Physical characteristics of TTV03, a new high spatial resolution time-of-flight positron tomograph

Mazoyer, Bernard; Trébossen, R.; Schoukroun, C.; Verrey, B.; Syrota, A.; Vacher, J.; Lemasson, Ph.; Monnet, O.; Bouvier, A.; Lecomte, J.

doi:10.1109/23.106714

Cited by 89 publications

(34 citation statements)

References 6 publications

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“…27 Briefly, this scanner collects 7 parallel transaxial planes, 9 mm thick and 12 mm apart, with a reconstructed 7-mm in-plane resolution (full width at half maximum). 27 We used the skin marks drawn on the subjects' face in the MR imager to ensure an exact repositioning of the head in the PET session. In addition, the crossed laser beams permanently attached on the PET tomograph allowed us to monitor the subjects' head position throughout the examination.…”

Section: Functional Imagesmentioning

confidence: 99%

Primary Somatosensory Cortex Activation Is Not Altered in Patients With Ventroposterior Thalamic Lesions

Rémy

Zilbovicius

Césaro

et al. 1999

Stroke

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Background and Purpose-We know remarkably little about the mechanisms underlying cortical activation. Such mechanisms might be better understood by studying the effect of well-localized lesions on the cortical activations in simple paradigms. Methods-We used H 2 15 O and positron emission tomography to measure regional cerebral blood flow (rCBF) at rest and during hand vibration in 7 patients with unilateral thalamic lesion involving the ventroposterior (VP) somatosensory thalamic relay nuclei. We compared the results with those obtained in 6 patients with thalamic lesions sparing the VP nuclei and 6 healthy controls. Results-The patients with VP lesions had a selective hypoperfusion at rest in the ipsilesional primary sensorimotor cortex (SM1). This hypoperfusion was significantly correlated with the degree of contralateral somatosensory deficit. This abnormality may reflect the deafferentation of SM1 from its somatosensory thalamic input. Despite this deafferentation, the ipsilesional SM1 was normally activated by the vibration of the hypesthetic hand. Conclusions-The fact that a lesion of the somatosensory thalamic relay nuclei alters the rCBF at rest in SM1 but not its activation by hand vibration indicates that the mechanism of cortical activation is complex, even in the case of simple sensory stimulation. In addition, a dissociation may occur between obvious neurological deficits and apparently normal activation patterns, which suggests that activation studies should be interpreted cautiously in patients with focal brain lesions. (Stroke. 1999;30:2651-2658.)

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Section: Functional Imagesmentioning

confidence: 99%

Primary Somatosensory Cortex Activation Is Not Altered in Patients With Ventroposterior Thalamic Lesions

Rémy

Zilbovicius

Césaro

et al. 1999

Stroke

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“…19 To obtain reproducible head positioning (both interanimal and intra-animal), the baboon's head was fixed in a specially designed frame with ear bars placed in the external bony auditory canal (checked by a radiogram). Through the use of external laser beams, seven planes (-27 mm to +45 mm relative and parallel to the canthomeatal line) were imaged, according to an anatomic PET atlas.20 A 'Ga-'Ge transmission scan was performed before each PET session.…”

Section: Positron Emission Tomography Proceduresmentioning

confidence: 99%

In vivo mapping of brain benzodiazepine receptor changes by positron emission tomography after focal ischemia in the anesthetized baboon.

Sette

Baron

Young

et al. 1993

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143

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Background and Purpose: Recent reports have shown an increase in specific binding (in vitro) of [3H]PK 11195 to peripheral-type benzodiazepine receptors in both experimental animals and humans, reflecting a glial/macrophagic reaction within and around focal ischemic insults. We have evaluated by positron emission tomography the time course of changes in brain uptake in vivo of "C-labeled PK 11195 and flumazenil (an antagonist of central benzodiazepine receptors) as indirect and direct markers of neuronal loss, respectively, after focal cerebral ischemia.Methods: Ten anesthetized baboons were submitted to sequential positron emission tomography studies between day 1 and day 91 after unilateral middle cerebral artery occlusion. The studies consisted of

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“…The idea to use TOF information was originally proposed in the early stages of PET scanner development (1)(2)(3), and the first TOF PET systems were developed in the 1980s (4)(5)(6)(7)(8). A good summary of this early work has been published (9,10).…”

mentioning

confidence: 99%

Benefit of Time-of-Flight in PET: Experimental and Clinical Results

Surti²,

et al. 2008

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Significant improvements have made it possible to add the technology of time-of-flight (TOF) to improve PET, particularly for oncology applications. The goals of this work were to investigate the benefits of TOF in experimental phantoms and to determine how these benefits translate into improved performance for patient imaging. Methods: In this study we used a fully 3-dimensional scanner with the scintillator lutetium-yttrium oxyorthosilicate and a system timing resolution of ;600 ps. The data are acquired in list-mode and reconstructed with a maximum-likelihood expectation maximization algorithm; the system model includes the TOF kernel and corrections for attenuation, detector normalization, randoms, and scatter. The scatter correction is an extension of the model-based singlescatter simulation to include the time domain. Phantom measurements to study the benefit of TOF include 27-cm-and 35-cm-diameter distributions with spheres ranging in size from 10 to 37 mm. To assess the benefit of TOF PET for clinical imaging, patient studies are quantitatively analyzed. Results: The lesion phantom studies demonstrate the improved contrast of the smallest spheres with TOF compared with non-TOF and also confirm the faster convergence of contrast with TOF. These gains are evident from visual inspection of the images as well as a quantitative evaluation of contrast recovery of the spheres and noise in the background. The gains with TOF are higher for larger objects. These results correlate with patient studies in which lesions are seen more clearly and with higher uptake at comparable noise for TOF than with non-TOF. Conclusion: TOF leads to a better contrast-versus-noise trade-off than non-TOF but one that is difficult to quantify in terms of a simple sensitivity gain improvement: A single gain factor for TOF improvement does not include the increased rate of convergence with TOF nor does it consider that TOF may converge to a different contrast than non-TOF. The experimental phantom results agree with those of prior simulations and help explain the improved image quality with TOF for patient oncology studies. There has been considerable advancement of the technology and instrumentation in PET over the last 30 y since the first tomography ring systems were developed. Significant improvements have been made in detectors, hardware, and image processing that impact both image quality and accuracy of quantification. Some of the major achievements include (a) the development and incorporation of new scintillators and detector configurations for higher spatial resolution and sensitivity, (b) the evolution from 2-dimensional (2D) systems with septa to 3-dimensional (3D) systems with larger axial fields of view for improved sensitivity, (c) the transition from analytic filtered-backprojection reconstruction algorithms to fully 3D iterative techniques with data corrections included in the system model for improved image quality and quantification, and (d) the combination of a CT scanner with the PET instrument for both attenuation ...

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Physical characteristics of TTV03, a new high spatial resolution time-of-flight positron tomograph

Cited by 89 publications

References 6 publications

Primary Somatosensory Cortex Activation Is Not Altered in Patients With Ventroposterior Thalamic Lesions

Primary Somatosensory Cortex Activation Is Not Altered in Patients With Ventroposterior Thalamic Lesions

In vivo mapping of brain benzodiazepine receptor changes by positron emission tomography after focal ischemia in the anesthetized baboon.

Benefit of Time-of-Flight in PET: Experimental and Clinical Results

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