[MR tomography in cardiology. II: Flow phenomena]

Area of Science:

• Medical Imaging
• Biophysics
• Cardiovascular Imaging

Context:

• Flow phenomena significantly impact Magnetic Resonance Imaging (MRI) tomograms, often causing artifacts that reduce image quality.
• However, when combined with electrocardiogram (ECG) triggering and specific excitation modes, flow effects can yield diagnostically relevant information.
• Understanding these flow dynamics is crucial for assessing cardiac function and blood flow in vessels.

Purpose:

• To explore how flow phenomena influence MRI image quality and diagnostic information.
• To investigate the effects of different pulse sequence parameters (TR, TE) on blood signal intensity.
• To analyze phase shifts and their impact on image artifacts and signal intensity in flowing blood.

Summary:

• Flowing blood typically exhibits low signal intensity in spin echo (SE) MRI, though the TR-effect can increase it.
• The TE-effect reduces blood signal with increasing velocity, while phase shifts cause line-shaped artifacts and decrease odd spin echo intensities.
• Even echoes can show higher signal than odd echoes due to phase recombination, particularly with reduced flow velocities, and time-of-flight effects can occur in multi-slice acquisitions.

Impact:

• Optimized MRI techniques can leverage flow phenomena for enhanced diagnostic insights into cardiovascular health.
• Improved understanding of flow-related artifacts allows for better image quality and more reliable diagnoses.
• This research contributes to the development of more accurate and informative MRI protocols for blood flow and cardiac function assessment.