Study rationale: 18F FDG PET CT is the standard of care imaging technique used to evaluate treatment response and suspected recurrence in patients of head and neck cancer who have undergone definitive surgery or chemo-radiation. However, FDG PET CT often struggles to discriminate between post treatment inflammatory changes and recurrent disease. Because of this reason FDG PET CT has relatively poor positive predictive value. 68Ga Trivehexin is a novel PET based radiotracer that preferentially targets alpha’V’beta’6’ integrin which is hyperexpressed in head and neck squamous cell carcinoma HNSCC. Early studies suggest that this tracer is able to suceesfully diferentiate post treatment changes from recurrent disease. However, these are retrospective studies or have relatively small sample size.  In this study we want to see if 68Ga Trivehexin PET can be used as a complementary tool to standard FDG PETCT in detecting recurrent or residual HNSCC.

General aim: To evaluate the feasibility of using 68Ga Trivehexin PET CT in assessing residual and recurrent head and neck squamous cell carcinoma

Objectives: 

Primary objective: To find out the pattern of 68Ga Trivehexin PET CT findings in patients of HNSCC, post definitive or  curative treatment with an equivocal or positive 18F FDG PETCT scan during the follow up period 

Secondary objectives: 1) To find out the diagnostic accuracy of 68Ga Trivehexin PET CT in detecting residual recurrent disease 2) To see if quantitative PET parameters (SUVmax, SUVmean, lesion to back ground ratio) and qualitative patterns of PET uptake in 68Ga Trivehexin PET scan can be used to differentiate post treatment inflammatory changes from viable residual/recurrent disease. 3) To compare the diagnostic accuracy of 68Ga Trivehexin PETCT in detecting residual/recurrent disease 4) To assess the prognostic value of 68Ga Trivehexin scan in predicting progression free survival 

Hypothesis: 68Ga Trivehexin PET CT can be successfully used to distinguish post treatment inflammatory changes from viable residual/recurrent disease with reasonable accuracy.

Sample size: In our institutional study NI-RADS system had an PPV of 46 percent . If the PPV improves to 61 percent then with an (one sided) of 0.05 and power of 80 percent, sample size comes to 68. If we consider a drop off rate of 10 percent then the sample size comes to 75.

Study methodology: HNSCC patients who have undergone 18F-FDG PETCT for response assessment or in suspicion of recurrence following any definitive treatment during the follow up period will be screened for the study. Two experienced nuclear medicine physicians will review the scans and assign NI-RADS score. Patients with NI-RADS score of 2 or above will be explained about the study and ICF will be given to them. Consenting patients will be taken for 68Ga Tivehexine PETCT scan. The duration between 18F FDG PETCT and 68Ga Trivehexin PETCT scan should not be more than 15 days. 68Ga Trivehexin PET CT scans will be reviewed by two experienced nuclear medicine physicians. Follow up of the patient will be done as per the established standard.