Fabrication of Customizable Intraplaque Hemorrhage Phantoms for Magnetic Resonance Imaging

Matteo A Bomben; Alan R Moody; James M Drake; Naomi Matsuura

doi:10.1007/s11307-022-01722-4

Fabrication of Customizable Intraplaque Hemorrhage Phantoms for Magnetic Resonance Imaging

Mol Imaging Biol. 2022 Oct;24(5):732-739. doi: 10.1007/s11307-022-01722-4. Epub 2022 Apr 29.

Authors

Matteo A Bomben^{1

2}, Alan R Moody^{3

4}, James M Drake^{1

2

5}, Naomi Matsuura^{6

7

8}

Affiliations

¹ Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON, Canada.
² The Wilfred and Joyce Posluns Centre for Image Guided Innovation and Therapeutic Intervention, The Hospital for Sick Children, Toronto, ON, Canada.
³ Department of Medical Imaging, University of Toronto, Toronto, ON, Canada.
⁴ Sunnybrook Hospital, Toronto, ON, Canada.
⁵ Institute of Biomedical Engineering, University of Toronto, 184 College Street, Room 140, Toronto, ON, M5S 3E4, Canada.
⁶ Department of Medical Imaging, University of Toronto, Toronto, ON, Canada. naomi.matsuura@utoronto.ca.
⁷ Institute of Biomedical Engineering, University of Toronto, 184 College Street, Room 140, Toronto, ON, M5S 3E4, Canada. naomi.matsuura@utoronto.ca.
⁸ Department of Materials Science and Engineering, University of Toronto, Toronto, ON, Canada. naomi.matsuura@utoronto.ca.

Abstract

Purpose: Magnetic resonance (MR) imaging detection of methemoglobin, a molecular marker of intraplaque hemorrhage (IPH), in atherosclerotic plaque is a promising method of assessing stroke risk. However, the multicenter imaging studies required to further validate this technique necessitate the development of IPH phantoms to standardize images acquired across different scanners. This study developed a set of phantoms that modeled methemoglobin-laden IPH for use in MR image standardization.

Procedures: A time-stable material mimicking the MR properties of methemoglobin in IPH was created by doping agarose hydrogel with gadolinium and sodium alginate. This material was used to create a phantom that consisted of 9 cylindrical IPH sites (with sizes from 1 to 8 mm). Anatomical replicas of IPH-positive atherosclerosis were also created using 3D printed molds. These plaque replicas also modeled other common plaque components including a lipid core and atheroma cap. T1 mapping and a magnetization-prepared rapid acquisition gradient echo (MPRAGE) carotid imaging protocol were used to assess phantom realism and long-term stability.

Results: Cylindrical phantom IPH sites possessed a T1 time of 335 ± 51 ms and exhibited little change in size or MPRAGE signal intensity over 31 days; the mean (SD) magnitude of changes in size and signal were 6.4 % (2.7 %) and 7.3 % (6.7 %), respectively. IPH sites incorporated into complex anatomical plaque phantoms exhibited contrast comparable to clinical images.

Conclusions: The cylindrical IPH phantom accurately modeled the short T1 time characteristic of methemoglobin-laden IPH, with the IPH sites exhibiting little variation in imaging properties over 31 days. Furthermore, MPRAGE images of the anatomical atherosclerosis replicas closely matched those of clinical plaques. In combination, these phantoms will allow for IPH imaging protocol standardization and thus facilitate future multicenter IPH imaging.

Keywords: Carotid plaque; Intraplaque hemorrhage; MR imaging; MRI phantoms; Magnetic resonance angiography; Methemoglobin.

Publication types

Multicenter Study
Research Support, Non-U.S. Gov't

MeSH terms

Alginates
Atherosclerosis* / diagnostic imaging
Atherosclerosis* / pathology
Carotid Arteries / diagnostic imaging
Carotid Stenosis* / pathology
Gadolinium
Hemorrhage / pathology
Humans
Hydrogels
Lipids
Magnetic Resonance Imaging / methods
Methemoglobin
Plaque, Atherosclerotic* / diagnostic imaging
Plaque, Atherosclerotic* / pathology
Sepharose

Substances

Gadolinium
Methemoglobin
Sepharose
Alginates
Hydrogels
Lipids

Grants and funding

426350/CIHR/Canada