Objective: To evaluate the added value of single breath-hold diffusion-weighted imaging (DWI) in detection of small HCC lesions (<or=3 cm) in patients with chronic liver disease, by comparing the detection sensitivity of DWI/conventional dynamic contrast enhancement (DCE) MRI and that of conventional DCE MRI alone.
Methods: A total of 54 patients with chronic liver diseases underwent abdominal MRI at 1.5 T, including T1-weighted (T1WI), T2-weighted (T2WI), and 2D conventional DCE. For each patient study, axial DWI was performed with a single-shot echo-planar imaging (EPI) sequence using modified sensitivity encoding (mSENSE) with b-value of 500 seconds/mm2. A total of 20-24 slices were obtained during a 15-17-second breath-hold. Two observers independently interpreted the combined DWI/conventional DCE MRI images and the conventional DCE MRI images in random order. For all small HCC lesions and micro-hepatocellular carcinoma (smaller than 10 mm MHCC), the diagnostic performance using each imaging techniques were evaluated by ROC analysis. Sensitivity and positive predictive values were also calculated.
Results: The mean areas under the ROC curve (Az) of combined DWI/conventional DCE MRI images (0.945, 0.86) were statistically higher than those of conventional DCE MRI alone (0.86, 0.64) for all small HCC lesions and MHCC (micro hepatocellular carcinoma) lesions (P<0.01). The lesion detection sensitivities using the combined technique of both observers were significantly higher than those using the conventional DCE MRI alone for all small lesions and for MHCC (P<0.01). For MHCC, the sensitivities using the combined technique and the conventional DCE MRI alone were 95.8%-96.0% and 62.5%-68.0%, respectively. The positive predictive values for MHCC using the combined imaging technique (95.8%-96.0%) were higher than those using the conventional DCE MRI alone (94.1%-94.4%) (P<0.05). For all small HCC lesions, the positive predictive values using the combined imaging technique and the conventional DCE MRI alone were 98.6%-98.7% and 95.5%-95.7%, respectively and there was no statistical difference.
Conclusion: Combined use of Breath-hold 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. Furthermore, DWI could provide additional valuable information that benefits the differential diagnosis.