An integrated MR/PET system: prospective applications

Schlemmer, Heinz Peter; Pichler, Bernd J.; Krieg, Robert; Heiss, Wolf Dieter

doi:10.1007/s00261-008-9450-2

Cited by 65 publications

(31 citation statements)

References 27 publications

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“…This is the reason why MRI is regarded as the first-line imaging procedure for diagnostic problems in oncology associated with soft-tissue regions (e.g., tumors in the brain, the head-and-neck region, or the pelvis). Because PET has proven valuable for several of these diagnostic problems, a potential added value of combined MRI and PET over PET/CT can be expected for these indications (1)(2)(3)(4)(5). In principle, PET and MRI data may be fused in retrospect using dedicated software registration algorithms; however, these approaches often encounter problems with patient position and motion (6,7).…”

mentioning

confidence: 99%

First Clinical Experience with Integrated Whole-Body PET/MR: Comparison to PET/CT in Patients with Oncologic Diagnoses

Drzezga

Souvatzoglou²,

Eiber³

et al. 2012

J Nucl Med

466

313

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The recently introduced first integrated whole-body PET/MR scanner allows simultaneous acquisition of PET and MRI data in humans and, thus, may offer new opportunities, particularly regarding diagnostics in oncology. This scanner features major technologic differences from conventional PET/CT devices, including the replacement of photomultipliers with avalanche photodiodes and the need for MRI-based attenuation correction. The aim of this study was to evaluate the comparability of clinical performance between conventional PET/CT and PET/MR in patients with oncologic diseases. Methods: Thirty-two patients with different oncologic diagnoses underwent a single-injection, dual-imaging protocol consisting of a PET/CT and subsequent PET/MR scan. PET/CT scans were performed according to standard clinical protocols (86 6 8 min after injection of 401 6 42 MBq of 18 F-FDG, 2 min/ bed position). Subsequently (140 6 24 min after injection), PET/ MR was performed (4 min/bed position). PET images of both modalities were reconstructed iteratively. Attenuation and scatter correction as well as regional allocation of PET findings were performed using low-dose CT data for PET/CT and Dixon MRI sequences for PET/MR. PET/MR and PET/CT were compared visually by 2 teams of observers by rating the number and location of lesions suspicious for malignancy, as well as image quality and alignment. For quantitative comparison, standardized uptake values (SUVs) of the detected lesions and of different tissue types were assessed. Results: Simultaneous PET/MR acquisition was feasible with high quality in short acquisition time (#20 min). No significant difference was found between the numbers of suspicious lesions (n 5 80) or lesion-positive patients (n 5 20) detected with PET/MR or PET/CT. Anatomic allocation of PET/ MR findings by means of the Dixon MRI sequence was comparable to allocation of PET/CT findings by means of low-dose CT. Quantitative evaluation revealed a high correlation between mean SUVs measured with PET/MR and PET/CT in lesions (r = 0.93) and background tissue (r = 0.92). Conclusion: This study demonstrates, for what is to our knowledge the first time, that integrated whole-body PET/MR is feasible in a clinical setting with high quality and in a short examination time. The reliability of PET/ MR was comparable to that of PET/CT in allowing the detection of hypermetabolic lesions suspicious for malignancy in patients with oncologic diagnoses. Despite different attenuation correction approaches, tracer uptake in lesions and background correlated well between PET/MR and PET/CT. The Dixon MRI sequences acquired for attenuation correction were found useful for anatomic allocation of PET findings obtained by PET/MR in the entire body. These encouraging results may form the foundation for future studies aiming to define the added value of PET/MR over PET/CT.

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mentioning

confidence: 99%

First Clinical Experience with Integrated Whole-Body PET/MR: Comparison to PET/CT in Patients with Oncologic Diagnoses

Drzezga

Souvatzoglou²,

Eiber³

et al. 2012

J Nucl Med

466

313

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“…[54][55][56][57][58][59][60][61][62][63][64][65][66][67][68][69][70][71][72] Such a system would allow exploiting, in addition to the above discussed applications, the power of MR spectroscopy (MRS) to measure the regional biochemical content and to assess the metabolic status or the presence of neoplasia and other diseases in specific tissue areas. Until concurrent PET/MRI technologies for whole-body imaging become more mature and economically viable, other approaches for so-called sequential PET/MR imaging have been researched.…”

Section: Historical Development Of Pet/mrimentioning

confidence: 99%

“…201 Despite the fact that the clinical role of PET/MRI in clinical setting is controversial and has not been yet addressed properly, the prospective applications of a whole-body PET/ MRI system in clinical oncology have been explored in the literature. [54][55][56][57][58][59][60][61][62][63][64][65][66][67][68][69][70][71][72] The potential of nanoparticle-based dual-modality PET/MRI contrast agents is also being investigated. Some scientific arguments on the advantages of simultaneous imaging of morphological and functional information using hybrid PET/MRI technology will improve tissue characterization.…”

Section: Clinical Relevance Of Pet/mrimentioning

confidence: 99%

An outlook on future design of hybrid PET/MRI systems

2011

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Early diagnosis and therapy increasingly operate at the cellular, molecular, or even at the genetic level. As diagnostic techniques transition from the systems to the molecular level, the role of multimodality molecular imaging becomes increasingly important. Positron emission tomography (PET) and magnetic resonance imaging (MRI) are powerful techniques for in vivo molecular imaging. The inability of PET to provide anatomical information is a major limitation of standalone PET systems. Combining PET and CT proved to be clinically relevant and successfully reduced this limitation by providing the anatomical information required for localization of metabolic abnormalities. However, this technology still lacks the excellent soft-tissue contrast provided by MRI. Standalone MRI systems reveal structure and function but cannot provide insight into the physiology and/or the pathology at the molecular level. The combination of PET and MRI, enabling truly simultaneous acquisition, bridges the gap between molecular and systems diagnosis. MRI and PET offer richly complementary functionality and sensitivity; fusion into a combined system offering simultaneous acquisition will capitalize the strengths of each, providing a hybrid technology that is greatly superior to the sum of its parts. A combined PET/MRI system provides both the anatomical and structural description of MRI simultaneously with the quantitative capabilities of PET. In addition, such a system would allow exploiting the power of MR spectroscopy (MRS) to measure the regional biochemical content and to assess the metabolic status or the presence of neoplasia and other diseases in specific tissue areas. This paper briefly summarizes state-of-the-art developments and latest advances in dedicated hybrid PET/MRI instrumentation. Future prospects and potential clinical applications of this technology will also be discussed.

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“…In this respect, there are clear indications that several manufacturers are focusing their efforts on the development of various designs of MR-compatible wholebody PET systems. In parallel, potential applications of this technology are being explored in the scientific literature [13][14][15][16]. These technologies will allow exploitation of the full potential of anatomical MRI in terms of high soft tissue contrast sensitivity in addition to the many other possibilities offered by this modality including BOLD imaging, functional MRI (fMRI), diffusion-weighted imaging (DWI), perfusion-weighted imaging (PWI), diffusion tensor imaging (DTI) and MR spectroscopy (MRS) [17].…”

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confidence: 99%

Navigating beyond the 6th dimension: a challenge in the era of multi-parametric molecular imaging

Zaidi

2009

Eur J Nucl Med Mol Imaging

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This is an exciting time for molecular imaging as we are witnessing a convergence and combination of various imaging modalities driven by an unprecedented multidisciplinary collaboration between scientists. A consequence of this growth is a paradigm shift in health care delivery that is now revolutionizing clinical practice. Within the spectrum of macroscopic medical imaging, sensitivity ranges from the detection of millimolar to submillimolar concentrations of contrast media with computed tomography (CT) and magnetic resonance imaging (MRI), respectively, to picomolar concentrations in positron emission tomography (PET): a 10 8 -10 9 difference [1]. Despite the remarkable progress and outstanding scientific innovations achieved and the much worthwhile successful research carried out both in academic and corporate settings, there are still plenty of open research questions that offer ample opportunities for the new generation of molecular imaging scientists [2]. There is no shortage of challenges and opportunities nowadays for developing novel molecular imaging probes and technologies and for establishing their role through innovative applications in clinical and research settings. The only limit is the imagination and creativity of the investigators and the challenge is the ability of opinion leaders to attract the best scientists into this discipline.

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An integrated MR/PET system: prospective applications

Abstract: Radiology is strongly depending on medical imaging technology and consequently directing technological progress. A novel technology can only be established, however, if improved diagnostic accuracy influence on therapeutic management and/or overall reduced cost can be evidenced.

Cited by 65 publications

References 27 publications

First Clinical Experience with Integrated Whole-Body PET/MR: Comparison to PET/CT in Patients with Oncologic Diagnoses

First Clinical Experience with Integrated Whole-Body PET/MR: Comparison to PET/CT in Patients with Oncologic Diagnoses

An outlook on future design of hybrid PET/MRI systems

Navigating beyond the 6th dimension: a challenge in the era of multi-parametric molecular imaging

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