Table 2.

Comparison of 4D Flow MRI Validation Methods

Validation method	Advantages	Disadvantages	When to use (examples)	Examples
In-vivo	Fidelity with respect to clinical or research use of the method	Physiological variability, commonly a lack of gold standard	Verification that method works in vivo	[83–86]
Phantoms	Controllable, easier to get a gold standard than in-vivo studies, even simple experiments can be of value	Realistic models challenging to construct and control	Evaluation variables/parameters in a repeatable setting in real MRI hardware	[87–91, 168]
Simulations	Very controllable, different sources of error can be separated, underlying numerical velocity data serves as ground truth	Fidelity uncertain, computational cost	Rapid feedback during development, when the desired evaluation cannot be realized in a phantom setup or in vivo	[92–94, 169]