ZTE MR-based attenuation correction in brain FDG-PET/MR: performance in patients with cognitive impairment
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One of the main challenges of integrated PET/MR is to achieve an accurate PET attenuation correction (AC), especially in brain acquisition. Here, we evaluated an AC method based on zero echo time (ZTE) MRI, comparing it with the single-atlas AC method and CT-based AC, set as reference.
Fifty patients (70 ± 11 years old, 28 men) underwent FDG-PET/MR examination (SIGNA PET/MR 3.0 T, GE Healthcare) as part of the investigation of suspected dementia. They all had brain computed tomography (CT), 2-point LAVA-flex MRI (for atlas-based AC), and ZTE-MRI. Two AC methods were compared with CT-based AC (CTAC): one based on a single atlas, one based on ZTE segmentation. Impact on brain metabolism was evaluated using voxel and volumes of interest–based analyses. The impact of AC was also evaluated through comparisons between two subgroups of patients extracted from the whole population: 15 patients with mild cognitive impairment and normal metabolic pattern, and 22 others with metabolic pattern suggestive of Alzheimer disease, using SPM12 software.
ZTE-AC yielded a lower bias (3.6 ± 3.2%) than the atlas method (4.5 ± 6.1%) and lowest interindividual (4.6% versus 6.8%) and inter-regional (1.4% versus 2.6%) variabilities. Atlas-AC resulted in metabolism overestimation in cortical regions near the vertex and cerebellum underestimation. ZTE-AC yielded a moderate metabolic underestimation mainly in the occipital cortex and cerebellum. Voxel-wise comparison between the two subgroups of patients showed that significant difference clusters had a slightly smaller size but similar locations with PET images corrected with ZTE-AC compared with those corrected with CT, whereas atlas-AC images showed a notable reduction of significant voxels.
ZTE-AC performed better than atlas-AC in detecting pathologic areas in suspected neurodegenerative dementia.
• The ZTE-based AC improved the accuracy of the metabolism quantification in PET compared with the atlas-AC method.
• The overall uptake bias was 21% lower when using ZTE-based AC compared with the atlas-AC method.
• ZTE-AC performed better than atlas-AC in detecting pathologic areas in suspected neurodegenerative dementia.
KeywordsPET/MR ZTE MRI Attenuation correction Fluoro-2-deoxy-d-glucose (FDG) Neurodegenerative dementia
Automated anatomical labeling
- AC-PC line
Anterior commissure–posterior commissure line
Convolutional neural networks
Montreal Neurological Institute
Magnetic resonance–based attenuation correction
Magnetic resonance imaging
Positron emission tomography
Point spread function
Statistical parametric mapping
Standard uptake value
Time of flight
Zero time echo
The authors would like to thank GE Healthcare for providing access to research tools and prototype pulse sequences.
The authors also would like to thank ARC foundation which allowed Dr. SGARD to get a fellowship for a year of research during which he was able to carry out this study.
The authors state that this work has not received any funding.
Compliance with ethical standards
The scientific guarantor of this publication is Aurélie Kas, MD, PhD, Department of Nuclear Medicine, Pitié-Salpêtrière C. Foix Hospital, APHP, Paris, France. Phone: 33 1 42 17 62 80. Fax: 33 1 42 17 62 92. Email: firstname.lastname@example.org
Conflict of interest
The authors of this manuscript declare relationships with the following companies:
Maya Khalifé received a research grant from GE Healthcare.
Brice Fernandez and Gaspar Delso are GE Healthcare employees. Only non-GE employees had control of inclusion of data and information that might present a conflict of interest for authors who are employees of GE Healthcare. No other potential conflict of interest relevant to this article was reported.
Aurélie Kas received honoria for lectures from GE Healthcare and Piramal.
Marie-Odile Habert received honoraria for lectures from Lilly.
Statistics and biometry
One of the authors has significant statistical expertise.
No complex statistical methods were necessary for this paper.
Written informed consent was obtained from all subjects (patients) in this study.
Data of this study were extracted from the PET/MR examinations database of the Pitié-Salpêtrière Hospital, Paris, France, which was approved by the French authority for the protection of privacy and personal data in clinical research (CNIL, approval no. 2111722). All procedures performed in this study were in accordance with the ethical standards of the institutional research committee and with the 1964 Helsinki Declaration and its later amendments.
• Performed at one institution
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