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Basic Science Investigation |
1 Service de Biophysique et Médecine Nucléaire, Hôpital de Hautepierre, Strasbourg, France; and 2 ENST GET/TSI, Paris, France
Correspondence: For correspondence or reprints contact: André Constantinesco, MD, PhD, Service de Biophysique et Médecine Nucléaire, CHU Hautepierre, 1 av. Molière, 67098, Strasbourg, France. E-mail: andre.constantinesco{at}chru-strasbourg.fr
Localization of regions with increased uptake of radiotracer in small-animal SPECT is greatly facilitated when using coregistration with anatomic images of the same animal. As MRI has several advantages compared with CT (soft-tissue contrast and lack of ionizing radiation) we developed a SPECT/low-field MRI hybrid device for small-animal imaging. Methods: A small-animal single-pinhole
-camera (pinhole, 1.5 mm in diameter and 12 cm in focal length) adjacent to a dedicated low-field (0.1 T) small MR imager (imaging volume, 10 x 10 x 6 cm3) was used. The animal was placed in a warmed nonmagnetic polymethyl methacrylate imaging cell for MR acquisition, which was followed immediately by SPECT after translation of the imaging cell from one modality to the other. 3-Dimensional T1-weighted sequences were used for MRI. Phantom studies enabled verification of a low attenuation (10%) for 99mTc and 201Tl and a very slight increase in Compton scattering due to the radiofrequency coil and polymethyl methacrylate imaging cell. Results: SPECT/MRI data acquisition and image coregistration of selected examples using different radiotracers for lungs, kidneys, and brain were obtained in 3 nude mice with isotropic spatial resolutions of 0.5 x 0.5 x 0.5 mm3 for MRI and 1 x 1 x 1 mm3 for SPECT. The total acquisition time for combined SPECT and MRI lasted 1 h 45 min. Conclusion: A low-magnetic-field strength of 0.1 T is a simple and useful solution for a small-animal dual-imaging device combining pinhole SPECT with the adjacent MR imager.
Key Words: small animals dual modality SPECT MRI molecular imaging
COPYRIGHT © 2008 by the Society of Nuclear Medicine, Inc.
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