Simultaneous positron emission tomography and magnetic resonance imaging for the detection and characterisation of liver lesions in patients with colorectal cancer: A pictorial review.

Patients with colorectal cancer undergo frequent diagnostic imaging to stage the extent of metastatic disease and assess response to treatment. Imaging is typically via diagnostic contrast-enhanced CT or combined FDG-PET/CT. However, recent research has demonstrated promising benefits of combined FDG-PET/MRI in oncologic imaging due to the superior soft-tissue contrast of MRI. The extent of both intrahepatic and extrahepatic disease is important in establishing treatment options for colorectal cancer patients, and FDG-PET/CT and dedicated liver imaging are often both required. FDG-PET/MRI offers the advantage of a single examination which can be completed within a similar duration as dedicated liver MRI imaging. This improves patient convenience and anatomical co-registration between PET and MRI imaging and provides a potential cost benefit. The diagnostic benefits of FDG-PET/MRI include the simultaneous characterisation of focal liver lesions, exclusion of extrahepatic disease, the detection of additional hepatic metastases and extrahepatic disease, and the multi-parametric assessment of treatment response. This pictorial review highlights examples of these benefits.