title: Perfusion CT: noninvasive surrogate marker for stratification of pancreatic cancer response to concurrent chemo- and radiation therapy.
abstract: OBJECTIVE
  To prospectively determine whether perfusion computed tomography (CT) parameters, such as volume transfer constant (K(trans)) between blood plasma and extracellular extravascular space (EES) and blood volume calculated from dynamic CT data, can be used to predict response of pancreatic cancer to concurrent chemotherapy and radiation therapy (CCRT).
  
  
  METHODS
  This prospective study was institutional review board approved, and written informed consent was obtained. Thirty patients with pancreatic cancer underwent perfusion CT with 64-detector row CT before gemcitabine-based CCRT. Two perfusion parameters (K(trans) and blood volume) measured before treatment were compared between patients who responded to treatment and those who did not, as determined with World Health Organization criteria from first and second posttherapeutic follow-up CT examinations, which were performed at 3- and 6-month follow-up. Statistical analysis was performed with the two-sample t test. A receiver operating characteristic curve was used to determine the best cutoff value of perfusion parameters for differentiation of responders from nonresponders.
  
  
  RESULTS
  Twenty of 30 patients examined at 3-month follow-up responded to therapy. Their pretreatment K(trans) value was significantly higher than that of nonresponders (50.8 mL/100 mL/min +/- 30.5 [standard deviation] vs 19.0 mL/100 mL/min +/- 10.8, P = .001). The best cutoff value for differentiating between responders and nonresponders was 31.8 mL/100 mL/min, which yielded 75.0% sensitivity and 90.0% specificity. Ten of 18 patients examined at 6-month follow-up responded to therapy. Their pretreatment K(trans) value was significantly higher than that of nonresponders (58.6 mL/100 mL/min +/- 43.2 vs 19.8 mL/100 mL/min +/- 10.9, P = .002). Responders also had higher blood volume values, but this difference was not significant.
  
  
  CONCLUSIONS
  Tumors with a high pretreatment K(trans) value tended to respond better to CCRT than did tumors with a low pretreatment K(trans) value. Perfusion CT may be used to predict tumor response to CCRT in patients with pancreatic cancer. This might aid in development of a tailored approach to therapy in these patients.
authors.affiliation: Department of Diagnostic Radiology, Institute of Gastroenterology, Severance Hospital, Yonsei University College of Medicine, Seodaemun-ku, Shinchon-dong 134, Seoul 120-752, South Korea. radpms@yuhs.ac
authors.forename: Mi-Suk
authors.initials: MS
authors.lastname: Park
authors.forename: Ernst
authors.initials: E
authors.lastname: Klotz
authors.forename: Myeong-Jin
authors.initials: MJ
authors.lastname: Kim
authors.forename: Si Young
authors.initials: SY
authors.lastname: Song
authors.forename: Seung Woo
authors.initials: SW
authors.lastname: Park
authors.forename: Seung-Whan
authors.initials: SW
authors.lastname: Cha
authors.forename: Joon Soek
authors.initials: JS
authors.lastname: Lim
authors.forename: Jinsil
authors.initials: J
authors.lastname: Seong
authors.forename: Jae Bok
authors.initials: JB
authors.lastname: Chung
authors.forename: Ki Whang
authors.initials: KW
authors.lastname: Kim
mesh_terms: D000368:Aged; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D001810:Blood Volume / Q000502:physiology; D003131:Combined Modality Therapy; D003287:Contrast Media; D003841:Deoxycytidine / Q000008:administration & dosage / Q000031:analogs & derivatives; D045604:Extracellular Fluid / Q000378:metabolism; D005260:Female; D018495:Fluid Shifts / Q000502:physiology; D005500:Follow-Up Studies; D006801:Humans; D007479:Iopamidol; D008297:Male; D008875:Middle Aged; D010190:Pancreatic Neoplasms / Q000098:blood supply / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000532:radiotherapy*; D010953:Plasma Volume / Q000502:physiology; D011172:Portography / Q000379:methods*; D011446:Prospective Studies; D012372:ROC Curve; D011879:Radiotherapy Dosage; D036542:Tomography, Spiral Computed / Q000379:methods*; D016896:Treatment Outcome; D000093542:Gemcitabine
chemical_list: D003287:Contrast Media; D003841:Deoxycytidine; D007479:Iopamidol; D000093542:Gemcitabine