0000000000035828
AUTHOR
U. Renneisen
Parametric assessment of myocardial perfusion by densitometric evaluation of digital subtraction coronary angiograms: a comparison with tomographic TL-201 scintigraphy results
Densitometric results about local myocardial perfusion are compared with those derived from a quantitative analysis of TL-201 single photon emission computer tomograms (TL-201 SPECT). Ten patients underwent conventional TL-201 SPECT at rest and after maximum bicycle stress and dipyridamole infusion the day prior to the investigation. SPECT was applied to provide improved spatial resolution for the detection of perfusion abnormalities. During the catheterization procedure four digital subtraction coronary angiograms were performed, two of the left and two of the right coronary artery both before and after pharmacologically induced hyperemia by intracoronary papaverine. The densitometric para…
Densitometry and parametric imaging with quality control
X-ray contrast image series of the myocardium were studied using the approaches of densitometry and parametric imaging accompanied by quality control. Contrast angiograms were digitized at six predefined phases of the heart cycle. For densitometry, regions of interest (ROIs) were defined semi-automatically for all phases. The resulting six densograms were summed up and weighted according to their quality determined by a measure. Previously validated parameters such as rise time were calculated. The enddiastolic images were only used for the calculation of color-coded parametric images accompanied by pixel-densogram-quality information. An observer gives a score for the perfusion of roughly …
New techniques for visualization of losses due to image compression in grayscale medical still images
To evaluate the visual influence of irreversible compression on medical images, changes of the images have to be visualized. The authors have explored alternative techniques to be used instead of the usual side-by-side comparison, where the information contained in both images is perceived in a single image, preserving the context between compression errors and image structures. Thus fast and easy comparison can be done. These techniques make use of the human ability to perceive information also in the dimensions of color, space, and time. A study was performed with JPEG-compressed coronary angiographic images. Changes in the resulting images for six compression factors from 7 to 30 were sc…
Parametric assessment of myocardial perfusion during interventional cardiac catheterization by means of X-ray densitometry-short-and long-term results.
X-ray densitometric evaluation of digital subtraction angiocardiograms allows an assessment of myocardial perfusion by means of the parameter 'MEAN RISE TIME' (MRT), defined as the time from the onset of local myocardial contrast medium opacification to the point of maximum opacification. Best results are obtained when the response of that parameter is compared before and after stimulation of coronary flow by papaverine. A prolongation of this parameter, especially after papaverine, was indicative of an impairment of myocardial perfusion, when compared to the results of TL-201 scintigraphy. In 50 patients with single vessel coronary artery disease the results of MRT pre and post papaverine …
Computerized estimation of quality standards for the X-ray densitometric assessment of myocardial perfusion
The densitometric evaluation of heart-phase-gated digital subtraction coronary angiograms derives different parameters which provide information about coronary blood flow, myocardial perfusion, and coronary flow reserve: appearance time, rise time, mean ascending time, and maximum intensity. The reliability and reproducibility of these measurements and of the derived parameters were investigated. Four digital subtraction coronary angiograms were obtained in ten patients, including two baseline measurements and two measurements under hyperemia induced by papaverine ic. Different reproducibility results were found for the parameters, depending on the heart phase of the densogram (diastolic be…
Determination of myocardial perfusion and coronary flow reserve by densitometric measurements: a selective classification of regions of interest
To evaluate the functional effect of a coronary artery stenosis on the dependent myocardium, digitized coronary angiograms (DCAs) were recorded. The DCAs, acquired during heart catheterization, provide information about myocardial perfusion and coronary flow reserve of areas supplied by this coronary artery. For each analysis the myocardium is separated into different regions of interest (ROIs); 16 ROIs in the distribution of the LCA and 8 ROIs for the RCA. In addition to that, the ROIs of the diseased vessels are divided into ROIs which are proximal, within and distal to the stenosis. Using a semiautomatic procedure, densograms are constructed from which the parameter rise time is calculat…