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Notes for CERIMED imaging platform presentation at the Timone
Seminar 15 feb 2011 - Eric Guedj (Invitation P. Roubertoux) « L'imagerie moléculaire isotopique : principes et enjeux »
Nuclear medicine – tracing of metabolism with a radioactively labelled tracer.
Gamma radiation with camera for hospital – beta camera is known as a “TEP” – I think this must be PET (positron emission tomography) – works for C, H, O, F, N… whereas gamma cameras use technetium, iode, thallium, indium. PET camera at Timone since 2003. 18-F has a half-life of 2 hours. Production is industrial, made in a cyclotron. Whereas hospitals can generate their own gamma-emitters.
Mapping consumption of glucose – fixation with 18F-D-glucose. Cancers will preferentially fix the glucose showed an example of a Hodgkin’s lymphoma. Also target with a tracer for amyloid plaques in Alzheimer’s so as to target before death rather than confirm after death histologically.
18F-fluoro-thymidine also. Can also mark cells eg. Own leukocytes with the 18F-DG. Works (in research) with a medication eg a chemotherapy. Make sure that well targeted, and perhaps optimize doses.
Label estradiol to see if tumor expresses in vivo the receptor, and if the tumor would be receptive to certain therapies.
Possible to target melanin deposits, for example? What kind of resolution is possible – detectability of the tracer?
Neuroendocrine tumors – routine test for somatostatin receptors, AChR, F-DOPA to look at tyrosine metabolism to dopamine etc.
Imaging during epilepsy. – can inject product during the crisis, and analyze an hour or two afterward, by subtracting signal. What was injected? Glucose?
Can look at dopamine transporter for example, in Parkinson’s disease – how many cells still viable in substantia nigra?
Certain functional anomalies will precede morphological atrophy for example, which could be seen on MRI.
18FDG fixation intensity is correlated with tumoral aggressivity – can show therapeutic response – avoid ineffective treatment and move on to another.
Often use the glucose question for metabolism/activity.
Can develop tracers that emit gamma (for image) and beta (for therapy)
Project “CERIMED” – imagerie, preclinical trials using rodents, pigs, primates. Also SPECT-CT and PET-CT (combined machines to map functional images on the whole body imaging from CT)
Question – spatial resolution: 4mm. small – technetium actually has a BETTER resolution because no scatter, whereas the F scatters over 2 mm.
One cyclotron of the two they have, devoted to research. What about a targeted way to demonstrate activity in NCM, perhaps invasivity, certainly localization/presence? Already can see with focused MRI (3T locally available) but perhaps better functional measurement?
SPECT technology – definition slightly under 1 mm whereas PET with beta positron is 1 mm before scinds into two (protons?).
Possibility to develop animal model for NCM?!
PET quantifies a cell process. Can then localize with other imaging technique.
EOPS is not A2 qualification for animal facility – problem for lentiviral/AAV delivery.
Tubes en plexi – filtered – allow to bring animal in correct conditions from one room to another.
Specific markers for muscles, for example, to watch a marker in that tissue? Eg mitochondrial marker. Skin? Eg tracers for melanoma. Interest of tracers is that it is possible to produce locally. Either technetium or iodine, or beta emitters.
Possibility to mark an antibody, for example, though these generally go into the liver – now there are modified antibodies that can get to their targets better. Biodistribution wrt pathological process as well as localization of therapy in non-targeted tissue. Have combined locally (in Marseille) an ultrasound machine (morphology) elastrometry for a characteristic of the tissue, and a PET tracer.
--Heather 08:35, 15 February 2011 (EST)