The effect of patient positioning aids on PET quantification in PET/MR imaging

Mantlik, Frederic; Hofmann, Matthias; Werner, Matthias; Sauter, Alexander; Kupferschläger, Jürgen; Schölkopf, Bernhard; Pichler, Bernd J.; Beyer, Thomas

doi:10.1007/s00259-010-1721-9

Cited by 36 publications

(29 citation statements)

References 12 publications

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“…Therefore, in whole-body applications, AC methods that do not account for bone may be sufficient for a wide variety of clinical applications (10). In addition to generating a suitable map from the MR images, the attenuation of MRI radiofrequency coils and ancillary devices must also be accounted for (11,12).…”

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confidence: 99%

MRI-Based Attenuation Correction for Whole-Body PET/MRI: Quantitative Evaluation of Segmentation- and Atlas-Based Methods

Hofmann¹,

Bezrukov²,

Mantlik³

et al. 2011

J Nucl Med

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PET/MRI is an emerging dual-modality imaging technology that requires new approaches to PET attenuation correction (AC). We assessed 2 algorithms for whole-body MRI-based AC (MRAC): a basic MR image segmentation algorithm and a method based on atlas registration and pattern recognition (AT&PR). Methods: Eleven patients each underwent a whole-body PET/ CT study and a separate multibed whole-body MRI study. The MR image segmentation algorithm uses a combination of image thresholds, Dixon fat-water segmentation, and component analysis to detect the lungs. MR images are segmented into 5 tissue classes (not including bone), and each class is assigned a default linear attenuation value. The AT&PR algorithm uses a database of previously aligned pairs of MRI/CT image volumes. For each patient, these pairs are registered to the patient MRI volume, and machine-learning techniques are used to predict attenuation values on a continuous scale. MRAC methods are compared via the quantitative analysis of AC PET images using volumes of interest in normal organs and on lesions. We assume the PET/CT values after CT-based AC to be the reference standard. Results: In regions of normal physiologic uptake, the average error of the mean standardized uptake value was 14.1% 6 10.2% and 7.7% 6 8.4% for the segmentation and the AT&PR methods, respectively. Lesion-based errors were 7.5% 6 7.9% for the segmentation method and 5.7% 6 4.7% for the AT&PR method. Conclusion: The MRAC method using AT&PR provided better overall PET quantification accuracy than the basic MR image segmentation approach. This better quantification was due to the significantly reduced volume of errors made regarding volumes of interest within or near bones and the slightly reduced volume of errors made regarding areas outside the lungs.

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mentioning

confidence: 99%

MRI-Based Attenuation Correction for Whole-Body PET/MRI: Quantitative Evaluation of Segmentation- and Atlas-Based Methods

Hofmann¹,

Bezrukov²,

Mantlik³

et al. 2011

J Nucl Med

Self Cite

259

211

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“…[33][34][35]44 A recent study demonstrated that reconstructed Combined PET/MRI for Improving Quantitative Imaging radioactivity concentrations in brain tissue from a combined UTE/Dixon 45 four tissue class attenuation correction approach correlated tightly (r 2 ¼ 0.99) with those produced using CT-based attenuation correction. 35 More recently, work has been presented on MR-based attenuation correction for whole body imaging, [46][47][48][49][50][51][52][53][54][55][56][57][58][59] including the impact of surface coils and truncation artifacts from a limited MR transaxial field-of-view. Non-rigid registration of MR to CT in order to produce a pseudo-CT from MR for attenuation correction was not found to be as successful as the aforementioned non-rigid approaches for MR-based attenuation correction in the brain.…”

Section: Attenuation Correctionmentioning

confidence: 99%

CHAPTER 10. Combined PET/MRI for Improving Quantitative Imaging

Fryer¹

2013

New Developments in NMR

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“…What is new compared with standalone MRI is that care has to be taken that any additional positioning aids do not result in significant attenuation of the 511-keV photons (14). In PET/MRI, surface coils are used to increase MRI image quality and reduce imaging time, just as in standalone MRI.…”

Section: In-bed Patient Preparationmentioning

confidence: 99%

Workflow and Scan Protocol Considerations for Integrated Whole-Body PET/MRI in Oncology

et al. 2012

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Learning Objectives: On successful completion of this activity, participants should be able to describe (1) special requirements for planning whole-body PET/MRI examinations; (2) general aspects of whole-body PET/MRI protocols in oncology; and (3) possible artifacts in PET/MRI.Financial Disclosure: An author of this article is a meeting participant or lecturer for Siemens AG. No other relevant relationships that could be perceived as a real or apparent conflict of interest were reported. CME Credit: SNMMI is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to sponsor continuing education for physicians. SNMMI designates each JNM continuing education article for a maximum of 2.0 AMA PRA Category 1 Credit. Physicians should claim only credit commensurate with the extent of their participation in the activity. For CE credit, participants can access this activity through the SNMMI Web site (http:// www.snmmi.org/ce_online) through September 2013.Integrated PET/MRI systems open exciting possibilities for clinical and research applications. However, compared with PET/CT, PET/MRI is a complex technique resulting in new problems and challenges, especially regarding workflow, scan protocols, and data analysis. This complexity applies in particular to examinations in oncology with partial-or whole-body coverage extending over several bed positions. Unlike diagnostic PET/CT, for which the clinical CT protocols can largely be copied from stand-alone CT, the design of a diagnostic MRI protocol for partial-or whole-body coverage is more complex and has to be adapted to the special requirements of PET/MRI to be both time-efficient and comprehensive. Here, we describe basic considerations concerning workflow, imaging protocols, and image analysis for whole-body PET/MRI in oncology, based on our experience with the first integrated PET/MRI scanner. The aim is to fully and optimally make use of the combined PET/MRI measurements in oncology, including identifying and reducing image artifacts as well as optimizing workflow beyond the mere fusion of 2 image datasets. Thesuccessofcombi ned PET and CT has demonstrated the clinical value of multimodality imaging technology, providing both anatomic and molecular information within a single imaging session. However, whereas CT and especially modern multislice CT are a powerful imaging tool, they still have shortcomings, such as low soft-tissue contrast when compared with MRI. Thus, the combination of PET and MRI might be clinically advantageous over PET/ CT for some indications. Moreover, because MRI has more potential for functional and molecular imaging than does CT, the combination of PET with MRI offers completely new opportunities for research applications and for molecular imaging in general.As a consequence, a lot of effort has been put into the development of combined PET and MRI. The first preclinical combined PET/MRI systems were introduced in the 1990s (1-3). Clinically, a PET insert for a standard 3.0-T MRI scanner for simultaneous PET/MRI of t...

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The effect of patient positioning aids on PET quantification in PET/MR imaging

Cited by 36 publications

References 12 publications

MRI-Based Attenuation Correction for Whole-Body PET/MRI: Quantitative Evaluation of Segmentation- and Atlas-Based Methods

MRI-Based Attenuation Correction for Whole-Body PET/MRI: Quantitative Evaluation of Segmentation- and Atlas-Based Methods

CHAPTER 10. Combined PET/MRI for Improving Quantitative Imaging

Workflow and Scan Protocol Considerations for Integrated Whole-Body PET/MRI in Oncology

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