Correlation of Diffusion weighted MR Imaging and ADC values of hepatic metastasis of Gastrointestinal Stromal and Gastroenteropancreatic Neuroendocrine Tumors

Abstract

Background: DWI and ADC-mapping was performed to analyze hepatic metastasis of GIST, GEP-NET.

Objective: The objective of this study is to present hepatic metastasis of GIST and GEP-NET with Diffusion weighted MR imaging(DWI) and the Apparent diffusion coefficients (ADC) values of masses.

Method: 18 GIST patients and 8 GEP-NET patients were examined retrospectively. 11 males and 6 females were present in GIST group, 7 males to 5 females were involved in GEP-NET group. 18 primary GIST and 10 hepatic metastasis of GIST, 8 original GEP-NET and 19 hepatic metastasis of GEP-NET; total 55 GIST and GEP-NET masses were analysed by ADC mapping. MR images were acquired by 1,5 T MR units (32 mT/min gradient strength- Achieva; Philips Healthcare, Best, Netherlands and 32 channel GE Signa GE-Wisconsin-USA); by using a 4-8 channel standard phased-array torso XL coil, all images were evaluated by an Abdominal MRI experienced radiologist. DWI was performed in the transverse plane by using spin-echo-planar imaging sequence.

Result: No statistical differences were observed between GIST and GEP-NET patients according to age and gender variations. No significant statistical differences were observed according to the diameters and ADC values of GIST and GEP-NET patients. A significant statistical difference was observed between GIST and GEP-NET groups in terms of size of liver metastasis which was significantly higher in GIST patients. All three groups (GIST_Hep. MET, GEP-NET_Liver_Met and normal) were statistically differed according to ADC values. With the ROC curve analysis: Hepatic metastasis of GIST(n=10) and normal liver (n:47) had cut-off value for ADC: 0.925 under AUC: 0.939 with regard to ADC values and regarded 89.4 % Sensitivity, 100% Specificity, 100% PPV and 66.7% PPV. ROC curve of GEP NET_ Hepatic metastasis (n=19) group and normal liver (n:47) group presented cut-off value for ADC: 0.860 under AUC: 0.967 correlated to ADC values with 93.6 % sensitivity, 89.5% specificity, 95.7% PPV and 85% PPV.

Conclusion: High cellular tumors resulted from liver metastasis of GIST and GEP-NET's, and a positive correlation was observed between ADC values and cellularity/differentiation ratios of metastatic masses.

Keywords: MR; diffusion; hepatic; imaging; metastasis; ppancreatic; stromal.