RT Journal Article
SR Electronic
T1 Uniformity phantom test of PET/MR
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 1816
OP 1816
VO 59
IS supplement 1
A1 KIM, BYUNG JIN
A1 Lee, Yong-Seok
A1 Cho, Yong-Hyun
A1 Kim, Moonsun
A1 ILLSANG, MOON
A1 LEE, HONG JAE
A1 Noh, Gyeong Woon
A1 Paeng, Jin Chul
A1 Lee, Jae Sung
A1 Kang, Keon Wook
A1 Lee, Dong Soo
A1 Chung, June-Key
YR 2018
UL http://jnm.snmjournals.org/content/59/supplement_1/1816.abstract
AB 1816Purpose: Image uniformity of PET using pure water phantom is hard to visualize with PET/MR 3T unlike PET/CT. The water phantom for the PET/MR needs appropriate additives to control susceptibility and conductivity in the water. The purpose of this study was to investigate the optimal concentration of gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA) and sodium chloride (NaCl) solution for acquiring good image uniformity with a water phantom on PET/MR. Materials and Methods: A cylindrical phantom of 9.52L was filled with demineralized water, 21 kBq/ml F-18 solution, Gd-DTPA as a T1 relaxation modifier and NaCl as a conductivity modifier. Various concentrations of Gd-DTPA (0-0.2 mM) and NaCl (0-200 mM) mixtures were prepared for the phantoms. DIXON MR sequences were simultaneously performed with PET acquisitions. PET/MR image of each phantom was acquired for 10 minutes per bed position. PET data were reconstructed using OSEM with 2 iterations, 21 subsets and a 6 mm FWHM of Gaussian filter. The MR Image uniformity was estimated with a percent integral uniformity (PIU) and the nonuniformity of PET image was evaluated by a coefficient of variation (CV). Results: MR-based attenuation correction (MRAC) maps that acquired from the water phantom without Gd-DTPA or NaCl solution caused image artifacts along to a phase direction in MR. When Gd-DTPA was only added in the water phantom, artifacts of the MRAC showed a tendency to decrease but did not disappear completely. A mixture of 0.2 mM Gd-DTPA and 150 mM NaCl was the most suitable concentration for water filled uniformity phantom at the PET/MR image without artifacts. The PIU corresponding to the MRAC map and the DIXON image was 100%, 83.1% respectively. The CV of PET was 6.3%. Conclusion: We suggest that Gd-DTPA and NaCl are useful additives which are easily accessible and handle safely in clinical practice when performing a uniformity phantom test with water on PET/MR.