Accurate hybrid template-based and MR-based attenuation correction using UTE images for simultaneous PET/MR brain imaging applications

Jakub Baran, Zhaolin Chen, Francesco Sforazzini, Nicholas Ferris, Sharna Jamadar, Ben Schmitt, David Faul, Nadim Jon Shah, Marian Cholewa, Gary F. Egan

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Background: Attenuation correction is one of the most crucial correction factors for accurate PET data quantitation in hybrid PET/MR scanners, and computing accurate attenuation coefficient maps from MR brain acquisitions is challenging. Here, we develop a method for accurate bone and air segmentation using MR ultrashort echo time (UTE) images. Methods: MR UTE images from simultaneous MR and PET imaging of five healthy volunteers was used to generate a whole head, bone and air template image for inclusion into an improved MR derived attenuation correction map, and applied to PET image data for quantitative analysis. Bone, air and soft tissue were segmented based on Gaussian Mixture Models with probabilistic tissue maps as a priori information. We present results for two approaches for bone attenuation coefficient assignments: one using a constant attenuation correction value; and another using an estimated continuous attenuation value based on a calibration fit. Quantitative comparisons were performed to evaluate the accuracy of the reconstructed PET images, with respect to a reference image reconstructed with manually segmented attenuation maps. Results: The DICE coefficient analysis for the air and bone regions in the images demonstrated improvements compared to the UTE approach, and other state-of-the-art techniques. The most accurate whole brain and regional brain analyses were obtained using constant bone attenuation coefficient values. Conclusions: A novel attenuation correction method for PET data reconstruction is proposed. Analyses show improvements in the quantitative accuracy of the reconstructed PET images compared to other state-of-the-art AC methods for simultaneous PET/MR scanners. Further evaluation is needed with radiopharmaceuticals other than FDG, and in larger cohorts of participants.

Original languageEnglish
Article number41
Number of pages16
JournalBMC Medical Imaging
Volume18
Issue number1
DOIs
Publication statusPublished - 6 Nov 2018

Keywords

  • Attenuation correction
  • Brain
  • PET/MR
  • UTE

Cite this

Baran, Jakub ; Chen, Zhaolin ; Sforazzini, Francesco ; Ferris, Nicholas ; Jamadar, Sharna ; Schmitt, Ben ; Faul, David ; Shah, Nadim Jon ; Cholewa, Marian ; Egan, Gary F. / Accurate hybrid template-based and MR-based attenuation correction using UTE images for simultaneous PET/MR brain imaging applications. In: BMC Medical Imaging. 2018 ; Vol. 18, No. 1.
@article{bcbfea2c3f6147f6a73655a865f51d06,
title = "Accurate hybrid template-based and MR-based attenuation correction using UTE images for simultaneous PET/MR brain imaging applications",
abstract = "Background: Attenuation correction is one of the most crucial correction factors for accurate PET data quantitation in hybrid PET/MR scanners, and computing accurate attenuation coefficient maps from MR brain acquisitions is challenging. Here, we develop a method for accurate bone and air segmentation using MR ultrashort echo time (UTE) images. Methods: MR UTE images from simultaneous MR and PET imaging of five healthy volunteers was used to generate a whole head, bone and air template image for inclusion into an improved MR derived attenuation correction map, and applied to PET image data for quantitative analysis. Bone, air and soft tissue were segmented based on Gaussian Mixture Models with probabilistic tissue maps as a priori information. We present results for two approaches for bone attenuation coefficient assignments: one using a constant attenuation correction value; and another using an estimated continuous attenuation value based on a calibration fit. Quantitative comparisons were performed to evaluate the accuracy of the reconstructed PET images, with respect to a reference image reconstructed with manually segmented attenuation maps. Results: The DICE coefficient analysis for the air and bone regions in the images demonstrated improvements compared to the UTE approach, and other state-of-the-art techniques. The most accurate whole brain and regional brain analyses were obtained using constant bone attenuation coefficient values. Conclusions: A novel attenuation correction method for PET data reconstruction is proposed. Analyses show improvements in the quantitative accuracy of the reconstructed PET images compared to other state-of-the-art AC methods for simultaneous PET/MR scanners. Further evaluation is needed with radiopharmaceuticals other than FDG, and in larger cohorts of participants.",
keywords = "Attenuation correction, Brain, PET/MR, UTE",
author = "Jakub Baran and Zhaolin Chen and Francesco Sforazzini and Nicholas Ferris and Sharna Jamadar and Ben Schmitt and David Faul and Shah, {Nadim Jon} and Marian Cholewa and Egan, {Gary F.}",
year = "2018",
month = "11",
day = "6",
doi = "10.1186/s12880-018-0283-3",
language = "English",
volume = "18",
journal = "BMC Medical Imaging",
issn = "1471-2342",
publisher = "Springer-Verlag London Ltd.",
number = "1",

}

Accurate hybrid template-based and MR-based attenuation correction using UTE images for simultaneous PET/MR brain imaging applications. / Baran, Jakub; Chen, Zhaolin; Sforazzini, Francesco; Ferris, Nicholas; Jamadar, Sharna; Schmitt, Ben; Faul, David; Shah, Nadim Jon; Cholewa, Marian; Egan, Gary F.

In: BMC Medical Imaging, Vol. 18, No. 1, 41, 06.11.2018.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Accurate hybrid template-based and MR-based attenuation correction using UTE images for simultaneous PET/MR brain imaging applications

AU - Baran, Jakub

AU - Chen, Zhaolin

AU - Sforazzini, Francesco

AU - Ferris, Nicholas

AU - Jamadar, Sharna

AU - Schmitt, Ben

AU - Faul, David

AU - Shah, Nadim Jon

AU - Cholewa, Marian

AU - Egan, Gary F.

PY - 2018/11/6

Y1 - 2018/11/6

N2 - Background: Attenuation correction is one of the most crucial correction factors for accurate PET data quantitation in hybrid PET/MR scanners, and computing accurate attenuation coefficient maps from MR brain acquisitions is challenging. Here, we develop a method for accurate bone and air segmentation using MR ultrashort echo time (UTE) images. Methods: MR UTE images from simultaneous MR and PET imaging of five healthy volunteers was used to generate a whole head, bone and air template image for inclusion into an improved MR derived attenuation correction map, and applied to PET image data for quantitative analysis. Bone, air and soft tissue were segmented based on Gaussian Mixture Models with probabilistic tissue maps as a priori information. We present results for two approaches for bone attenuation coefficient assignments: one using a constant attenuation correction value; and another using an estimated continuous attenuation value based on a calibration fit. Quantitative comparisons were performed to evaluate the accuracy of the reconstructed PET images, with respect to a reference image reconstructed with manually segmented attenuation maps. Results: The DICE coefficient analysis for the air and bone regions in the images demonstrated improvements compared to the UTE approach, and other state-of-the-art techniques. The most accurate whole brain and regional brain analyses were obtained using constant bone attenuation coefficient values. Conclusions: A novel attenuation correction method for PET data reconstruction is proposed. Analyses show improvements in the quantitative accuracy of the reconstructed PET images compared to other state-of-the-art AC methods for simultaneous PET/MR scanners. Further evaluation is needed with radiopharmaceuticals other than FDG, and in larger cohorts of participants.

AB - Background: Attenuation correction is one of the most crucial correction factors for accurate PET data quantitation in hybrid PET/MR scanners, and computing accurate attenuation coefficient maps from MR brain acquisitions is challenging. Here, we develop a method for accurate bone and air segmentation using MR ultrashort echo time (UTE) images. Methods: MR UTE images from simultaneous MR and PET imaging of five healthy volunteers was used to generate a whole head, bone and air template image for inclusion into an improved MR derived attenuation correction map, and applied to PET image data for quantitative analysis. Bone, air and soft tissue were segmented based on Gaussian Mixture Models with probabilistic tissue maps as a priori information. We present results for two approaches for bone attenuation coefficient assignments: one using a constant attenuation correction value; and another using an estimated continuous attenuation value based on a calibration fit. Quantitative comparisons were performed to evaluate the accuracy of the reconstructed PET images, with respect to a reference image reconstructed with manually segmented attenuation maps. Results: The DICE coefficient analysis for the air and bone regions in the images demonstrated improvements compared to the UTE approach, and other state-of-the-art techniques. The most accurate whole brain and regional brain analyses were obtained using constant bone attenuation coefficient values. Conclusions: A novel attenuation correction method for PET data reconstruction is proposed. Analyses show improvements in the quantitative accuracy of the reconstructed PET images compared to other state-of-the-art AC methods for simultaneous PET/MR scanners. Further evaluation is needed with radiopharmaceuticals other than FDG, and in larger cohorts of participants.

KW - Attenuation correction

KW - Brain

KW - PET/MR

KW - UTE

UR - http://www.scopus.com/inward/record.url?scp=85056113505&partnerID=8YFLogxK

U2 - 10.1186/s12880-018-0283-3

DO - 10.1186/s12880-018-0283-3

M3 - Article

VL - 18

JO - BMC Medical Imaging

JF - BMC Medical Imaging

SN - 1471-2342

IS - 1

M1 - 41

ER -