HYBRID Publications (1): „A consensus recommendation for quality control of PET/MRI systems”

In September last year, several fellows and PI’s from the HYBRID consortium published a paper on quality control for PET/MRI systems. Alejandra Valladares is first author of this paper (link to publication below).

Alejandra’s project focuses on standardized quality control protocols for multi-parametric imaging. Imaging systems such as PET, MRI, and CT can be combined to gain the advantages of two systems in one scan. Aligned protocols and quality control of these multi-parametric imaging systems ensures that images from different hospitals can be compared. This is essential for consortia such as HYBRID to be able to share data and perform research together.

In the consensus statement authored by Valladares et al., a recommendation for quality control of PET/MRI systems was formulated. Alejandra followed a four-step method to get to this recommendation. First, she made an overview of existing quality control recommendations for PET and MRI separately. Second, she assessed the variations in quality control protocols used in centres that are part of the HYBRID consortium. Third, she summarized quality control recommendations by the manufacturers of PET/MRI systems. Finally, all the collected information was pooled to jointly develop a consensus recommendation of quality control protocols for PET/MRI systems.

PET/MRI

The combination of PET and MRI in one system has several advantages. MRI provides high resolution images of organs and other soft tissues in the body, while PET is able to visualize and quantify ongoing processes (e.g. glucose use by organs or tumours).

However, PET/MRI systems are not yet very common. Therefore research on this new imaging method depends on collaborations between centres. But different centres use different standards for quality control. This makes comparison of images difficult.

To improve the performance of PET/MRI and compare images among centres, a set of minimum quality control protocols was formulated. This is the first recommendation for quality control of PET/MRI systems.

Existing recommendations for PET and MRI

Alejandra found that existing QC guidelines differ greatly from each other for both PET and MRI. For example, only a daily quality control (provided by the manufacturer) and a test for image uniformity are included in all PET guidelines. The inclusion of other tests as well as the suggested testing frequencies differed widely across the guidelines.

Survey on quality control

To investigate the actual implementation of PET and MRI quality control protocols, Alejandra sent a survey to all HYBRID centres. For PET, only the daily quality control was performed in all centres. Other tests and testing frequencies were highly variable among the centres, both for PET and MRI.

Consensus recommendation

Based on the existing guidelines for PET and MRI, and the protocols implemented by the centres and manufacturers, a minimum protocol was formulated for quality control of PET/MRI systems. For PET this includes the daily quality control as recommended by the manufacturer, a calibration test once every three months, and a general image quality assessment once per year. For MRI, the MRI coils should be checked for proper function once every month, and a general assessment of MR image quality should be performed every three months.

Publication: Valladares A, Ahangari S, Beyer T, Boellaard R, Chalampalakis Z, Comtat C, DalToso L, Hansen AE, Koole M, Mackewn J, Marsden P, Nuyts J, Padormo F, Peeters R, Poth S, Solari E and Rausch I (2019) Clinically Valuable Quality Control for PET/MRI Systems: Consensus Recommendation From the HYBRID Consortium. Front. Phys. 7:136. doi: 10.3389/fphy.2019.00136

Alejandra explains her findings in a video: https://www.youtube.com/watch?v=pw_r1JcvZ5o&t=124s.