Objective: The purpose was to examine whether MR and CT imaging can detect extracapsular invasion of hepatocellular carcinoma (HCC) and, if this is possible, to determine its characteristic signs on MR and CT images.
Materials and methods: Thirty-eight patients with small HCC (< or = 3.0 cm in diameter) were studied to correlate the findings in surgically resected specimens with the findings on MR and CT images.
Results: Ten of 38 patients had histologically proven extracapsular invasion of HCC. Of these 10 patients with extracapsular invasion, partial projections of the tumor into the surrounding area or satellite nodules in the immediate vicinity of the tumor were observed in 9 patients on T1-weighted images and in 5 patients on postcontrast CT images. Partial tumor projection or satellite nodules were not observed in patients without extracapsular invasion of HCC. The detection rate for these characteristic signs was 90% on MR and 50% on CT.
Conclusion: Magnetic resonance and CT imaging were useful for detection of extracapsular invasion of HCC. The characteristic signs for extracapsular invasion of HCC were partial tumor projection into the surrounding area and satellite nodules in the immediate vicinity of the tumor.