title: Neuroendocrine liver metastases: Value of apparent diffusion coefficient and enhancement ratios for characterization of histopathologic grade.
abstract: To assess the value of apparent diffusion coefficient (ADC) measured with diffusion-weighted imaging (DWI) and enhancement ratios (ER) measured with contrast-enhanced T1-weighted imaging (CE-T1WI) for the characterization of histopathologic tumor grade of neuroendocrine tumor liver metastases (NETLM).
  
  
  
  Twenty-two patients with pathology-proven NETLM and pretreatment 1.5 Tesla (T) and 3T MRI including DWI were included in this Institutional Review Board-approved retrospective study. ADC histogram parameters, including mean, minimum (min), skewness, and kurtosis as well as ER, were computed for all lesions. Tumor grading was based on the World Health Organization 2010 classification. Kruskal-Wallis and Mann-Whitney test were used to assess for differences in ADC and ER between different tumor grades. MRI parameters were correlated with pathologic findings using Spearman correlation test. Receiver operating characteristic analysis was performed to determine optimum thresholds for predicting tumor grade.
  
  
  
  Forty-eight NETLM (mean size 3.5 cm) were analyzed with the following grade distribution: G1 (n = 25), G2 (n = 16), and G3 (n = 7). ADC-mean (×10-3mm2/s) of G3 tumors (0.87 ± 0.43) was significantly lower than that of G1 (1.47 ± 0.63) and G2 (1.27 ± 0.63; P = 0.042). A weak significant negative correlation was observed between ADC and tumor grade (ADC-mean: r = -0.33, P = 0.02; ADC-min: r = -0.37, P = 0.01) and Ki-67 (ADC-mean: r = -0.31, P = 0.03; ADC-min: r = -0.39, P = 0.007). AUROC, sensitivity and specificity of ADC-mean/ADC-min/ER (measured at the early arterial phase) for differentiation of G3 versus G1-G2 were 0.80/0.76/0.67, 100%/50%/70%, and 68.4%/84.2%/66.6%, respectively.
  
  
  
  ADC is a promising marker for characterization of histopathologic grade of NETLM. These results should be confirmed in a prospective study. J. Magn. Reson. Imaging 2016;44:1432-1441.
authors.affiliation: Department of Radiology, Body MRI, Icahn School of Medicine at Mount Sinai, New York, USA.|Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, USA.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Besa
authors.affiliation: Department of Pathology, Icahn School of Medicine at Mount Sinai, New York, USA.
authors.forename: Stephen
authors.initials: S
authors.lastname: Ward
authors.affiliation: Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, USA.|Department of Radiology, Peking University Cancer Hospital & Beijing Cancer Hospital, Beijing, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Cui
authors.affiliation: Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, USA.
authors.forename: Guido
authors.initials: G
authors.lastname: Jajamovich
authors.affiliation: Department of Medicine, Division of Gastroenterology, Icahn School of Medicine at Mount Sinai, New York, USA.
authors.forename: Michelle
authors.initials: M
authors.lastname: Kim
authors.affiliation: Department of Radiology, Body MRI, Icahn School of Medicine at Mount Sinai, New York, USA.|Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, USA.
authors.forename: Bachir
authors.initials: B
authors.lastname: Taouli
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008113:Liver Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology* / Q000556:secondary*; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D018358:Neuroendocrine Tumors / Q000000981:diagnostic imaging / Q000473:pathology* / Q000556:secondary*; D015588:Observer Variation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: contrast enhancement; diffusion weighted imaging; magnetic resonance imaging; neuroendocrine tumors