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  • 1
    Electronic Resource
    Electronic Resource
    On a conjecture of gross on special values ofL-functions (1989)
    Springer
    Mathematische Zeitschrift 201 (1989), S. 391-400 
    Details
    ISSN: 1432-1823
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01214904
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Enhanced methods for visualizing myocardial perfusion with peripheral venous injection of Levovist®: Application of triggered harmonic imaging and triggered harmonic power Doppler imaging techniques (2000)
    Springer
    The international journal of cardiovascular imaging 16 (2000), S. 233-246 
    Details
    ISSN: 1573-0743
    Keywords: harmonic imaging ; microbubbles ; myocardial contrast echocardiography ; peripheral venous injection ; power Doppler
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Objectives:The purpose of this study was to determine whether triggered harmonic imaging (THI) or triggered harmonic power Doppler imaging (THPDI) could obtain the myocardial contrast enhancement using peripheral venous injection of a first generation echocardiographic contrast agent, Levovist®. Methods:In a phantom model, we examined the influence of an acoustic power, harmonic filters, transmitted frequencies and focus positions of transducer on Levovist®. Then fundamental, harmonic or harmonic power Doppler imaging were performed with ECG-triggered imaging in eight closed-chest dogs using bolus injection of Levovist®. Results:In a phantom model, the highest transmission power (Mechanical index 1.6), a medium harmonic filter and a focus position (6 cm) resulted in the best enhanced contrast in both THI and THPDI. Furthermore, higher pulse repetition frequency (5500 Hz) of harmonic power Doppler made clearer enhancement. In animal models, we could not observe the apparent myocardial contrast using triggered fundamental imaging, and the intensity of each region of interest (ROI) of myocardium had not changed significantly. However, homogeneous myocardial contrast could be obtained using THI, which was conditioned on the highest transmission power, a medium harmonic filter same as the phantom model, at a lower transmitted frequency (1.8 MHz) and a focus position, which were located in the middle portion of the left ventricle. The peak intensity of each ROI increased significantly in a gray level. Furthermore, THPDI caused emphasized myocardial contrast visually. Conclusions:These results indicate that THI and THPDI produce obvious MCE using peripheral venous injection of Levovist®.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026592629450
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  • 3
    Electronic Resource
    Electronic Resource
    Wall composition in intravascular ultrasound layered appearance of human coronary artery (1996)
    Springer
    Heart and vessels 11 (1996), S. 152-159 
    Details
    ISSN: 1615-2573
    Keywords: Intravascular ultrasound ; Coronary atherosclerosis ; Layered appearance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary To evaluate the impact of histological factors on the appearance of the wall of the coronary artery by intravascular ultrasound (IVUS), we performed an in vitro study of 34 coronary artery segments from eight autopsied patients. We assumed the coronary cross section to be divided into four equal parts, and assessed the quadrants with maximal and minimal wall thickness by IVUS (30MHz; 4.3Fr; 1 800rpm) and by a histological study. The histological layer thickness and composition were also evaluated in terms of their contribution to the appearance of the ultrasound layer. Fifty-eight quadrants were clearly visible on ultrasound. A threelayered appearance, with inner echogenic, subjacent sonolucent, and outer echogenic layers, was observed in 32 quadrants, while 26 quadrants showed a two-layered appearance, with inner and outer echogenic layers. The thickness of the inner echogenic layer (0.77 ± 0.38mm) was moderately correlated with the intimal thickness (0.51 ± 0.45mm;r = 0.85, standard error of estimate [SEE] = 0.24 mm); however, the correlation was significantly improved when the thickness of the inner echogenic plus sonolucent layers (0.89 ± 0.47mm) was compared with that of the intima plus media (0.69 ± 0.47 mm;r = 0.94, SEE = 0.15 mm;P = 0.012 between the coefficients). Discriminant analysis showed that intimal hyalinization, associated with intimal thickening, was strongly related to the presence of the three-layered appearance on IVUS (F to enter 40.0,P 〈 0.0001). These results indicate that the ultrasound layered appearance of human coronary arteries varies with histological alterations. We suggest that the thickness of the inner echogenic plus sonolucent layers on IVUS represents the intimal plus medial thickness observed by histology, and that the use of this value may be appropriate in the assessment of coronary wall thickening associated with atherosclerosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01745173
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  • 4
    Electronic Resource
    Electronic Resource
    Intravascular ultrasound evidence of angiographically undetected left main coronary artery disease and associated trauma during interventional procedures (1996)
    Springer
    Heart and vessels 11 (1996), S. 262-268 
    Details
    ISSN: 1615-2573
    Keywords: Left main coronary artery ; Intravascular ultrasound ; Atherosclerosis ; Transluminal angioplasty
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary To determine the clinical significance of angiographically undetected left main coronary artery (LMCA) disease, we analyzed data from 47 patients, with a mean age of 58 years, who were examined with intravascular ultrasound (3.5Fr, 30MHz). For assessment of atherosclerosis, the lesion area was calculated from the ultrasound images by the formula, {(total vessel area — lumen area)/total vessel area} × 100(%). In 37 LMCA segments of patients with significant distal coronary stenosis (〉50%), the percent intima-media area (the index) was 39 ± 11% (mean ± SD), significantly greater than that of 10 patients without distal disease (27 ± 4%,P 〈 0.01). Among those with significant coronary stenosis, the index was markedly greater in patients with multi-vessel coronary stenosis (46 ± 12%,n = 19) than in patients with single-vessel disease (33 ± 9%,n = 18;P 〈 0.01). At three LMCA sites associated with multi-vessel disease, ultrasound analysis demonstrated disruption of the intima at the site where the guiding catheter for balloon angioplasty had been positioned. These results indicate that LMCA disease is more prominent in patients with multi-vessel distal coronary disease than in those with single vessel disease, even in the absence of angiographic stenosis. We suggest that LMCA trauma can occur where the guiding catheter for angioplasty is positioned, particularly in patients with multi-vessel distal disease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01746207
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  • 5
    Electronic Resource
    Electronic Resource
    Usefulness of the subendocardial myocardial velocity gradient in low-dose dobutamine stress echocardiography (2000)
    Springer
    Heart and vessels 15 (2000), S. 11-17 
    Details
    ISSN: 1615-2573
    Keywords: Key words Ischemic heart disease ; Dobutamine stress echocardiography ; M-mode tissue Doppler imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The subendocardial side of myocardium makes a major contribution to left ventricular (LV) contraction and is very susceptible to ischemia. In this study we sought to quantify regional wall motion during low-dose dobutamine stress echocardiography (DSE) by using the myocardial velocity gradient (MVG) derived from tissue Doppler imaging (TDI). We then compared the usefulness of subendocardial MVG with that of transmural MVG in detecting subtle wall motion abnormalities. Fourteen patients (single vessel disease = 6; normal coronary arteries = 8) underwent low-dose DSE (10 μg/kg per min). M-Mode TDI of the LV posterior wall was recorded using a Toshiba SSA-380A combined with custom computer software, and analyzed for both subendocardial and transmural MVG. Visual estimation and transmural MVG failed to clearly demonstrate the differing responses between the nonischemic (systole: 3.0 ± 0.8/s to 4.9 ± 1.9/s, not significant; diastole: −4.3 ± 1.3/s to −5.7 ± 1.4/s, not significant; mean ± SD, P versus ischemic segments) and ischemic (systole: 3.3 ± 1.2/s to 3.8 ± 1.0/s; diastole: −5.4 ± 2.0/s to −5.3 ± 1.1/s) segments during low-dose DSE. Subendocardial MVG demonstrated a significant change in the nonischemic segments (systole: 4.1 ± 1.0/s to 7.7 ± 2.2/s, P = 0.012; diastole: −6.5 ± 1.8/s to −11.3 ± 2.2/s, P = 0.001), whereas the response remained unchanged in the ischemic segments (systole: 4.6 ± 2.4/s to 4.8 ± 1.2/s; diastole: −7.0 ± 1.9/s to −7.3 ± 1.1/s). Subendocardial MVG, particularly diastolic subendocardial MVG, may serve as a useful indicator of subtle ischemic changes in wall motion induced by low-dose DSE.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003800070042
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  • 6
    Electronic Resource
    Electronic Resource
    Impact of presence of abnormal wall motion on echocardiographic determination of left ventricular function with automated boundary detection technique: re-evaluation (1998)
    Springer
    The international journal of cardiovascular imaging 14 (1998), S. 253-259 
    Details
    ISSN: 1573-0743
    Keywords: automated boundary detection ; echocardiography ; left ventricular function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract It is still unclear whether echocardiography with an automated boundary detection technique (ABD) can accurately determine the left ventricular (LV) volume and function particularly in the presence of LV wall asynergy. We intended to re-evaluate the reliability and application of the ABD, which was based on the acoustic quantification technique (Sonos 2500, Hewlett Packard) for the LV volume measurement in patients without or with LV wall asynergy. A total of 80 patients (mean age 56 years) who underwent left ventriculography (LVG) were divided into two groups. The group A consisted of 29 patients with normal LV wall motion and the group B consisted of 51 patients with generalized or regional LV wall motion abnormality. In group A patients, the LV end-diastolic volume (LVEDV) was 96 ± 25 ml by ABD and 112 ± 33 ml by LVG and those of LV end-systolic volume (LVESV) were 44 ± 14 ml by ABD and 48 ± 17 ml by LVG, thus resulting in the underestimation of LV volume by 12% in average. Under these conditions, the LV ejection fraction (LVEF) by ABD, 54 ± 8%, correlated well with that by LVG, 58 ± 7%. Although underestimation of LV volume by 17% in average also occurred in groups B (N.S.), LVEF was found to correlate well with that by LVG; 27 ± 8% vs 30 ± 11% (r=0.87, SEE=3.1%) for 21 patients with the generalized LV asynergy; 39 ± 10% vs 39 ± 12% (r=0.86. SEE=3.3%) for 30 patients with the regional LV asynergy. These results demonstrate the feasibility of the ABD in determining the LVEF, although underestimation can occur in measuring the absolute LV volume in patients with or without LV asynergy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006060105703
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    Paper (German National Licenses)
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