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G Koning

Publications and source records attributed to G Koning.

At least 19 recordsLinked to original sources
PubMed2003

Homeopathically prepared gibberellic acid and barley seed germination.

The potentisation process by which homeopathic preparations are produced raises the concern that these medicines have placebo effects only, since they theoretically no longer contain active molecules of the diluted substance. Plant models offer a method of examining the efficacy of homeopathically prepared solutions. This study examined the effects of homeopathically prepared gibberellic acid (HGA3) on the germination performance of barley (Hordeum vulgare L.) seeds. The effect of HGA3 (4-200 cH) on seed germination rate and seedling development was compared to that of the most commonly used form of gibberellic acid (GA3), 0.5 g l(-1), and control (distilled water). The extent and type of response was dependent on the vigour level of the seedlot. Treating seeds from three vigour groups in HGA3 consistently resulted in larger seedlings. High-vigour seeds treated with HGA3 4, 30 and 200 cH germinated faster, and roots of medium-vigour seedlots treated in HGA3 15 cH were longer. Biphasic effects of HGA3 were also demonstrated. As a plant model, germinating barley seeds successfully demonstrated the ability of HGA3 to produce a biological response.

Germination↗
PubMed2001

Suitability of the Cordis Stabilizer marker guide wire for quantitative coronary angiography calibration: an in vitro and in vivo study.

Catheters usually are used for calibration purposes in quantitative coronary angiography (QCA). The systematic and random errors in these calibration factors (CFs) are dependent on the size and quality of the catheters and limited by out-of-plane magnification (OPM). Theoretically, a guide wire with evenly spaced marker bands would solve many of these potential problems. For this reason, we tested the Cordis Stabilizer marker wire, featuring 10 radiopaque platinum marker bands 15 mm apart, in in vitro and in vivo studies. To assess the effect of foreshortening, wires were positioned in a tube phantom; a centimeter grid was used as the gold standard. Radiographic images were acquired at 5-inch and 7-inch image-intensifier sizes, 512(2) and 1,024(2) matrix sizes and angulations from 0 degrees to 70 degrees in steps of 10 degrees. It was concluded that the relative errors in CFs are less than 7% if the foreshortening angles remain less than 20 degrees. In DICOM images of 15 patients, 65 measurements were taken after calibration on an 8F catheter and on a guide wire positioned in the coronary lesion. In all but two cases, the wire CFs were larger than the catheter CFs (relative difference, 24.7 +/- 19.6%). The measurements were divided into four groups: (I) no apparent OPM or foreshortening (n = 7), (II) only OPM (n = 4), (III) only foreshortening (n = 10), and (IV) the combination of both (n = 44). In group I (no OPM or foreshortening) the QCA results were similar using the guide wire or catheter as the calibration device (relative CF difference, 2.9% only). In group III the diameters were overestimated using the guide wire (obstruction diameter difference, 0.22 +/- 0.11 mm; reference diameter difference, 0.35 +/- 0.06 mm). For only OPM (group II) and the combination of OPM and foreshortening (group IV), the lesion length was underestimated on average by 2.4 mm using the catheter instead of the guide wire. In conclusion, if accurate assessment of the lesion length is important, the marker wire should be used for calibration purposes. For vessel diameter measurements, the conventional catheter calibration approach is the method of choice.

Angiography, Digital Subtraction↗
PubMed2000

American College of Cardiology/European Society of Cardiolgoy International Study of Angiographic Data Compression Phase II: the effects of varying JPEG data compression levels on the quantitative assessment of the degree of stenosis in digital coronary angiography. Joint Photographic Experts Group.

OBJECTIVES: This report describes whether lossy Joint Photographic Experts Group (UPEG) image compression/decompression has an effect on the quantitative assessment of vessel sizes by state-of-the-art quantitative coronary arteriography (QCA). BACKGROUND: The Digital Imaging and Communications in Medicine (DICOM) digital exchange standard for angiocardiography prescribes that images must be stored loss free, thereby limiting JPEG compression to a maximum ratio of 2:1. For practical purposes it would be desirable to increase the compression ratio (CR), which would lead to lossy image compression. METHODS: A series of 48 obstructed coronary segments were compressed/decompressed at CR 1:1 (uncompressed), 6:1, 10:1 and 16:1 and analyzed blindly and in random order using the QCA-CMS analytical software. Similar catheter and vessel start- and end-points were used within each image quartet, respectively. All measurements were repeated after several weeks using newly selected start- and end-points. Three different sub-analyses were carried out: the intra-observer, fixed inter-compression and variable inter-compression analyses, with increasing potential error sources, respectively. RESULTS: The intra-observer analysis showed significant systematic and random errors in the calibration factor at JPEG CR 10:1. The fixed inter-compression analysis demonstrated systematic errors in the calibration factor and recalculated vessel parameter results at CR 16:1 and for the random errors at CR 10:1 and 16:1. The variable inter-compression analysis presented systematic and random errors in the calibration factor and recalculated parameter results at CR 10:1 and 16:1. Any negative effect at CR 6:1 was found only for the calibration factor of the variable inter-compression analysis, which did not show up in the final vessel measurements. CONCLUSIONS: Compression ratios of 10:1 and 16:1 affected the QCA results negatively and therefore should not be used in clinical research studies.

Adult↗
PubMed2000

American College of Cardiology/ European Society of Cardiology international study of angiographic data compression phase II. The effects of varying JPEG data compression levels on the quantitative assessment of the degree of stenosis in digital coronary angiography.

OBJECTIVES: This report describes whether lossy Joint Photographic Experts Group (JPEG) image compression/decompression has an effect on the quantitative assessment of vessel sizes by state-of-the-art quantitative coronary arteriography (QCA). BACKGROUND: The Digital Imaging and Communications in Medicine (DICOM) digital exchange standard for angiocardiography prescribes that images must be stored loss free, thereby limiting JPEG compression to a maximum ratio of 2:1. For practical purposes it would be desirable to increase the compression ratio (CR), which would lead to lossy image compression. METHODS: A series of 48 obstructed coronary segments were compressed/decompressed at CR 1:1 (uncompressed), 6:1, 10:1 and 16:1 and analyzed blindly and in random order using the QCA-CMS analytical software. Similar catheter and vessel start- and end-points were used within each image quartet, respectively. All measurements were repeated after several weeks using newly selected start- and end-points. Three different sub-analyses were carried out: the intra-observer, fixed inter-compression and variable inter-compression analyses, with increasing potential error sources, respectively. RESULTS: The intra-observer analysis showed significant systematic and random errors in the calibration factor at JPEG CR 10:1. The fixed inter-compression analysis demonstrated systematic errors in the calibration factor and recalculated vessel parameter results at CR 16:1 and for the random errors at CR 10:1 and 16:1. The variable inter-compression analysis presented systematic and random errors in the calibration factor and recalculated parameter results at CR 10:1 and 16:1. Any negative effect at CR 6:1 was found only for the calibration factor of the variable inter-compression analysis, which did not show up in the final vessel measurements. CONCLUSIONS: Compression ratios of 10:1 and 16:1 affected the QCA results negatively and therefore should not be used in clinical research studies.

Cardiology↗
PubMed2000

Automated calibration in vascular X-ray images using the accurate localization of catheter marker bands.

RATIONALE AND OBJECTIVES: To develop a new automated calibration method for vessel measurements in vascular x-ray images. METHODS: Radiopaque marker bands mounted equidistantly on a small catheter were acquired in vitro at five image intensifier (II) sizes in x-ray projection images. The positions of the marker centers were detected by using a Hough transform and were computed at subpixel precision by using either a novel, iterative center-of-gravity approach (CGA) or a symmetry filter. Curve-fitting procedures were used to reject false-positive marker detections and to calculate intermarker distances. The calibration factor was calculated from the true marker distance and the average of the measured distances in pixels. Results were compared statistically with a grid calibration method, which was taken as the gold standard. A simulation study was performed to assess the influence of image noise on the CGA method. RESULTS: The iterative CGA method was convergent and faster than the symmetry-based technique. For four II sizes (17, 20, 25, and 31 cm), the results from the CGA method were not significantly different from the results obtained with grid calibration. For the II size of 38 cm, a significant difference (0.3% of the grid calibration factor) was found; however, this was caused by the quantification error in the image data and was not clinically relevant. In general, the performance of the CGA method improved with increasing signal-to-noise ratio. CONCLUSIONS: A practical new calibration method for small catheter sizes was developed and validated for quantitative vascular arteriography.

Algorithms↗
PubMed1999

Quantitative measurements in IVUS images.

IntraVascular UltraSound (IVUS) is a catheter-based technique which provides real-time high resolution tomographic images of both the lumen and arterial wall of a coronary segment, this in contrast to X-ray arteriography that provides a shadow image (luminogram) of the entire lumen. Nowadays the lumen and vessel parameters are measured manually, which is very time consuming and suffers from high inter- and intra-obser variability. With the continuing improvement in IVUS imaging, it is now feasible to develop and clinically apply automated methods of three-dimensional quantitative analysis of the coronary vessel morphology in an objective and reproducible way with automated contour detection techniques (QCU). Quantification, in 2D and 3D, as well as volume rendering for visualization of the IVUS images requires segmentation of the images (contour detection). The 3D contour detection system described in this article is based on the combination of contour detection in the transversal and sagital view. This article provides some of the basic principles of IVUS, the IVUS image quantification, the three-dimensional reconstruction and the contour detection and quantification in three-dimensional IVUS images.

Coronary Disease↗
PubMed1998

The effect of DICOM on QCA and clinical trials.

Almost without any exemption, new cardiac catheterization laboratories are entirely digital without 35 mm cinefilm as the storage medium. In addition, existing laboratories are increasingly converting to the digital world. Aside from the organizational aspects, this has significant implications for the daily diagnostic review process of the procedures, and for the quantitative analysis of selected frames by QCA. The DICOM standard has now been well accepted in the catheterization laboratories. In stead of mechanical cine projectors, a department must decide on so-called DICOM-Viewers or 'digital Tagarno's'. In this paper the effects of DICOM on image quality and therefore on the visual interpretation of these images, as well as on QCA are discussed. Since the digital images can be enhanced, these look sharper than the conventional cinefilm images. However, edge enhancement has an effect on QCA, reason why the digital data must be stored in raw format. With the enormous amounts of digital data produced in a catheterization laboratory, image compression is of great importance. Currently, an international study is being carried out to determine which compression level is still acceptable from a visual interpretation and QCA point of view. Finally, the implications of the digital era on clinical trials are discussed. One of the important conclusions is that one should be encouraged not to switch from cinefilm to digital in the course of a trial, while a mixed population from the beginning is no problem, as long as the proper statistical calculations are carried out. In conclusion, despite the fact that there are still a number of items to be checked and possibly modified in the standard, the existing DICOM standard has succeeded in bringing widespread utilization of QCA in cardiac angiography closer than ever.

Cardiac Catheterization↗
PubMed1997

Effect of lossy data compression on quantitative coronary measurements.

With the accepted use of (lossy) data compression at low compression factors (2, 3 and 4 on the Philips DCI), the question was posed whether higher lossy compression ratios can also be used without statistically affecting the results of quantitative coronary arteriography. In this study the influence of two data compression schemes (LOT and JPEG) at three different compression factors (5, 8 and 12) on coronary measurements was assessed with the Automated Coronary Analysis (ACA) package. A series of 30 original acquired digital images were compressed and decompressed at the different factors, and together with the original non-compressed images processed using the ACA package. In these images a total of 37 obstructed coronary segments were analyzed twice to assess the intra-observer variabilities in the obstruction and reference diameters and in the percent diameter stenosis. The results of the first and second measurements in each image were averaged, and from the differences in corresponding images with different compression ratios, the inter-compression variability was obtained. The results show that the intra-observer systematic errors in the absolute diameters are all small (< 0.07 mm), and statistically not significantly different. The intra-observer random errors for the compressed/decompressed series, however, were all larger (up to 0.21 mm) than for the original series (< 0.13 mm). Statistically significant differences in the intra-observer random errors were found for the JPEG compression scheme at a compression ratio of 5 and for the LOT scheme at a compression ratio of 12. The inter-compression systematic errors in the absolute diameter measurements were also small (< 0.07 mm) and not significant, while the random errors were found to be high in the range between 0.23 mm and 0.31 mm. Given the higher intra-observer variabilities for the compressed/decompressed image series as compared to original images, and the fact that all inter-compression variabilities were found to be so high, we must conclude that the higher compression ratios affect the results of QCA in a negative sense. In conclusion, the use of lossy data compression with JPEG or LOT compression schemes at ratios 5, 8 and 12 must be discouraged for QCA.

Algorithms↗
PubMed1996

Comparisons of angiographic core laboratory analyses of phantom and clinical images: interlaboratory variability.

Centralized, quantitative coronary analysis (QCA) has become the standard for determining change in coronary anatomy in clinical investigations. QCA systems and laboratory methods, however, vary among core facilities, and analysis variability among angiographic core laboratories (ACL) has not be studied. We evaluated QCA accuracy and variability among active ACL, using differing QCA systems by comparing analyses of phantom and clinical cinefilm images. Automated, unedited analyses were performed on images of 11 plexiglass phantom lumens (0.67-5.05 mm) acquired under varying radiographic conditions. Analysis differences from actual luminal diameters ranged widely (+0.42 - (-)0.45 mm) among ACL. Measurement of diameters < 1.0 mm were overestimated and diameters > 3.0 mm were underestimated. Measurements of midrange diameters (> 1.0 mm and < 3.0 mm) were most comparable among ACL (93% within +/- 0.2 mm). Clinical image analysis was performed using differing QCA systems and laboratory methodology on 11 randomly selected study films. Comparative analyses revealed significant variability between laboratories in the assessment of minimal lumen diameter (0.22 +/- 0.38 mm P < 0.05). These data describe analysis variability among ACL and demonstrate a need for establishing ACL performance standards.

Clinical Laboratory Techniques↗
PubMed1996

Inaccuracy of quantitative coronary arteriography when analyzed from S-VHS videotape.

In the transition period between 35-mm cinefilm as the medium for coronary arteriographic data and digital media such as CD-R, S-VHS videotape has been used both as an exchange and store medium, and for quantitative coronary arteriographic (QCA) studies. To determine the extent to which S-VHS video tape affects QCA measurements, an X-ray phantom study was completed. A plexiglass phantom with 12 straight circular tubes (0.51-5.00 mm in diameter) filled with contrast medium was recorded under clinical conditions using both the 5" and 7" modes of the image intensifier with the phantom tubes positioned horizontally as well as vertically in the field of view. The digitally acquired images were recorded on S-VHS tape without any image enhancement (raw data) and with default image enhancement. Video frames were then selected on a professional VCR such that individual tubes were positioned in the center of the field of view and digitized (512(2) x 8 bits) with a high-quality frame grabber onto a QCA workstation. The contours along the individual tubes were defined using previously validated automated contour detection techniques. For each tube, an average diameter (mm) and a standard deviation (mm) were calculated. Calibration was based on a cm-grid acquired at the same geometry as the phantom. Due to the poor signal-to-noise ratio and the limited bandwidth of the S-VHS video tape, the following objective observations were made: 1) large overestimations (up to 0.87 mm) occur for tube sizes below 1 mm for vertically positioned tubes; 2) random errors in measurements are much larger for vertically positioned tubes (0.36 mm, 7" II) than for horizontally positioned tubes (0.17 mm, 7" II); and 3) little differences in results between enhanced and nonenhanced images were found due to these deteriorating factors. In conclusion, S-VHS video tape is unacceptable for QCA and should be excluded from quantitative angiographic clinical trials.

Coronary Angiography↗
PubMed1996

Left ventricular regression equations from single plane cine and digital X-ray ventriculograms revisited.

For the assessment of left ventricular volume from X-ray ventriculograms, widely known regression equations are used to correct for the irregular shape of the left ventricular lumen and the presence of the papillary muscles and trabeculations. These regression equations were derived in the late nineteen sixties and seventies. With all the changes in X-ray technology that have taken place over the past 20-30 years, the question was raised whether these regression equations were still valid. Therefore, 23 left ventricular casts of known volume were imaged in RAO20, RAO30 and RAO40 angiographic views and recorded on 35 mm cinefilm as well as in digital format. All the frames were traced manually by two observers and the volumes calculated by the Area Length and Simpson Rule approaches. The following conclusions could be drawn: inter- and intra-observer variations were small (systematic differences < 1.5 ml; random differences < 2.9 ml) and statistically not significant; the regression equations are virtually the same for the RAO20, RAO30 and RAO40 views under the different circumstances; the Area Length method was associated with slightly smaller values for the standard-error-of-the-estimate (SEE) suggesting a slight preference for this approach versus the Simpson Rule; significant differences were found between the cinefilm and digital regression equations; and the following new regression equations are proposed, which indeed differ significantly from the earliest proposals and less from the monoplane formulas proposed by Kennedy & Lange in the 1970s: [table: see text]

Angiography, Digital Subtraction↗
PubMed1995

Effect of data compression on quantitative coronary measurements.

Digital coronary and left ventricular angiography demand high transfer rates and very large data storage if all the clinical data are to be achieved. If appropriate compression schemes were available without compromising the quality and resolution of the image data, such demands could be lessened. In this study we compared the influence of different compression factors of the Adaptive Real Time Image Compression (ARTIC) scheme used on the Philips DCI-SX systems on coronary measurements assessed with the Automated Coronary Analysis (ACA) package. Loss-free acquired images of size 512(2) x 8 bits, which had been stored digitally on tape, were reloaded into the DCI with compression factors of 2, 3, and 4; only the factor 2 is loss free. To evaluate the effect of the different data compressions on the accuracy of the measurements, the diameters of a vessel phantom (tube sizes ranging from 0.687 to 5.062 mm) were determined. To evaluate the reproducibility of the results, the intraobserver variability was determined for the different compression factors from 40 coronary obstructions. The differences in the reference diameter measurements of the vessel phantom were -0.03 +/- 0.06 mm, 0.01 +/- 0.07 mm, and 0.04 +/- 0.08 mm for the compression factors 2 (loss free), 3, and 4, respectively. The results were not statistically significantly different. The intraobserver variabilities in the obstruction diameter measurements of the coronary obstructions were -0.04 +/- 0.13 mm, 0.00 +/- 0.14 mm, and 0.02 +/- 0.13 mm for the compression factors 2, 3 and 4, respectively. The intraobserver variabilities in the reference diameter measurements were -0.02 +/- 0.12 mm, 0.01 +/- 0.09 mm, and 0.03 +/- 0.09 mm for the compression factors 2, 3, and 4, respectively. The intraobserver variabilities of the percent diameter stenosis were 0.96 +/- 4.19%, -0.01 +/- 4.88% and -0.04 +/- 4.68% for the compression factors 2, 3, and 4, respectively. None of these differences were statistically significant. Both from a qualitative and quantitative point of view, data compression factors 3 and 4 are acceptable in digital coronary arteriography.

Coronary Angiography↗
PubMed1993

Accuracy and precision of quantitative digital coronary arteriography: observer-, short-, and medium-term variabilities.

Coronary arteriograms are increasingly acquired and stored in digital format, which allows instantaneous review of the pictorial data during the cardiac catheterization procedure. To support the angiographer in choosing the optimal sizes of the recanalization devices and studying the efficacy of the recanalization procedures, we have developed a new analytical software package (Automated Coronary Analysis = ACA) on the Philips DCI (-SX) digital cardiac imaging system. The ACA-package allows the objective and reproducible assessment of the morphologic and functional severity of coronary obstructions. Required user interaction is limited to the definition of the start and end points of the coronary segment to be analyzed. Automated contour detection is based on the use of first and second derivative functions along scanlines perpendicular to the automatically computed vessel pathline in the first iteration and perpendicular to the initial contours in the second iteration. These derivative functions have been modified based on the line spread function of the X-ray imaging chain, which is of particular importance for the accurate measurement of small vessel sizes. Phantom studies have indeed demonstrated that vessel sizes down to 0.66 mm can be measured accurately and reproducibly. Inter- and intraobserver variability studies have demonstrated a variability in the obstruction diameter of 0.11 mm and 0.10 mm, respectively, and in the percent diameter stenosis of 5.64% and 3.18%, respectively. These variability studies have been extended to short-term studies with repeated acquisition in the same angiographic views after 5 min and to medium-term studies with repeated acquisition in the initial angiographic views at the end of the catheterization procedures. With these standardized repeated acquisition and analysis procedures, the variabilities in the obstruction diameters increased to 0.19 and 0.18 mm, respectively, and remained below 6% in the percent diameter stenosis (5.61% and 5.28%, respectively). With an analysis time of approximately 15 sec on the DCI-SX, an efficient tool is now available in the catheterization laboratory for the objective and reproducible assessment of vessel dimensions and changes therein as a result of recanalization procedures.

Coronary Angiography↗
PubMed1992

Angiographic assessment of dimensions of 6F and 7F Mallinckrodt Softouch coronary contrast catheters from digital and cine arteriograms.

Coronary contrast catheters are almost exclusively used for calibration purposes in quantitative coronary arteriography. In this study we have assessed the suitability of new 6F and 7F Mallinckrodt nylon catheter with Softouch tip with improved imaging specifications for such calibration purposes both from digital and cinefilm images using new analytical QCA-software packages (Philips DCI/ACA and Medis CMS). The average signed differences between the angiographically measured dimensions at 100% contrast fillings and acquired at 3 different kV-levels (60, 75 and 90 kV) were -3.3% and 0.6% for the 6F and 7F catheter tips, respectively as measured with the ACA-package on digital images, and -0.4% and 2.1%, respectively, as measured with the CMS-system on cinefilm images. The pooled standard deviations were 0.102 mm and 0.107 mm for the 6F and 7F catheter tips, respectively, as measured with the ACA-package, and 0.080 mm and 0.083 mm, as measured with the CMS-system. The deviations for the nylon shafts were much larger. It became also clear that neither the filling of the catheters, nor the kV-level used, had any appreciable effect on the measurement accuracy for the Softouch tips, which facilitates the frame selection in QCA-studies. From these data it can be concluded that the nontapering parts of the 6F and 7F Mallinckrodt Softouch tips are very well suitable for QCA calibration purposes, but that the nylon shafts are not.

Calibration↗
PubMed1991

Advantages and limitations of two software calipers in quantitative coronary arteriography.

Software calipers allowing the measurement of the distances between pairs of manually defined picture elements in digitized images may be useful tools for a rapid assessment of the morphology of coronary vessels, e.g. for choosing the appropriate balloon or stent sizes before or during cardiac intervention procedures. In this paper we have studied extensively the advantages and limitations of two manual software calipers--one developed for a PC-based cinefilm analysis workstation, the other for the Philips DCI system. Based on analyses of a perspex vessel phantom with 17 sectors of known size filled with different concentrations (50 and 100%) of the contrast agent and acquired at two kV-levels (68 and 92 kV), it was found that the cinefilm approach is characterized by a very small overall (averaged over te data from three observers) systematic overestimation of 0.03 mm, and the DCI system by a systematic underestimation of 0.07 mm; the worst case accuracy value for an individual observer on frames with 100% contrast dye concentration was 0.20 mm for cinefilm, and -0.34 mm for the DCI, respectively. The overall variabilities in the measurements (precision) were almost identical for the two approaches (overall 0.07 and 0.08 mm for the cinefilm and digital approaches, respectively, and worst case for individual observers on the 100% contrast frames, 0.16 and 0.13 mm, respectively. Inverting the images (bright or dark contrast containing structures) of the phantom at 100% contrast concentration and acquired at 62 kV had no significant effect on the results obtained with the cinefilm analysis system (overall accurary -0.12 mm for both situations), whereas it had on the results from the DCI system (overall accuracies -0.29 (dark vessels on bright background) and -0.08 mm (bright vessels on dark background), respectively). Enhancing the digital images on the DCI with unsharp masking techniques did not significantly influence the measurement accuracy and precision. Finally, it was found that woven dacron, polyurethane and polyvinylchloride catheters filled with 100% contrast dye can be measured with an overall accuracy of better than 0.13 mm on the DCI system. On the PC-based system the woven dacron and polyvinylchloride catheters would result in an overall accuracy better than 0.17 mm, and the polyurethane catheter better than 0.30 mm. The evaluation study has made clear that the nylon catheter should not be applied in QCA-studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Catheterization↗
PubMed1990

Usefulness of digital angiography in the assessment of left ventricular ejection fraction.

With modern digital cardiac systems the image data are digitized on-line and in real-time, allowing the replay and subsequent interpretation and analysis during or directly after the cardiac catheterization procedure. In this study we have evaluated the advantages and limitations of a manual tracing technique for left ventricular digital angiograms on the Phillips DCI system. Thirty-three patients who were catheterized for suspected coronary artery disease were studied. The manual tracings were performed by a senior cardiologist and an experienced function-analyst. It was found that the short- and long-term intraobserver variabilities in the assessment of the global ejection fraction were very small; short-term mean difference +/- standard deviation (correlation coefficient): 0.5 +/- 2.7 (r = 0.97) global EF%-units; long term; 0.7 +/- 2.7 (r = 0.96) EF%-units. The interobserver variabilities (5.1 +/- 4.8 (r = 0.93) EF%-units) were slightly higher than the intraobserver variabilities. A decrease by 25% in the amount of contrast medium administered did not significantly influence the variabilities in the contour tracings, which would suggest the use of smaller doses. At the average, the cardiologist and the function-analyst required 6 and 11 min of analysis time for a left ventricular study, respectively, emphasizing the need for further developments towards automated contour detection. Finally, an excellent correlation was found with a standard off-line cinefilm analysis procedure. Thus, it may be concluded that quantitative digital left ventricular angiography based on manual tracing of the outlines performed immediately following the cardiac catheterization (post-processing) is feasible as a routine procedure for the assessment of left ventricular function.

Aged↗