Khaled M. Elsayes

Imaging Manifestations of Meckel's Diverticulum

OBJECTIVE Meckels diverticulum is the most common congenital anomaly of the gastrointestinal tract, found in 2% of the population in autopsy studies. Most patients remain asymptomatic during their lifetime. Complications of Meckels diverticulum are reported to occur in approximately 4-40% of patients and include inflammation (diverticulitis), hemorrhage, intussusception, small-bowel obstruction, stone formation, and neoplasm. The purpose of this article is to familiarize the radiologist with the current imaging of Meckels diverticulum and its presenting complications. The spectrum of diagnostic findings on various imaging techniques will be reviewed. CONCLUSION Meckels diverticulum and its complications are a serious health problem. Familiarity of the radiologist with the appearance of this pathologic entity enables an accurate diagnosis in emergent settings.

Inflammatory Pseudotumor: The Great Mimicker

OBJECTIVE The purpose of this review is to describe the pathophysiologic findings, differential diagnosis, imaging features, and management of inflammatory pseudotumor in various locations throughout the body. CONCLUSION Inflammatory pseudotumor is a rare benign process mimicking malignant processes and has been found in almost every organ system. Radiologists should be familiar with this entity as a diagnostic consideration to avoid unnecessary surgery.

Imaging of the Placenta: A Multimodality Pictorial Review

The placenta is often overlooked in the routine evaluation of a normal gestation, receiving attention only when an abnormality is detected. Although uncommon, abnormalities of the placenta are important to recognize owing to the potential for maternal and fetal morbidity and mortality. Pathologic conditions of the placenta include placental causes of hemorrhage, gestational trophoblastic disease, retained products of conception, nontrophoblastic placental tumors, metastases, and cystic lesions. Sonography remains the imaging modality of choice for evaluation of the placenta. Magnetic resonance (MR) imaging can be of added diagnostic value when further characterization is required, particularly in the setting of invasive placental processes such as placenta accreta and gestational trophoblastic disease. Computed tomography (CT) has a limited role in the evaluation of placental disease owing to limited tissue characterization, compared with that of MR imaging, and the radiation risk to the fetus; this risk often outweighs the benefit. The primary role for CT is in the evaluation of trauma and gestational trophoblastic disease, for which it allows characterization of the primary lesion and distant metastases.

CT Enterography: Principles, Trends, and Interpretation of Findings

Computed tomographic (CT) enterography is an emerging alternative to traditional fluoroscopy for the assessment of disorders of the small bowel. The greatly improved spatial and temporal resolution provided by multidetector CT scanners, combined with good luminal distention provided by negative oral contrast agents and with good bowel wall visualization, have made CT enterography the main imaging modality not only for investigating proved or suspected inflammatory bowel disease but also for detecting occult gastrointestinal tract bleeding, small bowel neoplasms, and mesenteric ischemia. CT enterography is particularly useful for differentiating between active and fibrotic bowel strictures in patients with Crohn disease, thus enabling selection of the most appropriate treatment (medical management or intervention) for an improved outcome. CT enterography allows excellent visualization of the entire thickness of the bowel wall and depicts extraenteric involvement as well, providing more detailed and comprehensive information about the extent and severity of the disease process.

Cross-Sectional Imaging of Acute and Chronic Gallbladder Inflammatory Disease

OBJECTIVE The purpose of this article is to provide a comprehensive review of the clinical and cross-sectional imaging features of a variety of acute and chronic gallbladder inflammatory diseases. CONCLUSION Inflammatory gallbladder diseases are a common source of abdominal pain and cause considerable morbidity and mortality. Although acute uncomplicated cholecystitis and chronic cholecystitis are frequently encountered, numerous other gallbladder inflammatory conditions may also occur that can be readily diagnosed by cross-sectional imaging.

Vascular Malformation and Hemangiomatosis Syndromes: Spectrum of Imaging Manifestations

OBJECTIVE The purpose of this review is to describe the role of imaging and associated findings in the diagnosis of blue rubber bleb nevus syndrome, Proteus syndrome, Klippel-Trénaunay syndrome, and Kasabach-Merritt syndrome. CONCLUSION Blue rubber bleb nevus, Proteus, Klippel-Trénaunay, and Kasabach-Merritt syndromes are a diverse group of vascular malformation and hemangiomatosis syndromes. Both cutaneous and visceral vascular lesions are associated with these disorders. Accurate diagnosis of these syndromes is important because they can be associated with serious complications, including life-threatening hemorrhage.

Imaging of Female Urethral Diverticulum: An Update

Female urethral diverticulum is an uncommon pathologic entity and can manifest with a variety of symptoms involving the lower urinary tract. Selection of the appropriate imaging modality is critical in establishing the diagnosis. Urethrography has traditionally been used in the evaluation of urethral diverticulum but provides only intraluminal information. Ultrasonography is advantageous in that it does not involve ionizing radiation and has the capacity to help detect a diverticulum without contrast agent filling. Multidetector computed tomographic (CT) voiding urethrography yields urethral images during micturition. In addition, the diverticulum and diverticular orifice can be visualized on two- and three-dimensional reformatted CT images. Interactive virtual urethroscopy provides simulated visualization of the intraluminal anatomy and the diverticular orifice. New magnetic resonance imaging techniques that make use of a surface or endoluminal coil have higher diagnostic accuracy and can delineate the diverticular cavity and help detect related complications. Clinicians should consider the possibility of a urethral diverticulum in women with chronic or recurrent lower urinary tract symptoms. Moreover, because female urethral diverticulum is becoming more prevalent in clinical practice, radiologists should be familiar with its imaging features and with the imaging techniques that are optimal for its evaluation.

MR Imaging of Prostate Cancer in Radiation Oncology: What Radiologists Need to Know

Radiation therapy (RT) is one of the principal treatment modalities for localized or locally advanced prostate cancer. The two major forms of RT for prostate cancer are external-beam RT (EBRT) with a photon or proton beam and brachytherapy. With modern conformal techniques for EBRT (three-dimensional conformal RT, intensity-modulated RT, and image-guided RT) and advanced computer-based planning systems for brachytherapy, the dose can be more precisely delivered to the prostate while reducing unnecessary radiation to normal tissue. The dominant intraprostatic tumor can be targeted with a higher dose, so-called dose painting. Magnetic resonance (MR) imaging plays a pivotal role in pretreatment assessment of prostate cancer. Multiparametric MR imaging, a combination of anatomic and functional MR imaging techniques (diffusion-weighted imaging, dynamic contrast material-enhanced imaging, and MR spectroscopy), significantly improves the accuracy of tumor localization and local staging. For pretreatment planning, anatomic MR imaging provides highly accurate local staging information, particularly about extraprostatic extension and seminal vesicle invasion. The dominant intraprostatic tumor and local recurrence in the prostatectomy bed can be better localized with multiparametric MR imaging for dose painting. MR imaging allows excellent delineation of the contours of the prostate and surrounding structures. It can also be used in early posttreatment evaluation after brachytherapy.

Imaging Features of Fibrolamellar Hepatocellular Carcinoma

OBJECTIVE Fibrolamellar hepatocellular carcinoma (HCC) is a rare primary liver tumor, which significantly differs from conventional HCC. This article reviews the molecular cytogenetics, pathology, imaging features, and management of this relatively rare tumor. CONCLUSION Fibrolamellar HCC predominantly occurs in young patients without underlying hepatitis or cirrhosis. Serum α-fetoproteins are not elevated in most cases, and hence imaging plays an important role in diagnosis, staging, and surveillance.

Subtypes of renal cell carcinoma: MRI and pathological features

Renal cell carcinoma (RCC) is the most common malignant tumor involving the kidney. Determining the subtypes of renal cell carcinoma is among the major goals of preoperative radiological work-up. Among all modalities, magnetic resonance imaging (MRI) has several advantages, such as inherent soft tissue contrast, detection of lipid and blood products, and excellent sensitivity to detect small amounts of intravenous contrast, which facilitate the discrimination of subtypes of RCC. In this article, we review MRI and pathological features used for determining the main histologic subtypes of RCC, including clear cell, papillary, collecting duct, chromophobe, multilocular cystic, and unclassified RCC.