Objectives To determine the added value of diffusionweighted imaging (DWI) to standard magnetic resonance imaging (MRI) to differentiate malignant from benign soft tissue tumours at 3.0 T. Methods 3.0 T MR images including DWI in 63 patients who underwent surgery for soft tissue tumours were retrospectively analyzed. Two readers independently interpreted MRI for the presence of malignancy in two steps: standard MRI alone, standard MRI and DWI with qualitative and quantitative analysis combined. Results There were 34 malignant and 29 non-malignant soft tissue tumours. In qualitative analysis, hyperintensity relative to skeletal muscle was more frequent in malignant than benign tumours on DWI (P=0.003). In quantitative analysis, ADCs of malignant tumours were significantly lower than those of nonmalignant tumours (P≤0.002): 759±385 vs. 1188±423 μm 2 / sec minimum ADC value, 941±440 vs. 1310±440 μm 2 /sec average ADC value. The mean sensitivity, specificity and accuracy of both readers were 96 %, 72 %, and 85 % on standard MRI alone and 97 %, 90 %, and 94 % on standard MRI with DWI.Conclusions The addition of DWI to standard MRI improves the diagnostic accuracy for differentiation of malignant from benign soft tissue tumours at 3.0 T. Key Points • DWI has added value for differentiating malignant from benign soft tissue tumours. • Addition of DWI to standard MRI at 3.0 T improves the diagnostic accuracy. • Measurements of both ADC min within solid portion and ADC av are helpful.

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Escherichia coli is the best-established microbial host strain for production of proteins and chemicals, but has a weakness for not secreting high amounts of active heterologous proteins to the extracellular culture medium, of which origins belong to whether prokaryotes or eukaryotes. In this study, Candida antarctica lipase B (CalB), a popular eukaryotic enzyme which catalyzes a number of biochemical reactions and barely secreted extracellularly, was expressed functionally at a gram scale in culture medium by using a simple amino acid-tag system of E. coli. New fusion tag systems consisting of a pelB signal sequence and various anion amino acid tags facilitated both intracellular expression and extracellular secretion of CalB. Among them, the N-terminal five aspartate tag changed the quaternary structure of the dimeric CalB and allowed production of 1.9 g/L active CalB with 65 U/mL activity in culture medium, which exhibited the same enzymatic properties as the commercial CalB. This PelB-anion amino acid tag-based expression system for CalB can be extended to production of other industrial proteins hardly expressed and exported from E. coli, thereby increasing target protein concentrations and minimizing purification steps.