Tehran University of Medical Sciences Basic & Clinical Cancer Research 2228-6527 13 1 2021 11 11 9 20 Asma Gulzar sheri kashmir institute of medical sciences Tahleel Shera sheri kashmir institute of medical sciences Omair Shah sheri kashmir institute of medical sciences Naseer Choh sheri kashmir institute of medical sciences Tariq Gojwari sheri kashmir institute of medical sciences Mudasir Bhat sheri kashmir institute of medical sciences Shadab Maqsood sheri kashmir institute of medical sciences 2021 07 01 2021 09 20 Background: We evaluated the role of early diffusion weighted imaging (DWI) in predicting response to TACE in patients with HCC and compare the results with contrast enhanced magnetic resonance imaging. METHODS: 24 patients with documented HCC were taken up for TACE after a pre-procedural contrast CT and MRI. Post procedural DWI was taken on day 5-7 and the mean ADC values were documented and compared to pre procedural values. The change in ADC values was grouped into 4 categories: group 1- <25%, group 2 26-50%, group 3- 51-75% and group 4- >75%. The increase in ADC values signifying response was correlated with 5 week CEMRI scan and a threshold ADC increase signifying response in majority of the cases was calculated. RESULTS: The mean ADC of the lesions changed from 1.21× 10-3 (pre TACE) to 2.02× 10-3 mm2/sec (post TACE) [p<0.001]. Taking CE MRI as gold standard, DWI imaging had a sensitivity of 80%, specificity of 94.7% with a positive predictive value of 80%, negative predictive value of 94.7% and overall accuracy of 91.7%. Complete response was seen in19 (79%) and incomplete in 5 (21%) patients in our study. The change in ADC was significantly higher in responders (884.15 ± 161.60) as compared to non responders (564.80 ± 221.05) [p =0.001]. CONCLUSION: Early DWI after TACE can predict response of a HCC lesion to chemoembolization. The change in ADC values can earmark responders from non-responders. Early DWI results are concordant with CEMRI results in most of the cases. DWI can act as a substitute to CEMRI when contrast administration is not advised. https://bccr.tums.ac.ir/index.php/bccrj/article/view/394