Parametric assessment of myocardial perfusion during interventional cardiac catheterization by means of X-ray densitometry — short — and long-term results

Haude, Michael; Brennecke, R.; Erbel, Raimund; Lang, Martin; Deutsch, Hans‐Peter; Renneisen, U.; Meyer, Jürgen

doi:10.1007/bf01833987

Cited by 4 publications

(1 citation statement)

References 17 publications

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“…In 89% of the ROI's the weighted mean of densograms was of good quality. In another study with 50 patients [15] the diagnostic value of some densitometric parameters was examined. Good values were achieved e.g.…”

Section: Discussionmentioning

confidence: 99%

Improving the applicability of myocardial densitometry and parametric imaging by extended automated densogram analysis

et al. 1995

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In clinical applications the analysis of X-ray contrast densograms acquired in regions of interest (ROI's) over the myocardium is disturbed by many complex factors. For this reason we acquire redundant densogram information for quality control before extracting densitometric parameters. In our approach, initially some stable measures of quality for densograms are used to lower the influence of poor quality densograms by a quality weighted averaging. For example a shape quality measure, Q1, is calculated using regions of optimal and minimal acceptable quality defined with respect to a prototype densogram. Not a few myocardial ROI's yield densograms that differ from single-source densograms (SSD's) due to e.g. superposition of different perfusion beds or the position of the ROI relative to the coronary sinus or stenoses. This might result in a densogram shape with oscillating or plateau behavior. For densograms of a such general shape many parameters defined in the usual way do not depend smoothly on the densogram values. The conventional definitions of some parameters (appearance time, rise time) are therefore extended for application to multi-maxima densograms as well as to SSD's. These new methods are evaluated using digitized clinical angiocardiograms and are applied to parametric imaging (pixeldensograms) in a slightly modified way. Taking into account the densogram quality, its shape and its origin results in a considerable improvement both for densitometry and parametric imaging of myocardial perfusion.

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Section: Discussionmentioning

confidence: 99%

Improving the applicability of myocardial densitometry and parametric imaging by extended automated densogram analysis

et al. 1995

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3D-reconstruction of coronary arteries in view of flow measurement

et al. 1992

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An angiographic method for measurement of absolute coronary blood flow in patients was developed. It is based on 3D-reconstruction of the left or right coronary tree from digitized biplane coronary cineangiograms. The apparatus is presently composed of a 35 mm cinefilm projector with a video camera and a 512 x 512 x 8 bits image array processor controlled by a VAX-11/750 computer. First, the parameters of the two angiographic projections are determined in form of two 4 x 3 matrices from a pair of cineframes showing a 4 cm cube bearing markers. The cube is filmed after the coronary injection, with unchanged geometric configuration. The coronary arteries of interest are then 3D-reconstructed from a pair of cineframes showing them fully opacified. This allows to compute the intravascular volumes needed for flow determination. In vitro experiments showed that the obtained volume are reasonably accurate. For the measurement of coronary flow, the concentration of contrast medium along the involved arteries is computed (in arbitrary units) from two cineframes taken one (or two) cardiac cycle after onset of the injection. This yields a 'concentration-distance' curve per artery. The volume of fluid (contrast medium mixed with blood) which flows into the arteries during this (or these two) cardiac cycle is determined by applying a concentration threshold to the obtained concentration-distance curves. Measurements performed on a constant flow model were satisfying. Preliminary measurements in 12 patients showed that flow values obtained angiographically into the left anterior descending coronary artery correlate well with the values measured simultaneously by thermodilution in the great cardiac vein (Qangio = 0.83 x Qthermo + 16.1 ml, r = 0.87, n = 29).

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Computer simulation of the propagation of contrast medium in a coronary artery during one cardiac cycle

et al. 1995

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In some angiographic methods for measurement of mean coronary flow in ml/min, a threshold is applied to 'concentration-distance' curves obtained from a constant rate injection by computing the intravascular contrast medium concentration along the main coronary branches. If the shape of the velocity profile would remain parabolic throughout the cardiac cycle, the correct threshold value would be '50% of the concentration at the injection site'. But, coronary flow being strongly pulsatile, the shape of the velocity profile must be expected to vary appreciably within the cardiac phase. In order to investigate if a single, appropriate threshold value nevertheless exists for a great variety of coronary flow pulses and velocity profiles, the spreading of contrast medium injected continuously in a tube perfused by a time varying flow Q(t) was studied by computer simulation. While the particular time courses of flow and velocity profile appear to be of secondary importance, the ratio 'injection rate to peak coronary flow' has a major impact. If it is equal to or greater than 1, a threshold value of 47% is the best choice. If the ratio is markedly less than 1, no appropriate threshold exists and use of the 47% threshold will result in considerable flow underestimations. This was fully confirmed by measurements of absolute coronary flow performed in patients.

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Parametric assessment of myocardial perfusion during interventional cardiac catheterization by means of X-ray densitometry — short — and long-term results

Cited by 4 publications

References 17 publications

Improving the applicability of myocardial densitometry and parametric imaging by extended automated densogram analysis

Improving the applicability of myocardial densitometry and parametric imaging by extended automated densogram analysis

3D-reconstruction of coronary arteries in view of flow measurement

Computer simulation of the propagation of contrast medium in a coronary artery during one cardiac cycle

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