AbstractBackground: Monitoring tumor response to loco-regionaltherapy is an increasingly important task in oncologic imaging.Aim of Study: The aim of the study is to highlight thegrowing role of diffusion and dynamic MRI in the follow-upof patients with hepatocellular carcinoma after radiofrequencyablation, and hence playing a crucial role in evaluating treat-ment effectiveness and therefore in taking important decisionsin the management of these patients.Patients and Methods: This study included 80 patients,61 males and 19 females, patients ages ranged from 32 to 85years with the mean age of 60 years underwent Radiofrequencyablation of 100 hepatic focal lesions over a period of 19months (July 2018-February 2020). The study was conductedin the Radiology Department at a private radiology centre.Results: 69 lesions (69%) were resolved lesions while 31lesions (31%) had residual/recurrent tumor viability. Themeasured cut off value between the completely ablated lesionsand residual/recurrent lesions was 1.18±0.24 X10–3mm2/safter the 1st month and 1.22±0.30 X 10–3mm2/s after 3-4months. The ablated zones can be differentiated from liverparenchyma visually in the DWIs and by means of ADC inall patients. There is no statistical difference in the mean ADCvalues between the ablated zones of the resolved and unre-solved lesions. All the 31 malignant lesions show arterialphase enhancement with 16 lesions out of 31 show persistentenhancement on the portal phase and show washout of thecontrast on the delayed phase with 15 malignant lesion showwashout of the contrast on the portovenous and delayed phasesof the study. The enhancement is considered only if provedby the subtracted images.Conclusion: MRI is a powerful tool in detection of tumourviability and response after RFA of hepatocellular carcinoma.Imaging protocols should include dynamic study, diffusionimaging with post processing of the images to obtain subtractedimages and ADC measurements for precise tissue characteri-zation and should be performed at regular time intervals.