hepatocellular cholangiocarcinoma tends to present with an more aggressive behavior and a poorer prognosis than either hepatocellular carcinoma or cholangiocarcinoma. An accurate preoperative diagnosis and aggressive treatment planning can play crucial roles in appropriate patient management.

Obstetric (nonfetal) complications.

Pregnancy predisposes women to a wide array of obstetric and gynecological complications which are often complex, challenging and sometimes life-threatening. While some of these are unique to pregnancy, a few that occur in nonpregnant women are more common during pregnancy. Imaging plays a crucial role in the diagnosis and management of pregnancy-related obstetric and gynecologic complications. Ultrasonography and magnetic resonance imaging confer the least risk to the fetus and should be the preferred examinations for evaluating these complications. Multidetector computed tomography should be used after carefully weighing the risk-benefit ratio based on the clinical condition in question. Interventional radiology is emerging as a preferred, noninvasive or minimally invasive treatment option that can obviate surgery and its antecedent short term and long term complications. Knowledge of appropriateness of imaging and image guided intervention is necessary for accurate patient management.

Gestational trophoblastic disease.

Imaging plays a crucial role in diagnosis and management of gestational trophoblastic disease. Ultrasonography is the initial investigation of choice for the diagnosis. Pelvic magnetic resonance (MR) imaging is used as a problem-solving tool for assessment of degree of local invasion. Chest radiography is the recommended initial radiographic staging modality, and chest computed tomography is performed if the radiograph is negative. (18)F-Fluorodeoxyglucose positron emission tomography has been shown to be useful in assessing the active or viable sites of metastases, thereby determining the need for tumor resectability in chemoresistant disease.

Current concepts in the diagnosis and management of endometrial and cervical carcinomas.

Cross-sectional imaging modalities play a pivotal role in the diagnosis and multidisciplinary management of patients with endometrial and cervical carcinomas. Ultrasonography, including sonohysterography, permits evaluation of endometrial abnormalities and characterization of adnexal masses. Computed tomography, particularly in conjunction with (18)(F)-fluorodeoxyglucose positron emission tomography, is increasingly used to stage the cancers and to detect disease recurrence. Magnetic resonance imaging plays a major role in accurate locoregional staging of these cancers, and significantly influences treatment decisions and outcomes. This article discusses the role of imaging modalities in the diagnosis, management, and surveillance of these cancers.

Managing incidental findings on abdominal and pelvic CT and MRI, part 1: white paper of the ACR Incidental Findings Committee II on adnexal findings.

This white paper describes adnexal (ovarian and paraovarian) incidental findings found on CT and MRI in nonpregnant postmenarchal patients in whom no adnexal disorder is clinically known or suspected. This represents the first of 4 such papers from the ACR Incidental Findings Committee II, which used a consensus method based on repeated reviews and revisions and a collective review and interpretation of relevant literature. Recommendations for the management of incidental adnexal findings are organized into 4 main categories: benign-appearing cysts, probably benign cysts, adnexal masses with characteristic features, and all other adnexal masses, with pathways on the basis of patient menstrual status or age (when last menstrual period is unknown). A table and flowchart are provided for reference.

Chronic fibrosing conditions in abdominal imaging.

Chronic fibrosing conditions of the abdomen are relatively poorly understood and involve varied and often multiple organ systems. At histopathologic analysis, they share the unifying features of proliferative fibrosis and chronic inflammation. Different conditions in this group are often found in association with each other and with other fibrosing conditions outside the abdomen. Some of the confusion about these conditions stems from their complex nomenclature, which includes a gamut of alternate terms and eponyms. Many of them can be categorized within two large subgroups: the fibromatoses and immunoglobulin G4 (IgG4)-related disorders. While many of these entities are of uncertain etiology, some, especially the IgG4-associated conditions, appear to have an immune-mediated pathogenesis. Nephrogenic systemic fibrosis, sclerosing peritonitis, and retroperitoneal fibrosis have iatrogenic associations, while some of the fibromatoses are genetically inherited. Imaging differentiation of these conditions is difficult due to considerable overlap in their radiologic findings. However, certain conditions such as penile fibromatosis and sclerosing peritonitis may have unique imaging features that can help the radiologist make the diagnosis. Others such as deep fibromatoses and inflammatory pseudotumor demonstrate fibroproliferative mass formation and cannot be differentiated from neoplastic conditions at imaging. Thus, histopathologic correlation is often required to confirm their diagnosis.

Laparoscopic adjustable gastric banding: what radiologists need to know.

Laparoscopic adjustable gastric banding (LAGB) is performed with increasing frequency for the management of morbid obesity. Although LAGB is less invasive than other bariatric surgical procedures, it is associated with various complications that may lead to nonspecific abdominal symptoms several months or years after the procedure. Because complications of LAGB may be encountered incidentally at imaging for other indications, all radiologists should be familiar with the appearances of correctly positioned and malpositioned gastric bands, normal and abnormal appearances of the postprocedural pouch and stomach, and imaging features suggestive or indicative of early or delayed complications of LAGB. Familiarity with the techniques and systems currently approved by the Food and Drug Administration for use in this procedure may help radiologists detect postoperative complications and guide their management. Both commercially available systems include a silicone gastric band with an inflatable inner surface, a reservoir port, and a tube that connects the port to the gastric band. All these components of LAGB systems should be visible at radiologic imaging; however, older models of gastric bands may not be radiopaque and therefore may not be depicted on images. The most common complications of LAGB are gastric band slippage and associated pouch dilatation, intragastric erosion of the band, gastric perforation, and abscess formation. Complications that occur with less frequency include tube migration, tube disconnection, port-site infection, and small bowel obstruction.

Uncommon primary pelvic retroperitoneal masses in adults: a pattern-based imaging approach.

There is a broad spectrum of primary pelvic retroperitoneal masses in adults that demonstrate characteristic epidemiologic and histopathologic features and natural histories. These masses may be classified into five distinct subgroups using a pattern-based approach that takes anatomic distribution and certain imaging characteristics into account, allowing greater accuracy in their detection and characterization and helping to optimize patient management. The five groups are cystic (serous and mucinous epithelial neoplasms, pelvic lymphangioma, tailgut cyst, ancient schwannoma), vascular or hypervascular (solitary fibrous tumor, paraganglioma, pelvic arteriovenous malformation, Klippel-Trénaunay-Weber syndrome, extraintestinal GIST [gastrointestinal stromal tumor]), fat-containing (lipoma, liposarcoma, myelolipoma, presacral teratoma), calcified (calcified lymphocele, calcified rejected transplant kidney, rare sarcomas), and myxoid (schwannoma, plexiform neurofibroma, myxoma).Cross-sectional imaging modalities help differentiate the more common gynecologic neoplasms from more unusual masses. In particular, the tissue-specific multiplanar capability of high-resolution magnetic resonance imaging permits better tumor localization and internal characterization, thereby serving as a road map for surgery.

Rare, miscellaneous primary ovarian neoplasms: spectrum of cross-sectional imaging.

There is a diverse group of rare, primary benign and malignant ovarian tumors that show characteristic histomorphology and natural history. Some of these tumors may demonstrate typical imaging features. However, due to the rarity of these tumors, imaging characteristics of these diverse lesions are not well described in the literature. Knowledge of these select ovarian entities is essential and facilitates optimal management of patients who often manifest with nonspecific symptoms.

Rare (<1%) histological subtypes of renal cell carcinoma: an update.

Recent advances in genetics and pathology have allowed description of several new histological subtypes of renal cell carcinoma (RCC) as well as better characterization of other rare subtypes. We herein present a comprehensive review of taxonomy, epidemiology, pathology, imaging findings, and natural history of a wide spectrum of rare subtypes of RCCs that individually constitute <1% of all the RCCs.

Immunological diseases of the pancreatico-hepatobiliary system: update on etiopathogenesis and cross-sectional imaging findings.

Immunological diseases of the hepatobiliary system and the pancreas include a broad spectrum of disorders that manifest characteristic histopathology/serology and variable clinical features and imaging findings. Recent studies have thrown fresh light on the complex role of genetics and autoimmunity in the pathogenesis and natural history of these diverse disorders that include autoimmune hepatitis, primary biliary cirrhosis, primary sclerosing cholangitis, IgG4-related cholangitis, overlap/outlier syndromes, and autoimmune pancreatitis.

Genetics and imaging of hepatocellular adenomas: 2011 update.

Hepatocellular adenomas are benign liver neoplasms with specific but varied histopathologic findings and tumor biology. The results from recent studies of the pathologic and genetic basis of hepatocellular adenomas provide important insights into the pathogenesis and molecular changes, as well as the putative oncologic pathways used by diverse adenoma subtypes. On the basis of the genetic and pathologic features, hepatocellular adenomas are categorized into three distinct subtypes: (a) inflammatory hepatocellular adenomas, (b) hepatocyte nuclear factor 1 α-mutated hepatocellular adenomas, and (c) ß-catenin-mutated hepatocellular adenomas. Different subtypes show variable clinical behavior, imaging findings, and natural history, and thus the options for treatment and surveillance may vary. Cross-sectional imaging plays an important role in the diagnosis, subtype characterization, identification of complications, and surveillance of hepatocellular adenomas. New schemas for genotype-phenotype classification of hepatic adenomas, as well as management triage of patients with specific subtypes of adenomas, are being proposed in an attempt to improve clinical outcomes.

Wunderlich syndrome: cross-sectional imaging review.

Wunderlich syndrome (WS) is a rare condition characterized by acute onset of spontaneous, nontraumatic renal hemorrhage into the subcapsular and perirenal spaces. Wunderlich syndrome is classically characterized by the Lenk's triad: acute flank pain, flank mass, and hypovolemic shock. However, the clinical manifestations can be varied and nonspecific. A wide spectrum of neoplastic and nonneoplastic renal pathologies may result in WS. Renal neoplasms are the most common cause for WS, with angiomyolipoma being the most common benign neoplasm, whereas renal cell carcinoma is the most common malignant neoplasm. Other causative conditions of WS include vascular causes (vasculitis [polyarteritis nodosa being the most common cause], renal artery aneurysms, arteriovenous malformations and fistulas, and venous thrombosis), cystic renal diseases, renal infections, calculus disease, nephritis, and coagulation disorders. Cross-sectional imaging findings help in the detection of the subcapsular and/or perinephric hemorrhage and may identify underlying etiology. Renal angiography not only helps in diagnosis of the underlying cause in select cases but also allows control of active bleeding, which can avoid unnecessary emergent radical surgery.

Histologic, molecular, and cytogenetic features of ovarian cancers: implications for diagnosis and treatment.

Ovarian epithelial carcinoma (OEC), the most common ovarian malignancy, is a heterogeneous disease with several histologic subtypes that show characteristic cytogenetic features, molecular signatures, oncologic signaling pathways, and clinical-biologic behavior. Recent advances in histopathology and cytogenetics have provided insights into pathophysiologic features and natural history of OECs. Several studies have shown that high- or low-grade serous, endometrioid, and clear cell carcinomas are characterized by mutations involving the TP53, K-ras/BRAF, CTNNB1, and PIK3CA genes, respectively. High-grade serous carcinomas, the most common subtype, often manifest with early transcoelomic spread of disease beyond the ovaries, whereas low-grade serous and mucinous carcinomas commonly manifest with early-stage disease, with a resultant excellent prognosis. On the basis of pathogenetic mechanisms, recent findings suggest a dualistic model of ovarian carcinogenesis consisting of types I and II. Type I (low-grade serous, mucinous, and endometrioid) cancers commonly arise from well-described, genetically stable precursor lesions (usually borderline tumors); manifest as large adnexal masses with early-stage disease; and have a relatively indolent clinical course, with an overall good prognosis. In contrast, type II carcinomas (high-grade serous, endometrioid, mixed, and undifferentiated variants) originate de novo from the adnexal epithelia, often demonstrate chromosomal instability, and have aggressive biologic behavior. Better knowledge of hereditary ovarian cancer syndromes and associated cytogenetic abnormalities has led to increased interest in novel biomarkers and molecular therapeutics. Genetic changes, pathologic features, imaging findings, and natural histories of a variety of histologic subtypes of OEC are discussed in this article.