Abstract

PurposeTo assess the predictive value of volumetric apparent diffusion coefficient (vADC) histogram quantification obtained before and 6weeks (6w) post-treatment for assessment of hepatocellular carcinoma (HCC) response to (90)Yttrium radioembolization (RE).MethodsIn this retrospective study, 22 patients (M/F 15/7, mean age 65y) who underwent lobar RE were included between October 2013 and November 2014. All patients underwent routine liver MRI pre-treatment and 6w after RE. Two readers assessed index tumor response at 6months after RE in consensus, using mRECIST criteria. vADC histogram parameters of index tumors at baseline and 6w, and changes in vADC (vADC) histogram parameters were calculated. The predictive value of ADC metrics was assessed by logistic regression with stepwise parameter selection and ROC analyses.ResultsTwenty two HCC lesions (mean size 3.92.9cm, range 1.2-12.3cm) were assessed. Response at 6months was as follows: complete response (CR, n=6), partial response (PR, n=3), stable disease (SD, n=12) and progression (PD, n=1). vADC median/mode at 6w (1.81-1.82 vs. 1.29-1.35x10(-3)mm(2)/s) and vADC median/max (27-44% vs. 0-10%) were significantly higher in CR/PR vs. SD/PD (p=0.011-0.036), while there was no significant difference at baseline. Logistic regression identified vADC median at 6w as an independent predictor of response (CR/PR) with odds ratio (OR) of 3.304 (95% CI: 1.099-9.928, p=0.033) and AUC of 0.77. vADC mean was identified as an independent predictor of CR with OR of 4.153 (95%CI: 1.229-14.031, p=0.022) and AUC of 0.91.ConclusionDiffusion histogram parameters obtained at 6w and early changes in ADC from baseline are predictive of subsequent response of HCCs treated with RE, while pre-treatment vADC histogram parameters are not. These results need confirmation in a larger study.Trial registrationThis retrospective study was IRB-approved and the requirement for informed consent was waived.