PET-MR

This technique combines an MRI scanner with fully integrated PET detectors allowing for the simultaneous acquisition of PET data during the application of regular MRI techniques.

Overview

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A new hybrid whole-body Positron Emission Tomography-Magnetic Resonance Imaging (PET-MRI) scanner (Biograph mMR, Siemens, Erlangen, Germany) has recently been installed in Edinburgh Imaging facility QMRI. This was funded by the MRC as part of the Dementias Platform UK (DPUK) Imaging Network (Edinburgh Imaging PI: Professor Edwin van Beek). The new scanner combines a 3T MRI scanner with fully integrated PET detectors (56 LSO-APD detector blocks arranged in 8 rings), allowing for the simultaneous acquisition of PET data during the application of the MRI techniques described elsewhere on this website (structural imaging, diffusion, perfusion, fMRI, spectroscopy). Research studies can now benefit from the high sensitivity of PET and its ability to quantify radiotracer metabolism alongside the unrivalled soft-tissue contrast of MRI and the useful functional information that it can also provide. A wealth of information can be obtained from a standard 60-minute scan slot removing the need for research participants to commit to multiple separate scans.  Importantly the radiation burden for participants undergoing a PET-MRI scan is reduced compared to those having a PET-CT scan.

There are several proposed dementia PET-MRI studies currently in the planning stages in collaboration with the DPUK. One study will carry out amyloid and tau PET imaging of dementia patients alongside structural and functional MRI with the aim of identifying biomarkers of change in patients with prodromal Alzheimer’s disease.  Clinically focussed studies will run alongside technical-based studies with the aim of ensuring consistency of PET and MRI protocols between the different DPUK sites.

The first PET-MRI study to be set up in Edinburgh is an assessment of cerebral amyloid angiopathy (CAA) in patients who have suffered a lobar haemorrhage (PI: Professor Rustam Salman Al-Shahi). CAA is the build-up of an abnormal protein called amyloid in the blood vessels in the brain. The aim of this study is to gain a greater understanding of the role that CAA plays in haemorrhage. Many other neuro-related studies are expected to benefit from using this new scanner.

Another major area of interest is cardiac PET-MRI. Recently, Professor David Newby was successful in securing a British Heart Foundation Programme grant to study human coronary atherothrombosis. As part of this, previous innovative cardiac PET-CT work will be translated onto the PET-MRI scanner and then the aim is to develop new protocols for imaging coronary artery plaques and thrombus. The first cardiac study that will be carried out on the PET-MRI scanner will compare the MRI-based attenuation correction maps with CT-based maps in a group of patients who will be scanned using both PET-CT and PET-MRI. 

There is growing recognition of the benefits of using PET-MRI for oncology imaging, such as applications in prostate cancer, and it is anticipated that the new scanner will host several oncology projects. Lastly, this system may be beneficial to Paediatric oncology patients in particular, given the reduction in radiation burden compared to PET-CT.