title: List-mode reconstruction for the Biograph mCT with physics modeling and event-by-event motion correction.
abstract: Whole-body PET/CT scanners are important clinical and research tools to study tracer distribution throughout the body. In whole-body studies, respiratory motion results in image artifacts. We have previously demonstrated for brain imaging that, when provided with accurate motion data, event-by-event correction has better accuracy than frame-based methods. Therefore, the goal of this work was to develop a list-mode reconstruction with novel physics modeling for the Siemens Biograph mCT with event-by-event motion correction, based on the MOLAR platform (Motion-compensation OSEM List-mode Algorithm for Resolution-Recovery Reconstruction). Application of MOLAR for the mCT required two algorithmic developments. First, in routine studies, the mCT collects list-mode data in 32 bit packets, where averaging of lines-of-response (LORs) by axial span and angular mashing reduced the number of LORs so that 32 bits are sufficient to address all sinogram bins. This degrades spatial resolution. In this work, we proposed a probabilistic LOR (pLOR) position technique that addresses axial and transaxial LOR grouping in 32 bit data. Second, two simplified approaches for 3D time-of-flight (TOF) scatter estimation were developed to accelerate the computationally intensive calculation without compromising accuracy. The proposed list-mode reconstruction algorithm was compared to the manufacturer's point spread function + TOF (PSF+TOF) algorithm. Phantom, animal, and human studies demonstrated that MOLAR with pLOR gives slightly faster contrast recovery than the PSF+TOF algorithm that uses the average 32 bit LOR sinogram positioning. Moving phantom and a whole-body human study suggested that event-by-event motion correction reduces image blurring caused by respiratory motion. We conclude that list-mode reconstruction with pLOR positioning provides a platform to generate high quality images for the mCT, and to recover fine structures in whole-body PET scans through event-by-event motion correction.
authors.affiliation: Biomedical Engineering, Yale University, New Haven, CT, USA. xiao.jin@yale.edu
authors.forename: Xiao
authors.initials: X
authors.lastname: Jin
authors.forename: Chung
authors.initials: C
authors.lastname: Chan
authors.forename: Tim
authors.initials: T
authors.lastname: Mulnix
authors.forename: Vladimir
authors.initials: V
authors.lastname: Panin
authors.forename: Michael E
authors.initials: ME
authors.lastname: Casey
authors.forename: Chi
authors.initials: C
authors.lastname: Liu
authors.forename: Richard E
authors.initials: RE
authors.lastname: Carson
mesh_terms: D000465:Algorithms; D000818:Animals; D001921:Brain / Q000000981:diagnostic imaging; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008962:Models, Theoretical; D009068:Movement; D010215:Papio; D055585:Physical Phenomena; D049268:Positron-Emission Tomography; D014057:Tomography, X-Ray Computed / Q000379:methods*
references.citation: Med Phys. 2007 Jul;34(7):2774-84
references.pmid: 17821984
references.citation: Phys Med Biol. 2003 Apr 21;48(8):959-78
references.pmid: 12741495
references.citation: Phys Med Biol. 2013 Mar 21;58(6):1759-73
references.pmid: 23442264
references.citation: Med Phys. 2013 Nov;40(11):112507
references.pmid: 24320466
references.citation: IEEE Trans Med Imaging. 2004 Sep;23(9):1176-85
references.pmid: 15377126
references.citation: Phys Med Biol. 2007 Sep 7;52(17):5187-204
references.pmid: 17762080
references.citation: IEEE Trans Med Imaging. 2012 Dec;31(12):2224-33
references.pmid: 22899574
references.citation: Phys Med Biol. 2009 Sep 7;54(17):5321-39
references.pmid: 19687531
references.citation: Ann Nucl Med. 2010 Dec;24(10):745-50
references.pmid: 20842466
references.citation: J Nucl Med. 2003 Oct;44(10):1644-8
references.pmid: 14530480
references.citation: IEEE Trans Med Imaging. 2013 Feb;32(2):141-52
references.pmid: 22759442
references.citation: Med Image Anal. 2002 Mar;6(1):29-46
references.pmid: 11836133
references.citation: IEEE Trans Med Imaging. 2010 Nov;29(11):1892-906
references.pmid: 20562034
references.citation: Phys Med Biol. 2007 Mar 7;52(5):1505-26
references.pmid: 17301468
references.citation: J Nucl Med. 2012 Jun;53(6):908-16
references.pmid: 22573821
references.citation: Med Phys. 2007 Jul;34(7):3067-76
references.pmid: 17822014
references.citation: Phys Med Biol. 2011 Apr 21;56(8):2375-89
references.pmid: 21427485
references.citation: IEEE Nucl Sci Symp Conf Rec (1997). 2009 Oct 24;2009:3199-3202
references.pmid: 20607125
references.citation: IEEE Trans Med Imaging. 1999 May;18(5):393-403
references.pmid: 10416801
references.citation: IEEE Trans Med Imaging. 2006 Jul;25(7):907-21
references.pmid: 16827491
references.citation: Phys Med Biol. 2005 Oct 7;50(19):4507-26
references.pmid: 16177486
references.citation: IEEE Trans Med Imaging. 2006 Apr;25(4):476-85
references.pmid: 16608062
references.citation: J Nucl Med. 2011 Dec;52(12):1914-22
references.pmid: 22080447
references.citation: Med Phys. 2011 May;38(5):2715-23
references.pmid: 21776808