Dynamic contrast enhanced MR

Newer MR imaging techniques for head and neck

Dynamic and functional imaging techniques are being developed to improve the evaluation of various pathologic processes of the head and neck region. These techniques include dynamic contrast-enhanced MR imaging for evaluating soft tissue masses and cervical lymph nodes, the use of ultrasmall superparamagnetic iron oxide contrast agent, and functional techniques such as in vivo and in vitro MR spectroscopy of head and neck cancer and lymph nodes and apparent diffusion coefficient mapping of parotid glands. These techniques can help to differentiate nonmalignant tissue from malignant tumors and lymph nodes and can aid in differentiating residual malignancies from postradiation changes. From methodological development, they are making the critical transition to preclinical and clinical validating methods and eventually to widespread clinical tools.

Dynamic contrast-enhanced MRI in clinical oncology: current status and future directions

Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is performed after the administration of intravenous contrast medium to noninvasively access tumor vascular characteristics. DCE-MRI techniques utilizing low-molecular-weight contrast media have successfully made the transition from methodological development to preclinical and clinical validation and are now rapidly becoming mainstream clinical tools. DCE-MRI using macromolecular contrast medium (MMCM) can also assay microvascular characteristics of human tumor xenografts. MMCM approval for human use will occur soon. The success of both techniques depends on their ability to demonstrate quantitative differences of contrast medium behavior in a variety of tissues. Evidence is mounting that kinetic parameters correlate with immunohistochemical surrogates of tumor angiogenesis, including microvessel density, and with pathologic tumor grade. DCE-MRI is being applied to monitor the clinical effectiveness of a variety of treatments, including antiangiogenic drugs. Kinetic parameter changes following treatment have correlated with histopathological outcome and patient survival. This article reviews the current clinical status of low-molecular-weight DCE-MRI and reviews the potential of MMCM techniques for evaluating human tumors. Ongoing challenges faced by DCE-MRI as clinical and research tools will be explored.