Investigating the state-of-the-art in whole-body MR-based attenuation correction: an intra-individual, inter-system, inventory study on three clinical PET/MR systems

Beyer, Thomas; Lassen, Martin Lyngby; Boellaard, Ronald; Delso, Gaspar; Yaqub, Maqsood; Sattler, Bernhard; Quick, Harald H.

doi:10.1007/s10334-015-0505-4

Cited by 64 publications

(82 citation statements)

References 33 publications

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“…The resulting AC‐map is truncated at the lateral edges of the FOV. Sequence parameters of the Dixon‐VIBE technique are: image matrix 192 × 126 × 128, resolution 2.6 × 2.6 × 3.1 mm³, TE 1 1.23 ms, TE 2 2.46 ms, TR 3.6 ms, FA 10°, which correspond to the Siemens standard protocol for Dixon‐VIBE MR‐based attenuation correction …”

Section: Methodsmentioning

confidence: 99%

“…In combined PET/MR hybrid imaging, the attenuation and scatter correction of the human body is based on MR data and subsequent tissue class segmentation. State of the art is a segmentation approach based on a Dixon‐VIBE MR sequence, which divides the object of study into four tissue classes (background air, lung, fat and soft tissue) and which assigns predefined linear attenuation coefficients (LAC) . This method today is in wide use for clinical PET/MR studies, but it has certain limitations compared with CT‐based AC.…”

Section: Introductionmentioning

confidence: 99%

“…Accordingly, in the majority of PET/MR examinations, the patient dimensions exceed the above‐mentioned spatial constraints of the MR FOV in left‐right dimension. Consequently, truncation artifacts often affect the arms from the shoulder region down to the upper legs . Such truncation artifacts in MR‐based AC occur independently of the PET/MR hybrid system model and can thus be considered an inherent limitation for MR‐based AC for all current PET/MR systems …”

Section: Introductionmentioning

confidence: 99%

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MR‐based truncation and attenuation correction in integrated PET/MR hybrid imaging using HUGE with continuous table motion

Lindemann¹,

Oehmigen²,

Blumhagen

et al. 2017

Medical Physics

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The HUGE method for truncation correction combined with continuous table movement extends the lateral MR field-of-view and effectively reduces truncations along the outer contours of the patient's arms in whole-body PET/MR imaging. HUGE as a fully MR-based approach is independent of the choice of radiotracer, thus also offering robust truncation correction in patients that are not injected with Fluordesoxyglucose (FDG) as radiotracer. Therefore, this method improves the standard Dixon MR-based attenuation correction and PET image quantification in whole-body PET/MR imaging applications.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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MR‐based truncation and attenuation correction in integrated PET/MR hybrid imaging using HUGE with continuous table motion

Lindemann¹,

Oehmigen²,

Blumhagen

et al. 2017

Medical Physics

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“…12 Corrections. Susceptibility artifacts induced in the sternum and close to the heart were corrected by filling the erroneously segmented tissues with tissue-ATN values corresponding to the tissue-segmentations surrounding the artifact.…”

Section: Pet/mr Imagingmentioning

confidence: 99%

“…Transformation from MR-images into AC maps are based on segmentation algorithms, which segment the images into four tissue types, with each tissue classification assigned to a vendor-specific attenuation (ATN) value. 12 In the Siemens Biograph mMR system, the segmented AC map is based on a DIXON-VIBE sequence, composed of inand opposed-phase images that are recomposed into fat and water images, and segmented into four tissue types (fat, soft tissue, background, and lung tissue). 13 The lack of bone attenuation information in the DIXON-attenuation correction (DIXON-AC) maps gives rise to average quantification errors of 2% for tissues in the vicinity of osseous structures for wholebody oncological scans.…”

Section: Introductionmentioning

confidence: 99%

Assessment of attenuation correction for myocardial PET imaging using combined PET/MRI

Lassen

Rasul

Beitzke

et al. 2019

Journal of Nuclear Cardiology

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Objective. To evaluate the frequency of artifacts in MR-based attenuation correction (AC) maps and their impact on the quantitative accuracy of PET-based flow and metabolism measurements in a cohort of consecutive heart failure patients undergoing combined PET/MR imaging.Methods. Myocardial viability studies were performed in 20 patients following a dualtracer protocol involving the assessment of myocardial perfusion ( 13 N-NH 3 : 813 ± 86 MBq) and metabolism ( 18 F-FDG: 335 ± 38 MBq). All acquisitions were performed using a fully-integrated PET/MR system, with standard DIXON-attenuation correction (DIXON-AC) mapping for each PET scan. All AC maps were examined for spatial misalignment with the emission data, total lung volume, susceptibility artifacts, and tissue inversion (TI). Misalignment and susceptibility artifacts were corrected using rigid co-registration and retrospective filling of the susceptibility-induced gaps, respectively. The effects of the AC artifacts were evaluated by relative difference measures and perceived changes in clinical interpretations.Results. Average respiratory misalignment of (7 ± 4) mm of the PET-emission data and the AC maps was observed in 18 (90%) patients. Substantial changes in the lung volumes of the AC maps were observed in the test-retest analysis (ratio: 1.0 ± 0.2, range: 0.8-1.4). Susceptibility artifacts were observed in 10 (50%) patients, while six (30%) patients had TI artifacts. Average differences of 14 ± 10% were observed for PET images reconstructed with the artifactual AC maps. The combined artifact effects caused false-positive findings in three (15%) patients.Conclusion. Standard DIXON-AC maps must be examined carefully for artifacts and misalignment effects prior to AC correction of cardiac PET/MRI studies in order to avoid misinterpretation of biased perfusion and metabolism readings from the PET data. (J Nucl Cardiol 2017)

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Current commercial techniques for MRI‐guided attenuation correction are insufficient and will limit the wider acceptance of PET/MRI technology in the clinic

Catana

Quick

Zaidi³

2018

Medical Physics

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OVERVIEWWhole-body hybrid PET/MR imaging has been used since its introduction in 2010 in clinical and research settings for diagnosis, staging and restaging, assessment of response to treatment, and radiation therapy planning. However, the quantitative potential of PET/MRI is challenged by the lack of reliable and accurate MRI-guided attenuation correction (MRAC) owing to the lack of direct relationship between MRI signal, reflecting proton density and relaxation time properties, and electron density, which is linked to photon attenuation properties of biological tissues. Despite the progress made during the last decade, MRAC is still in its infancy and remains problematic particularly in whole-body imaging. While some think that current techniques implemented on commercial systems for MRAC do not constitute a viable solution and are hampering the wider acceptance of PET/MRI technology in the clinic, others think that, despite their limitations, these techniques provide adequate correction fulfilling the requirements of the different clinical applications of this technology. This is the topic of this month's Point/Counterpoint debate.Arguing for the Proposition is Ciprian Catana, MD, PhD. Over the last decade, he has concentrated on further developing and validating this novel technology, identifying and implementing methods to best exploit the combined data, and developing quantitative PET/MRI for human use. Working closely with dozens of basic science researchers and physician-scientists, Dr. Catana is currently applying these advanced tools to the study of normal brain and neuropsychiatric diseases as well as exploring the clinical potential of this technology for wholebody oncological applications. Dr. Catana has authored more than 75 peer-reviewed manuscripts and book chapters and holds or has filed provisional patent applications for several technological and methodological innovations in the field of PET/MRI.

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Investigating the state-of-the-art in whole-body MR-based attenuation correction: an intra-individual, inter-system, inventory study on three clinical PET/MR systems

Abstract: Significant differences of MRμMaps generated for the same subjects but different PET/MR systems resulted in differences in attenuation correction factors, particularly in the thorax. These differences currently limit the quantitative use of PET/MR in multi-center imaging studies.

Cited by 64 publications

References 33 publications

MR‐based truncation and attenuation correction in integrated PET/MR hybrid imaging using HUGE with continuous table motion

MR‐based truncation and attenuation correction in integrated PET/MR hybrid imaging using HUGE with continuous table motion

Assessment of attenuation correction for myocardial PET imaging using combined PET/MRI

Current commercial techniques for MRI‐guided attenuation correction are insufficient and will limit the wider acceptance of PET/MRI technology in the clinic

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