AIM To noninvasively investigate tumor cellularity measured using diffusion-weighted magnetic resonance imaging(DW-MRI) and glucose metabolism measured by 18 Flabeled fluorodeoxyglucose positron emission tomography/computed tomography(18F-FDG-PET/CT) during radiation therapy(RT) for human papillomavirus negative(HPV-) head and neck squamous cell carcinoma(HNSCC).METHODS In this prospective study, 6 HPV- HNSCC patients underwent a total of 34 multimodality imaging examinations(DW-MRI at 1.5 T Philips MRI scanner [(n = 24) pre-, during-(2-3 wk), and post-treatment(Tx), and 18F-FDG PET/CT pre- and post-Tx(n = 10)]. All patients received RT. Monoexponential modeling of the DW-MRI data yielded the imaging metric apparent diffusion coefficient(ADC) and the mean of standardized uptake value(SUV) was measured from 18F-FDG PET uptake. All patients had a clinical follow-up as the standard of care and survival status was documented at 1 year.RESULTS There was a strong negative correlation between the mean of pretreatment ADC(ρ =-0.67, P = 0.01) and the pretreatment 18F-FDG PET SUV. The percentage(%) change in delta(?) ADC for primary tumors and neck nodal metastases between pre- and Wk2-3 Tx were as follows: 75.4% and 61.6%, respectively, for the patient with no evidence of disease, 27.5% and 32.7%, respectively, for those patients who were alive with disease, and 26.9% and 7.31%, respectively, for those who were dead with disease.CONCLUSION These results are preliminary in nature and are indicative, and not definitive, trends rendered by the imaging metrics due to the small sample size of HPV- HNSCC patients in a Meixoeiro Hospital of Vigo Experience. AIM To noninvasively investigate tumor cellularity measured using diffusion-weighted magnetic resonance imaging (DW-MRI) and glucose metabolism measured by 18 Flabeled fluorodeoxyglucose positron emission tomography / computed tomography (18F-FDG-PET / CT) during radiation therapy HPV-HNSCC patients underwent a total of 34 multimodality imaging examinations (DW-MRI at 1.5 T Philips MRI scanner [(n = 24 ) pre-, during- (2-3 wk), and post-treatment (Tx), and 18F-FDG PET / CT pre- and post- Tx (n = 10)]. All patients received RT. Monoexponential modeling of the The mean-standardized uptake value (SUV) was measured from 18F-FDG PET uptake. All patients had a clinical follow-up as the standard of care and survival status was documented at 1 year.RESULTS There was a strong negative correlation between The mean (%) change in delta (?) ADC for primary tumors and neck nodal metastases between pre- and Wk2-3 Tx were as follows: 75.4% and 61.6%, respectively, for the patient with no evidence of disease, 27.5% and 32.7%, respectively, for those patients who were alive with disease, and 26.9% and 7.31% respectively respectively, for those who were dead with disease. CONCLUSION These results were preliminary in nature and are indicative, and not definitive, trends rendered by the imaging metrics due to the small sample size of HPV- HNSCC patients in a Meixoeiro Hospital of Vigo Experience.