Simultaneous PET/MRI in breast cancer: Development of the technology

The ability to acquire high resolution anatomical data as well as quantitative functional information in vivo is becoming an increasingly important factor in the diagnosis of disease. This has clearly been reflected in the recent use of combined PET/CT as a clinical diagnostic tool as well as in the in the availability of commercial PET and CT scanners. However, while PET can provide high sensitivity and high specificity functional information, CT exhibits poor soft tissue contrast, and also subjects the patient to a significant additional radiation dose along with dose received with PET. On the other hand, MRI provides excellent soft tissue contrast and anatomical detail, and does not subject the patient to any additional radiation dose. Simultaneous PET/MRI imaging would provide the ability to acquire in vivo quantitative functional information and high resolution anatomical data in animal or human subjects. Simultaneous acquisition of PET and MRI data would also provide essentially perfect co-registration between the two images which is particularly important for tissues whose position and shape can change between sequential scans. (Examples are head and neck imaging, colon imaging and breast imaging). There are several other advantages to combining PET and MRI into a single scanner. There are: - MRI can be used to correct for partial volume effects in the PET image; - It would be possible to perform functional MRI studies simultaneously with PET physiological studies; - It would be possible to perform magnetic resonance spectroscopy to identify chemical species while observing the distribution and kinetics with PET; - The high magnetic field of the MRI causes positrons to curl up, reducing their range, which improves PET spatial resolution