Recent advances in MR imaging for cancer diagnosis

The recent development in magnetic resonance (MR) hardware and techniques allows the acquisition of functional information, such as perfusion or metabolism, in addition to conventional anatomical information in of cancers. In this review article, various molecular imaging methods based on MR are introduced and their application and usefulness for diagnosis of cancer are discussed. Diffusion weighted image (DWI) is believed to correlate cell density and reflect malignancy of tumor DWI has been widely used for the diagnosis and evaluation of responses to cancer treatment. Arterial spin labeling (ASL) allows acquisition of perfusion data without the use of any contrast agent and is expected to be an alternative or complementary method to dynamic contrast enhanced MR imaging. Amide proton transfer (APT) imaging reflects the amount of mobile peptide and proteins in cancer tissue, and could be a useful tool for assessing tumor malignancy or evaluating treatment responses. More specific measurement of cancer metabolites is available at the cost of spatial resolution by MR spectroscopy (MRS). Finally, the positron emission tomography (PET)/MR hybrid system enables simultaneous acquisition of functional/ anatomical information from MR imaging and molecular/metabolic information from PET imaging. Combining various molecular MR imaging methods with PET tracers may have a huge potential for clinical diagnosis of cancer.