Role of Diffusion Weighted Imaging in assessing response to Transcatheter Arterial Chemoembolization in Hepatocellular Carcinoma patients.

Abstract

BACKGROUND: Transarterial chemoembolization(TACE) is a popular method and widely used interventional procedure in the treatment of hepatocellular carcinoma(HCC). Diffusion weighted MRI can be used in evaluating reponse to TACE by detection of residual tumour tissue.

OBJECTIVES: To assess the role of early diffusion weighted imaging (DWI) in predicting response to TACE in patients with HCC in terms of

• Percentage change in ADC of tumour pre TACE and post TACE.
• Normal liver parenchymal ADC change pre TACE snd post TACE.

PARTICIPANTS: Patients diagnosed as HCC on the basis of imaging and AFP or biopsy.

STUDY DESIGN: Prospective observational study.

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.

 IMPLICATION: The change in ADC values can earmark responders from non-responders.

KEYWORDS: Transarterial Chemoembolization, Magnetic Resonance Imaging., Hepatocellular Carcinoma, Diffusion-Weighted Imaging, Apparent Diffusion Coefficient.