Simultaneous in vivo magnetic resonance imaging and radioactive measurements with the beta-MicroProbe.
OBJECTIVE
Multimodal instrumentation is a new technical approach allowing simultaneous and complementary in vivo recordings of complementary biological parameters. To elucidate further the physiopathological mechanisms in intact small animal models, especially for brain studies, a challenging issue is the actual coupling of magnetic resonance imaging (MRI) techniques with positron emission tomography (PET): it has been shown that running the technology for radioactive imaging in a magnet alters the spatiotemporal performance of both modalities. Thus, we propose an alternative coupling of techniques that uses the beta-MicroProbe instead of PET for local measurements of radioactivity coupled with MRI.


METHODS
We simultaneously recorded local radioactivity due to [(18)F]MPPF (a 5-HT(1A) receptor PET radiotracer) binding in the hippocampus with the beta-MicroProbe and carried out anatomical MRI in the same anaesthetised rat.


RESULTS
The comparison of [(18)F]MPPF kinetics obtained from animals in a magnet with kinetics from a control group outside the magnet allowed us to determine the stability of tracer biokinetic measurements over time in the magnet. We were thus able to show that the beta-MicroProbe reliably measures radioactivity in rat brains under an intense magnetic field of 7 Tesla.


CONCLUSIONS
The biological validation of a beta-MicroProbe/MRI dual system reported here opens up a wide range of future multimodal approaches for functional and pharmacological measurements by the probe combined with various magnetic resonance technologies, including anatomical MRI, functional MRI and MR spectroscopy.
Desbrée
A
A
IRSN, BP 17, 92262, Fontenay aux roses, France. aurelie.desbree@irsn.fr
Rbah
L
L
Langlois
J-B
JB
Grenier
D
D
Mastrippolito
R
R
Pain
F
F
Pinot
L
L
Lanièce
P
P
Zimmer
L
L
Gurden
H
H
D000818:Animals; D004867:Equipment Design; D019544:Equipment Failure Analysis; D015902:Gamma Cameras; D006624:Hippocampus / Q000000981:diagnostic imaging* / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation* / Q000379:methods; D008297:Male; D008904:Miniaturization; D049268:Positron-Emission Tomography / Q000295:instrumentation* / Q000379:methods; D051381:Rats; D017207:Rats, Sprague-Dawley; D013382:Subtraction Technique / Q000295:instrumentation*