Current opinion in radiology最新文献

The development and clinical studies of contrast agents for cross-sectional abdominal imaging presently focus on the diagnosis of liver diseases and suitable oral contrast agents for MR imaging. The well-known paramagnetic agent, gadopentetate dimeglumine is now used for improving the differential diagnosis of liver lesions such as focal nodular hyperplasia in dynamic MR studies. Preclinical studies and initial clinical trials indicate that the new paramagnetic hepatobiliary contrast agent, manganese dipyridoxal diphosphate, might improve the sensitivity of MR imaging in the detection of liver lesions. With respect to dynamic contrast-enhanced CT in the detection of liver lesions, interest has focused on the question of the optimal scanning technique. Promising results have been obtained in initial studies of contrast agents for sonography, called microbubbles. This substance produces good visualization of the vascular status of liver tumors. Nuclear medicine somatostatin receptor imaging may be of special clinical interest because it allows even very small somatostatin-positive metastases to be detected and thus provides specific information for therapy planning in patients with positive scan results. Initial studies have shown that using contrast enhancement with MR imaging of the pancreas improves the contrast between pancreatic tissue and lesions. Manganese dipyridoxal diphosphate is taken up by pancreatic tissue, though the exact mechanism remains to be clarified, and may therefore have potential as a future MR contrast agent for evaluation of the pancreas. A number of oral MR contrast agents have now been tested in larger clinical trials. Both positive and negative oral agents are safe and well tolerated and achieve the aim of reliably delineating the gastrointestinal tract from other organs and pathologies in the abdomen.

Quality assurance is essential in the cost-effective provision of radiologic services. Technical aspects include the routine measurement of equipment performance and the control of reject and retake rates. The current emphasis is on reducing patient radiation dose while maintaining acceptable image quality. The reduction of unnecessary radiologic investigations is also a priority. Clinical and medical audits, integral parts of the quality assurance process, form part of a continuously repeated cycle designed to raise standards of performance by changing clinical practice on the basis of outcome analysis. Quality assurance in mammography is presented as an example.

The traditional areas of interest in pediatric gastrointestinal radiology (gastroesophageal reflux, malrotation, necrotizing enterocolitis) were the source of many new and important studies in the past year. Information gleaned from correlative nonradiologic studies or from newer modalities provided the new focus of interest. The imaging and treatment of intussusception remains a topic in which literature is evolving. Pneumatic reduction is repeatedly being shown to be safe and effective. There have been a large number of studies addressing polysplenia, biliary atresia, and liver transplantation. Images of the anomalies associated with polysplenia were published in several sources. One paper reported better than previously described results of liver transplantation in the subset of patients with polysplenia and biliary atresia.

The application of interventional radiographic procedures in the management of patients with liver and pancreatic pathology continues to expand. Percutaneous hepatobiliary interventional procedures that have received considerable attention in the past year include technical refinements of the transjugular intrahepatic portosystemic shunt procedure used in patients with portal hypertension and esophageal varices, transshunt embolotherapy of persistent varices in patients with small-caliber mesocaval shunts, percutaneous and transcatheter embolotherapy of hepatic malignancies in patients with primary or metastatic lesions, and MR angiography in the preoperative evaluation of patients awaiting liver transplantation. Other topics reviewed include percutaneous and transvenous biopsy of orthotopic liver transplants, management of bile leaks and strictures after liver transplantation, use of a biopsy gun and larger gauge needles to obtain specimens for histologic analysis in patients with orthotopic liver and pancreatic transplants, percutaneous treatment of caval and hepatic venous stenoses in patients with Budd-Chiari syndrome using self-expanding stainless steel stents, percutaneous treatment of patients with hepatic Echinococcus granulosus cysts, and percutaneous managements of iatrogenic hepatic vascular injuries. General diagnostic evaluation and interventional procedures highlighted include using selective intra-arterial injection of calcium to localize small insulinomas. Recent review papers describing complications of percutaneous transabdominal fine-needle biopsy are analyzed. The diagnostic and therapeutic options available for treating patients with hepatic and pancreatic diseases are summarized in greater detail.

The year 1991 was a year of innovation, with interesting papers published in the imaging as well as the medical and surgical literature. Several reports described novel techniques using transcutaneous ultrasound to evaluate the swallowing mechanism; another used CT and ultrasound of the neck for staging esophageal carcinoma. The new field of endoscopic ultrasound was again a subject of much investigation and was compared with CT in the staging of esophageal cancer. One study suggested that endoscopic ultrasound was superior to CT in staging esophageal cancer whereas another found that endoscopic ultrasound had an accuracy rate of only 59% in detecting local invasion. MR imaging and CT were reevaluated for staging esophageal carcinoma using criteria that were modified slightly from previous techniques. These new criteria simplified the detection of aortic and pericardial invasion and staged esophageal carcinoma accurately. The definition of "normal" was refined this year. For instance, in a study of swallowing in asymptomatic and presumably normal elderly individuals, a number of findings were encountered that are considered abnormal in the younger patient. Another study documents normal swallowing patterns in the infant. Other papers provided refinements in radiographic examination techniques as well as excellent reviews of anomalies, esophagitis, and the management of esophageal foreign bodies. The review is divided into two sections that discuss the pharynx and the esophagus.

Although endoscopic retrograde cholangiopancreatography is the technique of choice for examining the biliary tract when ultrasonography does not demonstrate dilated ducts, the transhepatic cholangiopancreatogram was shown to be useful when endoscopic retrograde cholangiopancreatography fails. On cholangiography, ultrasonography, and CT, clonorchiasis and cryptosporidiosis were found to have duct dilatation and contour irregularity, and in some patients, papillary stenosis. The value of cholangiography in determining the prognosis and appearance of primary sclerosing cholangitis and in diagnosing Klatskin tumor was examined. Patients with high-grade extrahepatic strictures, diffuse intrahepatic strictures, and marked intrahepatic dilatation had decreased survival. The preoperative cholangiogram diagnosis of Klatskin tumor was found to be accurate in only two-thirds of cases. In patients with liver transplantation who had dilatation of both donor and native extrahepatic bile ducts and abnormal liver function tests, but no evidence of anastomotic stricture, malfunction of the sphincter of Oddi was suggested as a possible cause. The sonographic features of acute gallbladder disease were evaluated and striations in the thickened gallbladder wall were shown not to be a specific sign for acute cholecystitis. Also, the ultrasonographic diagnosis of early gallbladder carcinoma was not accurate enough, but ultrasonography was reaching a sensitivity of 70% to 80% for advanced gallbladder cancer.

Numerous papers have appeared in the past year outlining the expanded role of the radiologist in the treatment of patients with biliary disease, including papers describing palliative treatment of patients with obstructive jaundice due to malignant disease using self-expanding metallic biliary endoprostheses placed percutaneously, extracorporeal shock-wave lithotripsy used to treat patients with gallstones and intrahepatic stones, percutaneous rotational contact biliary lithotripsy, pulsed dye laser biliary lithotripsy, percutaneous biliary intervention via a minicholecystotomy, conventional percutaneous fluoroscopic management of bile duct stones, and percutaneous management of biliary strictures including transluminal biopsy. Percutaneous evaluation and treatment of patients with biliary disease using cholangioscopy as an adjuvant to biliary intervention, radionuclide imaging for improved evaluation of suspected biliary injury after laparoscopic cholecystectomy, and percutaneous treatment of the critically ill patient with cholecystitis or the patient with a perforated gallbladder are also discussed. Diagnostic and therapeutic options available to radiologists for treating patients with biliary disease are summarized.

Magnetic resonance spectroscopy holds promise as another tool for functional and metabolic assessment in diagnosis and in monitoring therapy. Although the maturation and acceptance of MR spectroscopy as a clinical tool lags significantly behind that of MR imaging, important technical and methodologic advances continue at a rapid pace. Some of the advances that have occurred recently are described in this review.

Advances in the imaging of peritoneal pathology are reviewed. Papers published in the past year in the radiologic, surgical, and pediatric literature discussed the detection, quantification, characterization, and management of fluid collections in the trauma patient or the patient with intra-abdominal sepsis; the assessment of various imaging modalities in the evaluation of unexplained fever or pain; and the detection, characterization, and localization of primary, recurrent, or metastatic abdominal neoplasms.

Selected papers published over the past year in the areas of radionuclide hepatobiliary imaging, gastric emptying, and gastrointestinal bleeding are reviewed. Two advances in cholescintigraphy are particularly emphasized and discussed. First, morphine-augmented cholescintigraphy has established itself as an accurate alternative to 2 to 4 hour delayed imaging for the diagnosis of acute cholecystitis. Second, sincalide-stimulated cholescintigraphy with calculation of a gallbladder ejection fraction has proven to be a useful test for confirming the clinical diagnosis of chronic acalculous cholecystitis. Other hepatobiliary papers reviewed include those on the utility of cholescintigraphy in gallbladder perforation, hepatocellular carcinoma, liver transplantation, enterogastric reflux, and for the diagnosis of the postoperative complications of laparoscopic cholecystectomy and gallstone lithotripsy. The second major area of review includes papers published over the past year on gastric emptying, including investigations of methodology, physiology and pathophysiology, and clinical utility. A few papers utilizing radionuclide techniques for localizing gastrointestinal bleeding will also be reviewed.