Added value of breathhold diffusion-weighted MRI in detection of small hepatocellular carcinoma lesions compared with dynamic contrast-enhanced MRI alone using receiver operating characteristic curve analysis.

ABSTRACT

PURPOSE: To evaluate the added value of single-breathhold diffusion-weighted MRI (DWI) in detection of small hepatocellular carcinoma (HCC) lesions (< or =2 cm) in patients with chronic liver disease, by comparing the detection sensitivity of combined DWI/conventional dynamic contrast-enhanced (DCE)-MRI to that of conventional DCE-MRI alone. MATERIALS AND METHODS: A total of 37 patients with chronic liver diseases underwent abdominal MRI at 1.5T, including T1-weighted imaging (T1WI), T2-weighted imaging (T2WI), and 2D conventional DCE. For each patient study, axial DWI was performed with a single-shot echo-planar imaging (EPI) sequence using a modified sensitivity-encoding (mSENSE) technique with b-value of 500 seconds/mm(2). A total of 20-24 slices were obtained during a 15-17-second breathhold. Two observers independently interpreted the combined DWI/conventional DCE-MRI images and the conventional DCE-MRI images alone in random order. For all small HCC lesions, the diagnostic performance using each imaging set was evaluated by receiver operating characteristic (ROC) curve analysis. Sensitivity and positive predictive values were also calculated and analyzed. RESULTS: A total of 47 small HCCs were confirmed as final result. The area under the ROC curve (Az) of combined DWI/conventional DCE-MRI images (observer 1, 0.922; observer 2, 0.918) were statistically higher than those of conventional DCE-MRI alone (observer 1, 0.809; observer 2, 0.778) for all small HCC lesions (P < 0.01). The lesion detection sensitivities using the combined technique for both observers were significantly higher than those using conventional DCE-MRI alone (P < 0.01). The sensitivity values for two observers using the combined technique were 97.87% and those using conventional DCE-MRI alone were 85.11% to 82.98%. The positive predictive values for two observers using the combined imaging technique (97.87%) were slightly higher than those using conventional DCE-MRI alone (92.86-93.02%), but there was no significant difference between the two imaging sets. CONCLUSION: Combined use of breathhold DWI with conventional DCE-MRI helped to provide higher sensitivities than conventional DCE-MRI alone in the detection of small HCC lesions in patients with chronic liver disease.