title: Value of FDG PET/Contrast-Enhanced CT in Initial Staging of Colorectal Cancer - Comparison with Contrast-Enhanced CT.
abstract: BACKGROUND
  FDG PET/CT is at an equivocal stage to recommend for staging of colorectal cancer as compared to contrast-enhanced CT (ceCT). This study was intended to evaluate the value of FDG PET/ceCT in colorectal cancer staging as compared to ceCT alone.
  
  
  METHODS
  PET/ceCT was performed for 61 colorectal cancer patients who were prospectively enrolled in the study. Three patients were excluded due to loss to follow-up. PET/ceCT findings and ceCT results alone were read separately. The treatment planning was then determined by tumor board consensus. The criteria for T staging were determined by the findings of ceCT. Nodal positive by PET/ceCT imaging was determined by visual analysis of FDG uptake greater than regional background blood pool activity. The diagnostic accuracy of T and N staging was determined only in patients who received surgery without any neoadjuvant treatment.
  
  
  RESULTS
  Of 58 patients, there were 40 with colon cancers including sigmoid cancers and 18 with rectal cancers. PET/ceCT in pre-operative staging detected bone metastasis and metastatic inguinal lymph nodes (M1a) that were undepicted on CT in 2 patients (3%), clearly de ned 19 equivocal lesions on ceCT in 18 patients (31%) and excluded 6 metastatic lesions diagnosed by ceCT in 6 patients (10%). These resulted in alteration of management plan in 15 out of the 58 cases (26%) i.e. changing from chemotherapy to surgery (4), changing extent of surgery (9) and avoidance of futile surgery (2). Forty four patients underwent surgery within 45 days after PET/CT. The diagnostic accuracy for N staging with PET/ceCT and ceCT alone was 66% and 48% with false positive rates of 24% (6/25) and 76% (19/25) and false negative rates of 47% (9/19) and 21% (4/19), respectively. All of the false negative lymph nodes from PET/ceCT were less than a centimeter in size and located in peri-lesional regions. The diagnostic accuracy for T staging was 82%. The sensitivity of the peri-lesional fat stranding sign in determining T3 stage was 94% and the specificity was 54%.
  
  
  CONCLUSIONS
  Our study suggested promising roles of PET/ceCT in initial staging of colorectal cancer with better diagnostic accuracy facilitating management planning.
authors.affiliation: National Cyclotron and PET Centre, Division of Nuclear Medicine, Chulabhorn Hospital, Thailand E-mail : Chanisa.ja@gmail.com.
authors.forename: Anchisa
authors.initials: A
authors.lastname: Kunawudhi
authors.forename: Karun
authors.initials: K
authors.lastname: Sereeborwornthanasak
authors.forename: Chetsadaporn
authors.initials: C
authors.lastname: Promteangtrong
authors.forename: Bunchorn
authors.initials: B
authors.lastname: Siripongpreeda
authors.forename: Saiphet
authors.initials: S
authors.lastname: Vanprom
authors.forename: Chanisa
authors.initials: C
authors.lastname: Chotipanich
mesh_terms: D000328:Adult; D000368:Aged; D015179:Colorectal Neoplasms / Q000473:pathology*; D003287:Contrast Media / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods; D009367:Neoplasm Staging / Q000379:methods; D000072078:Positron Emission Tomography Computed Tomography / Q000379:methods*; D049268:Positron-Emission Tomography / Q000379:methods; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media