Journal Article

FZJ-2020-01108

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Improving the CT (140 kVp) to PET (511 keV) conversion in PET/MR Hardware Component Attenuation Correction

Oehmigen, M. (Corresponding author) ; Lindemann, M. E. ; Tellmann, L.FZJ* ; Lanz, T. ; Quick, H. H.

2020
AAPM College Park, Md.

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Please use a persistent id in citations: http://hdl.handle.net/2128/25626  doi:10.1002/mp.14091

Abstract: PurposeToday, attenuation correction (AC) of positron emission tomography/magnetic resonance (PET/MR) hardware components is performed by using an established method from PET/CT hybrid imaging. As shown in previous studies, the established mathematical conversion from computed tomography (CT) to PET attenuation coefficients may, however, lead to incorrect results in PET quantification when applied to AC of hardware components in PET/MR. The purpose of this study is to systematically investigate the attenuating properties of various materials and electronic components frequently used in the context of PET/MR hybrid imaging. The study, thus, aims at improving hardware component attenuation correction in PET/MR.Materials and methodsOverall, 38 different material samples were collected; a modular phantom was used to for CT, PET, and PET/MR scanning of all samples. Computed tomography‐scans were acquired with a tube voltage of 140 kVp to determine Hounsfield Units (HU). PET transmission scans were performed with 511 keV to determine linear attenuation coefficients (LAC) of all materials. The attenuation coefficients were plotted to obtain a HU to LAC correlation graph, which was then compared to two established conversions from literature. Hardware attenuation maps of the different materials were created and applied to PET data reconstruction following a phantom validation experiment. From these measurements, PET difference maps were calculated to validate and compare all three conversion methods.ResultsFor each material, the HU and corresponding LAC could be determined and a bi‐linear HU to LAC conversion graph was derived. The corresponding equation was urn:x-wiley:00942405:media:mp14091:mp14091-math-0001 . While the two established conversions lead to a mean quantification PET bias of 4.69% ± 0.27% and −2.84% ± 0.72% in a phantom experiment, PET difference measurements revealed only 0.5 % bias in PET quantification when applying the new conversion resulting from this study.ConclusionsAn optimized method for the conversion of CT to PET attenuation coefficients has been derived by systematic measurement of 38 different materials. In contrast to established methods, the new conversion also considers highly attenuating materials, thus improving attenuation correction of hardware components in PET/MR hybrid imaging.

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Contributing Institute(s):

1. Physik der Medizinischen Bildgebung (INM-4)

Research Program(s):

1. 573 - Neuroimaging (POF3-573) (POF3-573)

Appears in the scientific report 2020

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Database coverage:
; ; ; Clarivate Analytics Master Journal List ; Current Contents - Clinical Medicine ; Current Contents - Life Sciences ; Ebsco Academic Search ; IF < 5 ; JCR ; PubMed Central ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Web of Science Core Collection

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