Comparison of multiecho postprocessing schemes for SWI with use of linear and nonlinear mask functions.

BACKGROUND AND PURPOSE: SWI is an MR technique conventionally implemented with single-echo gradient-echo data. The purpose of this study was to compare single-echo SWI processing and 2 multiecho SWI processing schemes: postaverage, where an SWI image is created for each echo and then averaged to create a single volume; and frequency-based, where a SWI image is generated from an average frequency image. Linear and nonlinear mask functions were investigated for all 3 processing schemes. MATERIALS AND METHODS: Comprehensive optimizations were performed. Single and multigradient-echo data were acquired at 3T in 10 volunteers. Contrast-to-noise ratio was measured in various structures. Visibilities of the same structures were ranked in different SWI images by trained raters. RESULTS: When image evaluation was based on measurements of contrast-to-noise ratio, the nonlinear mask and frequency-based scheme were superior. However, when image evaluation was based on ranks of qualitative visibility, the linear mask and postaverage scheme were superior. Although the nonlinear mask and frequency-based scheme allow increased contrast of paramagnetic perturbers such as the globus pallidus, periventricular veins, red nucleus, and subthalamic nucleus, they do not necessarily increase the information content of the image; rather, they result in a harsh contrast that is visually unpleasing to radiologists and wherein more subtle structure is relatively less apparent. CONCLUSIONS: Linearly masked postaverage SWI is the recommended implementation of multiecho SWI for radiologic use; however, nonlinearly masked frequency-based SWI may have use in computer-based segmentation or registration.

Influence of prolonged hospitalization on overall bed occupancy: a five-year single-centre study.

BACKGROUND: Effective bed use is crucial to an efficient NHS. Current targets suggest a decrease in mean occupancy as the most appropriate method of improving overall efficiency. The elderly and those suffering from complex medical problems are thought to account for a high proportion of overall bed occupancy. AIM: To assess the effect of prolonged hospital stay (>100 days) on overall bed occupancy in a modern teaching hospital. DESIGN: Retrospective analysis. METHODS: Analysis of all admission episodes (n = 117,178) over a five-year period in a large teaching hospital in a single UK region, serving a population of approximately 200,000. A logistic regression multi-factorial model was used to assess the effect of demographic and diagnostic variables on duration of stay. RESULTS: A prolonged stay (>100 days) was seen in 648 admission episodes (0.6%). These accounted for 11% of the overall bed occupancy over the 5-year period. Excluding all prolonged admission episodes from our analysis made no difference to the overall median length of stay. DISCUSSION: Prolonged hospitalizations have a significant impact on bed occupancy. Targeting these very long (>100 days) hospital stays may better improve overall efficiency, compared to targeting mean or median length of stay.

From hard copy to computer integration: developing clinical indicators for quality improvement.

The Clinical Indicator Workbook is a computerized tool that allows users to develop measures of healthcare quality. The electronic workbook, which includes selected clinical indicators to measure various aspects of patient care and teaching examples, was developed by using a major word processing package and uses a point-and-click feature. Its distribution and installation are managed by a program that enables users to select one of three options: (a) installation of the required files and indicator documents, (b) duplication of material on two diskettes for future distribution within the user's facility, and (c) on-line help. Once the workbook is installed, users are able to copy and customize the indicators for use with interdisciplinary teams in clinical settings. A survey of initial users, who are, for the most part, quality managers in the Veterans Affairs system, indicated that they are satisfied with this tool overall.