Fat-containing liver lesions expanding the magnetic resonance imaging signature of hepatoblastoma

BACKGROUND: Fat-containing liver lesions have been widely discussed in the radiology literature and include various benign and malignant lesions. However, data on the presence and imaging characteristics of intralesional fat in hepatoblastoma remain limited. OBJECTIVE: To investigate the presence of intralesional fat in hepatoblastoma using dual-echo magnetic resonance imaging (MRI) and to correlate imaging findings with histopathology. MATERIALS AND METHODS: This retrospective study included 22 pediatric patients with hepatoblastoma who underwent pretreatment MRI with a dual-echo gradient-recalled echo sequence. Qualitative visual assessment and semiquantitative analysis using region-of-interest (ROI) measurement were performed to evaluate intralesional fat. Histopathology was accepted as the reference standard for fat detection. RESULTS: Twenty-two patients (8 girls, 14 boys; median age, 11.5 months; range, 3-192 months) with pretreatment dual-echo MRI were included. Histopathologic evaluation demonstrated intratumoral fat in 10 of 22 tumors (45%). On MRI, intralesional fat was detected in eight lesions. Six lesions showed both histopathologic fat and signal loss on dual-echo MRI, whereas four lesions had histopathologic fat without detectable signal loss (< 1%). Two lesions demonstrated signal loss on MRI despite the absence of histopathologic fat. Using histopathology as the reference standard, MRI demonstrated a sensitivity of 60% and a specificity of 83.3% with an overall accuracy of 72.7% for detecting intratumoral fat in hepatoblastoma. Interobserver agreement for the four-level visual fat score was substantial (weighted Cohen's κ=0.789). CONCLUSION: Intralesional fat can be present in hepatoblastoma and may be detected on MRI, expanding the recognized imaging features of this tumor.