title: Sporadic insulinomas on volume perfusion CT: dynamic enhancement patterns and timing of optimal tumour-parenchyma contrast.
abstract: OBJECTIVE
  To assess enhancement patterns of sporadic insulinomas on volume perfusion CT (VPCT), and to identify timing of optimal tumour-parenchyma contrast.
  
  
  METHODS
  Consecutive patients who underwent VPCT for clinically suspected insulinomas were retrospectively identified. Patients with insulinomas confirmed by surgery were included, and patients with familial syndromes were excluded. Two radiologists evaluated VPCT images in consensus. Tumour-parenchyma contrast at each time point was measured, and timing of optimal contrast was determined. Time duration of hyperenhancement (tumour-parenchyma contrast >20 Hounsfield units, HU) was recorded. Perfusion parameters were evaluated.
  
  
  RESULTS
  Three dynamic enhancement patterns were observed in 63 tumours: persistent hyperenhancement (hyperenhancement time window ≥10 s) in 39 (61.9%), transient hyperenhancement (hyperenhancement <10 s) in 19 (30.2%) and non-hyperenhancement in 5 (7.9%). Timing of optimal contrast was 9 s after abdominal aorta threshold (AAT) of 200 HU, with tumour-parenchyma contrast of 77.6 ± 57.2 HU. At 9 s after AAT, 14 (22.2%) tumours were non-hyperenhancing, nine of which had missed transient hyperenhancement. Insulinomas with transient and persistent hyperenhancement patterns had significantly increased perfusion.
  
  
  CONCLUSIONS
  Insulinomas have variable enhancement patterns. Tumour-parenchyma contrast is time-dependent. Optimal timing of enhancement is 9 s after AAT. VPCT enables tumour detection even if the hyperenhancement is transient.
  
  
  CONCLUSIONS
  • Enhancement patterns of insulinomas are variable and tumour-parenchyma contrast is time-dependent. • An optimized single-phase scan found 77.8% tumours to be hyperenhancing. • Hyperenhancing tumours increase to 84.1% and 87.3% with biphasic/triphasic scan. • Volume perfusion CT enables detection of insulinomas with missed transient hyperenhancement.
authors.affiliation: Department of Radiology, Peking Union Medical College Hospital, Shuaifuyuan No.1, Dongcheng District, Beijing, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Zhu
authors.affiliation: Department of General Surgery, Peking Union Medical College Hospital, Shuaifuyuan No.1, Dongcheng District, Beijing, China.
authors.forename: Wen-Ming
authors.initials: WM
authors.lastname: Wu
authors.affiliation: Department of Radiology, Peking Union Medical College Hospital, Shuaifuyuan No.1, Dongcheng District, Beijing, China. bjdanna95@hotmail.com.
authors.forename: Hua-Dan
authors.initials: HD
authors.lastname: Xue
authors.affiliation: Department of Radiology, Peking Union Medical College Hospital, Shuaifuyuan No.1, Dongcheng District, Beijing, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.affiliation: Department of Radiology, Peking Union Medical College Hospital, Shuaifuyuan No.1, Dongcheng District, Beijing, China.
authors.forename: Xuan
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Radiology, Peking Union Medical College Hospital, Shuaifuyuan No.1, Dongcheng District, Beijing, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Sun
authors.affiliation: Department of Radiology, Peking Union Medical College Hospital, Shuaifuyuan No.1, Dongcheng District, Beijing, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Li
authors.affiliation: Department of General Surgery, Peking Union Medical College Hospital, Shuaifuyuan No.1, Dongcheng District, Beijing, China.
authors.forename: Yu-Pei
authors.initials: YP
authors.lastname: Zhao
authors.affiliation: Department of Radiology, Peking Union Medical College Hospital, Shuaifuyuan No.1, Dongcheng District, Beijing, China.
authors.forename: Zheng-Yu
authors.initials: ZY
authors.lastname: Jin
mesh_terms: D000328:Adult; D000368:Aged; D054893:Cone-Beam Computed Tomography / Q000379:methods; D003287:Contrast Media; D005260:Female; D006801:Humans; D007340:Insulinoma / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D010190:Pancreatic Neoplasms / Q000000981:diagnostic imaging*; D010477:Perfusion; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods; D012189:Retrospective Studies; D013997:Time Factors
chemical_list: D003287:Contrast Media
keywords: Enhancement; Insulinoma; Multidetector computed tomography; Perfusion; Sporadic