Engineered phantoms for perfusion imaging applications
View Patent ↗In various embodiments, microengineered phantoms with microvascular networks serve as calibration standards for perfusion imaging systems.
1. A method for improving image-based characterization of perfusion in microvascular networks, comprising the steps of:
(a) perfusing a phantom comprising an artificial microvascular network of known structure and dimensions with a fluid;
(b) selecting a perfusion parameter and determining, based on the known structure and dimensions of the network, a first value of the selected perfusion parameter;
(c) inducing contrast in a portion of the fluid present in the artificial microvascular network;
(d) acquiring a series of images of the phantom in accordance with an imaging scheme;
(e) computing from the series of images a second value for the selected perfusion parameter based on an analysis scheme; and
(f) varying at least one of the imaging scheme or the analysis scheme based on a comparison of the first and second values.
2. The method of claim 1 wherein the imaging scheme is varied, and further comprising characterizing perfusion in a second microvascular network by (i) acquiring a series of images in accordance with the varied imaging scheme and (ii) computing from the series of images a second perfusion parameter.
3. The method of claim 2 wherein the second microvascular network is a biological microvascular network.
4. The method of claim 1 wherein the analysis scheme is varied, and further comprising characterizing perfusion in a second microvascular network by (i) acquiring a series of images and (ii) computing from the series of images a second perfusion parameter based on the varied analysis scheme.
5. The method of claim 4 wherein the second microvascular network is a biological microvascular network.
6. The method of claim 1 wherein step (f) comprises varying a variable parameter of the analysis scheme so as to reduce a difference between the first and second values.
7. The method of claim 1 further comprising computing a third value for the selected perfusion parameter from the series of images based on an alternative analysis scheme, and, if a difference between the first value and the third value is smaller than a difference between the first value and the second value, substituting the analysis scheme with the alternative analyses scheme.
8. The method of claim 1 wherein the analysis scheme comprises at least one of distributed parameter analysis, Patlak analysis, deconvolution, dynamic contrast enhancement analysis, or dynamic susceptibility contrast analysis.
9. The method of claim 1 wherein the perfusion parameter is selected from the group consisting of a fluid volume, a flow rate, a mean transit time, a permeability, a diffusion constant, a transfer constant, a peak flow rate, a rise time, a rise slope, a decay time, a decay slope, and a recirculation rate.
10. The method of claim 1 wherein step (d) comprises employing at least one of computed tomography, magnetic resonance imaging, positron emission tomography, single photon emissions computed tomography, or acoustic imaging.
11. The method of claim 1 wherein the imaging scheme is varied by adjusting image acquisition settings.
12. The method of claim 1 wherein step (c) comprises injecting a contrast agent into the fluid.
13. The method of claim 12 wherein step (c) comprises injecting a known bolus of contrast agent.
14. The method of claim 1 wherein step (c) comprises imparting a magnetic polarization on a portion of the fluid.
15. The method of claim 1 wherein the dimensions of every structural feature in the artificial microvascular network are each known within a tolerance of five percent.
16. The method of claim 1 wherein the phantom is designed for at least one of a specific tissue or a specific patient.
17. The method of claim 1 wherein the phantom further comprises a three-dimensional compartment and a membrane separating the compartment from the artificial microvascular network.
18. The method of claim 17 wherein each cross-sectional dimension of the compartment is greater than a cross-sectional dimension of a microchannel of the artificial microvascular network.
19. A method for characterizing perfusion in a biological microvascular network, comprising the steps of:
(a) calibrating a perfusion imaging system comprising an imaging apparatus and an image analysis module by (i) perfusing a phantom comprising an artificial microvascular network of known structure and dimensions with a fluid; (ii) selecting a perfusion parameter and determining, based on the known structure and dimensions of the network, a first value of the selected perfusion parameter; (iii) inducing contrast in a portion of the fluid present in the artificial microvascular network; (iv) acquiring a series of images of the phantom with the imaging apparatus in accordance with an imaging scheme; (v) computing from the series of images a second value for the selected perfusion parameter based on an analysis scheme employed by the image analysis module; and (vi) varying at least one of the imaging scheme or the analysis scheme based on a comparison of the first and second values;
(b) inducing contrast in a portion of a fluid present in the biological microvascular network, and acquiring a series of images of the biological microvascular network with the imaging apparatus; and
(c) computing a perfusion parameter of the biological microvascular network with the image analysis module.