title: Differentiation between pancreatic metastases from renal cell carcinoma and hypervascular neuroendocrine tumour: Use of relative percentage washout value and its clinical implication.
abstract: OBJECTIVE
  To compare computed tomography (CT) findings in patients with pancreatic metastasis from renal cell carcinoma (pRCC) and patients with hypervascular pancreatic neuroendocrine tumour (pNET) with a focus on the relative percentage washout (RPW).
  
  
  METHODS
  We evaluated 16 patients with 37 pRCCs and 28 patients with 31 hypervascular pNETs using a protocol consisting of arterial and portal phase CT. Imaging findings were analyzed for comparison between the two groups. The RPW of each tumour using biphasic CT was obtained by two observers for evaluation of diagnostic performance. Interobserver agreement of each value and optimal cut-off level of RPW for discrimination between groups were evaluated.
  
  
  RESULTS
  Tumour multiplicity showed significant difference in both groups. The mean RPW of the pRCC group (observer 1, 27.0%; observer 2, 29.4%) was significantly higher than that of the pNET group (observer 1, 0.5%; observer 2, 3.2%) (p<0.001 for each observer). Interobserver agreement for both attenuation values and RPWs was excellent. A RPW value of 19% was selected as the optimal cut-off for pRCC determination, and showed good performance (accuracy 83.8%, sensitivity 83.8%, and specificity 83.9%).
  
  
  CONCLUSIONS
  With multiplicity, RPW of the tumour on CT could be helpful for differentiating pRCCs from hypervascular pNETs.
authors: Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Ilwon-Ro, Gangnam-gu, Seoul 135-710, Republic of Korea.
authors: Tae Wook
authors: TW
authors: Kang
authors: Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Ilwon-Ro, Gangnam-gu, Seoul 135-710, Republic of Korea. Electronic address: kshyun@skku.edu.
authors: Seong Hyun
authors: SH
authors: Kim
authors: Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Ilwon-Ro, Gangnam-gu, Seoul 135-710, Republic of Korea.
authors: Jisun
authors: J
authors: Lee
authors: Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Ilwon-Ro, Gangnam-gu, Seoul 135-710, Republic of Korea.
authors: Ah Yeong
authors: AY
authors: Kim
authors: Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Ilwon-Ro, Gangnam-gu, Seoul 135-710, Republic of Korea.
authors: Kyung Mi
authors: KM
authors: Jang
authors: Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Ilwon-Ro, Gangnam-gu, Seoul 135-710, Republic of Korea.
authors: Dongil
authors: D
authors: Choi
authors: Biostatics Unit, Samsung Biomedical Research Institute, Samsung Medical Center, Seoul 135-710, Republic of Korea.
authors: Min Ji
authors: MJ
authors: Kim
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002292:Carcinoma, Renal Cell / Q000000981:diagnostic imaging* / Q000473:pathology*; D015331:Cohort Studies; D003287:Contrast Media; D054541:Family Conflict; D005260:Female; D006801:Humans; D007472:Iohexol; D007668:Kidney / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D018358:Neuroendocrine Tumors / Q000473:pathology*; D010179:Pancreas / Q000000981:diagnostic imaging; D010190:Pancreatic Neoplasms / Q000000981:diagnostic imaging* / Q000556:secondary*; D011856:Radiographic Image Enhancement; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D007472:Iohexol
keywords: Computed tomography; Metastasis; Neuroendocrine tumour; Pancreas; Renal cell carcinoma