Changes in CT utilization between 1981 and 1984: implications for Medicare payment for MR imaging under the prospective payment system

Methamphetamine-induced dopaminergic neurotoxicity as a model of Parkinson's disease

Parkinson's disease (PD) is a progressive neurodegenerative disease with a high prevalence, approximately 1 % in the elderly population. Numerous studies have demonstrated that methamphetamine (MA) intoxication caused the neurological deficits and nigrostriatal damage seen in Parkinsonian conditions, and subsequent rodent studies have found that neurotoxic binge administration of MA reproduced PD-like features, in terms of its symptomatology and pathology. Several anti-Parkinsonian medications have been shown to attenuate the motor impairments and dopaminergic damage induced by MA. In addition, it has been recognized that mitochondrial dysfunction, oxidative stress, pro-apoptosis, proteasomal/autophagic impairment, and neuroinflammation play important roles in inducing MA neurotoxicity. Importantly, MA neurotoxicity has been shown to share a common mechanism of dopaminergic toxicity with that of PD pathogenesis. This review describes the major findings on the neuropathological features and underlying neurotoxic mechanisms induced by MA and compares them with Parkinsonian pathogenesis. Taken together, it is suggested that neurotoxic binge-type administration of MA in rodents is a valid animal model for PD that may provide knowledge on the neuropathogenesis of PD.

Deciding to buy expensive technology. The case of biliary lithotripsy

Acquiring expensive, new medical technology requires an evaluation of the efficacy and effectiveness, safety, profitability, feasibility, and risk of a project in the context of the hospital's social responsibility and institutional strategy. A case study of the decision to bring biliary lithotripsy to Strong Memorial Hospital illustrates how these criteria offer managers a coherent approach to difficult and consequential decisions about acquiring medical technology.

Integrating technology assessment and medical practice evaluation into hospital operations

The Johns Hopkins Program for Medical Technology and Practice Assessment, established in 1986, assesses the clinical efficacy, safety, and cost of specific technologies; evaluates the costs and benefits of alternative approaches to management of clinical problems; and examines the clinical and economic impact of health care program innovations. For example, program faculty have conducted analyses of clinical economic, and health policy issues related to radiographic contrast media. The director of the program chairs a committee that formulates guidelines for the appropriate use of low-osmolality contrast media and that will develop a mechanism to ensure compliance with guidelines. Program faculty are currently studying variations in the pre-, intra-, and postoperative management of patients with cataract and the relationship between such variations and outcomes. Faculty are also attempting to develop an improved mechanism for paying health maintenance organizations that enroll Medicare beneficiaries. Program activities have had a direct impact on decision making within the Johns Hopkins Health System.

Clinical utility of partial flip angle T2-weighted spin-echo imaging of the brain

To assess the clinical usefulness of partial flip angle (PFA) spin-echo (SE) brain imaging, a total of eighty patients were examined with both conventional double echo T2-weighted SE (2500/30, 80/90 degrees/one excitation) and PFA double echo SE (1200/30, 70/45 degrees/two excitations) on 2.0T system. Two comparative studies were performed: (1) in 65 patients PFA SE technique was compared with conventional SE without flow compensating gradients, and (2) in 15 patients the former was compared with the latter with flow compensating gradients. Imaging time was nearly identical in each sequence. In both studies we found that PFA T2-weighted SE images were almost identical to those obtained with the conventional SE technique in the contrast characteristics and the detection rate of the abnormalities (100%, 85/85 lesions), and more importantly, PFA SE revealed few flow artifacts in the brain stem, temporal lobes and basal ganglia which were frequently seen on conventional SE without flow compensating gradients. Additionally, PFA SE images demonstrated no suppression of CSF flow void in the aqueduct which was commonly seen on conventional SE with flow compensating gradients. In overall image quality, the PFA SE images, particularly the second echo images, were almost comparable with those of conventional SE with flow compensating gradients. A flip angle of 45 degrees seems to be close to Ernst angle, the angle at which maximum signal occurs, for a given TR of 1200 msec for CSF and most of the abnormalities containing higher water content.(ABSTRACT TRUNCATED AT 250 WORDS)