Diffusion-weighted MRI in head and neck cancer

PURPOSE OF REVIEW Diffusion-weighted MRI (DWI) is a noninvasive imaging technique allowing some degree of tissue characterization by showing and quantifying molecular diffusion. Cell size, density and integrity influence the signal intensity seen on diffusion-weighted images. A number of recent reports suggest that this technique may have interesting applications in the evaluation of head and neck cancer, by distinguishing tumoural from nontumoural tissue. RECENT FINDINGS In squamous cell cancer, DWI appears helpful in staging neck nodal disease and in distinguishing radiotherapy-induced tissue changes from persistent or recurrent cancer. DWI may also have prognostic value before and during radiotherapy of head and neck cancer. The technique may also be useful in characterizing thyroid nodules and salivary gland neoplasms. SUMMARY Early evidence suggests that DWI may become a useful tool, complementary to existing imaging techniques, in the evaluation of head and neck malignancies. Further technical improvements and clinical validation are needed.