title: Contrast-enhancement ratio on multiphase enhanced computed tomography predicts recurrence of pancreatic neuroendocrine tumor after curative resection.
abstract: OBJECTIVE
  No previous study has quantitatively investigated the degree of enhancement of pancreatic neuroendocrine tumors (pNETs) using a routine preoperative modality. The aim of this study was to evaluate the contrast-enhancement ratio (CER) of pNETs using multiphase enhanced CT and to assess the impact of the CER on disease recurrence after surgery.
  
  
  METHODS
  A retrospective study was performed using data from 47 consecutive patients with pNETs who had undergone curative surgery. The CER of the tumor was calculated by dividing the CT attenuation value obtained during the maximum-enhanced phase by that obtained during the pre-enhanced phase. A region of interest was placed in the largest tumor dimension plane so as to cover as much surface of the tumor as possible while avoiding adjacent normal structures, calcification, and necrotic areas of the tumor.
  
  
  RESULTS
  During a median follow-up period of 51 months (range, 1-132 months), a total of 4 patients (8.5%) developed disease recurrence. The median CER value was significantly lower for the patients with recurrence than for the patients without recurrence (2.9 vs. 4.3, P = 0.013). Univariate analyses showed that a CER ≤3.2 was significantly associated with disease recurrence (P < 0.001). All the patients with disease recurrence had tumors that were both large (>20 mm) and weakly enhanced (CER ≤ 3.2), whereas no recurrences were observed even in patients with tumors >20 mm when the CER was greater than 3.2.
  
  
  CONCLUSIONS
  CER might be a useful predictor of disease recurrence in patients with pNETs.
authors: Department of Surgery, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, 390-8621, Japan.
authors: Takuma
authors: T
authors: Arai
authors: Department of Surgery, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, 390-8621, Japan. Electronic address: kbys@shinshu-u.ac.jp.
authors: Akira
authors: A
authors: Kobayashi
authors: Department of Radiology, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, 390-8621, Japan.
authors: Yasunari
authors: Y
authors: Fujinaga
authors: Department of Surgery, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, 390-8621, Japan.
authors: Takahide
authors: T
authors: Yokoyama
authors: Department of Surgery, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, 390-8621, Japan.
authors: Akira
authors: A
authors: Shimizu
authors: Department of Surgery, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, 390-8621, Japan.
authors: Hiroaki
authors: H
authors: Motoyama
authors: Department of Surgery, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, 390-8621, Japan.
authors: Noriyuki
authors: N
authors: Kitagawa
authors: Department of Surgery, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, 390-8621, Japan.
authors: Tsuyoshi
authors: T
authors: Notake
authors: Department of Surgery, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, 390-8621, Japan.
authors: Tomoki
authors: T
authors: Shirota
authors: Department of Surgery, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, 390-8621, Japan.
authors: Kentaro
authors: K
authors: Fukushima
authors: Department of Surgery, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, 390-8621, Japan.
authors: Hitoshi
authors: H
authors: Masuo
authors: Department of Radiology, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, 390-8621, Japan.
authors: Masumi
authors: M
authors: Kadoya
authors: Department of Surgery, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, 390-8621, Japan.
authors: Shin-Ichi
authors: S
authors: Miyagawa
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media; D018572:Disease-Free Survival; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging*; D018358:Neuroendocrine Tumors / Q000000981:diagnostic imaging / Q000601:surgery*; D010180:Pancreatectomy; D010190:Pancreatic Neoplasms / Q000000981:diagnostic imaging / Q000601:surgery*; D016577:Pancreaticoduodenectomy; D011300:Preoperative Care; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016896:Treatment Outcome
chemical_list: D003287:Contrast Media
keywords: Computed tomography; Contrast-enhancement ratio; Disease recurrence; Neuroendocrine tumor; Pancreas; Preoperative prediction