PubMed · 2674922
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E D Vlachogianni. 1989. Cardiovascular function during sleep apnoeas.. https://doi.org/10.1136/pgmj.65.760.67
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Over the last several years, cardiovascular MRI has benefited from a number of technical advances which have improved routine clinical imaging techniques. As a result, MRI is now well positioned to realize its longstanding promise of becoming the comprehensive cardiac imaging test of choice in many clinical settings. This may be achieved using a combination of basic advanced techniques. In this overview, the basic cardiac MRI techniques which are clinically useful are reviewed, and the recent technical advances which are clinically promising are described. These advances include routine black blood and cine bright blood techniques that are high speed (<10s per black blood image or cine slice), multislice whole heart perfusion imaging methods, and recently emerging real-time imaging methodologies. J Magn. Reson. Imaging 1999;10:590-601.
Dynamic nuclear medicine studies can generate large quantities of data, and their analysis consists essentially of a reduction of these data to a small number of relevant parameters which will assist in clinical decision making. This review examines some of the mathematical techniques that have been used in the process of data reduction and attempts to explain the principles behind their application. It particularly identifies the techniques that have stood the test of time and demonstrated their usefulness, many of which are now available as standard tools on nuclear medicine processing computers. These include curve processing tools such as smoothing, fitting and factor analysis, as well as tools based on empirical models, such as the Patlak/Rutland plot and deconvolution. Compartmental models and vascular models are also examined and the review finishes with a summary of some functional images and condensed images. It is concluded that an appreciation of the principles and limitations of these mathematical tools is valuable for their correct usage and interpretation of the results produced.
BACKGROUND: Despite technological advances in dialysis equipment, the morbidity and quality of life of uraemic patients undergoing regular haemodialytic treatment are still severely affected by acute intradialytic complications possibly related to the treatment itself. Cardiovascular instability still affects >30% of dialytic sessions and, although its pathogenesis is multifactorial, dialysate sodium concentration (and, consequently, intradialytic sodium removal) is one of the main factors affecting intradialytic hypotension. Convective treatment modalities and so-called biocompatible membranes increasingly are recognized as improving acute and particularly chronic dialytic complications because a number of the pathways activated in patients during dialysis with 'bioincompatible' membranes have the potential to produce many side effects. METHODS: The main clinical studies are reviewed to highlight the advantages of on-line monitoring and convective modalities on acute intradialytic symptoms. RESULTS: The conductivity kinetic model has been shown to be a reliable and inexpensive method of matching intradialytic sodium removal and interdialytic load. By applying this model to patients prone to dialysis hypotension, a smaller reduction in intradialytic systolic blood pressure has been observed, without any change in dialysate and reinfusate sodium concentrations or dry body weight. Furthermore, a new model of haemodialysis potassium removal based on a decreasing intradialytic potassium concentration and a constant plasma-dialysate potassium gradient is capable of reducing the arrhythmogenic effect of standard haemodialysis. Despite the proven biological superiority of biocompatible membranes, there is no definitive evidence that membrane biocompatibility and/or flux lead to a decrease in acute intradialytic clinical symptoms. CONCLUSIONS: On-line monitoring of intradialytic sodium removal and the potassium gradient is capable of reducing intradialytic hypotension and the arrhythmogenic effect of haemodialysis, and thus having a considerable clinical impact on acute intradialysis complications. As far as the effects of biocompatibility and/or flux on the incidence of acute intradialytic clinical symptoms are concerned, further trials involving a sicker patient population with higher prevalence of intradialytic hypotension are needed in order to achieve statistical power.