Intra-thoracic blood volume measurement by contrast magnetic resonance imaging
M Mischi1, H C M van den Bosch, J A den Boer
1Eindhoven University of Technology, Department of Electrical Engineering, Eindhoven, The Netherlands. m.mischi@tue.nl
Insights
A new dynamic MRI technique noninvasively measures intra-thoracic blood volume (ITBV), crucial for assessing cardiac function. This method offers a safer alternative to invasive procedures for cardiovascular diagnostics.
Area of Science:
- Cardiovascular Imaging
- Medical Physics
- Diagnostic Technology
Background:
- Intra-thoracic blood volume (ITBV) is vital for evaluating cardiac preload and left ventricular function.
- Current ITBV measurement relies on invasive indicator dilution techniques requiring double catheterization.
- Accurate ITBV assessment is critical for diagnosing and managing cardiovascular dysfunctions.
Purpose of the Study:
- To introduce a novel, noninvasive dynamic MRI technique for assessing intra-thoracic blood volume (ITBV).
- To validate the feasibility and accuracy of this new MRI-based method for cardiovascular diagnostics.
Main Methods:
- Dynamic MRI with intravenous gadolinium chelate injection.
- Simultaneous imaging of right and left ventricles to detect indicator bolus first pass.
- Derivation of transpulmonary indicator dilution curves and cardiac output via phase contrast MRI angiography.
- Comparison of mathematical models for interpreting dilution curves.
Main Results:
- In vitro calibration demonstrated a correlation coefficient > 0.99.
- Preliminary volunteer tests confirmed the method's feasibility.
- The ITBV is calculated using transpulmonary mean transit time and cardiac output.
Conclusions:
- The novel dynamic MRI technique provides a noninvasive method for ITBV assessment.
- This approach enhances quantitative cardiovascular diagnostics, offering a safer alternative to invasive methods.
- The study opens new avenues for noninvasive monitoring of cardiac function.
Abstract:
The intra-thoracic blood volume (ITBV) is a cardiovascular parameter related to the cardiac preload and left ventricular function. Its assessment is, therefore, important for diagnosis and follow-up of several cardiovascular dysfunctions. Nowadays, the ITBV can be accurately measured only by invasive indicator dilution techniques, which require a double catheterization of the patient. In this study, a novel technique is presented for ITBV assessment by dynamic magnetic resonance imaging after intravenous injection of a small bolus of gadolinium chelate. The dose was chosen on the basis of in vitro calibration. The bolus first pass is detected from a simultaneous dynamic image series of the right and left ventricles. Two indicator dilution curves are derived and used to inspect the transpulmonary dilution system. Various mathematical models for the interpretation of the measured indicator dilution curves are compared. The ITBV is assessed as the product of the transpulmonary mean transit time of the indicator and the cardiac output, obtained by phase contrast magnetic resonance angiography. In vitro measurements showed a correlation coefficient larger than 0.99 and preliminary tests with volunteers proved the feasibility of the method, opening new possibilities for noninvasive quantitative cardiovascular diagnostics.
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