Pathophysiologic effects of biliary shockwave lithotripsy in a canine model.

At least 10 extracorporeal shockwave lithotripters are under investigation in the United States for treatment of biliary stone disease. Few reports, however, have documented the potential side effects of this new treatment method. In this study, we performed a series of acute and chronic studies in dogs exposed to varying numbers of shockwaves directed at the gallbladder wall via a transthoracic or transabdominal targeting approach. When shockwaves were directed transthoracically, pulmonary hemorrhagic contusions were found which were sometimes large in size. When a transabdominal approach was used, however, only focal areas of hemorrhage were found in the gallbladder wall and adjacent liver with no alterations in postlithotripsy pancreatic or liver enzymes, and normal cholecystokinin-octapeptide stimulated oral cholecystograms were obtained 6 days after treatment. Biliary shockwaves appear to cause few side effects under normal conditions but should be used with caution in patients with potential bleeding disorders. Until further studies are performed, lung tissue should be avoided in the shockwave beam path during treatment.

Near-monochromatic X-ray beams produced by the free electron laser and Compton backscatter.

The intense photon output of a free electron laser may be made to collide with its own high energy electron beam to create nearly monochromatic x-rays using Compton backscatter techniques. These x-rays can be used for imaging and non-imaging diagnostic and therapeutic experiments. The initial configuration of the Vanderbilt Medical Free Electron Laser (Sierra Laser Systems, Sunnyvale, CA) produces intense x-rays up to 17.9 keV, although higher energies are easily attainable through the use of frequency doubling methods, alteration of the energy of the electron beam and coupling to conventional laser inputs.

Principles of biliary extracorporeal lithotripsy. Technical considerations and clinical implications.

After recent reports of the successful use of extracorporeal shock-wave lithotripsy for the treatment of gallstone disease, at least 10 different manufacturers have developed lithotripsy systems and initiated clinical trials in the United States. The three major types of lithotripters, classified by the method used to generate shock waves, are the spark-gap, piezoelectric, and electromagnetic systems. Although each type of system generates shock waves by different methods, all currently available systems appear to be able to fragment gallstones. However, there does not appear to be any system that has demonstrated clear clinical superiority in terms of either efficacy or safety. Additional information, both clinical and experimental, is needed before it can be determined if the type of shock-wave generator has a significant effect on outcome. Clearly more than the physical principles of shock-wave lithotripters must be evaluated.

Antitrust aspects of exclusive contracts in medical imaging.

Exclusive contracts between radiologists and hospitals may be more frequently scrutinized for antitrust violations because of the Hyde v Jefferson Parish Hospital District No. 2 case. In the Hyde case, the lower court decided antitrust law had been violated, and it was the first antitrust case about exclusive medical contracts to be reviewed by the U.S. Supreme Court. The case is a precedent for considering similar circumstances according to traditional business antitrust analyses such as per se violations, tying arrangements, group boycott, and market foreclosure. Areas that may be scrutinized for anticompetitiveness include hospital privileges when radiologists have exclusive contracts with the community's only hospital or provide services unique within an area, and physicians' access to scarce resources (e.g., computed tomography [CT], magnetic resonance [MR] imaging). Radiologists must understand antitrust implications of their hospital contracts; examine the terms of staff appointment, bylaws, and rights; and be able to guide their attorneys through contract negotiations.

Current perspectives on medical imaging.

Advances in biomedical technology have expanded the potential of medical imaging. Selected aspects of developments in sonography, nuclear medicine, nuclear magnetic resonance and digital imaging are addressed, stressing the wide scope permitted by these newer modalities.

Facility report. Department of Medical Imaging and Radiological Sciences at Vanderbilt University.

This department is presented as an academic prototype to meet the health care and research challenges of the next decade. Composed of four separate divisions (diagnostic radiology, radiation oncology, nuclear medicine, radiologic sciences) with appropriate sections, it is organized according to the concept of an integrated basic science-service facility.

Economic considerations in MRI.

The newest product of the medical technologic revolution, magnetic resonance imaging ( MRI ), has come at a time when many medical facilities are under unusual financial strain. Ultimately, MRI must be justified economically as a means of shortening hospital stays, reducing the need for other services, or both. Further, MRI introduces special problems referable to purchase decisions.

The detection of spinal pseudarthrosis in ankylosing spondylitis.

Spinal pseudarthrosis in ankylosing spondylitis can be difficult to detect radiologically. This paper assesses the value of bone radioscintigraphy in relation to radiological examination. The patterns of tracer uptake in the spine were recorded in 16 patients in whom established ankylosing spondylitis was complicated by pseudarthrosis. Twenty such lesions were identified in 16 patients, mostly occurring at one level in a junctional region of the spine. Four patients had two lesions. Standard radiography failed to demonstrate this abnormality in seven patients and in these, tomography was required to confirm the scintigraphic findings. On the other hand, bone scanning was much less accurate in detecting the minor forms of marginal vertebral end plate destruction (spondylo-discitis) than conventional radiology. This study suggests that 99TcmMDP scanning is a useful primary investigation for the detection of spinal pseudarthrosis in patients with chronic ankylosing spondylitis who suffer late onset back pain.

A double-blind, crossover trial of mefenamic acid, sulindac and flurbiprofen in rheumatoid arthritis.

A double-blind crossover trial was carried out in 24 patients to compare the effects of mefenamic acid, flurbiprofen, sulindac and placebo. Each drug was given for 2 weeks, the treatment sequence being randomized. Daily doses were 1500 mg mefenamic acid, 150 mg flurbiprofen or 150 mg sulindac. All of the active drugs were significantly superior to placebo in terms of pain score, patients' assessment, articular index of joint tenderness, and duration and severity of morning stiffness. There was improvement in grip strength compared with placebo, but the differences were not statistically significant with sulindac. There was slight reduction in joint circumference but this was only statistically significant in the right hand with flurbiprofen and sulindac. No significant differences were found in technetium uptake in knee joints. The three drugs appeared to be equally effective and tolerated, and no significant differences were noted.