Comparison between subtraction and dynamic MRI in assessing treatment response following radiofrequency ablation in patients with hepatocellular carcinoma

Abstract

Background Hepatocellular carcinoma (HCC) is one of the most prevalent cancers worldwide, and if left untreated, one of the most lethal. Ablative therapies including radiofrequency ablation (RFA) play increasingly important role for patients with liver tumors who are not surgical candidates. Monitoring treatment response following ablation is crucial in oncologic imaging. Dynamic contrast-enhanced MRI can assess changes in tumor vascularity and perfusion while subtraction imaging is useful in differentiating residual tumor from post-ablation parenchymal changes. The aim of this study is to compare the role of subtraction MRI and conventional dynamic MRI in assessing treatment response following RFA in patients with HCC. Results The study included 48 patients with 62 HCC lesions who underwent RFA from May to October 2020, followed by MRI evaluation with 1-month interval. Two readers with experience in hepatic imaging interpreted the dynamic and subtraction dynamic MRI. The hepatic focal lesions were classified into “well-ablated” and “residual” groups according to MRI findings, and the agreement between the two readers was evaluated. Using dynamic MRI, the first reader reported 38 well-ablated lesions, and the second reader agreed in 34 of them (89.5%). Residual disease was reported by the first reader in 22 lesions and the second reader disagreed in 10 of them (45.5%) where complete ablation was reported. Thirty-eight out 44 well-ablated lesions (86.4%) showed high signal intensity on non-enhanced T1 images, and 28 lesion (63.6%) showed intermediate T2 signal. All the mis-matched readings occurred in lesions with a high signal intensity in pre-contrast T1 images. Moderate agreement between the two readers was found with Kappa value of 0.467. Significant additive value of subtraction technique to dynamic MRI was detected with a P value of 0.009. No major complications recorded except for a single case of major portal vein branch occlusion. Conclusion MRI is a powerful imaging tool in assessing tumor viability and complications after RFA in patients with HCC. Dynamic MRI study is the gold standard in detecting recurrent lesions while subtraction technique is crucial in differentiating between arterial enhancement due to residual disease and normal hyperintense T1 signal of the ablation zone.

Magnetic Fields and Cancer: Epidemiology, Cellular Biology, and Theranostics

“…Primary liver cancer is the second most common cause of cancer mortality worldwide and the sixth most common cancer overall [398]. MRI is superior to CT in sensitivity, specificity, and accuracy [399] and can be used to determine the differential diagnosis [400][401][402], variant analysis [403], arterial phase hyperenhancement [404], small precursor and recurrent lesions [405,406], liver perfusion [407], histological grade, microvascular invasion status, local and systemic therapeutic responses, prognosis [408,409], and as a preoperative marker [410] in hepatocellular carcinoma patients. PET/MRI imaging is also used for the diagnosis of patients with hepatocellular carcinoma [411][412][413], whereas multi-phasic MRI staging was found to be more accurate than the straight hepatocellular carcinomagrading approach [414].…”

“…DCE-MRI is used in the prediction of staging B or C hepatocellular carcinoma [415] and for the quantification of perfusion metrics [420] with a superior modal-ity for diagnosis compared with dynamic contrast-enhanced CT-scan [421]. DWI-MRI is the gold standard in detecting recurrent lesions [405], monitoring response to therapy, predicting response, assessing prognosis, and distinguishing tumor recurrence from the treatment effect [422]; however, DWI adds little value to MRI in target delineation [423].…”