title: Is the combination of MR and CT findings useful in determining the tumor grade of pancreatic neuroendocrine tumors?
abstract: OBJECTIVE
  To retrospectively elucidate the findings useful in determining the tumor grade of pancreatic neuroendocrine tumors (PNETs) by combined assessment of magnetic resonance (MR) and dynamic computed tomography (CT) images.
  
  
  METHODS
  Eighty-nine patients with PNETs (96 lesions) were included, and classified as G1, 59; G2, 29; and G3, 8 lesions. Image analysis included lesion diameter, shape, enhancement pattern on arterial phase (AP) and delayed phase CT images, calcification, cystic portion, main pancreatic duct dilatation, signal-intensity on T1-, T2-weighted MR images, and appearance of apparent diffusion coefficient (ADC).
  
  
  RESULTS
  Significant differences among G1, G2, and G3 groups were noted in tumor maximal diameter (p < 0.0001), shape (p < 0.0001), enhancement pattern on AP image (p < 0.0001), cystic portion (p = 0.012), and ADC finding. In multivariate analysis, ADC finding was the independent factor (p = 0.002). The combination findings of low ADC ratio (ADC value of the lesion/ADC value of the parenchyma <0.94), not homogeneous hyper-attenuation, lobulated shape, and hyper-intensity on T2-weighted image were suggestive of G2 or G3 with a probability of 100%. Conversely, all lesions with high ADC ratio and small size (≤25 mm) belonged to the G1 group.
  
  
  CONCLUSIONS
  Combined assessment of MR and CT findings could improve the prediction of tumor grading in PNETs.
authors.affiliation: Department of Radiology, Kanazawa University Graduate School of Medical Science, 13-1 Takara-machi, Kanazawa, Ishikawa, 920-8641, Japan. fumihitotoshima@gmail.com.
authors.forename: Fumihito
authors.initials: F
authors.lastname: Toshima
authors.affiliation: Department of Radiology, Kanazawa University Graduate School of Medical Science, 13-1 Takara-machi, Kanazawa, Ishikawa, 920-8641, Japan.
authors.forename: Dai
authors.initials: D
authors.lastname: Inoue
authors.affiliation: Department of Radiology, Kanazawa University Graduate School of Medical Science, 13-1 Takara-machi, Kanazawa, Ishikawa, 920-8641, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Komori
authors.affiliation: Department of Radiology, Kanazawa University Graduate School of Medical Science, 13-1 Takara-machi, Kanazawa, Ishikawa, 920-8641, Japan.
authors.forename: Kotaro
authors.initials: K
authors.lastname: Yoshida
authors.affiliation: Department of Radiology, Kanazawa University Graduate School of Medical Science, 13-1 Takara-machi, Kanazawa, Ishikawa, 920-8641, Japan.
authors.forename: Norihide
authors.initials: N
authors.lastname: Yoneda
authors.affiliation: Department of Radiology, Kanazawa University Graduate School of Medical Science, 13-1 Takara-machi, Kanazawa, Ishikawa, 920-8641, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Minami
authors.affiliation: Department of Radiology, Kanazawa University Graduate School of Medical Science, 13-1 Takara-machi, Kanazawa, Ishikawa, 920-8641, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Matsui
authors.affiliation: Department of Pathology, Kanazawa University Graduate School of Medical Science, 13-1 Takara-machi, Kanazawa, Ishikawa, 920-8641, Japan.
authors.forename: Hiroko
authors.initials: H
authors.lastname: Ikeda
authors.affiliation: Department of Radiology, Kanazawa University Graduate School of Medical Science, 13-1 Takara-machi, Kanazawa, Ishikawa, 920-8641, Japan.
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Gabata
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D060787:Neoplasm Grading; D018358:Neuroendocrine Tumors / Q000000981:diagnostic imaging* / Q000473:pathology*; D010190:Pancreatic Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D055815:Young Adult
keywords: Computed tomography (CT); Magnetic resonance imaging (MRI); Neuroendocrine carcinoma; Neuroendocrine tumors G1; Neuroendocrine tumors G2; Pancreatic neuroendocrine tumors