A decade of multi-modality PET and MR imaging in abdominal oncology

Abstract

Objectives: To investigate trends observed in a decade of published research on multimodality PET(/CT)+MR imaging in abdominal oncology, and to explore how these trends are reflected by the use of multimodality imaging performed at our institution.

Methods: First, we performed a literature search (2009-2018) including all papers published on the multimodality combination of PET(/CT) and MRI in abdominal oncology. Retrieved papers were categorized according to a structured labelling system, including study design and outcome, cancer and lesion type under investigation and PET-tracer type. Results were analysed using descriptive statistics and evolutions over time were plotted graphically. Second, we performed a descriptive analysis of the numbers of MRI, PET/CT and multimodality PET/CT+MRI combinations (performed within a ≤14 days interval) performed during a similar time span at our institution.

Results: Published research papers involving multimodality PET(/CT)+MRI combinations showed an impressive increase in numbers, both for retrospective combinations of PET/CT and MRI, as well as hybrid PET/MRI. Main areas of research included new PET-tracers, visual PET(/CT)+MRI assessment for staging, and (semi-)quantitative analysis of PET-parameters compared to or combined with MRI-parameters as predictive biomarkers. In line with literature, we also observed a vast increase in numbers of multimodality PET/CT+MRI imaging in our institutional data.

Conclusions: The tremendous increase in published literature on multimodality imaging, reflected by our institutional data, shows the continuously growing interest in comprehensive multivariable imaging evaluations to guide oncological practice.

Advances in knowledge: The role of multimodality imaging in oncology is rapidly evolving. This paper summarizes the main applications and recent developments in multimodality imaging, with a specific focus on the combination of PET+MRI in abdominal oncology.

Figure 1.

Literature selection process

Figure 2.

Evolution in the annual numbers of PET studies inpublished multimodality imaging research, specified for the PET-tracer(s) used. FDG: 18F-fluorodeoxyglucose; PSMA: prostate-specific membrane antigen; octreotide analogues: 68Ga-labelled somatostatin receptor ligands; ‘Other tracers’ includes tracers used in a single or few of the retrieved studies (e.g. fluciclovine, fluorothymidine (18F-FLT), fluoromisonidazole (18F-FMISO), dihydroxyphenylalanine (18F-DOPA)).

Figure 3.

Evolution in the annual numbers of original research publications on multimodality combinations of FDG-PET/CT+MRI or PET/MRI in abdominal oncology specified per acquisition approach, i.e. retrospective combination of separately acquired FDG-PET/CT and MRI (with or without retrospective image fusion) versus prospective combination of PET and MRI using either bed-system combined acquisition or fully hybrid acquisition.

Figure 4.

Evolution in the annual numbers of original research publications on multimodality combinations of FDG-PET/CT+MRI inabdominal oncology, specified per image evaluation approach, i.e. visual (qualitative) assessment, quantitative assessment, technical studies (i.e. protocol optimization and testing) and “other” (e.g. delineation studies for radiotherapy planning).

Figure 5.

Annual growth of MR imaging studies, PET/CTs and multimodality MRI+PET/CT imaging combinations observed in our institution relative to the benchmark year 2008.