Takuya Hinoda1, Yasutaka Fushimi1, Tomohisa Okada1,2, Ryusuke Nakamoto1, Yuji Nakamoto1, and Kaori Togashi1
1Radiology, Graduate school of Mediine, Kyoto University, Kyoto, Japan, 2Human Brain Research Center, Graduate school of Mediine, Kyoto University, Kyoto, Japan
Synopsis
“Flexible PET (fxPET)”, a
dual-head mobile DOI-TOF PET system with MR compatibility, is a newly developed
device which enable us to examine the positron-emission tomography. In this
first trial of the central nervous system (CNS), we tried to confirm the
clinical feasibility of the fxPET with a 1.5T MRI scanner. The result of this
study showed that fxPET have clinical feasibility in comparison with PET-CT. PET/MRI
is an emerging modality. PET/MRI can provide us useful metabolic information to
MRI images. Purpose
“Flexible PET (fxPET)”, a
dual-head mobile DOI-TOF PET system with MR compatibility, is a newly developed
device which enable us to examine the positron-emission tomography everywhere. PET-MRI
has been applied to malignant neoplasms, and could play an important role in all
phases of patient’s management
12. Recently several faculty introduce a hybrid
PET/MRI system, but the size and cost is an issue to resolve. The fxPET can solve
such issues because fxPET can be equipped with an existing MR unit. In this
first trial of the central nervous system (CNS), we tried to confirm the
clinical feasibility of the fxPET with a 1.5T MRI scanner.
Materials and Methods
Flexible
PET; dual-head mobile DOI-TOF PET system with MR compatibility (Shimadzu). (Fig.1a)
fxPET/MRI; the FlexiblePET was equipped
with 1.5T MRI scanner (Excelart Vantage, Toshiba) (Fig.1b)
Patients;
10 patients
with known CNS tumor who underwent 18F-FDG PET/CT for pre-operative examination.
(M: F = 4:6; age range, 42-72 years old; median, 58) were enrolled.
Protocol; every patients underwent 18F-FDG-PET/CT,
and then PET and MRI images were acquired at the FlexiblePET/MRI unit.
SUVmax was calculated from
images of the PET/CT and the fxPET/MRI. The linear regression analysis for
SUVmax between PET/CT and fxPET/MRI was conducted. Two individual
neuro-radiologists evaluated the image of FxPET/MRI, focusing the image registration
and image quality.
Results
Phantom
images
NEMA body phantom image was
shown in Fig.2a.
MRI phantom images were shown
in Fig.2b-d.
In NEMA phantom, there was
some distortion in vertical plane due to detector form. In MRI phantom, there
was almost no degradation and noise.
Patient
Images
All of the images were
excellent with minimum mis-resgistration and sufficient for clinical usage
(Fig. 3 and 4). The values of SUVmax in the fxPET had excellent correlation
with those in the PET/CT (R2 = 0.87, r = 0.98) (Fig. 5).
Discussion
This result showed that fxPET
have clinical feasibility in comparison with PET-CT. PET/MRI is an emerging modality. PET/MRI can provide us useful metabolic information to MRI images.
In CNS, we struggle with a dilemma that we cannot remove all of the lesions to
preserve the function and should evaluate only small biopsy specimen of the
lesions in spite of the tumor-heterogeneity. We can perform more accurate
biopsy if we acquire a high-quality fused images of PET and MRI. So fxPET/MRI
would be meaningful in patient’s management.
Conclusion
Newly developed fxPET provide good fused PET-MRI images, and have clinical feasibility.
Acknowledgements
This study was supported by New Energy and Industrial Technology Development Organization (NEDO).References
1. Catalano et al.: Clinical
Impact of PET/MR Imaging in Patients with Cancer Undergoing Same-Day PET/CT:
Initial Experience in 134
Patients—A Hypothesis-generating Exploratory Study; Radiology, 2013
2. Rosenkratz et al.: Current
Status of Hybrid PET/MRI in Oncologic Imaging; AJR, 2015