Importance of diffusion imaging in liver metastases

CLINICAL/METHODICAL ISSUE: Detection and characterization of focal liver lesions. STANDARD RADIOLOGICAL METHODS: Due to its excellent soft tissue contrast, the availability of liver-specific contrast agents and the possibility of functional imaging, magnetic resonance imaging (MRI) is the method of choice for the evaluation of focal liver lesions. METHODICAL INNOVATIONS: Diffusion-weighted imaging (DWI) enables generation of functional information about the microstructure of a tissue besides morphological information. PERFORMANCE: In the detection of focal liver lesions DWI shows a better detection rate compared to T2w sequences and a slightly poorer detection rate compared to dynamic T1w sequences. In principle, using DWI it is possible to distinguish malignant from benign liver lesions and also to detect a therapy response at an early stage. ACHIEVEMENTS: For both detection and characterization of focal liver lesions, DWI represents a promising alternative to the morphological sequences; however, a more detailed characterization with the use of further sequences should be carried out particularly for the characterization of solid benign lesions. For the assessment and prognosis of therapy response, DWI offers advantages compared to morphological sequences. PRACTICAL RECOMMENDATIONS: For the detection of focal liver lesions DWI is in principle sufficient. After visual detection of a solid liver lesion a more detailed characterization should be carried out using further sequences (in particular dynamic T1w sequences). The DWI procedure should be used for the assessment and prognosis of a therapy response.