الفهرس 
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Abstract
Malignant liver tumors including primary liver cancers and metastases are among the most common tumors in the world.
Accurate detection of these tumors is of clinical importance before treatment by resection or radiofrequency ablation as a potential curative treatment. Palliative interventions such as chemo- embolization also require exact lesion localization. Accurate detection is necessary to ensure correct staging, to prevent tumors from being falsely rated as inoperable and patients with inoperable tumors from being scheduled for surgical procedures.
Triphasic CT was believed to be the standard in evaluating the hepatic focal lesions and together with alpha fetoprotein, the lesions were decided either non conclusive and needing biopsy or conclusive. According to number and distribution of the lesions (if proved malignant); surgery, radiofrequency ablation or chemo-or chemoembolization was decided. Unfortunately, not all cases with HCC having high alpha fetoprotein and not all cases having typical imaging criteria of HCC and also, not all lesions detected by US are seen in the dynamic CT study.
MRI; having many sequences; markedly helps in the detection of small lesions and in reaching the diagnosis easily even without contrast injection.
Diffusion-weighted imaging (DWI) has been reported to be useful for the early detection of focal liver lesions. Moreover, DWI offers the possibility to obtain criteria for lesion characterization- without the need for contrast agent administration-by quantifying diffusion effects via apparent diffusion coefficient (ADC) measurements, with better results compared with those of conventional MR imaging.
In this study, we concluded that DW imaging significantly improves detection of smaller malignant lesions (diameter less than 2 cm) compared with standard breath-hold T2-weighted imaging.
DW imaging could potentially improve care of patients with cancer in cirrhotic liver by improving lesion detection over that achieved with standard breath-hold T2-weighted imaging.
DWI is also a promising technique in earlier prediction of tumor response to treatment.