INTERVENTIONAL Added value of FDG-PET imaging in the diagnostic workup for yttrium-90 radioembolisation in patients with colorectal cancer liver metastases Charlotte E. N. M. Rosenbaum & M. A. A. J. van den Bosch & W. B. Veldhuis & J. E. Huijbregts & M. Koopman & M. G. E. H. Lam Received: 22 June 2012 / Revised: 6 September 2012 / Accepted: 30 September 2012 # European Society of Radiology 2012 Abstract Objective Yttrium-90 radioembolisation (Y90-RE) is rec- ommended for unresectable, chemorefractory liver- dominant disease; however, the incidence of extrahepatic disease (EHD) is high. FDG-PET may have additional value to CT in demonstrating EHD. Our aim was to evaluate the added diagnostic value of FDG-PET to abdominal CT and study the influence of FDG-PET findings on treatment decisions. Methods All consecutive patients with colorectal cancer liver metastases (CRCLM) referred for Y90-RE were in- cluded. Patients who underwent both CT and FDG-PET in the diagnostic workup were selected. Imaging reports were scrutinised for documented sites of EHD, and changes of management due to FDG-PET findings were determined. Results A total of 42 patients were included. Findings on CT and FDG-PET matched in 20 patients (no EHD, n 0 15; identical EHD, n 0 5). In 4 patients, lesions detected on CT were not FDG-avid, and in 18 patients, FDG-PET showed more lesions than CT (P <0.05). In 7/42 patients (17 %) a change of management was made based on the additional FDG-PET findings, i.e. exclusion from Y90-RE treatment (n 0 6) and change in treatment plan (whole liver rather than segmental treatment, n 0 1). Conclusions In patients with CRCLM referred for Y90-RE, FDG-PET showed significantly more EHD and led to a considerable change of management. Key Points • Yttrium-90 radioembolisation is a locoregional treatment for liver tumours • Detection of extrahepatic lesions, for which CT is widely used, is crucial • FDG-PET shows significantly more extrahepatic lesions compared to CT • FDG-PET findings led to a considerable change in treat- ment decisions Keywords Colorectal cancer . Liver metastases . Radioembolisation . Diagnostic workup . FDG-PET Introduction Yttrium-90 (Y-90) radioembolisation (Y90-RE) is an emerg- ing treatment technique for colorectal liver metastases (CRCLM). Rapidly accumulating evidence in the literature supports its safety and efficacy [1–4]. The microspheres are injected through a microcatheter in the arterial supply to the liver. They lodge in the microvasculature around the tumour where a high radiation dose is delivered [5, 6]. Resin micro- spheres containing 90 Y (SIR-Spheres®; Sirtex Medical Lim- ited, Lane Cove, Australia) and microspheres that incorporate Y-90 in a glass matrix (TheraSphere®; Nordion Inc., Ottawa, Canada) are the two commercially available treatment options. SIR-Spheres® have full approval from the US Food and Drug Administration (FDA) for the treat- ment of unresectable colorectal liver metastases. Thera- Sphere® has a Humanitarian Device Exception from the FDA for the treatment of unresectable hepatocellular carci- noma in the US. Both products are approved in the C. E. N. M. Rosenbaum (*) : M. A. A. J. van den Bosch : W. B. Veldhuis : J. E. Huijbregts : M. G. E. H. Lam Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, Room E.01.132, 3584 CX, Utrecht, The Netherlands e-mail: c.rosenbaum@umcutrecht.nl M. Koopman Department of Medical Oncology, University Medical Center Utrecht, Utrecht, The Netherlands Eur Radiol DOI 10.1007/s00330-012-2693-x