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A major remaining challenge for magnetic resonance-based attenuation correction methods (MRAC) is their susceptibility to sources of MRI artifacts (e.g. implants, motion) and uncertainties due to the limitations of MRI contrast (e.g.…

99m-Tc Ethyl-Cysteinate-Dimer SPECT and MR imaging play a significant role in diagnosing anosmia. In this study, two-tissue class and three-tissue class attenuation maps (2C-MR and 3CMR) obtained from MR images were compared with CT-based…

Quantitative PET attenuation correction (AC) for combined cardiac PET/MR is a challenging problem. We propose and evaluate an AC approach that uses coincidences from a relatively weak and physically fixed sparse external source, in…

Medical Physics · Physics 2023-01-02 Mi-Ae Park , Vlad G. Zaha , Ramsey D. Badawi , Spencer L. Bowen

Current methods for magnetic resonance-based positron emission tomography attenuation correction (PET-MR AC) are time consuming, and less able than computed tomography (CT)-based AC methods to capture inter-individual variability and skull…

MR-based attenuation correction (MRAC) is important for accurate quantification of the uptake of PET tracers in combined PET/MR scanners. However, current techniques for MRAC usually require multiple acquisitions or complex post-processing…

Medical Physics · Physics 2019-06-11 Matteo Cencini , Michela Tosetti , Guido Buonincontri

Attenuation correction (AC) is essential for the generation of artifact-free and quantitatively accurate positron emission tomography (PET) images. However, AC of PET faces challenges including inter-scan motion and erroneous transformation…

Image and Video Processing · Electrical Eng. & Systems 2023-10-04 Yu Guan , Bohui Shen , Xinchong Shi , Xiangsong Zhang , Bingxuan Li , Qiegen Liu

In PET/CT imaging, CT is used for PET attenuation correction (AC). Mismatch between CT and PET due to patient body motion results in AC artifacts. In addition, artifact caused by metal, beam-hardening and count-starving in CT itself also…

Image and Video Processing · Electrical Eng. & Systems 2019-09-05 Luyao Shi , John A. Onofrey , Enette Mae Revilla , Takuya Toyonaga , David Menard , Jo-seph Ankrah , Richard E. Carson , Chi Liu , Yihuan Lu

Attenuation and scatter correction (AC) is crucial for quantitative Positron Emission Tomography (PET) imaging. Recently, direct application of AC in the image domain using deep learning approaches has been proposed for the hybrid PET/MR…

Medical Physics · Physics 2022-06-30 Reza Jahangir , Alireza Kamali-Asl , Hossein Arabi

We propose a magnetic resonance (MR)-based method for estimation of continuous linear attenuation coefficients (LAC) in positron emission tomography (PET) using a physical compartmental model and ultrashort echo time (UTE)/multi-echo Dixon…

Attenuation correction (AC) is necessary for accurate activity quantification in positron emission tomography (PET). Conventional reconstruction methods typically rely on attenuation maps derived from a co-registered computed tomography…

Positron Emission Tomography (PET) is a functional imaging modality widely used in neuroscience studies. To obtain meaningful quantitative results from PET images, attenuation correction is necessary during image reconstruction. For PET/MR…

Medical Physics · Physics 2018-08-01 Kuang Gong , Jaewon Yang , Kyungsang Kim , Georges El Fakhri , Youngho Seo , Quanzheng Li

Positron Emission Tomography (PET) imaging requires accurate attenuation correction (AC) to account for photon loss due to tissue density variations. In PET/MR systems, computed tomography (CT), which offers a straightforward estimation of…

Image and Video Processing · Electrical Eng. & Systems 2025-04-11 Weijie Chen , James Wang , Alan McMillan

Patlak model is widely used in 18F-FDG dynamic positron emission tomography (PET) imaging, where the estimated parametric images reveal important biochemical and physiology information. Because of better noise modeling and more information…

Medical Physics · Physics 2020-09-15 Nuobei Xie , Kuang Gong , Ning Guo , Zhixing Qin , Jianan Cui , Zhifang Wu , Huafeng Liu , Quanzheng Li

Objective: In this work, we set out to investigate the accuracy of direct attenuation correction (AC) in the image domain for the myocardial perfusion SPECT imaging (MPI-SPECT) using two residual (ResNet) and UNet deep convolutional neural…

Attenuation correction is an essential requirement of positron emission tomography (PET) image reconstruction to allow for accurate quantification. However, attenuation correction is particularly challenging for PET-MRI as neither PET nor…

Photon attenuation and scatter are the two main physical factors affecting the diagnostic quality of SPECT in its applications in brain imaging. In this work, we present a novel Bayesian Optimization approach for Attenuation Correction…

Medical Physics · Physics 2021-09-27 Loizos Koutsantonis , Ayman Makki , Tiago Carneiro , Emmanuel Kieffer , Pascal Bouvry

Purpose: Magnetization transfer saturation (MTsat) mapping is commonly used to examine the macromolecular content of brain tissue. This study compared variable flip angle (VFA) T1 mapping against compressed sensing (cs)MP2RAGE T1 mapping…

Brain positron emission tomography (PET) imaging is broadly used in research and clinical routines to study, diagnose, and stage Alzheimer's disease (AD). However, its potential cannot be fully exploited yet due to the lack of portable…

Image and Video Processing · Electrical Eng. & Systems 2025-01-16 Eléonore V. Lieffrig , Takuya Toyonaga , Jiazhen Zhang , John A. Onofrey

Purpose: To implement and evaluate a sequential approach to obtain semi-quantitative T1-weighted MPRAGE images, unbiased by B1 inhomogeneities at 7T. Methods: In the reference gradient echo used for normalization of the MPRAGE image, flip…

Medical Physics · Physics 2021-05-13 H. Olsson , G. Helms

Pretraining on large-scale datasets has been shown to improve transformer generalizability, even for out-of-domain (OOD) modalities and tasks. However, two common assumptions often fail under OOD transfer: that downstream datasets can be…

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