Background: The purpose of this study was to test if diffusion-weighted imaging (DWI) identified persistent neck disease after chemoradiotherapy (CRT) for oropharyngeal cancer earlier and as accurately as subsequent positron emission tomography (PET)/CT. Methods: We performed a review of patients with oropharyngeal cancer treated with definitive CRT who underwent DWI and PET/CT at a median of 8 and 14 weeks posttreatment. Imaging characteristics were correlated with pathologically proven neck failure. Results: Forty-one patients and 58 hemi-necks were analyzed. With a median follow-up of 120 weeks, 4 neck failures were identified. The apparent diffusion coefficient (ADC) of lymph node failures was lower (1220 vs 1910 μm2/s; p =.003) than non-failures. Using an ADC threshold of 1500 μm2/s, the sensitivity, specificity, and positive and negative predictive values (PPV; NPV) were 100% (4/4), 92% (46/50), 50% (4/8), and 100% (46/46) for DWI, respectively, and 100% (3/3), 71% (22/31), 25% (3/12), and 100% (22/22) for PET/CT, respectively. Conclusion: Earlier DWI produced similar sensitivity and better specificity in identifying persistent neck disease as 3-month PET/CT.
- MRI diffusion-weighted imaging (DWI)
- oropharyngeal cancer
- positron emission tomography (PET)/CT
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