Diffusion kurtosis imaging of the liver at 3 Tesla: in vivo comparison to standard diffusion-weighted imaging.

Background Functional techniques like diffusion-weighted imaging (DWI) are gaining more and more importance in liver magnetic resonance imaging (MRI). Diffusion kurtosis imaging (DKI) is an advanced technique that might help to overcome current limitations of DWI. Purpose To evaluate DKI for the differentiation of hepatic lesions in comparison to conventional DWI at 3 Tesla. Material and Methods Fifty-six consecutive patients were examined using a routine abdominal MR protocol at 3 Tesla which included DWI with b-values of 50, 400, 800, and 1000 s/mm2. Apparent diffusion coefficient maps were calculated applying a standard mono-exponential fit, while a non-Gaussian kurtosis fit was used to obtain DKI maps. ADC as well as Kurtosis-corrected diffusion ( D) values were quantified by region of interest analysis and compared between lesions. Results Sixty-eight hepatic lesions (hepatocellular carcinoma [HCC] [n = 25]; hepatic adenoma [n = 4], cysts [n = 18]; hepatic hemangioma [HH] [n = 18]; and focal nodular hyperplasia [n = 3]) were identified. Differentiation of malignant and benign lesions was possible based on both DWI ADC as well as DKI D-values ( P values were in the range of 0.04 to < 0.0001). Conclusion In vivo abdominal DKI calculated using standard b-values is feasible and enables quantitative differentiation between malignant and benign liver lesions. Assessment of conventional ADC values leads to similar results when using b-values below 1000 s/mm2 for DKI calculation.

Semi-automatic Volumetric Measurement of Treatment Response in Hepatocellular Carcinoma After Trans-arterial Chemoembolization.

AIM: To perform a quantitative, volumetric analysis of therapeutic effects of trans-arterial chemoembolization (TACE) in hepatocellular carcinoma (HCC) patients. PATIENTS AND METHODS: Entire tumor volume and a subset of hypervascular tumor portions were analyzed pre- and post-TACE in magnetic resonance imaging datasets of 22 HCC patients using a semi-automated segmentation and evaluation tool from the Medical Imaging Interaction Toolkit. Results were compared to mRECIST measurements and inter-reader variability was assessed. RESULTS: Mean total tumor volume increased statistical significantly after TACE (84.6 ml pre- vs. 97.1 ml post-TACE, p=0.03) while hypervascular tumor volume decreased from 9.1 ml pre- to 3.7 ml post-TACE (p=0.0001). Likewise, mRECIST diameters decreased significantly after therapy (44.2 vs. 15.4 mm). In the inter-reader assessment, overlap errors were 12.3-17.7% for entire and 36.3-64.2% for the enhancing tumor volume. CONCLUSION: Quantification of therapeutic changes after TACE therapy is feasible using a semi-automated segmentation and evaluation tool. Following TACE, hypervascular tumor volume decreases significantly.