CT imaging in adults with neurofibromatosis-1: frequent asymptomatic plexiform lesions.

OBJECTIVE: The authors examined the incidence and radiologic characteristics of plexiform neurofibromas in neurofibromatosis-1 (NF-1) to define a cohort at greatest risk for malignant nerve-sheath tumors. BACKGROUND: Plexiform neurofibromas are a frequent complication of NF-1. They can impair function, produce disfigurement, and be the site for the development of malignant nerve-sheath tumors. The incidence and natural history of plexiform neurofibromas is unknown. METHODS: CT imaging of the chest, abdomen, and pelvis was performed in 91 of 125 consecutive adults (age, > or = 16 years) with NF-1. RESULTS: Twenty percent of patients had plexiform neurofibromas of the chest in the paraspinal, mediastinal, or supraclavicular area. Approximately 40% of patients had abnormal abdominal/pelvic scans. The paraspinal, sacral plexus, sciatic notch, and perirectal regions were the most common sites. Most plexiform neurofibromas were asymptomatic. Imaging also revealed a number of tumors, including malignant nerve-sheath tumors, adrenal tumors, carcinoids, and schwannomas. CONCLUSIONS: The frequency of plexiform lesions and other tumors in NF-1 indicates that clinicians should monitor young adults carefully; however, imaging characteristics alone cannot reliably distinguish benign from malignant lesions.

Normal erect swallowing. Normal function and incidence of variations.

Of 871 candidates presenting for upper gastrointestinal examinations, 16 met the rigorous criteria established for selecting asymptomatic normal volunteers. Frame-by-frame evaluation of their videorecorded pharyngeal swallow confirmed many observations made previously utilizing cine recording at much higher radiation dosages. In addition, new observations were made: the nasopharynx may not occlude until the bolus is entirely within the pharynx; air mixes with the bolus if the swallow is an "open" type; the epiglottis always inverts in normal individuals regardless of the type of swallow ("open," air filled oro-and hypopharynx into which the swallowed bolus is dropped; "closed," airless oropharynx into which the swallowed bolus is pushed by a continuous peristaltic drive of the tongue and palate, thus reconstituting the pharyngeal space); laryngeal descent may aid in stripping the bolus from the pharynx; the vestibule may not completely close during the swallow and the larynx can still be impervious to the bolus; the peristaltic wave does not begin until the bolus has breeched the cricopharyngeus; the cricopharyngeus may be seen frequently in normal individuals, but does not delay the passage of the bolus; asymmetric flow of the bolus around the larynx is common and may not be the result of epiglottic tilt or head positioning.

Timing in the normal pharyngeal swallow. Prospective selection and evaluation of 16 normal asymptomatic patients.

A review of timing of pharyngeal events with radiography has been made. A prospective selection of normal asymptomatic patients presenting for a gastrointestinal evaluation was made and timing of 55 events in the videorecorded pharyngeal swallow in these patients was performed. Only 16 normal asymptomatic patients as defined for selection were found among 870 patients presenting for gastroesophageal examination. A detailed description of their timing observations is presented. The timing data were used to temporally order events in the pharyngeal swallow. This ordering of events in the pharyngeal swallow and the data upon which it is based are reported here in detail.

The radiologic evaluation of acute abdominal pain of intestinal origin. A clinical approach.

The patient with acute abdominal pain presents the attending physician with a wide and varied gamut of diagnostic possibilities. Prompt and accurate diagnosis is essential for the proper care and management of these acutely ill patients. Diagnostic radiology is often an integral part of the emergent evaluation of these patients. This article focuses on some of the key plain-film findings in the patients suffering from acute abdominal pain of intestinal causes and reviews the radiologic evaluation of several major abdominal conditions such as acute appendicitis, diverticulitis, inflammatory bowel disease, bowel ischemia, and infarction.

Automated calculation of the centerline of the human colon on CT images.

RATIONALE AND OBJECTIVES: This article presents an evaluation of an automated technique for determining the colon centerline with computed tomographic (CT) data sets. MATERIALS AND METHODS: The technique proceeds as follows. After indication of a voxel in the rectum, voxels corresponding to air were segmented. Points along the colon centerline were estimated on the basis of centers of mass of grown voxels. A second segmentation and centerline calculation was initiated at the cecum. These two centerlines were then averaged. The resulting average was refined by using lumen data obtained perpendicular to the average centerline. The accuracy of the technique was investigated with simulation phantoms. The technique was also evaluated for 40 clinical colon cases. Calculated centerline points were compared with those indicated by radiologists for a randomly selected clinical case. RESULTS: In the simulation studies, the calculated centerline points were, on average, within 2.5 mm of the true centerlines but differed by up to 4 mm in regions of deep folds or sharp turns. In the clinical colon study, 40% of the centerlines were computed with a single seed point and 25% with two seed points. Average centerlines were computed in 1 minute. The root mean square difference between the computed centerline points and those indicated by the radiologists was 4-5 mm (comparable to interobserver variations). CONCLUSION: Accurate centerlines can be determined from colon CT data with this automated technique.

CT findings of regression in intraabdominal desmoplastic small-cell tumor.

We report the computed tomographic (CT) findings in a patient with intraabdominal desmoplastic small-cell tumor before and after 10 weeks of chemotherapy. This tumor is a rare, frequently fatal neoplasm of the peritoneum, seen predominantly in young males. Initial CT demonstrated large intraperitoneal masses, hepatic metastases, retroperitoneal and right axillary lymphadenopathy, ascites, and pleural effusion. Follow-up CT showed marked decrease of the main tumor bulk and complete regression in the axillary nodes.

CAD techniques, challenges, and controversies in computed tomographic colonography.

Computer-aided diagnosis (CAD) for computed tomographic colonography (CTC) automatically detects the locations of suspicious polyps and masses on CTC and provides radiologists with a second opinion. CAD has the potential to increase radiologists' diagnostic performance in the detection of polyps and masses and to decrease variability of the diagnostic accuracy among readers without significantly increasing the reading time. Technical developments have advanced CAD substantially during the past several years, and a fundamental scheme for the detection of polyps has been established. The most recent CAD systems based on this scheme produce a clinically acceptable high sensitivity and a low false-positive rate. However, CAD for CTC is still under active development, and the technology needs to be improved further. This report describes the expected benefits, the current fundamental scheme, the key techniques used for detection of polyps and masses on CTC, the current detection performance, as well as the pitfalls, challenges, controversies, and the future of CAD.

Diagnostic performance of virtual colonoscopy.

The most important diagnostic performance of virtual colonoscopy is the ability to detect colorectal polyps. However, its diagnostic value for evaluation of patients undergoing incomplete colonoscopy and the ability to detect unsuspected extracolonic findings are also important diagnostic features. Because of important differences between published patient populations, a meta-analysis combining data from different studies would not provide a reliable statistic. The by-patient sensitivity for patients with polyps 10 mm and larger ranges from 75% to 100% in most series and was 100% in the two largest series published to date. By-polyp sensitivity for polyps 10 mm and larger ranges from 50% to 100% and was 89-90% in the two largest series. Detailed data on smaller polyps are summarized. Virtual colonoscopy is an excellent test for evaluation of patients with incomplete colonoscopies. The incidence of significant extracolonic findings is 7-13%.

Radiology of the esophagus.

Plain films, esophagrams, and cross-sectional imaging studies have important roles in evaluating patients with suspected esophageal disease. The strengths and weaknesses of each technique are described in this article. The salient radiographic features of various inflammatory and neoplastic conditions of the esophagus are also described, with emphasis on the value of high-quality triphasic esophagography.

Virtual colonoscopy: a novel imaging modality for colorectal cancer.

Advances in computed tomography (CT) technology and computer capabilities have contributed to the development of a new imaging modality for colorectal lesions called CT colonography or virtual colonoscopy. Virtual colonoscopy is a rapid, minimally invasive scan of the cleansed and distended colon. Early work has demonstrated that this test is safe and well tolerated, and that it may be sensitive and specific enough to identify most significant precancerous or cancerous lesions. A number of technical and practical problems remain before virtual colonoscopy can be applied at a population level.

CT colonography: the next colon screening examination?

Computed tomographic (CT) colonography is a new-generation technique for detecting colorectal neoplasms by using volumetric CT data combined with specialized imaging software. Patient examinations require full colonic preparation, insufflation, and data acquisition with the patient in the supine and prone positions. Current CT technology allows a single image of the colon to be acquired in as little as 20 seconds with a minimum of patient discomfort. Specialized computer software for interpretation usually combines transverse, multiplanar reformation, and three-dimensional endoluminal images for the optimal visualization of the colon and rectum. As of the time this article was written, CT colonography was competitive as a full structural colonic examination for the detection of polyps and cancer. To the authors' knowledge, no study results have yet been reported in a screening population. The unique capabilities of CT colonography include the display of the proximal colon that is inaccessible at colonoscopy because of obstructing colonic lesions or because of incomplete endoscopic examinations and the assessment of extracolonic abdominal and pelvic organs. This abdominopelvic survey potential provides radiologists with an opportunity to discover other potentially life-threatening, asymptomatic conditions. Further technologic developments and validation studies are in progress. CT colonography is an exciting and promising technique with an enormous potential for colorectal screening in the future.

Polypoid and pseudopolypoid manifestations of inflammatory bowel disease.

The polypoid manifestations of the idiopathic inflammatory bowel diseases (ulcerative colitis and Crohn disease) are often confusing. Inflammatory polyps project above the level of the surrounding mucosa. Pseudopolyposis (in ulcerative colitis) or a cobblestone appearance (in Crohn disease) results when extensive ulceration develops and only scattered islands of relatively normal mucosa remain; thus, the ulcerated areas may be falsely perceived as the baseline and the islands as polyps. Postinflammatory (filiform) polyps--fingerlike projections of submucosa covered by mucosa on all sides--reflect healing of undermined mucosal and submucosal remnants and ulcers and are almost always multiple. Patients with ulcerative colitis or Crohn disease are at increased risk for developing adenocarcinoma. Occasionally, dysplasia occurs as a polypoid lesion. Dysplasia of the colon (mucosal atypia) is a histologic marker highly associated with adenocarcinoma. Because differentiating adenocarcinoma and dysplasia from inflammatory or postinflammatory polyps is sometimes difficult or impossible, endoscopy and biopsy are usually recommended for definitive diagnosis of suspicious lesions.

Colorectal carcinoma in young patients: CT detection of an atypical pattern of recurrence.

Colonic adenocarcinoma is an uncommon but aggressive neoplasm in patients under the age of 40. The goals of this study were to evaluate the utility of computed tomography (CT) in preoperative staging and detection of postoperative recurrences in young patients with colon cancer and to evaluate the pattern of recurrent disease. We reviewed 51 cases of adenocarcinoma in patients aged 40 years and younger. CT preoperatively staged 21 (72%) of 29 patients correctly and had a 100% positive predictive value for metastatic disease. Recurrent disease occurred in 23 (76%) of 30 nonstage D patients with at least 2 years of disease-free follow-up. CT accurately detected 21 (91%) of 23 cases of recurrent disease. Local recurrences were detected in 20 (87%) of 23 patients. Isolated local disease was the most frequent pattern of recurrence, seen in 17 (74%) of 23 patients. Hepatic metastases were rare and occurred in nine (13%) of 51 patients. Young patients with colon cancer have an increased prevalence of isolated local recurrences and decreased rate of hepatic metastases than the older population. In order to detect early, and therefore resectable recurrent disease, CT examinations should be obtained early and often in the postoperative period.

Hodgkin's disease of the gastrointestinal tract.

Hodgkin's disease (HD) is rarely considered in the differential diagnosis of gastrointestinal (GI) disorders. We report eight cases of GI HD. The patients, ages 16-64, all with stage IV disease of varied histologic subtypes and GI symptoms including pain, upper or lower GI bleeding and/or obstruction. There was diffuse gastric fold thickening in one case, a large submucosal mass along the proximal greater curvature in another case, and a large ulcerating mass along the lesser curvature in the third case. Two cases of jejunal disease manifested as either a short or long segment of luminal narrowing with prominent mucosal nodularity. Another case exhibited a short area of complete mucosal destruction, irregular cavitation and intraluminal filling defect. In one additional case there was diffuse jejunal nodularity. Colonic involvement (two cases) presented as a solitary polypoid mass in transverse colon in one patient and severe narrowing of the descending colon with adjacent mesenteric mass on CT in another. We conclude that although rare in Hodgkin's disease, GI involvement should be considered, particularly in patients with stage IV disease.

CT findings after laparoscopic repair of ventral hernia.

OBJECTIVE: We describe CT findings after laparoscopic repair of ventral hernia with emphasis on formation of postoperative fluid collections that can mimic recurrent bowel herniation or infected postoperative fluid collections. CONCLUSION: The porous property of the mesh used in laparoscopic repair of ventral hernia allows reaccumulation of fluid in the existing hernia sac or spaces in the subcutaneous tissues that can be created by laparoscopic manipulation. These fluid collections should be expected and are differentiated from infected fluid collections or hernia recurrence by clinical presentation, laboratory data, and lack of ancillary features associated with true hernia such as presence of hernia sac, herniated mesentery, or bowel obstruction.

Calcified intrahepatic portal vein thrombus: distinction from intrahepatic choledocholithiasis.

In a case of calcified intrahepatic portal vein thrombus CT demonstrated a branching calcified intrahepatic mass with peripheral enhancement following dynamic bolus contrast medium administration. The distinction from intrahepatic choledocholithiasis was made with normal cholangiography. Calcified portal vein thrombus should be considered an unusual cause of branching calcified intrahepatic mass on CT.

Collateral pathways in superior vena caval obstruction as seen on CT.

PURPOSE: Collateral venous pathways occurring with superior vena cava (SVC) obstruction were examined based on CT scans obtained from the thoracic inlet to the pubic symphysis. Similarities and variations from the prior classification scheme were analyzed. METHOD: A retrospective review of our database resulted in a cohort comprising 21 CT scans from 19 patients. The location and frequency of each collateral pathway and the level of the SVC obstruction were tabulated. An accepted classification scheme was applied to the collateral patterns in each case. Additional and atypical features were noted. RESULTS: Fifteen common collateral veins were found that could be grouped into one to four collateral pathways. Unusual shunts, including hepatic parenchymal and pulmonary pathways, were found. Thirteen cases (62%) varied from the standard classification owing to different occlusion levels or presence of other collaterals. No statistically significant relationship between the level of occlusion and the number of collateral pathway groups was found. The most common abdominal collateral veins were those along the liver surface (52.3% of cases), although 18 patients (94.7%) had at least one collateral vein visible in the abdomen. CONCLUSION: The spectrum of venous collateral formations as seen on thoracoabdominal CT scans often includes collaterals at or below the level of the diaphragm, including intrahepatic shunts. Many collateral patterns found in this series could not be classified with the existent classification scheme.

Portal and mesenteric venous calcification in patients with advanced cirrhosis.

OBJECTIVE: The incidence of calcification in the portal and mesenteric venous system was studied in patients with advanced cirrhosis undergoing evaluation for liver transplantation. The significance of portal and mesenteric calcification on liver transplantation was also investigated. CONCLUSION: An 11% incidence of portal and mesenteric venous calcification was found in patients with cirrhosis, which was much higher than anticipated. Two (29%) of seven patients who had calcification present on CT and underwent liver transplantation died at surgery as a result of portal venous thrombosis. Thus, venous calcification seen on CT is a significant finding in patients undergoing liver transplantation.

Mucocele of the appendix and pseudomyxoma peritonei.

Mucocele of the appendix is a descriptive term for an abnormal mucous accumulation distending the appendiceal lumen. Pseudomyxoma peritonei is characterized by mucinous ascites and implants throughout the abdominal cavity. Thirty-four cases of appendiceal mucocele and seven cases of pseudomyxoma peritonei of appendiceal origin on file at the Armed Forces Institute of Pathology were reviewed for their clinical, pathologic, and radiologic findings. These cases provided examples of the major radiologic findings reported in this entity. Previously unreported findings of dependent echoes within some mucoceles on sonography and pseudomyxoma peritonei tracking along the umbilical vein remnant or mimicking an intrahepatic mass are presented.

Cystic neoplasms of the pancreas. Radiological-pathological correlation.

Microcystic adenomas and mucinous cystic neoplasms of the pancreas have often been described interchangeably (cystadenoma, cystadenocarcinoma), causing confusion with respect to their radiographic characteristics. The former are composed of innumerable tiny cysts and are benign, whereas the latter contain large, unilocular or multilocular cysts, sometimes with shaggy excrescences, and are either frankly or potentially malignant. Microcystic adenomas are angiographically hypervascular and may have central calcification. Sonographically, they have a mixed hypoechoic and echogenic pattern, while CT numbers reflect a mixture of connective tissue and proteinaceous fluid and contrast enhancement is seen. Mucinous cystic neoplasms are hypovascular and may have peripheral calcification; ultrasound and CT reflect their predominantly cystic character and demonstrate excrescences when present.