Focal nodular hyperplasia: New findings at Doppler ultrasonography

OBJECTIVE: The aim of our study was to explore the features of focal nodular hyperplasia (FNH) at Doppler ultrasonography, analyzing specifically the presence of intratumoral venous flow in patients with an established diagnosis of FNH. Previous studies showed that using a venous Doppler spectrum, intratumoral vessels are often depicted in hepatocellular adenoma (HCA) but less frequently in FNH. PATIENTS AND METHODS: Forty-five FNHs from thirty-three consecutive patients (26 female, 7 male; mean±SD age: 40±13) underwent color Doppler ultrasonography and spectral analysis according to a standardized protocol. FNH diagnosis was established by the presence of typical behavior at contrast-enhanced ultrasound (CEUS) associated with another imaging technique (contrast-enhanced computed tomography [ceCT] or contrast-enhanced magnetic resonance [ceMR]). A biopsy was performed when imaging was inconclusive. All data concerning Doppler analysis were reviewed by two more operators, blinded to the final diagnosis, and the interobserver agreement for the presence of venous Doppler signal was determined by Cohen’s Kappa. RESULTS: Of the 33 patients, 24 had a single solitary focus, and 9 had multiple foci. Lesion diameter ranged between 1.2 and 8.9 cm (mean ± SD 3.2±1.6 cm). The central feeding artery with the typical arterial spectrum was detected in all 45 lesions, whereas the spoke-wheel sign was observed in 18 cases (40%). A venous Doppler signal was detected in 35 FNHs (77.8%), and in 60% of them, it was identified in the center of the lesion. CONCLUSIONS: Venous Doppler signal located in the center of the lesion suspected to be a hypervascular benign lesion cannot be considered a typical HCA feature since it has been detected in a high percentage of FNH cases.