Role of Diffusion Weighted MRI Imaging in Detection of Liver Metastases

Abstract

Liver cancer,is one of the leading causes of all cancer related deaths. In fact, the secondary hepatic malignancies (liver metastases) are more common than the primary ones. Almost all solid malignancies can metastasize to liver (1). Accurate diagnosis of liver metastases is essential for appropriate management of these patients. Multiple imaging modalities, including ultrasound ,computed tomography(CT), positron emission tomography, and MRI, are available for the evaluation of patients with suspected or known liver metastases(2). There is growing interest in the applications of diffusion-weighted-imaging (DWI) in oncologic area . DWI has important advantages because it does not require contrast medium, a very quick technique and it provides qualitative and quantitative information that can be helpful for tumor assessment(3). DWI is an imaging technique which provides tissue contrast by the measurement of diffusion properties of water molecules within tissues. Diffusion is expressed in an apparent diffusion coefficient (ADC), which reflects the diffusion properties unique to each type of tissue(4). Both low and high b-value DWI are effective in suppressing vascular structures that may mimic or obscure liver lesions, but low b-value DWI provides a higher signal-to-noise ratio, is less prone to cardiac motion-induced signal loss, and suffers less from eddy current-induced distortions. Previous studies have already shown that low b-value DWI is more sensitive than high b-value DWI in detecting malignant liver lesions (5).