The PET/CT scanner has been around since late 1998, when the first PET/CT prototype was installed for clinical evaluation at the University of Pittsburg Medical Center. The first commercial system reached the market in 2001. Since that time, the PET/CT has become increasing popular. But what about the PET/MRI? The first two clinical whole body systems were installed by Philips at Mount Sinai Medical Centre in 2010, and currently, four manufacturers make PET/MRI systems: Philips, Siemens, GE, and MR Solutions. But why hasn’t it taken off yet?
It has been argued that the only difference between PET/CT and PET/MRI is that PET/MRI is a version with less ionizing radiation. That is not the case, however. There are plenty of differences, including:
- PET/CT scanners cannot perform simultaneous data acquisition. PET/MRI can. This would especially be useful for brain imaging, cardiology, and oncology, as it allows essentially perfect temporal correlation of dynamically acquired data sets from both PET and MRI modalities.
- PET/CT has a significant radiation dose; PET/MRI uses much less ionizing radiation. (This was already mentioned but it’s necessary to reiterate.)
- PET/MRI offers better contrast among soft tissues as well as functional-imaging capabilities.
- Notable applications of PET/CT including lung and bone imaging cannot likely be replaced by PET/MRI.
- PET/MRI has longer acquisition time and higher costs compared to PET/CT.
As you can see, there are some advantages and disadvantages of PET/MRI over PET/CT. Some feel that PET/MRI would have technical limitations when it comes to operating within existing workflows (longer acquisition time as mentioned above,) and that since PET/MRI must rely on MR instead of X-Ray like the PET/CT, it has limited field of view and dependence on bone for AC calculations (attenuation correction). MR is a poor substitute for CT when it comes to AC calculations, and this is a huge problem for the PET/MRI gaining traction.
In the end, PET/CT and PET/MRI are similar and not so similar. The debate over which is better will likely continue as there are pros and cons to each. But as of right now, PET/CT is winning when it comes to popularity, and will continue to be the go-to modality for molecular imaging. However it’s still fascinating to read about PET/MRI in order to gain a well rounded idea of what will be the industry trends will be in the future.
If you’d like to discuss more about Amber’s PET/CT scanners or any of our other medical imaging modalities, give us a call or contact us here. We’d be happy to help.