SYSTEMS AND METHODS FOR FUNCTIONAL IMAGING OF THE PLACENTA

• US 20170086720A1
• Filed: 09/23/2016
• Published: 03/30/2017
• Est. Priority Date: 09/25/2015
• Status: Active Grant

• Current Assignee: Oregon Health & Science University
• Original Assignee: Oregon Health & Science University
• Inventors: Schabel, Matthias, Frias, Antonio, Kroenke, Christopher
• Granted Patent: US 10,835,159 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A61B 5/0263 using NMR
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: A61B 5/14542 for measuring blood gases A61B5/14551 takes precedence
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• CPC Class Codes: A61B 5/4343 Pregnancy and labour monitoring, e.g. for labour onset detection
• CPC Class Codes: A61B 5/4362 Assessing foetal parameters
• CPC Class Codes: A61B 5/7278 Artificial waveform generation or derivation, e.g. synthesising signals from measured signals A61B5/327 takes precedence
• CPC Class Codes: G01R 33/50 based on the determination of relaxation times , e.g. T1 measurement by IR sequences; T2 measurement by multiple-echo sequences
• CPC Class Codes: G01R 33/5608 Data processing and visualization specially adapted for MR, e.g. for feature analysis and pattern recognition on the basis of measured MR data, segmentation of measured MR data, edge contour detection on the basis of measured MR data, for enhancing measured MR data in terms of signal-to-noise ratio by means of noise filtering or apodization, for enhancing measured MR data in terms of resolution by means for deblurring, windowing, zero filling, or generation of gray-scaled images, colour-coded images or images displaying vectors instead of pixels image data processing or generation, in general G06T
• CPC Class Codes: G01R 33/5616 using gradient refocusing, e.g. EPI
• CPC Class Codes: G01R 33/56366 Perfusion imaging
• CPC Class Codes: G06F 30/20 Design optimisation, verification or simulation optimisation, verification or simulation of circuit designs G06F30/30

Abstract

A method for imaging and quantifying placental blood perfusion using magnetic resonance imaging is disclosed. The method provides a noninvasive means of assessing placental function and oxygenation from T₂* images without the administration of an exogenous contrast agent. The method provides quantitative information regarding the number and spatial distribution of perfusion domains which subdivide the placenta into functional units where oxygen transport occurs, along with estimates of fetal oxyhemoglobin concentration, descriptors of placental oxygen reserve, and parameters representing the facility with which oxygen transport from the maternal to fetal vasculature occurs.

Claims

1. A method for quantifying placental function, the method comprising:

receiving a set of magnetic resonance images, the magnetic resonance images depicting endogenous oxyhemoglobin-deoxyhemoglobin contrast data;

identifying a region of interest in the set of magnetic resonance images, wherein the region of interest delineates the placenta;

identifying the spatial location of a plurality of local maxima within the region of interest, wherein each local maximum in the plurality of local maxima corresponds to a site of oxygenated blood inflow from a maternal spiral artery;

defining a plurality of perfusion domains within the region of interest wherein each perfusion domain encompasses at least one local maximum;

fitting the data from the magnetic resonance image within the perfusion domain to a mathematical model of oxygen transport, wherein the mathematical model of oxygen transport describes the spatial variation of endogenous contrast as a function of distance from the site of blood inflow; and

indicating an estimate of placental function calculated from the mathematical model;

2. The method of claim 1, wherein indicating an estimate of placental function comprises quantifying fetal oxyhemoglobin concentration and a parameter representing the facility with which oxygen transport from the maternal to fetal vasculature occurs.

3. The method of claim 1, wherein the set of received magnetic resonance images is obtained using a T₂-weighted half-Fourier acquisition single-shot turbo spin-echo (HASTE) pulse sequence.

4. The method of claim 1, wherein the set of received magnetic resonance images is obtained using a multi-echo spoiled gradient echo recalled (SPGR) pulse sequence.

5. The method of claim 1 wherein the endogenous oxyhemoglobin-deoxyhemoglobin contrast data in the region of interest is used to compute transverse relaxation time T₂* for each voxel within the region of interest;

6. The method of claim 5, wherein computing transverse relaxation time T₂* is performed by using a weighed least squares algorithm to fit the equation:

log S=log S₀−

T_E/T₂*

where S is a signal intensity, S₀ is a baseline signal intensity, and T_E is an imaging echo time.

7. The method of claim 1, wherein defining the perfusion domain within the region of interest comprises performing using a multistencil fast-marching method, a level set method, an active contour method, or a watershed segmentation method.

8. The method of claim 1, wherein the mathematical model of oxygen transport is described by the equation: