Biomedical subjects
Publications and source records attributed to E J Ring.
Recent studies have emphasized the safety of fluoroscopically guided balloon dilatation for treatment of severe esophageal strictures. A case of esophageal rupture that followed dilatation of a distal esophageal stricture with a 20-mm balloon catheter is reported.
Percutaneous removal of gallstones was employed as the definitive form of therapy in three patients with acute cholecystitis. Percutaneous cholecystolithotomy may be an alternative form of therapy for selected patients with gallbladder calculi.
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Using a percutaneous approach, 18 of 20 staghorn calculi were completely removed from the upper urinary tract. The initial nephrostomy was performed in the radiology department with local anesthesia. Tract dilatation and stone removal ensued on the next day in the operating room under general anesthesia. Minor complications, including postoperative temperature spikes and pyelonephritis, occurred in seven patients. Two major complications, urosepsis and hemorrhage requiring transfusion, were encountered.
Interventional radiologic techniques can make a useful contribution to the management of patients with recurrent symptoms following surgical palliation of oriental cholangiohepatitis. Percutaneous removal of multiple, soft, pigmented biliary stones that form in this disease can be achieved by a combination of basket retrieval and crushing, as well as suction and irrigation techniques. Ducts that are obstructed by strictures can be drained by percutaneous catheters. Complete or partial symptomatic relief was obtained in six of eight patients, obviating additional surgical intervention.
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There are at least five potential mechanisms for enlarging the arterial lumen using the technique of percutaneous transluminal angioplasty. Each of these mechanisms is reviewed along with evidence from clinical or experimental angioplasty supporting or refuting an actual role for that mechanism in mechanical dilation of diseased vessels. Although plaque compaction is not plausible, each of the other four responses--redistributive modeling of plaque, embolization of plaque components, plastic stretching of the arterial wall, and phagocytic removal of plaque during healing after angioplasty--has been confirmed in at least some circumstances. Since the lesions probably differ in their biomechanical properties, we conclude that it is unlikely that a single mechanism will explain all of the successful dilations.
Percutaneous removal of upper urinary tract calculi has become an accepted alternative to surgical removal. Calculi may be removed through large nephrostomy tracts under fluoroscopic or endoscopic control. Close cooperation between the radiologist and urologist should increase the success rate of the procedure.
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The transhepatic placement of adequately sized endoprostheses for the palliation of malignant biliary obstruction is painful and requires large hepatic parenchymal tracks. Endoscopically placed biliary stents are smaller, but may not be adequate for long-term patency. The authors have used a combined peroral-transhepatic approach successfully to pull large endoprostheses through the alimentary track and into the biliary tree.
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The biliary tract may be approached through surgical drainage tracts, percutaneously through the liver, and perorally through the duodenum. Removal of retained stones through a surgical drainage tract can be performed on outpatients with 90%-95% success in experienced hands. The percutaneous approach through the liver is useful to drain malignant obstructions before surgical or drug treatment and can offer catheter stent palliation for tumors in the porta hepatis. Benign strictures also may be drained and dilated transhepatically. Ascites and multiple intrahepatic obstructions are relative contraindications to transhepatic entry. Hemorrhage is the most frequent serious complication, occurring in about 5% of procedures. Indwelling endoprostheses are preferred to external catheters to reduce the psychologic trauma of the catheter. A new procedure for inserting large endoprostheses by a combined peroral/transhepatic approach has the advantage of requiring only a small transhepatic tract.
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An in vitro model was developed to measure bile flow at varied pressures through several commonly used transhepatic drainage catheters. As expected, larger catheters conduct more bile flow at a given pressure. All catheters studied conduct adequate amounts of bile at normal physiologic pressure gradients. The clinical observation that large catheters (10-12 French) are necessary for adequate antegrade drainage in some patients must be explained by an abnormal bile viscosity, increased duodenal pressures, or reduced biliary secretory pressure.
Fourteen patients with a variety of aortic diseases were evaluated with magnetic resonance imaging (MRI). These included abdominal aortic aneurysms (eight cases), aortoiliac aneurysm (one), thoracoabdominal aneurysm (one), aortic dissections (four), and Takayasu arteritis (one). The size and extent of aneurysms, the presence of thrombus or atherosclerotic debris, the relation to renal and iliac arteries, and the effect of aneurysms on adjacent structures were readily demonstrated by MRI. The size of the residual lumen in a variety of vascular diseases and abnormal blood flow patterns could be assessed. In aortic dissection, MRI permitted identification of intimal flaps and determination of the origin of aortic branches from either of two lumina. Thickening of the wall and luminal narrowing of the aorta and arch vessels in Takayasu arteritis were clearly defined. These early results indicated that MRI achieved precise and complete assessment of a number of aortic abnormalities without the administration of any type of contrast material. Thus, early experience suggests that an important application of MRI will be as a totally noninvasive and reliable method for evaluating aortic disease.
The growing use of interventional radiologic techniques signals a need to redefine the radiologist's role in patient management. Radiologists must decide whether they want to participate more fully in clinical matters such as patient selection and follow-up care. The authors suggest that further development in the field will be slowed if radiologists do not take a more active clinical role. Training standards in radiology must also reflect the evolving role of the radiologist.