Simultaneous PET-MRI: a new approach for functional and morphological imaging

Judenhofer, Martin S.; Wehrl, Hans F.; Newport, D.F.; Catana, Ciprian; Siegel, Stefan; Becker, Markus; Thielscher, Axel; Kneilling, Manfred; Lichy, Matthias P.; Eichner, Martin; Klingel, Karin; Reischl, Gerald; Widmaier, Stefan; Röcken, Martin; Nutt, R.; Machulla, Hans-Juergen; Uludağ, Kâmil; Cherry, Simon R.; Claussen, Claus D.; Pichler, Bernd J.

doi:10.1038/nm1700

Cited by 905 publications

(641 citation statements)

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“…With the installation of PET/MR systems in a clinical environment, this integrated imaging modality, which is already utilized in preclinical research already is on the verge of being applied to the clinical neurosciences [17,18]. An integrated PET/MRI system will permit the simultaneous acquisition of several parameters (Table 1).…”

Section: Advantages Of An Integrated Pet/mr System For Image Fusionmentioning

confidence: 99%

The potential of PET/MR for brain imaging

Heiss

2008

Eur J Nucl Med Mol Imaging

129

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Introduction The completion of an integrated PET/MR prototype system for brain imaging is the latest step in the evolution of positron emission tomography. Early images with this new imaging system demonstrate that highresolution multiparametric studies can be combined without significant loss of performance of either imaging modality. Objective This new technology will make fusion of morphological and biological information much easier, yield real-time assessment of complementary variables and will provide dynamic information for kinetic model- IntroductionSince the first prototypes [1, 2] and the first commercial system [3], positron emission tomography (PET) has developed to multiring systems permitting high resolution and three-dimensional imaging of various physiological, functional and molecular targets. The first applications of PET were in brain research, and despite the many other diagnostic indications, particularly in oncology and cardiology, brain imaging remains a stronghold of PET.Therefore, this discussion of perspectives of an integrated PET/MR system is focused on research applications in neuroscience to which the combination of PET and MRI may add further impetus. This perspective is in parts speculative and it does not include a discussion of the technical or methodological challenges of combined PET/ MR imaging. These aspects are reviewed elsewhere in the articles of this supplement to EJNMMI. Development of PET for brain imagingThe progress in image quality may be followed by metabolic images of glucose consumption in one volunteer acquired on several generation PET systems over the years. The first transaxial image (Fig. 1a) was acquired on a single hexagonal array, the ECAT PET, which covered only the cortical rim. Early PET images suffered from limited spatial resolution (approximately 15 mm), low sensitivity and insufficient attenuation and scatter correction [3,4]. PET image quality improved with the four-ring PC-384 (Scanditronix) [5], which yielded seven simultaneous, partly overlapping transaxial images and that provided a spatial resolution of 8.4 mm FWHM across 12-mm slices (Fig. 1b) [6] and limited axial reconstruction (Fig. 2). Further improvements came with the Eur

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Section: Advantages Of An Integrated Pet/mr System For Image Fusionmentioning

confidence: 99%

The potential of PET/MR for brain imaging

Heiss

2008

Eur J Nucl Med Mol Imaging

129

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“…The realization of PET/MR tomographs beyond small-animal imaging prototypes [6,7], however, remains challenging. In particular, the lack of conventional or X-ray transmission sources mandates alternative approaches to AC of the complementary emission data [8].…”

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confidence: 99%

“…While early preclinical PET/MR design concepts did not include means for AC [6,7], a relatively simple two-class AC scheme was suggested for the first clinical prototype [5]. The lack of viable MR-AC methods today can be explained by the fact that attenuation is less critical in small animals than in patients, and, therefore, the issue of AC was of less importance in preclinical PET and PET/MRI.…”

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confidence: 99%

Towards quantitative PET/MRI: a review of MR-based attenuation correction techniques

Hofmann

Pichler

Schölkopf

et al. 2008

Eur J Nucl Med Mol Imaging

316

251

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Introduction Positron emission tomography (PET) is a fully quantitative technology for imaging metabolic pathways and dynamic processes in vivo. Attenuation correction of raw PET data is a prerequisite for quantification and is typically based on separate transmission measurements. In PET/CT attenuation correction, however, is performed routinely based on the available CT transmission data. Objective Recently, combined PET/magnetic resonance (MR) has been proposed as a viable alternative to PET/ CT. Current concepts of PET/MRI do not include CT-like transmission sources and, therefore, alternative methods of PET attenuation correction must be found. This article reviews existing approaches to MR-based attenuation correction (MR-AC). Most groups have proposed MR-AC algorithms for brain PET studies and more recently also for torso PET/MR imaging. Most MR-AC strategies require the use of complementary MR and transmission images, or morphology templates generated from transmission images. We review and discuss these algorithms and point out challenges for using MR-AC in clinical routine. Discussion MR-AC is work-in-progress with potentially promising results from a template-based approach applicable to both brain and torso imaging. While efforts are ongoing in making clinically viable MR-AC fully automatic, further studies are required to realize the potential benefits of MRbased motion compensation and partial volume correction of the PET data.

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“…Much of this growth is due to the enormous flexibility of the method and the large variation in tissue contrasts that can be achieved to reveal pathology and detailed structural and biochemical information. The clinical synergies that can be achieved by a multimodality approach [30] combining simultaneous or quasi-simultaneous PET and MRI in humans are still unknown, although first results from animal studies are rather promising [32]. To achieve maximum impact, the strengths and weaknesses of both imaging techniques need to be considered and strategies developed, which account for complementary imaging properties.…”

Section: Discussion and Outlookmentioning

confidence: 99%