Magnetic Resonance Imaging May Be Able to Identify the Origin of Neuroendocrine Tumor Liver Metastases.

OBJECTIVES: The aim of the study was to discriminate hepatic metastases from pancreatic neuroendocrine tumors (pNET) and hepatic metastases from midgut neuroendocrine tumors (mNET) with magnetic resonance imaging (MRI). METHODS: MRI examinations of 24 patients with hepatic metastases from pNET were quantitatively and qualitatively assessed by 2 blinded readers and compared to those obtained in 23 patients with hepatic metastases from mNET. Inter-reader agreement was calculated with kappa and intraclass correlation coefficient (ICC). Sensitivity, specificity, and accuracy of each variable for the diagnosis of hepatic metastasis from pNET were calculated. Associations between variables and primary tumor (i.e., pNET vs. mNET) were assessed by univariate and multivariate analyses. A nomogram was developed and validated using an external cohort of 20 patients with pNET and 20 patients with mNET. RESULTS: Interobserver agreement was strong to perfect (k = 0.893-1) for qualitative criteria and excellent for quantitative variables (ICC: 0.9817-0.9996). At univariate analysis, homogeneity on T1-weighted images was the most discriminating variable for the diagnosis of pNET (OR: 6.417; p = 0.013) with greatest sensitivity (88%; 21/24; 95% CI: 68-97%). At multivariate analysis, tumor homogeneity on T1-weighted images (p = 0.007; OR: 17.607; 95% CI: 2.179-142.295) and target sign on diffusion-weighted images (p = 0.007; OR: 19.869; 95% CI: 2.305-171.276) were independently associated with pNET. Nomogram yielded a corrected AUC of 0.894 (95% CI: 0.796-0.992) for the diagnosis of pNET in the training cohort and 0.805 (95% CI: 0.662-0.948) in the validation cohort. CONCLUSIONS: MRI provides qualitative features that can help discriminate between hepatic metastases from pNET and those from mNET.

MRI presentation of hepatocellular carcinoma in non-alcoholic steatohepatitis (NASH).

PURPOSE: To describe the magnetic resonance imaging (MRI) features of hepatocellular carcinoma (HCC) in patients with non-alcoholic steatohepatitis (NASH). METHODS: MRI examinations of 21 patients with HCC and NASH were analyzed by two observers. There were 18 men and 3 women with a mean age of 67.9 ±â€¯10.2 (SD) years (range: 36-85 years). Images were qualitatively and quantitatively analyzed with respect to imaging presentation. RESULTS: HCC presented as a single tumor in 13/21 patients (62%), with a mean longest diameter of 26.9 ±â€¯20.2 (SD) mm (range: 12-88 mm); 17/30 HCC (57%) had a largest diameter <20 mm. A signal drop between in- and out-of-phase T1-weighted MR images was observed in 16/30 HCC nodules (53%). All HCC nodules (30/30; 100%) showed hyperenhancement on arterial phase images and 12/30 HCC nodules (40%) did not show a wash-out on portal or delayed phase images. Encapsulation was observed in 18/30 HCC nodules (60%). MRI findings consistent with liver cirrhosis were present in 16/21 patients (76%). CONCLUSIONS: Our results show that 57% of HCC in NASH can present as a lesion smaller than 20 mm and 40% do not display wash-out. These results suggest that classical imaging criteria developed for noninvasive diagnosis of HCC should be applied with caution to HCC in patients with NASH.