Evaluation of the treated neck is complicated by significant treatment-related changes that can be difficult to differentiate from persistent disease after therapy or recurrence. MRI is less susceptible to metal artifact than CT and may perform better in the oral cavity where there can be significant artifact from dental implants. Conversely, MRI offers decreased spatial resolution compared to CT and is more susceptible to motion artifact because of longer scan times. One study found that MRI, much like CT, has low sensitivity and positive predictive value for detecting recurrence in treated oropharynx cancer but has importance in excluding recurrence with a high NPV (94%) [139]. FDG-PET/CT confers increased sensitivity compared to MRI and confers similarly to slightly increased specificity when evaluating for recurrence [43]. One study found that the combination of MRI with FDG-PET/CT has the best detection of locoregional recurrence [128]. Combined pre- and postcontrast imaging provides the best opportunity to correctly identify and delineate recurrent tumor, distinguishing it from surrounding soft tissues and treatment changes. MRI Orbits, Face, and Neck Without IV Contrast There is no relevant literature to support the use of MRI of the orbits, face, and neck without IV contrast in the follow-up imaging or evaluation of suspected or known recurrence of treated cancer of the oral cavity, oropharynx, hypopharynx, larynx, or cancer of unknown primary of the head and neck. Combined pre- and postcontrast imaging provides the best opportunity to identify and delineate local tumor recurrence, distinguishing it from treatment- related change and in evaluating local tumor response. The absence of IV contrast limits the ability to accurately delineate the margin and the soft tissue extent of tumor.
Staging and Post Therapy Assessment of Head and Neck Cancer. Evaluation of the treated neck is complicated by significant treatment-related changes that can be difficult to differentiate from persistent disease after therapy or recurrence. MRI is less susceptible to metal artifact than CT and may perform better in the oral cavity where there can be significant artifact from dental implants. Conversely, MRI offers decreased spatial resolution compared to CT and is more susceptible to motion artifact because of longer scan times. One study found that MRI, much like CT, has low sensitivity and positive predictive value for detecting recurrence in treated oropharynx cancer but has importance in excluding recurrence with a high NPV (94%) [139]. FDG-PET/CT confers increased sensitivity compared to MRI and confers similarly to slightly increased specificity when evaluating for recurrence [43]. One study found that the combination of MRI with FDG-PET/CT has the best detection of locoregional recurrence [128]. Combined pre- and postcontrast imaging provides the best opportunity to correctly identify and delineate recurrent tumor, distinguishing it from surrounding soft tissues and treatment changes. MRI Orbits, Face, and Neck Without IV Contrast There is no relevant literature to support the use of MRI of the orbits, face, and neck without IV contrast in the follow-up imaging or evaluation of suspected or known recurrence of treated cancer of the oral cavity, oropharynx, hypopharynx, larynx, or cancer of unknown primary of the head and neck. Combined pre- and postcontrast imaging provides the best opportunity to identify and delineate local tumor recurrence, distinguishing it from treatment- related change and in evaluating local tumor response. The absence of IV contrast limits the ability to accurately delineate the margin and the soft tissue extent of tumor.