PT  - JOURNAL ARTICLE
AU  - Chan, Rosanna
AU  - Hussey, Douglas
AU  - Moon, Sangkyu
AU  - Schaefferkoetter, Josh
AU  - Ortega, Claudia
AU  - Metser, Ur
AU  - Veit-Haibach, Patrick
TI  - Determining the impact of body truncation correction on PET SUV values using F-18 DCFPyL in Whole-Body PET/MR imaging
DP  - 2020 May 01
TA  - Journal of Nuclear Medicine
PG  - 3111--3111
VI  - 61
IP  - supplement 1
4099  - http://jnm.snmjournals.org/content/61/supplement_1/3111.short
4100  - http://jnm.snmjournals.org/content/61/supplement_1/3111.full
SO  - J Nucl Med2020 May 01; 61
AB  - 3111Objectives: Truncation techniques for attenuation correction maps (µ maps) have been widely used to better estimate SUV values for PET/MR imaging. Attenuation correction with truncation techniques can either use the PET emission data to create a maximum likelihood of activity and attenuation (MLAA) image or use the data acquired from a MR sequence that optimizes the readout gradients and compensates for artifacts due to B0 inhomogeneities, HUGE (B0 Homogenization Using Gradient Enhancement) [1]. Currently, there is a lack of data comparing the SUV values of reference tissues (parotid, blood pool and liver) and lesions for whole Body PET/MR imaging reconstructed with and without truncation techniques using a PSMA agent. This study aims to determine the variability in SUV values in reference tissues and lesions in whole body PET/MR imaging using F-18 DCFPyL reconstructed with (extended FOV using MLAA and HUGE) and without (2-point DIXON only) truncation techniques. Methods: Whole body PET/MR images from 10 male patients injected with F18-DCFPyL (300MBq ±10%) were analyzed retrospectively. At 158mins (±10mins) post injection, images were acquired from vertex to mid-thigh using 5 bed positions at 2mins each. PET/MR data were reconstructed using the 2-point Dixon MR AC, HDPET (Point-spread function), 3 iterations with 21 subsets, 172x172 matrix, Gaussian filter with a FWHM of 5mm and absolute scatter correction. The data were also post processed with 3 different MRAC µ maps: 1) the standard (2-point DIXON), 2) the standard with the MLAA truncation technique and 3) the standard with HUGE truncation technique. Sphere VOIs were drawn over the right parotid gland (1cm3 ±0.5cm3), the left ventricle cavity as a representative of blood pool (3cm3 ±0.5cm3), the caudal aspect of the right liver lobe (3cm3 ±0.5cm3) and PSMA avid lesions on all 3 sets of images. SUVmax, and SUVmean were calculated for all VOIs. Results: Compared to PET AC images using the standard 2-point DIXON µ map, the PET data with µ maps using the HUGE and MLAA techniques have a higher increase in SUVmax and SUVmean for the blood pool and liver than the parotid. The average increase using the HUGE technique compared to the standard for the blood pool was 16-20% while the increase was 4-5% using MLAA. As for the liver, the average increase using HUGE was 24-30% and 5-6% using MLAA. With the parotid, there was a change of less than 1% with HUGE and 2-3% with MLAA. The total average difference in SUVmax and SUVmean of PSMA lesions increased by 35-40% using HUGE and 4-5% using MLAA. All results produced a p-value of less than 0.05. Conclusions: When using truncation techniques for MRAC µ maps, there is an overall increase in SUV values for liver and blood pool reference tissues and lesions. Compared to the MLAA technique, the HUGE technique produced a higher percentage of change. While performing longitudinal studies using F-18 DCFPyL in whole body PET/MR imaging with semi-quantitative methods, the same truncation techniques should be maintained in order to preserve consistency.