Generation of a Four-Class Attenuation Map for MRI-Based Attenuation Correction of PET Data in the Head Area Using a Novel Combination of STE/Dixon-MRI and FCM Clustering.
OBJECTIVE
The aim of this study is to generate a four-class magnetic resonance imaging (MRI)-based attenuation map (μ-map) for attenuation correction of positron emission tomography (PET) data of the head area using a novel combination of short echo time (STE)/Dixon-MRI and a dedicated image segmentation method.


METHODS
MR images of the head area were acquired using STE and two-point Dixon sequences. μ-maps were derived from MRI images based on a fuzzy C-means (FCM) clustering method along with morphologic operations. Quantitative assessment was performed to evaluate generated MRI-based μ-maps compared to X-ray computed tomography (CT)-based μ-maps.


RESULTS
The voxel-by-voxel comparison of MR-based and CT-based segmentation results yielded an average of more than 95 % for accuracy and specificity in the cortical bone, soft tissue, and air region. MRI-based μ-maps show a high correlation with those derived from CT scans (R (2) > 0.95).


CONCLUSIONS
Results indicate that STE/Dixon-MRI data in combination with FCM-based segmentation yields precise MR-based μ-maps for PET attenuation correction in hybrid PET/MRI systems.
Research Center for Molecular and Cellular Imaging, Tehran University of Medical Sciences, Tehran, Iran.
Parisa
P
Khateri
Research Center for Molecular and Cellular Imaging, Tehran University of Medical Sciences, Tehran, Iran.|Department of Medical Physics and Biomedical Engineering, Tehran University of Medical Sciences, Tehran, Iran.
Hamidreza
H
Saligheh Rad
Department of Medical Physics and Biomedical Engineering, Tehran University of Medical Sciences, Tehran, Iran.|Research Center for Biomedical and Robotics Technology, Tehran University of Medical Sciences, Tehran, Iran.|MRI Imaging Center, Payambaran Hospital, Tehran, Iran.
Amir Homayoun
AH
Jafari
Research Center for Molecular and Cellular Imaging, Tehran University of Medical Sciences, Tehran, Iran.|Department of Medical Physics and Biomedical Engineering, Tehran University of Medical Sciences, Tehran, Iran.
Anahita
A
Fathi Kazerooni
Research Center for Molecular and Cellular Imaging, Tehran University of Medical Sciences, Tehran, Iran.
Afshin
A
Akbarzadeh
Research Center for Biomedical and Robotics Technology, Tehran University of Medical Sciences, Tehran, Iran.|MRI Imaging Center, Payambaran Hospital, Tehran, Iran.
Mohsen
M
Shojae Moghadam
Imaging Center, Imam Khomeini Hospital Complex, Tehran University of Medical Sciences, Tehran, Iran.
Arvin
A
Aryan
Chronic Respiratory Diseases Research Center, National Research Institute of Tuberculosis and Lung Diseases (NRITLD), Shahid Beheshti University of Medical Sciences, Tehran, Iran.|PET/CT and Cyclotron Center, Masih Daneshvari Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Pardis
P
Ghafarian
Research Center for Molecular and Cellular Imaging, Tehran University of Medical Sciences, Tehran, Iran. mohammadreza_ay@tums.ac.ir.|Department of Medical Physics and Biomedical Engineering, Tehran University of Medical Sciences, Tehran, Iran. mohammadreza_ay@tums.ac.ir.
Mohammad Reza
MR
Ay
D006257:Head / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D049268:Positron-Emission Tomography / Q000379:methods*; D014057:Tomography, X-Ray Computed
Attenuation correction; Attenuation map; FCM technique; PET/MRI; STE pulse sequence