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Stähr, Peter; Rupprecht, Hans-Jürgen; Voigtländer, Thomas; Kearney, Peter; Erbel, Raimund; Koch, Lothar; Kraß, Stefan; Brennecke, Rüdiger; Meyer, Jürgen
doi: 10.1007/BF01797734pmid: 8993983
Background: Intravascular ultrasound (IVUS) permits quantitative assessment of the lumen diameter and area of coronary arteries. The experimental study was performed to evaluate the accuracy of diameter and area measurements.Methods and results: Lumen quantitation (lumen diameter D and cross-sectional area A) in lucite tubes (lumen diameter 2.5 to 5.7 mm, Plexiglasℳ) was performed using a mechanical IVUS system (HP console, 3.5F catheter, Boston Scientific, 30 MHz). The influence of fluid type (blood, water and saline solution), fluid temperature (20°C/37°C), catheter to catheter variation, gain setting and ultrasound frequency (12, 20 and 30 MHz) was determined. In blood at 20°C there was a constant deviation of the measured diameter from the true luminal diameter of −0.29 ± −0.04 mm (p<0.06). In water and saline solution at 20°C the mean deviation from true diameter was −0.21 ± −0.06 mm (p<0.06). At 37°C, the deviation in blood was greater than at 20° (−0.34 ± −0.02 mm) which is >10% in a 3mm tube (p<0.06). Three of the ten catheters tested in water at 20°C underestimated true diameter by more than −0.3 mm. The deviation from true diameter (5mm tube) with varying gain settings was −0.14 mm to −0.23 mm compared to −0.19 mm at standard settings (p>0.288). At 12 MHz diameter measured was over-estimated. The error in absolute area estimation increased with increasing diameter tested in blood at 37°C (−1.21 to −2,72mm2), whereas the relative error ([Measured Area-True Area]/True Area × 100 [%]) was more striking at smaller diameters (up to −25% in the 2.5 mm tube).Conclusion: Luminal diameters and areas are underestimated by this particular IVUS system. When IVUS imaging and measurements are made during coronary interventions this error should be taken into account with regard to appropriate sizing of the device and the assessment of the postprocedure result. Because systematic errors might also occur in other IVUS systems (not tested in this study), it is advisable to ensure that each system is validated prior to clinical use, especially when exact measurements are required.
Baur, L.; Schipperheyn, J.; Velde, E.; Wall, E.; Reiber, J.; Geest, R.; Dijkman, P.; Gerritsen, J.; Eck-Smit, B.; Voogd, P.; Bruschke, A.
doi: 10.1007/BF01797736pmid:
Kupferwasser, Iri; Mohr-Kahaly, Susanne; Menzel, Thomas; Spiecker, Martin; Dohmen, Guido; Mayer, Eckhard; Oelert, Hellmut; Erbel, Raimund; Meyer, Jürgen
doi: 10.1007/BF01797737pmid: 8993986
The aim of this study was the evaluation of the diagnostic potentials of transesophageal 3D-echocardiography in the determination of mitral valve stenosis. 54 patients were investigated by transthoracic and multiplane transesophageal echocardiography. In 41 patients cardiac catheterization was performed. 3D-echocardiographic data acquisition was performed by automatic transducer rotation at 2° increments over a span of 180°. The transesophageal probe was linked to an ultrasound unit and to a 3D-workstation capable of ECG- and respiration gated data acquisition, postprocessing and 2D/ 3D image reconstruction. The mitral valve was visualized in sequential cross-sectional planes out of the 3D data set. The spatial position of the planes was indicated in a reference image. In the cross-sectional plane with the narrowest part of the leaflets the orifice area was measured by planimetry. For topographic information a 3D view down from the top of the left atrium was reconstructed. Measurements were compared to conventional transthoracic planimetry, to Doppler-echocardiographic pressure half time and to invasive data. The mean difference to transthoracic planimetry, pressure half time and to invasive measurements were 0.3 ± 0.1 cm2, 0.2 ± 0.1 cm2 and 0.1 ± 0.1 cm2, respectively. Remarkable differences between the 3D- echocardiographic and the 2D- or Doppler- echocardiographic methods were observed in patients with severe calcification or aortic regurgitation. In 22% of the patients the 3D data set was not of diagnostic quality. New diagnostic information from a 3D view of the mitral valve could be obtained in 69% of the patients. Thus, although image quality is limited, 3D- echocardiography provides new topographic information in mitral valve stenosis. It allows the use of a new quantitative method, by which image plane positioning errors and flow-dependent calculation is avoided.
Dittrich, H.; Henneke, K.; Pohlmann, M.; Pongratz, G.; Bachmann, K.
doi: 10.1007/BF01797738pmid: 8993987
Several provocation maneuvers are described in hypertrophic cardiomyopathy to Doppler echocardiographically distinguish the obstructive from the non obstructive type. No data are available about the value of orthostasis testing in comparison with nitrate application in this disease. In this study, 16 consecutive patients with hypertrophic cardiomyopathy were examined. 11 patients with hypertrophic cardiomyopathy were classified as obstructive, 5 patients with hypertrophic cardiomyopathy as non obstructive. Normal left ventricular outflow tract velocities as detected by the Doppler method were defined as < 2,0 m/s.
Giesler, Martin; Göller, Veit; Pfob, Alexander; Bajtay, Dionyz; Kochs, Matthias; Hombach, Vinzenz; Grossmann, Georg
doi: 10.1007/BF01797739pmid: 8993988
Assessment of regurgitant flow by the flow convergence method is based on reading absolute velocities from color Doppler maps. Velocity overestimation by high pass filtering above 100 Hz has been reported. An extremely low filter, however, is inpracticable in patients. A ratio of pulse repetition frequency (PRF)/filter of 10/1 usually results in good quality color maps as judged visually. We studied in vitro the influence of PRF and filter on the absolute velocities within color maps of the flow convergence, keeping PRF/filter at 10/1. The color maps were also compared with computerized flow simulations.
Stiel, Georg; Schaps, Klaus-Peter; Lattermann, Andreas; Nienaber, Christoph
doi: 10.1007/BF01797740pmid: 8993989
In order to review the morphological criterion for an interventional procedure, diameter stenosis (%DS) of 226 coronary lesions in 200 patients undergoing elective coronary angiography with an option for ‘prima vista’ angioplasty (pPTCA), was assessed on-site by both visual ‘eye balling’ (EB) and independent digital quantitative coronary angiography (DQCA) by means of an angiographic workstation. Compared to DQCA, EB overestimated the %DS between 50 and 80% and accounted for the majority of discrepancies with overestimation up to 45%. Concordant estimates of %DS by both methods were observed in only 10 of the total of 226 stenotic segments; in 20 of 226 cases, EB underestimated %DS up to 20%. EB revealed a %DS ≥ 60% in 166 stenoses (73.4%), an estimate that led to subsequent pPTCA. However, only 119 (52.6%) of these lesions had a %DS ≥ 60% as assessed objectively by DQCA. With regard to the criterion for PTCA 47 of 166 performed pPTCA (28.3%) would not meet the indication criteria based on objective DQCA information. EB and DQCA (± 5%DS) had concordant results and criteria for pPTCA only in 103 of 166 coronary lesions (62.1%). These results lead to the conclusion that, on-site and on-line DQCA by an independent cardiologist eliminates both under- and overestimation of stenoses as seen with EB. DQCA supports immediate decision-making and appears necessary for reliable evaluation of coronary morphology in an interventional catheterization laboratory setting and may eventually ensure intraprocedural quality control.
doi: 10.1007/BF01797741pmid: 8993990
The limited resolution of any imaging system causes edge blurring of objects acquired with X-ray. In digital angiography, this effect combined with noise gives rise to systematic and random errors in the determination of vessel dimensions. The influence of bandwidth limitation on the estimation of tube diameter is established by a theoretical approach: it leads to over and underestimations of catheter and vessel diameter dimensions. Therefore a correction is proposed that counterbalances the point spread function (PSF) offset. The residual inaccuracy and the variability of measurement of phantom tubes are analyzed and evaluated in controlled conditions. Some of the parameters which govern their extent are identified: field-of-view, catheter size, concentration of contrast agent.
Doriot, Pierre; Dorsaz, Pierre; Dorsaz, Lidia; Chatelain, Pascal; Rutishauser, Wilhelm
doi: 10.1007/BF01797742pmid: 8993991
Under ideal conditions, densitometric measurement of a coronary arterial cross section in biplane angiographic images should result in nearly equal cross sectional areas for both planes. However, quite appreciable discrepancies have been found by some authors in patients. In this study, the role of inadequate spatial orientation of the vessel axes relatively to the x-rays was assessed by use of a 3D technique applied to 60 stenoses (45 pre PTCA and 15 post PTCA) in simultaneously acquired digital biplane coronary angiograms of 27 CAD patients. The 3D technique yields two radius values per projection directly in mm at any arterial cross section of interest. This was used to determine the areas Ar (in mm2) of the reference cross sections. As with catheter calibration, these cross sections were thus assumed to be more or less circular, but out-of-plane effects and errors due to a catheter diameter determination in pixels were avoided. The areas of the stenotic sections were then determined densitometrically (in mm2) from the two projections (1 and 2) according to As1=ArDs1/Dr1, resp. As2=ArDs2/Dr2, where Dr1, Dr2, Ds1 and Ds2 are the conventional densitometric areas of the reference and stenotic cross sections measured in planes 1 and 2. As expected, the areas As1 and As2 correlated only moderately: As2=0.92 As1+0.7 mm2, r=0.82, n=60, SEE=1.4 mm2. The 3D method also yielded the two spatial angles between the local vessel axis and the x-rays of both planes. These two angles were then used to correct each densitometric area for inadequate orientation. With the corrected densitometric areas As1c and As2c, the correlation improved to: As2c=1.05 As1c+0.03 mm2, r=0.93, n=60, SEE=0.8 mm2. Inadequate orientation of the cross sections in space thus appears to be an important factor of inaccuracy in densitometric measurements of stenotic cross sections in patients.
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After myocardial infarction, left ventricular volume and ejection fraction can be assessed by echocardiography, magnetic resonance imaging and radionuclide angiography to guide therapy and determine prognosis. Whether a measured parameter gives the same results irrespective of the method used and the observer who performs the analysis is only partly known. Intra-observer and inter-observer variability were determined for echo and magnetic resonance imaging. Left ventricular ejection fraction measured by these techniques was related to radionuclide angiograms performed in the same period. Intra-observer variability for both echo and MRI was low and in most instances below 5%. Inter-observer variability for the echo and MRI measurements were substantially higher than intra-observer variability. Comparison of the three imaging modalities revealed systematic differences. Therefore, in clinical studies, left ventricular volume and function parameters have to be measured with the same technique and by the same observer in qualified core laboratories.