Detection of residual, recurrent, or second primary malignancies in head and neck cancers treated patients can be challenging. Soft tissue changes and anatomical disfigurement seen after surgery, radiotherapy, and chemotherapy can distort the anatomy of the head and neck and make post treatment imaging reporting very complex.

To evaluate the performance of the Neck imaging, and reporting data system template recently created by the American College of Radiology (ACR) Committee in the prediction of local and regional disease recurrence or persistence of head and neck squamous cell carcinoma after treatment by using CE MRI/ CT, and PET-CT in inconclusive cases. 

116 scans for 55patients with head and neck squamous cell cancerswere included after finishing their treatment, reporting done using the ACR NI-RADS reporting template and lexicon and NI-RADS category was assigned to each scan, the accuracy of this categorization was done by correlation with our gold standard: tissue pathological examination and/ or three months interval follow up scan. 

Out of the 116 scans included in our study, we had 232 targets for primary tumour sites and lymph nodes, the overall tumour recurrence have occurred in 53 targets out of the total of 232, with a total tumour recurrence rate of 22.8%, the recurrence rates for each NI-RADS category for the primary tumour site were: 3.9% (2/51) for NI-RADS 1 category, 17.6% (3/17) for NI-RADS 2a category, 18.2% (4/22) for NI-RADS 2b category , and 76.9% (20/26) for NI-RADS 3 category. Regarding the lymph nodes, the recurrence rates for the different NI-RADS categories were: 3.8% (3/80) for NI-RADS 1 category, 7.1% (1/14) for NI-RADS 2 category, and 81.8% (18/22) for NI-RADS 3 category. The recurrence rates for combined NI-RADS categories for both the primary tumour site and lymph nodes were (Table 7): 3.8% (5/131) for NI-RADS 1 category, 19.6% (10/51) forNI-RADS 2 category, and 76.2% (38/48) for NI-RADS 3 category. 

The performance of the ACR NI-RADS reporting system and its linked management recommendations is excellent, with statistically significant discrimination in between the different NIRADS categories for either the primary tumour site, lymph nodes and for both combined. The use of NI-RADS can help to direct the management plans towards more proper options.