Realistic 4D MRI abdominal phantom for the evaluation and comparison of acquisition and reconstruction techniques

Abstract

Purpose This work presents a 4D numerical abdominal phantom, which includes T1 and T2 relaxation times, proton density fat fraction, perfusion, and diffusion, as well as respiratory motion for the evaluation and comparison of acquisition and reconstruction techniques. Methods The 3D anatomical mesh models were non‐rigidly scaled and shifted by respiratory motion derived from an in vivo scan. A time series of voxelized 3D abdominal phantom images were obtained with contrast determined by the tissue properties and pulse sequence parameters. Two example simulations: (1) 3D T1 mapping under breath‐hold and free‐breathing acquisition conditions and (2) two different reconstruction techniques for accelerated 3D dynamic contrast‐enhanced MRI, are presented. The source codes can be found at https://github.com/SeiberlichLab/Abdominal_MR_Phantom. Results The proposed 4D abdominal phantom can successfully simulate images and MRI data with nonrigid respiratory motion and specific contrast settings and data sampling schemes. In example 1, the use of a numerical 4D abdominal phantom was demonstrated to aid in the comparison between different approaches for volumetric T1 mapping. In example 2, the average arterial fraction over the healthy hepatic parenchyma as calculated with spiral generalized autocalibrating partial parallel acquisition was closer to that from the fully sampled data than the arterial fraction from conjugate gradient sensitivity encoding, although both are elevated compared to the gold‐standard reference. Conclusion This realistic abdominal MR phantom can be used to simulate different pulse sequences and data sampling schemes for the comparison of acquisition and reconstruction methods under controlled conditions that are impossible or prohibitively difficult to perform in vivo.

MRSIGMA: Magnetic Resonance SIGnature MAtching for real‐time volumetric imaging

“…The proof‐of‐concept of MRSIGMA was first demonstrated using a numerical phantom with realistic abdominal anatomy and respiratory motion that was previously developed by the Seiberlich Lab at Case Western Reserve University . The source code for the phantom simulation was downloaded from https://github.com/SeiberlichLab/Abdominal_MR_Phantom.…”

Distortion‐free 3D diffusion imaging of the prostate using a multishot diffusion‐prepared phase‐cycled acquisition and dictionary matching

“…A numerical phantom (I reference ) was generated in MATLAB to mimic pelvic anatomy, 32 and was corrupted (I corruputed ) with the simulated ME as seen in Figure 2. A new set of magnitude errors (ME +90 ) was then simulated to generate the correspondent phase‐cycled image (I corruputed+90 ).…”

Integration of spatial distortion effects in a 4D computational phantom for simulation studies in extra‐cranial MRI‐guided radiation therapy: Initial results

“…25,26 As an alternative technique, the MR signal intensity can be derived by solving the Bloch equations directly, which allows one to model time-dependent effects such as the use of contrast agents. 27 Based on the approach by Wissmann et al, a 4D CT/MRI Breathing Anthropomorphic Thorax phantom (CoMBAT) has been developed for applications in MRgRT. 22 The phantom includes tissue parameters derived from experimental acquisitions, expressing the proton density and relaxation times (T1 and T2) for the main tissues in abdominal imaging.…”

“…Both approaches have been tested for applications in cardiac imaging 25,26 . As an alternative technique, the MR signal intensity can be derived by solving the Bloch equations directly, which allows one to model time‐dependent effects such as the use of contrast agents 27 …”