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Massimo Mischi - One of the best experts on this subject based on the ideXlab platform.

  • Automatic Indicator Dilution Curve extraction in dynamic-contrast enhanced imaging using spectral clustering
    Physics in Medicine and Biology, 2015
    Co-Authors: Salvatore Saporito, Ingeborg H F Herold, Patrick Houthuizen, Harrie C. M. Van Den Bosch, Hendrikus H. M. Korsten, Hans C. Van Assen, Massimo Mischi
    Abstract:

    Indicator Dilution theory provides a framework for the measurement of several cardiovascular parameters. Recently, dynamic imaging and contrast agents have been proposed to apply the method in a minimally invasive way. However, the use of contrast-enhanced sequences requires the definition of regions of interest (ROIs) in the dynamic image series; a time-consuming and operator dependent task, commonly performed manually. In this work, we propose a method for the automatic extraction of Indicator Dilution Curves, exploiting the time domain correlation between pixels belonging to the same region. Individual time intensity Curves were projected into a low dimensional subspace using principal component analysis; subsequently, clustering was performed to identify the different ROIs. The method was assessed on clinically available DCE-MRI and DCE-US recordings, comparing the derived IDCs with those obtained manually. The robustness to noise of the proposed approach was shown on simulated data. The tracer kinetic parameters derived on real images were in agreement with those obtained from manual annotation. The presented method is a clinically useful preprocessing step prior to further ROI-based cardiac quantifications.

  • on the physical and stochastic representation of an Indicator Dilution Curve as a gamma variate
    Physiological Measurement, 2008
    Co-Authors: Massimo Mischi, Den Ja Boer, Hhm Erik Korsten
    Abstract:

    The analysis of intravascular Indicator dynamics is important for cardiovascular diagnostics as well as for the assessment of tissue perfusion, aimed at the detection of ischemic regions or cancer hypervascularization. To this end, Indicator Dilution Curves are measured after the intravenous injection of an Indicator bolus and fitted by parametric models for the estimation of the hemodynamic parameters of interest. Based on heuristic reasoning, the Dilution process is often modeled by a gamma variate. In this paper, we provide both a physical and stochastic interpretation of the gamma variate model. The accuracy of the model is compared with the local density random walk model, a known model based on physics principles. Dilution Curves were measured by contrast ultrasonography both in vitro and in vivo (20 patients). Blood volume measurements were used to test the accuracy and clinical relevance of the estimated parameters. Both models provided accurate Curve fits and volume estimates. In conclusion, the proposed interpretations of the gamma variate model describe physics aspects of the Dilution process and lead to a better understanding of the observed parameters, increasing the value and credibility of the model, and possibly expanding its diagnostic applications.

  • Novel ultrasound contrast agent Dilution method for the assessment of ventricular ejection fraction
    European journal of echocardiography : the journal of the Working Group on Echocardiography of the European Society of Cardiology, 2007
    Co-Authors: A.h.m. Jansen, Massimo Mischi, Frank A. Bracke, Jan Melle Van Dantzig, Kathinka H. Peels, Evert Lamfers, Norbert M. Van Hemel, Hendrikus H. M. Korsten
    Abstract:

    Aims Left ventricular (LV) ejection fraction is an important determinant of prognosis in heart failure. We evaluated the accuracy of a novel algorithm for LV ejection fraction quantification based on Indicator Dilution Curve (IDC) principles using ultrasound contrast as Indicator, and compared the results with contrast enhanced biplane LV ejection fraction assessment. Method A diluted ultrasound contrast bolus (SonoVue w ) was injected intravenously in 31 patients (19 male, age 65+ 11) with known or suspected heart disease. A total of 68 recordings were made. The developed algorithm used the left atrium and LV IDC for LV ejection fraction measurement. Biplane enhanced LV ejection fraction measurements with pure ultrasound contrast (SonoVue w ) were determined in multiple four- and two-chamber recordings as reference. Results The mean LV ejection fraction measured by biplane and IDC method was 33+ 17% and 35+ 18%, respectively. A correlation coefficient r ¼ 0.93 was observed between the two methods. Bland–Altman analysis demonstrated a slight LV ejection fraction overestimation with IDC (mean 1.9+ 6.3%). Conclusion A new fast method for LV ejection fraction assessment based on IDC principles is described and comparison with contrast enhanced biplane LV ejection fraction quantification shows accurate results.

J S Forrester - One of the best experts on this subject based on the ideXlab platform.

Qiaojian Huang - One of the best experts on this subject based on the ideXlab platform.

  • noninvasive photoacoustic measurement of the composite Indicator Dilution Curve for cardiac output estimation
    Biomedical Optics Express, 2015
    Co-Authors: Dongyel Kang, Qiaojian Huang
    Abstract:

    Recently, the measurement of Indicator Dilution Curves using a photoacoustic (PA) technology was reported, which showed promising results on the noninvasive estimation of cardiac output (CO) that is an important hemodynamic parameter useful in various clinical situations. However, in clinical practice, measuring PA Indicator Dilution Curves from an arterial blood vessel requires an ultrasound transducer array capable of focusing on the targeted artery. This causes several challenges on the clinical translation of the PA Indicator Dilution method, such as high sensor cost and complexity. In this paper, we theoretically derived that a composite PA Indicator Dilution Curve simultaneously measured from both arterial and venous blood vessels can be used to estimate CO correctly. The ex-vivo and in-vivo experimental results with a flat ultrasound transducer verified the developed theory. We believe this new concept would overcome the main challenges on the clinical translation of the noninvasive PA Indicator Dilution technology.

N L Eigler - One of the best experts on this subject based on the ideXlab platform.

Hendrikus H. M. Korsten - One of the best experts on this subject based on the ideXlab platform.

  • Automatic Indicator Dilution Curve extraction in dynamic-contrast enhanced imaging using spectral clustering
    Physics in Medicine and Biology, 2015
    Co-Authors: Salvatore Saporito, Ingeborg H F Herold, Patrick Houthuizen, Harrie C. M. Van Den Bosch, Hendrikus H. M. Korsten, Hans C. Van Assen, Massimo Mischi
    Abstract:

    Indicator Dilution theory provides a framework for the measurement of several cardiovascular parameters. Recently, dynamic imaging and contrast agents have been proposed to apply the method in a minimally invasive way. However, the use of contrast-enhanced sequences requires the definition of regions of interest (ROIs) in the dynamic image series; a time-consuming and operator dependent task, commonly performed manually. In this work, we propose a method for the automatic extraction of Indicator Dilution Curves, exploiting the time domain correlation between pixels belonging to the same region. Individual time intensity Curves were projected into a low dimensional subspace using principal component analysis; subsequently, clustering was performed to identify the different ROIs. The method was assessed on clinically available DCE-MRI and DCE-US recordings, comparing the derived IDCs with those obtained manually. The robustness to noise of the proposed approach was shown on simulated data. The tracer kinetic parameters derived on real images were in agreement with those obtained from manual annotation. The presented method is a clinically useful preprocessing step prior to further ROI-based cardiac quantifications.

  • Novel ultrasound contrast agent Dilution method for the assessment of ventricular ejection fraction
    European journal of echocardiography : the journal of the Working Group on Echocardiography of the European Society of Cardiology, 2007
    Co-Authors: A.h.m. Jansen, Massimo Mischi, Frank A. Bracke, Jan Melle Van Dantzig, Kathinka H. Peels, Evert Lamfers, Norbert M. Van Hemel, Hendrikus H. M. Korsten
    Abstract:

    Aims Left ventricular (LV) ejection fraction is an important determinant of prognosis in heart failure. We evaluated the accuracy of a novel algorithm for LV ejection fraction quantification based on Indicator Dilution Curve (IDC) principles using ultrasound contrast as Indicator, and compared the results with contrast enhanced biplane LV ejection fraction assessment. Method A diluted ultrasound contrast bolus (SonoVue w ) was injected intravenously in 31 patients (19 male, age 65+ 11) with known or suspected heart disease. A total of 68 recordings were made. The developed algorithm used the left atrium and LV IDC for LV ejection fraction measurement. Biplane enhanced LV ejection fraction measurements with pure ultrasound contrast (SonoVue w ) were determined in multiple four- and two-chamber recordings as reference. Results The mean LV ejection fraction measured by biplane and IDC method was 33+ 17% and 35+ 18%, respectively. A correlation coefficient r ¼ 0.93 was observed between the two methods. Bland–Altman analysis demonstrated a slight LV ejection fraction overestimation with IDC (mean 1.9+ 6.3%). Conclusion A new fast method for LV ejection fraction assessment based on IDC principles is described and comparison with contrast enhanced biplane LV ejection fraction quantification shows accurate results.