title: Respiratory gated and prolonged acquisition 18F-FDG PET improve preoperative assessment of colorectal liver metastases.
abstract: BACKGROUND
  Detection of small liver metastases from colorectal cancer by 18F-FDG PET/CT is hampered by high physiologic uptake in the liver parenchyma and respiratory movements during image acquisition.
  
  
  OBJECTIVE
  To investigate whether two tailored 18F-FDG PET liver acquisitions (prolonged liver acquisition time [PL-PET] and repeated breath-hold respiratory gated liver acquisition [RGL-PET]) would improve detection of colorectal liver metastases, when added to a standard whole body PET (WB-PET).
  
  
  METHODS
  Twenty consecutive patients referred to our hospital for surgical treatment of colorectal liver metastases diagnosed with contrast-enhanced CT underwent preoperative 18F-FDG PET/CT tailored for detection of liver metastases. Concordance between preoperative imaging results and true findings (histology and/or follow-up imaging) as well as changes in clinical management, based on 18F-FDG PET/CT findings, were documented. Background noise, defined as the standard deviation measured in a reference region within the normal liver parenchyma, was compared between the three 18F-FDG PET/CT protocols.
  
  
  RESULTS
  WB-PET, PL-PET, and RGL-PET showed suspicious liver lesions in 18 out of 20 patients. Compared to WB-PET alone, the combination of PL-PET and RGL-PET showed additional lesions in the liver in seven out of the 18 patients. The combination of all three PET acquisitions changed clinical management in four patients. Two patients with negative PET results were later found to have benign liver lesions.
  
  
  CONCLUSIONS
  The addition of tailored liver-specific 18F-FDG PET/CT protocols (PL-PET and RGL-PET) to a WB-PET, improved the detection of intrahepatic colorectal metastases, compared to WB-PET alone. Such add-ons can change clinical patient management of potentially resectable colorectal liver metastases.
authors.affiliation: Department of Radiology and Nuclear Medicine, Oslo University Hospital, Norway mona.elisabeth.revheim@ous-hf.no.
authors.forename: Mona-Elisabeth
authors.initials: ME
authors.lastname: Revheim
authors.affiliation: Institute of Clinical Medicine, University of Oslo, Norway Department of Hepato-Pancreato-Biliary Surgery, Oslo University Hospital, Norway.
authors.forename: Sven-Petter
authors.initials: SP
authors.lastname: Haugvik
authors.affiliation: Department of Radiology and Nuclear Medicine, Oslo University Hospital, Norway Institute of Clinical Medicine, University of Oslo, Norway.
authors.forename: Kjersti
authors.initials: K
authors.lastname: Johnsrud
authors.affiliation: Department of Hepato-Pancreato-Biliary Surgery, Oslo University Hospital, Norway.
authors.forename: Øystein
authors.initials: Ø
authors.lastname: Mathisen
authors.affiliation: Department of Radiology and Nuclear Medicine, Oslo University Hospital, Norway Oslo and Akershus University College of Applied Sciences, Norway.
authors.forename: Jan Gunnar
authors.initials: JG
authors.lastname: Fjeld
authors.affiliation: Interventional Centre, Oslo University Hospital, Rikshospitalet, Norway.
authors.forename: Arne
authors.initials: A
authors.lastname: Skretting
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015179:Colorectal Neoplasms / Q000473:pathology*; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008099:Liver / Q000000981:diagnostic imaging; D008113:Liver Neoplasms / Q000000981:diagnostic imaging* / Q000556:secondary*; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods*; D011300:Preoperative Care / Q000379:methods*; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D055425:Respiratory-Gated Imaging Techniques / Q000379:methods*; D013997:Time Factors
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
keywords: 18F-FDG PET; colorectal cancer; liver metastasis; prolonged acquisition; respiratory gating