Multiplanar Reconstruction Improves Early Diagnosis of Occult Local Tumor Progression after Microwave Ablation for Hepatocellular Carcinoma

Objective To investigate early diagnosis feasibility and imaging manifestations of local tumour progression (LTP) after hepatocellular carcinoma (HCC) ablation. Methods Retrospective analysis of 62 HCC patients (78 nodules) treated with microwave ablation. Two radiologists independently reviewed conventional axial and multiplanar reconstruction (MPR) images using a double-blind method to analyse early LTP features and diagnostic efficacy. Results Postoperative LTP was diagnosed in 23/78 nodules. MPR significantly improved LTP detection sensitivity for both observers (0.65 vs. 0.96; P < 0.05). Inter-observer agreement was excellent. LTP lesions at ablation zone superior/inferior margins, in unfavorable locations, or showing arterial non-enhancement with portal/delayed phase washout and "cloud-like" morphology were more occult. Median time to clinical LTP diagnosis was 16 months. With MPR assistance, observers diagnosed LTP earlier (median 15 months). Conclusion Multiphasic CE-CT combined with MPR enables early diagnosis of LTP. This study describes the imaging characteristics of occult LTP lesions that are easily overlooked.