Initial performance of Tesio hemodialysis catheters.

PURPOSE: This retrospective study was performed to investigate the authors' clinical observations that suggest that Tesio hemodialysis catheters may initially have suboptimal blood flow rates, which improve spontaneously after several hemodialysis treatment sessions. MATERIALS AND METHODS: Sixty Tesio twin hemodialysis catheters were placed in 49 patients during a 2-year period. Thirty twin catheters were placed by radiologists, and 30 were placed by surgeons. The catheter blood flow rates and catheter line pressures, which were recorded during each of the first five hemodialysis treatment sessions, were reviewed and analyzed to determine the performance of each catheter during the first five hemodialysis treatments. In addition, the authors compared the site of catheter placement and responsible service (surgery or radiology) using this catheter performance data. RESULTS: Twenty-six catheters (43%) provided adequate blood flow (250 mL/min) throughout the first five hemodialysis sessions. Twenty-six catheters (43%) had inadequate or variable blood flow rates, some of which improved without intervention. Eight catheters (13%) required an intervention before the first five hemodialysis sessions had been completed. Right-sided catheters performed better than left-sided catheters. There was no difference in performance between catheters placed by surgeons and those placed by radiologists. CONCLUSION: This investigation supports the authors' suspicion that some Tesio catheters may have inadequate initial performance but the blood flows can improve, without intervention, during the first five hemodialysis sessions/2 weeks of use.

Digital image subtraction of temporally sequential chest images for detection of interval change.

An automated digital image subtraction technique for temporally sequential chest images has been developed in order to aid radiologists in the detection of interval changes. A number of small regions of interest (ROIs) are selected automatically in the lung areas of two temporally sequential chest images. A local matching, based on a cross-correlation method, is performed on each pair of corresponding ROIs in order to determine shift values for the coordinates of two images. A proper warping of x,y coordinates is obtained by fitting two-dimensional polynomials to the distributions of shift values. One of the images is warped and then subtracted from the other. Forty six pairs of chest images (42 with interval changes and 4 without interval change) were processed using this method. The subtraction images were able to enhance various important interval changes, such as differences in the size of tumor masses, changes in heart size, and changes in pulmonary infiltrates or pleural effusions. Approximately 70% of the pairs showed reasonably good registration.