title: MRI and FDG-PET for assessment of response to neoadjuvant chemotherapy in locally advanced rectal cancer.
abstract: BACKGROUND
  The purpose of this study was to assess the value of magnetic resonance imaging (MRI) and additional (18)F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) for tumor response to neoadjuvant chemotherapy (NAC) in patients with locally advanced rectal cancer (LARC).
  
  
  METHODS
  Data on 40 patients with LARC, who were treated with NAC and underwent MRI and FDG-PET/CT before and after NAC, were analyzed retrospectively. Surgery was performed at a median of 6 weeks after NAC and the images were compared with the histological findings. The tumor regression grade 3/4 was classified as a responder.
  
  
  RESULTS
  Sixteen patients were pathological responders. Receiver operating characteristic (ROC) analysis revealed that MRI total volume after NAC (MRI-TV2) and ΔMRI-TV had the highest performance to assess responders (area under the ROC curve [AUC] 0.849 and AUC 0.853, respectively). The reduction rate of the maximum standardized uptake value (ΔSUVmax) was also an informative factor (AUC 0.719). There seems no added value of adding FDG-PET/CT to MRI-TV2 and ΔMRI-TV in assessment of NAC responders judging from changes in AUC (AUC of ΔSUVmax and MRI-TV2 was 0.844, and AUC of ΔSUVmax and ΔMRI-TV was 0.846).
  
  
  CONCLUSIONS
  MRI-TV2 and ΔMRI-TV were the most accurate factors to assess pathological response to NAC. Although ΔSUVmax by itself was also informative, the addition of FDG-PET/CT to MRI did not improve performance. Patients with LARC who were treated by induction chemotherapy should receive an MRI examination before and after NAC to assess treatment response. A more than 70 % volume reduction shown by MRI volumetry may justify the omission of subsequent radiotherapy.
authors: Division of Surgical Oncology, Department of Surgery, Nagoya Graduate School of Medicine, Nagoya, Japan.
authors: Toshisada
authors: T
authors: Aiba
authors: Keisuke
authors: K
authors: Uehara
authors: Takashi
authors: T
authors: Nihashi
authors: Toyonori
authors: T
authors: Tsuzuki
authors: Hiroshi
authors: H
authors: Yatsuya
authors: Yuichiro
authors: Y
authors: Yoshioka
authors: Katsuhiko
authors: K
authors: Kato
authors: Masato
authors: M
authors: Nagino
mesh_terms: D000328:Adult; D000368:Aged; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D019540:Area Under Curve; D000069287:Capecitabine; D017024:Chemotherapy, Adjuvant; D003841:Deoxycytidine / Q000031:analogs & derivatives / Q000627:therapeutic use; D005260:Female; D019788:Fluorodeoxyglucose F18; D005472:Fluorouracil / Q000031:analogs & derivatives / Q000627:therapeutic use; D006801:Humans; D002955:Leucovorin / Q000627:therapeutic use; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D009944:Organoplatinum Compounds / Q000627:therapeutic use; D010071:Oxaloacetates; D049268:Positron-Emission Tomography; D012372:ROC Curve; D019275:Radiopharmaceuticals; D012004:Rectal Neoplasms / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000473:pathology / Q000601:surgery; D012189:Retrospective Studies; D016896:Treatment Outcome
chemical_list: D009944:Organoplatinum Compounds; D010071:Oxaloacetates; D019275:Radiopharmaceuticals; D003841:Deoxycytidine; D019788:Fluorodeoxyglucose F18; D000069287:Capecitabine; D002955:Leucovorin; D005472:Fluorouracil