PubMed · 14173438
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H BERGHAUS, T LAUBENBERGER. 1964. [PERIPROSTATIC SERIAL PHLEBOGRAPHY].. https://pubmed.ncbi.nlm.nih.gov/14173438/
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Screening and diagnostic tests are important in disease prevention or control. The predictive values of positive and negative (PPV and NPV) test results are two of four operational characteristics of a screening test. We review an existing method based on the generalized estimating equation (GEE) methodology for comparing predictive values from the same sample of subjects and propose two Wald test statistics derived from the weighted least squares (WLS) method for the analysis of categorical data. Using these results, we propose sample size calculation formulae for this problem. Simulation studies are conducted to compare the performances of the two Wald test statistics (one based on the difference of two PPVs or NPVs, another based on the logarithm of the ratio of two PPVs or NPVs) and the score/Wald test statistic derived from GEE. We recommend using the difference-based WLS approach.
The general design of catheters is bound by many needs. Angiographic catheters must be rigid enough to be torquable and to maintain lumen structural integrity, but also flexible enough to bend with the curves of a blood vessel. They should cause minimal tissue damage; avoid biocompatibility-related complications, and be reliable over time. This study proposes a new testing approach to clearly identify the flexural rigidity of catheters by using a buckling test to evaluate the peak compressive load. This study also tests several angiographic catheters for axial and torsional rigidity. Seven different catheters used for short-term procedures, with and without reinforcement and of various sizes, were evaluated as a preliminary evaluation of test methods for future in vitro testing of catheters; it was found that the buckling test works very well and provides repeatable results.
PURPOSE: A microangiographical technique is described, which allows visualization of small and capillary blood vessels and quantification of fasciocutaneous blood vessels by means of digital computer analysis in very small laboratory animals. MATERIALS AND METHODS: The left carotid artery of 20 nu/nu mice was cannulated (26 gauge) and a mixture of gelatin, bariumsulfate, and green ink was injected according to standardized protocol. Fasciocutaneous blood vessels were visualized by digital mammography and analyzed for vessel length and vessel surface area as standardized units [SU] by computer program. RESULTS: With the described microangiography method, fasciocutaneous blood vessels down to capillary size level can be clearly visualized. Regions of interest (ROIs) can be defined and the containing vascular network quantified. Comparable results may be obtained by calculating the microvascular area index (MAI) and the microvascular length index (MLI), related to the ROIs size. Identical ROIs showed a high reproducibility for measured [SU] < 0.01 +/- 0.0012%. CONCLUSION: Combining microsurgical techniques, pharmacological knowledge, and modern digital image technology, we were able to visualize small and capillary blood vessels even in small laboratory animals. By using our own computer analytical program, quantification of vessels was reliable, highly reproducible, and fast.