Positron-Emission Tomography
PET scans provide valuable information about organ and tissue function, metabolism, and the presence of disease.
This technology has revolutionized medical research and clinical practice, enabling eariler diagnosis, more accurate disease staging, and personalized treatment planning.
PET imaging is widely used in oncology, neurology, cardiology, and other fields to enhance understanding of physiological processes and improve patient outcomes.
Reasearchers and clinicians can leveraage the power of PET to advance scientific knowledge and deliver high-quality, reproducible results.
Most cited protocols related to «Positron-Emission Tomography»
The original method (SVCA6) uses six kinetic classes normal gray matter, normal white matter, blood, bone, and soft tissue regions, and gray matter with specific binding. The first five classes were defined on a separate set of normal controls while the last one, corresponding to gray matter with high microglia density, was obtained from the brain injury patients.
To extract the reference, the dynamic PET scan is first normalized as described by Turkheimer et al (2007) (link): each voxel value is reduced by the frame average and divided by the standard deviation. Therefore, the normalization is affected by the size of the reconstructed field of view; for this study, both definition of kinetic classes and application cluster analysis were preformed on scans acquired from the same scanner using similar scanning protocol. However, in case of using SVCA4, normalization was done on voxels that correspond with brain tissue only (based on MRI-derived coregistered gray- and white-matter segmentations). Thereby, this method also avoids the effects of differences in field of view between different scanners.
Next, each voxel TAC of this scan is analyzed using the set of predefined kinetic classes to find the scaling coefficient of each kinetic class, so that the total TAC is equal to the sum of these scaled kinetic classes. As the kinetic classes are not orthogonal, a nonnegative least squares algorithm (Turkheimer et al, 2007 (link)) is used for finding the scaling coefficients. Scaling coefficients of each kinetic class are stored in coefficient maps showing their spatial distribution.
Finally, to extract the reference tissue curve, the coefficient map from the (normal) gray-matter kinetic class is used to calculate the weighted average, as follows: where, N is the number of voxels, TACNS(t) the resulting reference tissue TAC, TACiVoxel(t) the TAC from voxel i of the (nonnormalized) dynamic PET scan, and wiGray the gray-matter kinetic class scaling coefficient estimated for voxel i.
The modified supervised cluster analysis method (SVCA4) (Boellaard et al, 2008 (link)) is similar to SVCA6, except that only four kinetic classes are used: gray matter with specific (R)-[11C]PK11195 binding, gray matter without specific binding, white matter, and blood. This modified method uses the mentioned coregistered segmented MRI scans to exclude skull and soft tissue parts from each frame of the PET scan before performing cluster analysis, same as mentioned above but now with only four kinetic classes. Removal of skull and soft tissue was simply done by setting voxel values to zero for nonbrain structures.
Most recents protocols related to «Positron-Emission Tomography»
Example 9
The following example provides details of a study used to determine whether pimavanserin or ketanserin induced changes in subjective experience during psilocybin therapy are due to changes in 5-HT2A occupancy. If not, downstream molecular and cellular effects that may be important in psilocybin's therapeutic effects may be preserved after co-treatment with a 5-HT2A specific antagonist and/or inverse agonist.
In this study, [11C]CIMBI-36 (a selective 5-HT2A receptor agonist positron emission tomography (PET radioligand) will be used to investigate whether 5-HT2A binding is affected by placebo vs. pimavanserin or ketanserin
At time t=0, subjects will be administered 25 mg psilocybin (PSI) in combination with either a placebo, or a low or high dose of pimavanserin or ketanserin. At t=2 hours, subjects will be given a tracer dose of [11C]CIMBI-36. At t=2-3 hours, a PET scan will be performed, to determine whether 5-HT2A binding is affected by either dose of pimavanserin or ketanserin.
Example 14
Eight NH2—PEGn-RGD peptides containing spacers of various PEG lengths (n=2, 4, 6, 8, 10, 12, 14, 16) will be prepared by adding the corresponding Boc-PEGn-NHS to RGD in a PBS buffer (pH=8.2), followed by Boc deprotection. Photo-ODIBO-NHS, prepared using previously reported procedures, will then be mixed with the prepared NH2—PEGn-RGD in a PBS buffer (pH=8.2) to produce photo-OIDBO-PEGn-RGD. N3-PEG4-cetuximab will be prepared using previously reported procedures. N3—PEG4-cetuximab and the eight photo-ODIBO-PEGn-RGD peptides (n=2, 4, 6, 8, 10, 12, 14, 16) will be used for in vitro screening (at 4° C. to minimize the internalization of targeting probes). As shown in
The ODIBO-PEGn-RGD containing the most potent PEG spacer will click with Tz-NOTA-N3 and then be radiolabeled with 64Cu, and the resulting Tz-(64Cu)NOTA-PEGn-RGD will be used for the in vitro avidity studies on U87MG cells. Tz-(64Cu)NOTA-RGD (without a PEG spacer) will be used as a negative control because the distance between RGD and cetuximab in the resulting heterodimer is too short to achieve avidity effect (proved in preliminary study,
Various references are cited in this document, which are hereby incorporated by reference in their entireties herein.
Example 6
The following example provides details of a study used to determine whether alprazolam-induced changes in subjective experience during psilocybin therapy are due to changes in 5-HT2A occupancy. If not, downstream molecular and cellular effects that may be important in psilocybin's therapeutic effects may be preserved after co-treatment with a benzodiazepine.
In this study, [11C]CIMBI-36 (a selective 5-HT2A receptor agonist positron emission tomography (PET) radioligand) will be used to investigate whether 5-HT2A binding is affected by placebo vs. alprazolam.
At time t=0, subjects will be administered 25 mg psilocybin (PSI) in combination with either a placebo, or alprazolam. At t=2 hours, subjects will be given a tracer dose of [11C]CIMBI-36. At t=2-3 hours, a PET scan will be performed, to determine whether 5-HT2A binding is affected by either dose of alprazolam.
This study may optionally be performed using diazepam instead of alprazolam.
At each study visit, participants completed comprehensive neuropsychological assessment and multiple questionnaires related to a broad array of factors, including lifestyle, modifiable risk factors, medical history and memory functioning. Sleep measures were added in two stages to the WRAP assessment protocol. To be eligible for the primary analyses, participants needed to have completed the full set of sleep measures at least once and be free of dementia at time of sleep assessment (n = 619). To be eligible for secondary analyses, participants needed to have completed at least one of the sleep questionnaires described below and had completed a Pittsburgh Compound B (PiB) PET scan.
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More about "Positron-Emission Tomography"
This revolutionary technology has transformed medical research and clinical practice, enabling earlier disease detection, more accurate staging, and personalized treatment planning.
PET scans leverage the unique properties of positron-emitting radiotracers to generate detailed images of organ and tissue function, metabolism, and the presence of disease.
By tracing the distribution and concentration of these radiotracers, clinicians and researchers can gain invaluable insights into physiological processes, including those related to oncology, neurology, cardiology, and other medical fields.
The versatility of PET imaging is further enhanced by the use of advanced scanners, such as the Biograph mCT, Inveon, Biograph mMR, Discovery 690, and Discovery STE.
These state-of-the-art PET/CT and PET/MRI systems combine the functional information provided by PET with the anatomical detail of other imaging modalities, enabling more comprehensive and accurate diagnoses.
To maximize the potential of PET research, researchers often leverage specialized software like MATLAB and PMOD, which facilitate data analysis, image processing, and the interpretation of PET scans.
Additionally, tools like the ECAT EXACT HR+ scanner and Gamma counters play a crucial role in acquiring and analyzing PET data, ensuring the reproducibility and accuracy of research findings.
By harnessing the power of PET technology, clinicians and scientists can advance their understanding of disease mechanisms, develop more effective treatments, and ultimately improve patient outcomes.
Whether you're a healthcare professional, a medical researcher, or simply interested in the latest advancements in medical imaging, the world of Positron Emission Tomography offers a wealth of opportunities to explore and discover.