Abstract

The purpose of the study is to assess the advantages of diffusion weighted resonance imaging (DWI) prospectively in the metastasis and benign differentiation of small (≤ 10 mm) focal liver lesions (FLL) detected in routine ultrasonography and/or computed tomography screening of patients with extrahepatic primary malignancy. A total of 77 small FLLs (33 metastasis, 27 cyst, 17 hemangioma) of 53 patients who received DWI in addition to conventional magnetic resonance imaging were assessed by 2 independent readers prospectively. Apparent diffusion coefficient (ADC) values were measured for each FLL. T-test was used to assess the statistically significant difference between average ADC values in differentiating between metastasis and benign FLLs. In the metastasis and benign differentiation of small FLLs, optimum cutoff values of ADC values were found by using receiver operating characteristic (ROC) analysis. Average ADC values of small focal liver metastases were statistically significantly lower than those of benign FLL (p < 0.001). Small focal liver metastases were differentiated from benign FLL with 100% sensitivity and 97.1% specificity by using 1.44 x 10-3 s/mm2 cutoff ADC value. This study shows that DWI can be useful in differentiating whether incidentally found small FLL is metastasis in patients who have extrahepatic primary malignancy.

Key words: Diffusion-weighted imaging, apparent diffusion coefficient, small focal liver lesions