A SPECT camera for simultaneous SPECT/MRI

We describe a single photon emission computed tomograph (SPECT) which can be operated inside state-of-the-art magnetic resonance imaging (MRI) systems. The combined SPECT/MRI system allows one to acquire simultaneously the data from both modalities and co-register the images in space and time. The new SPECT is based on the semiconductor cadmium zinc telluride (CZT) and application specific integrated circuits (ASICs) - two technologies which are MR-compatible and almost insensitive to magnetic fields. The SPECT camera has an energy resolution of 5.4 keV full-width-half-maximum (FWHM) at the 140-keV photo peak from
^99m
Tc for either inside or outside of the MRI. We acquired the first SPECT and MR images from resolution phantoms and mice in-vivo. The experiments show that the MRI is minimally affected by the SPECT camera inside the bore. Preliminary results for the SPECT camera show high sensitivity of about 1.6% and a spatial resolution of 4 mm FWHM.