Combination PET/MR scanners are a hot thing in oncology these days, providing a functional view of a tumor while locating it within the body, something that normally had to be done using a PET/CT or separately first in a PET scanner and then an MRI. PET/CT exposes the patient to a large radiation dose while providing poor soft tissue imaging, and doing separate PET and MR scans requires superimposing complicated imaging studies taken at different times.
Siemens so far is the only company offering a true PET/MR clinical system that performs both scans simultaneously, while a Philips system uses two nearby scanners with a shared table that moves the patient from one imaging modality to the other.
Looking to make PET/MR more ubiquitous for both clinical use as well as for research, engineers at University of Oslo shrunk the components of a PET system to be able to implant it within an MRI and do both kinds of imaging at the same time. Though the new combination system is designed for animal research studies, the U of Oslo team believes that clinical scanner manufacturers will be able to take advantage of their technology to build the next generation of PET/MR machines.
From University of Oslo press statement:
The new detectors are made from entirely new crystals and light guides. In each of the five layers of the detectors, crystal pins are placed on top of a transverse layer of light guide fibres.
‘This is a completely new way of measuring gamma particles.
The detectors are placed so that the space within the new scanner is square.’
‘Today, the scanners form a circle. This means that there is a gap between each detector block, and photons disappear through the gaps. Now, we have full coverage of crystals on all sides. We can capture several million particles a second. However, this does not happen at regular intervals. We measure each nanosecond. If we do not measure fast enough, we can get errors.’
All the parts of the PET scanner are put together like lego bricks. The system digitalises the data at an earlier stage than the current PET solutions. The data can be sent to any number of computers. The image processing takes place in parallel with the examination.
More from the University of Oslo: New Cancer Scanner Halves Radiation…
Flashbacks: Siemens Brings Together Magnetic Resonance and Positron Emission Tomography Into One Machine; Philips Unveils Ingenuity TF PET/MR Combo