Detection, classification, and characterization of focal liver lesions: Value of diffusion-weighted MR imaging, gadoxetic acid-enhanced MR imaging and the combination of both methods.

AIM: To evaluate diffusion-weighted MR imaging (DWI), gadoxetic acid-enhanced MR imaging and the combination of both methods in the detection, classification, and characterization of focal liver lesions (FLL). METHODS: A total of 119 FLL (28 HCCs, 39 metastases, 15 FNHs, 11 adenomas, 13 hemangiomas, 13 cysts) were retrospectively analyzed in 36 patients. In those patients MR imaging of the liver comprising respiratory-triggered DWI (b values of 50, 300, and 600 s/mm(2)) and gadoxetic acid-enhanced MR imaging including image acquisition in the hepatocyte-selective phase (20 min post injection) had been performed. Three image sets were assigned and compared: DWI only (set A), gadoxetic acid-enhanced MR imaging only (set B), and both modalities in combination (set C). Two readers independently interpreted the images in random order. For each reader and image set, the area under the receiver operating characteristic curve (Az) and sensitivity in the detection of FLL was determined as well as the accuracy in the classification and characterization of FLL. RESULTS: There was no significant difference between the three image sets in the detection of FLL with regards to Az. However, when only lesions with a diameter of 10 mm or less were analyzed, the Az values of set C were significantly higher than those of sets A and B for both readers. For classifying and characterizing FLL both set B and C were significantly superior to set A. CONCLUSION: Adding DWI to gadoxetic acid-enhanced MR imaging significantly increases the accuracy in the detection of small FLL.

Comparison of diffusion-weighted MR imaging and multidetector-row CT in the detection of liver metastases in patients operated for pancreatic cancer.

AIM: The purpose of this study is to determine the value of diffusion-weighted MR imaging (DWI) in the detection of liver metastases in patients with pancreatic tumors when compared to multidetector-row CT (MDCT). METHODS: DWI and MDCT were performed in 31 consecutive patients with newly diagnosed, potentially resectable pancreatic tumors. CT images were obtained in the arterial and the portal venous phase. For DWI, a respiratory-triggered single-shot echo-planar imaging sequence (b values: 0, 300, and 600 s/mm(2)) was acquired. Images were analyzed in consensus by two radiologists blinded to the clinical data. Imaging results were correlated with intraoperative surgical and ultrasound findings as well as with results of histopathologic analysis and imaging follow-up. RESULTS: Sensitivity and specificity in detecting liver metastases were 53.3% and 77.8% for MDCT and 86.7% and 97.5% for DWI, respectively. In our study population DWI would have changed the therapeutic management in 4 out of 31 patients (12.9%) when compared to MDCT. CONCLUSION: In the present pilot study, DWI performed significantly better than MDCT in the detection of liver metastases in patients with pancreatic tumors. Therefore, DWI may help to optimize therapeutic management in those patients in the future.