title: Effect of intravenous contrast agent volume on colorectal cancer vascular parameters as measured by perfusion computed tomography.
abstract: OBJECTIVE
  To determine the effect of two different contrast agent volumes on quantitative and semi-quantitative vascular parameters as measured by perfusion computed tomography (CT) in colorectal cancer.
  
  
  METHODS
  Following ethical approval and informed consent, eight prospectively recruited patients with proven colorectal adenocarcinoma underwent two separate perfusion CT studies on the same day after (a) 100 ml and (b) 50 ml of a 340 mg/ml iodinated contrast medium, respectively. Quantitative (blood volume, blood flow, permeability surface area product) and semi-quantitative (peak enhancement, time to peak enhancement) tumour vascular parameters were determined using commercial software based on distributed parameter analysis and compared using t-testing.
  
  
  RESULTS
  Tumour blood volume, blood flow, and permeability surface area product were not substantially different following the injection of 100ml and 50 ml contrast medium: 6.12 versus 6.23 ml/100 g tissue; 73.4 versus 71.3 ml/min/100 g tissue; 15.6 versus 15.3 ml/min/100 g tissue for 100 and 50 ml, respectively; p>0.05. Tumour peak enhancement and time to peak were significantly greater following the injection of 100ml versus 50 ml contrast medium: 41.2 versus 28.5 HU; 16.1 versus 11.8 s for 100ml and 50 ml, respectively; p=0.002; p=0.0003.
  
  
  CONCLUSIONS
  Quantitative parameters do not appear to change substantially with a higher contrast agent volume suggesting a combined diagnostic staging-perfusion CT study following a single injection is feasible for colorectal cancer.
authors.affiliation: Paul Strickland Scanner Centre, Mount Vernon Hospital, Northwood, London, UK.
authors.forename: V
authors.initials: V
authors.lastname: Goh
authors.forename: C
authors.initials: C
authors.lastname: Bartram
authors.forename: S
authors.initials: S
authors.lastname: Halligan
mesh_terms: D000230:Adenocarcinoma / Q000098:blood supply / Q000000981:diagnostic imaging*; D000368:Aged; D000369:Aged, 80 and over; D015179:Colorectal Neoplasms / Q000098:blood supply / Q000000981:diagnostic imaging*; D003287:Contrast Media / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D007275:Injections, Intravenous; D008297:Male; D008875:Middle Aged; D010477:Perfusion / Q000379:methods*; D011446:Prospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media