Simultaneous PET/Mri in Stroke: A Case Series

Werner, Peter; Saur, Dorothee; Zeisig, Vilia; Ettrich, Barbara; Patt, Marianne; Sattler, Bernhard; Jochimsen, Thies H.; Lobsien, Donald; Meyer, Philipp; Bergh, Florian Then; Dreyer, Antje; Boltze, Johannes; Claßen, Joseph; Fritzsch, Dominik; Hoffmann, Karl‐Titus; Sabri, Osama; Barthel, Henryk

doi:10.1038/jcbfm.2015.158

Cited by 51 publications

(38 citation statements)

References 20 publications

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“…Also, higher variability of PWI-derived CBF measures than of PET-derived CBF measures was detected. That study (36) revealed, in line with previous studies (32,37), an overestimation of PWI-based CBF measures. Overall, the PWI-DWI mismatch volume, as conventionally calculated, does not reliably reflect misery perfusion-that is, the penumbra, as defined by PET.…”

Section: Pwi Of Penumbrasupporting

confidence: 92%

Validation of MRI Determination of the Penumbra by PET Measurements in Ischemic Stroke

Heiss

Weber

2016

J Nucl Med

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The concept of the ischemic penumbra was formulated on the basis of animal experiments showing functional impairment and electrophysiologic disturbances with decreasing flow to the brain below defined values (the threshold for function) and irreversible tissue damage with blood supply further decreased (the threshold for infarction). The perfusion range between these thresholds was termed the "penumbra," and restitution of flow above the functional threshold was able to reverse the deficits without permanent damage. In further experiments, the dependency of the development of irreversible lesions on the interaction of the severity and the duration of critically reduced blood flow was established, proving that the lower the flow, the shorter the time for efficient reperfusion. As a consequence, infarction develops from the core of ischemia to the areas of less severe hypoperfusion. The translation of this experimental concept as the basis for the efficient treatment of stroke requires noninvasive methods with which regional flow and energy metabolism can be repeatedly investigated to demonstrate penumbra tissue, which can benefit from therapeutic interventions. PET allows the quantification of regional cerebral blood flow, the regional oxygen extraction fraction, and the regional metabolic rate for oxygen. With these variables, clear definitions of irreversible tissue damage and of critically hypoperfused but potentially salvageable tissue (i.e., the penumbra) in stroke patients can be achieved. However, PET is a research tool, and its complex logistics limit clinical routine applications. Perfusion-weighted or diffusion-weighted MRI is a widely applicable clinical tool, and the "mismatch" between perfusion-weighted and diffusion-weighted abnormalities serves as an indicator of the penumbra. However, comparative studies of perfusion-weighted or diffusionweighted MRI and PET have indicated overestimation of the core of irreversible infarction as well as of the penumbra by the MRI modalities. Some of these discrepancies can be explained by the nonselective application of relative perfusion thresholds, which might be improved by more complex analytic procedures. The heterogeneity of the MRI signatures used for the definition of the mismatch are also responsible for disappointing results in the application of perfusion-weighted or diffusion-weighted MRI to the selection of patients for clinical trials. As long as validation of the mismatch selection paradigm is lacking, the use of this paradigm as a surrogate marker of outcome is limited. ENERGY REQUIREMENTS OF BRAIN TISSUEBecause the energy demand of nervous tissue is very high, sufficient blood supply to the brain must be maintained consistently. The oxygen consumption of the brain is involved almost entirely in the oxidative metabolism of glucose which, in normal physiologic conditions, is the almost exclusive substrate for the energy metabolism of the brain (1). The glucose metabolized in neuronal cell bodies is used mainly to support cellular vegetative and hou...

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Section: Pwi Of Penumbrasupporting

confidence: 92%

Validation of MRI Determination of the Penumbra by PET Measurements in Ischemic Stroke

Heiss

Weber

2016

J Nucl Med

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“…Although PET/MRI examinations are very difficult to routinely perform in the acute phase of stroke, this much needed cross-validation could help elucidate the ongoing debate concerning the relationship between the perfusion-diffusion mismatch and the PET penumbra (90–93), which would have immediate clinical implications. The first such study performed on an integrated PET/MRI device revealed discrepancies between the PET- and MRI-derived perfusion measurements that the authors attributed to the limited accuracy of current MRI based techniques (94). …”

Section: Promising Research and Clinical Applicationsmentioning

confidence: 99%

Principles of Simultaneous PET/MR Imaging

Catana

2017

Magnetic Resonance Imaging Clinics of North America

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“…PET/MRI is the ideal imaging tool for cerebrovascular perfusion research as it allows temporally matched correlation of DWI with quantitative 15 O-H 2 O PET CBF, and evaluation of CBF with MRI and with the gold standard 15 O-H 2 O PET. 108 The practical application of 15 O-H 2 O PET to stroke research is challenging, however, because of difficulties in supplying a radiotracer with a short half-life within the appropriate timeframe to study cerebral hemodynamics during an acute stroke.…”

Section: Applicationsmentioning

confidence: 99%

Neurologic Applications of PET/MR Imaging

Miller‐Thomas

Benzinger

2017

Magnetic Resonance Imaging Clinics of North America

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Synopsis PET/MR benefits neurological clinical care and research by providing spatially and temporally matched anatomic MR imaging, advanced MR physiologic imaging, and metabolic PET imaging. MR imaging sequences and PET tracers can be modified to target physiology specific to a neurological disease process, with applications in neuro-oncology, epilepsy, dementia, cerebrovascular disease, and psychiatric and neurological research. Simultaneous PET/MR provides efficient acquisition of multiple temporally matched datasets, and opportunities for motion correction and improved anatomic assignment of PET data. Current challenges include optimizing MR based attenuation correction and necessity for dual expertise in PET and MR.

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Simultaneous PET/Mri in Stroke: A Case Series

Cited by 51 publications

References 20 publications

Validation of MRI Determination of the Penumbra by PET Measurements in Ischemic Stroke

Validation of MRI Determination of the Penumbra by PET Measurements in Ischemic Stroke

Principles of Simultaneous PET/MR Imaging

Neurologic Applications of PET/MR Imaging

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