title: Assessment of response to treatment of unresectable liver tumours with 90Y microspheres: value of FDG PET versus computed tomography.
abstract: BACKGROUND
  Selective internal radiation therapy (SIRT) with SIR spheres (90Y microspheres) is a treatment option for liver tumours in patients in whom other therapies are inappropriate or have failed. This study aims to assess the value of FDG PET in assessing the response to SIRT as compared to computed tomography (CT).
  
  
  METHODS
  Twenty-one patients (11 F, 10 M; age range 40-75 years, mean, 58 years) received SIR spheres at the Hammersmith Hospital. One patient received two treatments. Most patients had colorectal metastases (n=10), while the others (n=11) had liver metastasis from different primaries. The mean administered dose was 1.9 GBq (range, 1.2-2.5 GBq). Follow-up was done with FDG PET and CT at 6 weeks, and 6-monthly thereafter. Pre-therapy and post-therapy CT and PET scans were assessed visually (RECIST criteria for CT) and semi-quantitative for PET using the standardized uptake value (SUV).
  
  
  RESULTS
  Eighty-six percent of patients showed decreased PET activity at 6 weeks while only 13% showed a partial response in the size of tumour on CT scan. The mean pre-treatment SUV was 12.2+/-3.7 and the mean post-treatment SUV was 9.3+/-3.7 (P=0.01). CT imaging showed progressive disease in 27% patients and stable liver disease in 60% patients. Based on FDG PET results one patient had surgery for down-staged tumour.
  
  
  CONCLUSIONS
  FDG PET imaging is more sensitive than CT in the assessment of early response to SIR spheres, allowing clinicians to proceed with further therapeutic options.
authors.affiliation: Department of Nuclear Medicine, Hammersmith Hospital, Du Cane Road, London, UK.
authors.forename: Teresa
authors.initials: T
authors.lastname: Szyszko
authors.forename: Adil
authors.initials: A
authors.lastname: Al-Nahhas
authors.forename: Ruben
authors.initials: R
authors.lastname: Canelo
authors.forename: Nagy
authors.initials: N
authors.lastname: Habib
authors.forename: Long
authors.initials: L
authors.lastname: Jiao
authors.forename: Harpreet
authors.initials: H
authors.lastname: Wasan
authors.forename: Margarita
authors.initials: M
authors.lastname: Pagou
authors.forename: Paul
authors.initials: P
authors.lastname: Tait
mesh_terms: D000328:Adult; D015179:Colorectal Neoplasms / Q000188:drug therapy; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000494:pharmacology*; D006801:Humans; D008113:Liver Neoplasms / Q000628:therapy*; D008297:Male; D008863:Microspheres; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009369:Neoplasms / Q000188:drug therapy; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals / Q000494:pharmacology*; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016896:Treatment Outcome; D015021:Yttrium Radioisotopes / Q000627:therapeutic use*
chemical_list: D019275:Radiopharmaceuticals; D015021:Yttrium Radioisotopes; D019788:Fluorodeoxyglucose F18