Following renal transplantation, patients are often evaluated with ultrasonography (US) or radionuclide imaging to assess renal function and the presence of possible complications. Both modalities are inexpensive, noninvasive, and nonnephrotoxic. A basic understanding of the surgical techniques commonly used for renal transplantation is useful when imaging these patients in order to recognize complications and to direct further imaging or intervention. The most frequent complications of renal transplantation include perinephric fluid collections; decreased renal function; and abnormalities of the vasculature, collecting system, and renal parenchyma. Perinephric fluid collections are common following transplantation, and their clinical significance depends on the type, location, size, and growth of the fluid collection, features that are well-evaluated with US. Causes of diminished renal function include acute tubular necrosis, rejection, and toxicity from medications. Radionuclide imaging is the most useful modality for assessing renal function. Vascular complications of transplantation include occlusion or stenosis of the arterial or venous supply, arteriovenous fistulas, and pseudoaneurysms. Although the standard for evaluating these vascular complications is angiography, US is an excellent noninvasive method for screening. Other transplant complications such as abnormalities of the collecting system and renal parenchyma are well-evaluated with both radionuclide imaging and US.

Mesenteric venous thrombosis is an uncommon but potentially lethal cause of bowel ischemia. Several imaging methods are available for diagnosis, each of which has advantages and disadvantages. Doppler ultrasonography allows direct evaluation of the mesenteric and portal veins, provides semiquantitative flow information, and allows Doppler waveform analysis of the visceral vessels; however, it is operator dependent and is often limited by overlying bowel gas. Conventional contrast material-enhanced computed tomography (CT) allows sensitive detection of venous thrombosis within the central large vessels of the portomesenteric circulation and any associated secondary findings; however, it is limited by respiratory misregistration, motion artifact, and substantially decreased longitudinal spatial resolution. Helical CT and CT angiography, especially when performed with multi-detector row scanners, and magnetic resonance (MR) imaging, particularly gadolinium-enhanced MR angiography, enable volumetric acquisitions in a single breath hold, eliminating motion artifact and suppressing respiratory misregistration. Helical CT angiography and three-dimensional gadolinium-enhanced MR angiography should be considered the primary diagnostic modalities for patients with a high clinical suspicion of mesenteric ischemia. Conventional angiography is reserved for equivocal cases at noninvasive imaging and is also used in conjunction with transcatheter therapeutic techniques in management of symptomatic portal and mesenteric venous thrombosis.

Imaging of the gallbladder for cholelithiasis and its complications has changed dramatically in recent decades along with expansion of interventional techniques related to the disease. Ultrasonography (US) is the method of choice for detection of gallstones. The characteristic US findings of gallstones are a highly reflective echo from the anterior surface of the gallstone, mobility of the gallstone on repositioning the patient, and marked posterior acoustic shadowing. Oral cholecystography remains an excellent method of gallstone detection, but its role has been limited due to the advantages of US. Most people with cholelithiasis will not experience symptoms or complications related to gallstones. When biliary colic does occur, it is typically caused by transient obstruction of the cystic duct by a stone. The primary imaging modality in suspected acute calculous cholecystitis is usually US or cholescintigraphy. Detection of gallstones alone does not permit a diagnosis of acute cholecystitis; however, secondary US findings provide more specific information. In detection of choledocholithiasis, endoscopic retrograde cholangiopancreatography and magnetic resonance cholangiopancreatography are superior to US. In certain clinical settings, interventional radiologic procedures have become an important alternative to surgery in the treatment of gallstones and their complications; techniques include percutaneous cholecystostomy and gallstone removal.

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OBJECTIVE. The purposeof this investigationwasto determinethe prevalenceof lower esophagealmucosal rings and to correlate the relationship between these mucosal rings and thepresenceandanatomiclevel of symptomsevokedusinga marshmallowbolus. SUBJECTS AND METHODS. Our prospective studyincluded130 patientswho under went bariumexaminationof the esophagus. All patientscompleteda questionnaireregarding the anatomic location of their symptoms of dysphagia. In addition to a multiphasic examina tion of the esophagus, all patients also underwent fluoroscopic observation and videotaping while swallowing a marshmallow bolus; any symptoms that were provoked were recorded.RESULTS. Lower esophageal mucosalringswere shownin 26 (20%) of the 130 patients. The diameterof the ringswas 9â€"12 mm in six patients,13â€"20 mm in 18 patients,and larger than 20 mm in two patients. In 16 (62%) of the 26 patients, a marshmallow bolus became im pacted at the ring; the impaction caused dysphagia in 12 (75%) of the I6 patients. In these 12 patients, dysphagia was referred to the neck in seven,the sternal angle in two, the mid chest in two, and the lower chest in one patient. None of the 12 patients had a pharyngeal or cervical esophageal abnormality that would account for their symptoms.CONCLUSION. Becauseproximal referral of symptomsis common in patientswith loweresophageal mucosalrings,a thoroughradiographicexaminationof theentireesophagus and esophagogastricregion is required regardlessof the level of their swallowing complaints.

Our results show that fluoroscopic and endoscopic placement of enteral feeding tubes is highly effective. Fluoroscopic time in successful cases is usually less than i5 mm. Endoscopic placement of feeding tubes is successful after fluoroscopic failure. AJR

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Most patients with globus pharyngeus had normal results at pH monitoring and radiographic examination of the pharynx.