Phase-contrast acceleration mapping with synchronized encoding.

Purpose: To develop a phase-contrast (PC) -based method for direct and unbiased quantification of the acceleration vector field by synchronization of the spatial and acceleration encoding time points. The proposed method explicitly aims at in-vitro applications, requiring high measurement accuracy, as well as the validation of clinically relevant acceleration-encoded sequences.

Methods: A velocity-encoded sequence with synchronized encoding (SYNC SPI) was modified to allow direct acceleration mapping by replacing the bipolar encoding gradients with tripolar gradient waveforms.

Equivalent Scalar Stress Formulation Taking into Account Non-Resolved Turbulent Scales.

Purpose: Cardiovascular engineering includes flows with fluid-dynamical stresses as a parameter of interest. Mechanical stresses are high-risk factors for blood damage and can be assessed by computational fluid dynamics. By now, it is not described how to calculate an adequate scalar stress out of turbulent flow regimes when the whole share of turbulence is not resolved by the simulation method and how this impacts the stress calculation.

CFD validation using in-vitro MRI velocity data - Methods for data matching and CFD error quantification.

Predicting blood flow velocities in patient-specific geometries with Computational Fluid Dynamics (CFD) can provide additional data for diagnosis and treatment planning but the solution can be inaccurate. Therefore, it is crucial to understand the simulation errors and calibrate the numerical model. In-vitro velocity-encoded MRI is a versatile tool to validate CFD.

An unbiased method for PRF-shift temperature measurements in convective heat transfer systems with functional parts made of metal.

The purpose of this study is to provide a PRF-shift method for fluid temperature measurements in convective heat transfer systems, which contain functional parts made of metal. Such measurements are extremely useful to examine and design convective cooling systems for industrial devices. Metals like copper seem inevitable for such applications because no commonly available non-metallic material reaches the same level of thermal conductivity as for example copper.

Phase-contrast single-point imaging with synchronized encoding: a more reliable technique for in vitro flow quantification.

Purpose: The purpose of this study is to provide a standard method for flow velocity measurements with phase-contrast (PC) MRI. This method can be used for in vitro studies that place high demands on measurement accuracy. Clinically relevant PC MRI techniques can be validated using this method before being applied in vivo.