Nancy A. Hammond

Utility of diffusion‐weighted MRI in distinguishing benign and malignant hepatic lesions

To evaluate apparent diffusion coefficient (ADC) values for characterization of a variety of focal liver lesions and specifically for differentiation of solid benign lesions (focal nodular hyperplasia [FNH] and adenomas) from solid malignant neoplasms (metastases and hepatocellular carcinoma [HCC]) in a large case series.

Imaging of cystic diseases of the pancreas

Although the majority of cystic lesions of the pancreas seen in clinical practice represent postinflammatory pseudocysts, it is important for the radiologist to be knowledgeable of the wide spectrum of cystic masses of the pancreas and the variable prognoses they possess. As a result of similarities in the imaging features of these lesions, a definitive diagnosis is often not possible. By combining imaging features with clinical history, a reasonable differential diagnosis can be offered to the referring physician. In some cases, biopsy or fluid aspiration may be required prior to surgery. In a patient without the appropriate history of pancreatitis and the presence of a cystic pancreatic mass, it is incumbent upon the radiologist to offer alternative diagnoses of cystic neoplasms of the pancreas.

CT and MR Imaging for Evaluation of Cystic Renal Lesions and Diseases

Cystic renal lesions are commonly encountered in abdominal imaging. Although most cystic renal lesions are benign simple cysts, complex renal cysts, infectious cystic renal disease, and multifocal cystic renal disease are also common phenomena. The Bosniak classification system provides a useful means of categorizing cystic renal lesions but places less emphasis on their underlying pathophysiology. Cystic renal diseases can be categorized as focal, multifocal, or infectious lesions. Diseases that manifest with focal lesions, such as cystic renal cell carcinoma, mixed epithelial and stromal tumor, and cystic nephroma, are often difficult to differentiate but have differing implications for follow-up after resection. Multifocal cystic renal lesions can be categorized as acquired or heritable. Acquired entities, such as glomerulocystic kidney disease, lithium-induced nephrotoxicity, acquired cystic kidney disease, multicystic dysplastic kidney, and localized cystic renal disease, often have distinct imaging and clinical features that allow definitive diagnosis. Heritable diseases, such as autosomal dominant polycystic kidney disease, von Hippel-Lindau disease, and tuberous sclerosis, are usually easily identified and have various implications for patient management. Infectious diseases have varied imaging appearances, and the possibility of infection must not be overlooked when assessing a cystic renal lesion. A thorough understanding of the spectrum of cystic renal disease will allow the radiologist to make a more specific diagnosis and provide the clinician with optimal recommendations for further diagnostic testing and follow-up imaging.

MR imaging of the pancreas.

Magnetic resonance (MR) imaging of the pancreas is useful as both a problem-solving tool and an initial imaging examination of choice. With newer imaging sequences such as diffusion-weighted imaging, MR offers improved ability to detect and characterize lesions and identify and stage tumors and inflammation. MR cholangiopancreatography can be used to visualize the pancreatic and biliary ductal system. In this article, the use of MR to evaluate the pancreas, including recent advances, is reviewed and the normal appearance of the pancreas on different imaging sequences, as well as inflammatory diseases, congenital abnormalities, and neoplasms of the pancreas, are discussed.

Multidetector-row computed tomography diagnosis of small bowel obstruction: can coronal reformations replace axial images?

Feasibility of diagnosing small bowel obstruction on multidetector-row computed tomography (MDCT) using coronal reformations alone is evaluated. Three radiologists with subspecialty training in abdominal imaging reviewed abdominopelvic CT of 67 patients in consensus. Thirty-four patients had surgically proven small bowel obstruction. The remaining 33 patients had CT for other reasons and had no intestinal obstruction. The images were displayed in either axial or coronal planes and were reviewed on separate days . Each CT was evaluated for the presence of small bowel obstruction and its etiology when applicable. Thirty-three (100%) of 33 patients were correctly diagnosed not to have intestinal obstruction on coronal images. Thirty-four (100%) of 34 patients were correctly diagnosed to have small bowel obstruction on both forms of image display. There were five patients where the final surgical diagnosis for the etiology of small bowel obstruction did not agree with the interpretation of either the coronal or axial images; however, in all five patients, the interpretations of axial and coronal images were similar. In only one patient, the etiology of small bowel obstruction based on the coronal images did not agree with that of axial images and the surgical result; however, the site of small bowel obstruction was correctly diagnosed. There were approximately 20% fewer images in the coronal reformation data set, and the radiologists found review of these images to be easier for localizing the zone of transition in small bowel obstruction. Very high diagnostic accuracy can be achieved based on coronal reformations alone, and this form of image display may potentially be substituted for the conventional axial images. Since there are fewer images to review when the studies are displayed in coronal plane, this may positively impact radiologist workflow.

Incidence of visualization of the normal appendix on different MRI sequences

The purpose of this paper is to assess the incidence of visualization of the normal appendix on magnetic resonance imaging (MRI) examinations of the pelvis in a large adult population and to compare the yield of commonly used sequences. Pelvic MRI scans of 111 randomly selected patients were retrospectively reviewed by two fellowship-trained body imagers. Thirty-six cases, where the entire cecum and terminal ileum were not included in the field of view, were excluded. A normal appendix was definitively visualized in 55 of 71 patients on T1 spin echo (SE) sequences (78%). The appendix was seen on 25 of 42 (60%) half-Fourier single-shot turbo spin echo T2. Visualization rates were 42% on pre-gadolinium T1 FS GRE, 54% on post-gadolinium T1 fat-suppressed gradient echo, and 17% of short tau inversion recovery sequences. MRI is an effective modality for visualization of the normal appendix. This may have important implications in patients with abdominal or pelvic pain, as visualization of a normal appendix should exclude the possibility of acute appendicitis from the differential diagnosis.

Infectious and Inflammatory Diseases of the Kidney

Although the most common renal infection, acute pyelonephritis, can typically be diagnosed on clinical and laboratory examinations, radiologic studies play a role in evaluating for complications and in examining the high-risk patient for more serious complications and atypical infections. It is imperative that the radiologist be familiar with renal infections beyond the common acute pyelonephritis.

Imaging Features of Benign and Malignant Ampullary and Periampullary Lesions

The ampulla of Vater is an important anatomic landmark where the common bile duct and main pancreatic duct converge in the major duodenal papilla. Imaging evaluation of the ampulla and periampullary region poses a unique diagnostic challenge to radiologists because of the regions complex and variable anatomy and the variety of lesions that can occur. Lesions intrinsic to the ampulla and involved segment of the biliary tree can be neoplastic, inflammatory, or congenital. Neoplastic lesions include ampullary adenocarcinomas and adenomas, which often are difficult to differentiate, as well as pancreatic or duodenal adenocarcinomas, pancreatic neuroendocrine tumors, and cholangiocarcinomas. Ultrasonography (US), computed tomography, magnetic resonance (MR) imaging, and MR cholangiopancreatography are commonly used to evaluate this region. Endoscopic retrograde cholangiopancreatography or endoscopic US examination may be necessary for more definitive evaluation. Periampullary conditions in the duodenum that may secondarily involve the ampulla include neoplasms, duodenitis, duodenal diverticula, and Brunners gland hyperplasia or hamartomas. Because these lesions can exhibit a wide overlap of imaging features and subtle or nonspecific imaging findings, diagnosis is made on the basis of patient age, clinical history, and imaging and laboratory findings. Given the complexity of imaging evaluation of the ampulla and periampullary region, it is essential for radiologists to understand the variety of lesions that can occur and recognize their imaging characteristics.

MR imaging of acute bowel pathology: a pictorial review.

The purpose of this pictorial essay is to describe magnetic resonance (MR) imaging features of acute processes involving the bowel. While computed tomography (CT) is likely to remain the modality of choice in this setting, the advantages of MR include high soft tissue contrast, lack of ionizing radiation, and the ability to administer gadolinium in patients with a history of allergic reaction to iodinated contrast material. With the increasing utilization of abdominal/pelvic MR, radiologists must recognize the MR features of acute bowel pathology. Key MR findings of a variety of causes of acute abdominal pain are illustrated.

Correlation Between Findings on MRCP and Gadolinium-Enhanced MR of the Liver and a Survival Model for Primary Sclerosing Cholangitis

Primary sclerosing cholangitis is a chronic, progressive disease of inflammation and fibrosis of the bile ducts. The ability to predict survival is important for appropriate management and treatment decisions. The purpose of this study was to examine the relationship between specific findings on the enhanced magnetic resonance imaging (MRI) examination of the liver and the corresponding magnetic resonance cholangiopancreatogram (MRCP) and a survival model for primary sclerosing cholangitis (PSC), the Mayo Risk Score. During a five-year period, 47 patients with primary sclerosing cholangitis were identified who had a complete MRI/MRCP examination. The extent of anatomical changes of the biliary tree and the degree of peribiliary enhancement in the hepatic parenchyma were compared with the Mayo Risk Score for each patient. Peribiliary enhancement was present to a varying extent in 38 of 47 cases of PSC. Peribiliary enhancement 3 min after gadolinium administration had a weak correlation with the Mayo Risk Score (analysis of variance P < 0.01, Pearson correlation r = 0.37). No statistically significant relationship between the severity of extrahepatic or intrahepatic duct changes and the Mayo Risk Score was found (analysis of variance P = 0.24, P = 0.38, respectively). Although biliary tree changes on MRCP aid in the diagnosis of PSC, they do not correlate with survival, as predicted by the Mayo Risk Score. Peribiliary enhancement on MRI of the liver is a finding occurring to a variable extent in primary sclerosing cholangitis but does not correlate significantly with survival.