PT  - JOURNAL ARTICLE
AU  - Goetz, Christian
AU  - Breton, Elodie
AU  - Choquet, Philippe
AU  - Israel-Jost, Vincent
AU  - Constantinesco, André
TI  - SPECT Low-Field MRI System for Small-Animal Imaging
AID  - 10.2967/jnumed.107.044313
DP  - 2008 Jan 01
TA  - Journal of Nuclear Medicine
PG  - 88--93
VI  - 49
IP  - 1
4099  - http://jnm.snmjournals.org/content/49/1/88.short
4100  - http://jnm.snmjournals.org/content/49/1/88.full
SO  - J Nucl Med2008 Jan 01; 49
AB  - 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 γ-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 × 10 × 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 × 0.5 × 0.5 mm3 for MRI and 1 × 1 × 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.