Brain imaging of sequential acquisition using a flexible PET scanner and 3-T MRI: quantitative and qualitative assessment

• Published in: Annals of nuclear medicine Vol. 37; no. 4; pp. 209 - 218
• Main Authors: Nakajima, Satoshi, Fushimi, Yasutaka, Hinoda, Takuya, Sakata, Akihiko, Okuchi, Sachi, Arakawa, Yoshiki, Ishimori, Takayoshi, Nakamoto, Yuji
• Format: Journal Article
• Language: English
• Published: Singapore Springer Nature Singapore 01.04.2023; Springer Nature B.V
• Subjects: Attenuation; Brain; Brain - diagnostic imaging; Clarity; Computed tomography; Datasets; Distortion; Evaluation; Fluorine isotopes; Fluorodeoxyglucose F18; Glucose; Humans; Image acquisition; Image quality; Image segmentation; Imaging; Leukoaraiosis; Magnetic resonance imaging; Magnetic Resonance Imaging - methods; Medical imaging; Medicine; Medicine & Public Health; Multimodal Imaging - methods; Neuroimaging; Nuclear Medicine; Original Article; Physiology; Positron emission; Positron emission tomography; Positron-Emission Tomography - methods; Prospective Studies; Radiology; Scanners; MR-based attenuation correction; 3-T MRI; Brain PET/MRI; Flexible PET; CT-based attenuation correction
• ISSN: 0914-7187; 1864-6433
• DOI: 10.1007/s12149-022-01817-6

Objective A mobile PET scanner termed flexible PET (fxPET) has been designed to fit existing MRI systems. The purpose of this study was to assess brain imaging with fxPET combined with 3-T MRI in comparison with conventional PET (cPET)/CT. Methods In this prospective study, 29 subjects with no visible lesions except for mild leukoaraiosis on whole brain imaging underwent 2-deoxy-2-[ 18 F]fluoro-D-glucose ([ 18 F]FDG) cPET/CT followed by fxPET and MRI. The registration differences between fxPET and MRI and between cPET and CT were compared by measuring spatial coordinates. Three-dimensional magnetization-prepared rapid acquisition gradient-echo T1-weighted imaging (T1WI) was acquired. We applied two methods of attenuation correction to the fxPET images: MR-based attenuation correction, which yielded fxPET MRAC ; and CT-based attenuation correction, which yielded fxPET CTAC . The three PET datasets were co-registered to the T1WI. Following subcortical segmentation and cortical parcellation, volumes of interest were placed in each PET image to assess physiological accumulation in the brain. SUV mean was obtained and compared between the three datasets. We also visually evaluated image distortion and clarity of fxPET MRAC . Results Mean misregistration of fxPET/MRI was < 3 mm for each margin. Mean registration differences were significantly larger for fxPET/MRI than for cPET/CT except for the superior margin. There were high correlations between the three PET datasets regarding SUV mean . On visual evaluation of image quality, the grade of distortion was comparable between fxPET MRAC and cPET, and the grade of clarity was acceptable but inferior for fxPET MRAC compared with cPET. Conclusions fxPET could successfully determine physiological [ 18 F]FDG uptake; however, improved image clarity is desirable. In this study, fxPET/MRI at 3-T was feasible for brain imaging.