AIM:To retrospectively analyze the imaging features of hepatic focal nodular hyperplasia(FNH) in children on dynamic contrast-enhanced multi-slice computed tomography(MSCT) and computed tomography angiography(CTA) images.METHODS:From September 1999 to April 2012,a total of 218 cases of hepatic FNH were confirmed by either surgical resection or biopsy in the Sun Yat-sen Memorial Hospital of Sun Yat-sen University and the Cancer center of Sun Yat-sen University,including 12 cases(5.5%) of FNH in children(age ≤ 18 years old).All the 12 pediatric patients underwent MSCT.We retrospectively analyzed the imaging features of FNH lesions,including the number,location,size,margin,density of FNH demonstrated on pre-contrast and contrastenhanced computed tomography(CT) scanning,central scar,fibrous septa,pseudocapsule,the morphology of the feeding arteries and the presence of draining vessels(portal vein or hepatic vein).RESULTS:All the 12 pediatric cases of FNH had solitary lesion.The maximum diameter of the lesions was 4.0-12.9 cm,with an average diameter of 5.5 ± 2.5 cm.The majority of the FNH lesions(10/12,83.3%) had well-defined margins.Central scar(10/12,83.3%) and fibrous septa(11/12,91.7%) were commonly found in children with FNH.Central scar was either isodense(n = 7) or hypodense(n = 3) on pre-contrast CT images and showed progressive enhancement in 8 cases in the equilibrium phase.Fibrous septa were linear hypodense areas in the arterial phase and isodense in the portal and equilibrium phases.Pseudocapsule was very rare(1/12,8.3%) in pediatric FNH.With the exception of central scars and fibrous septa within the lesions,all 12 cases of pediatric FNH were homogenously enhanced on the contrast-enhanced CT images,significantly hyperdense in the arterial phase(12/12,100.0%),and isodense in the portal venous phase(7/12,58.3%) and equilibrium phase(11/12,91.7%).Central feeding arteries inside the tumors were observed on CTA images for all 12 cases of FNH,whereas no neovascularization of malignant tumors was noted.In 9 cases(75.0%),there was a spoke-wheel shaped centrifugal blood supply inside the tumors.The draining hepatic vein was detected in 8 cases of pediatric FNH.However,the draining vessels in the other 4 cases could not be detected.No associated hepatic adenoma or hemangioma was observed in the livers of the 12 pediatric cases.CONCLUSION:The characteristic imaging appearances of MSCT and CTA may reflect the pathological and hemodynamic features of pediatric FNH.Dynamic multi-phase MSCT and CTA imaging is an effective method for diagnosing FNH in children. AIM: To retrospectively analyze the imaging features of hepatic focal nodular hyperplasia (FNH) in children on dynamic contrast-enhanced multi-slice computed tomography (MSCT) and computed tomography angiography (CTA) images. METHODS: From September 1999 to April 2012, a total of 218 cases of hepatic FNH were confirmed by either surgical resection or biopsy in the Sun Yat-sen Memorial Hospital of Sun Yat-sen University and the Cancer center of Sun Yat-sen University, including 12 cases (5.5%) of FNH in children (age ≤ 18 years old) .All the 12 pediatric patients underwent MSCT.We retrospectively analyzed the imaging features of FNH lesions, including the number, location, size, margin, density of FNH demonstrated on pre-contrast and contrashanced computed tomography ( CT) scanning, central scar, fibrous septa, pseudocapsule, the morphology of the feeding arteries and the presence of draining vessels (portal vein or hepatic vein) .RESULTS: All the 12 pediatric cases of FNH had solitary lesion.The maximum d iameter of the lesions was 4.0-12.9 cm with an average diameter of 5.5 ± 2.5 cm. The majority of the FNH lesions (10/12, 83.3%) had well-defined margins. Central scar (10/12, 83.3%) and fibrous septa (11 / 12,91.7%) were commonly found in children with FNH.Central scar was either isodense (n = 7) or hypodense (n = 3) on pre-contrast CT images and showed progressive enhancement in 8 cases in the equilibrium phase. Fibrous septa were linear hypodense areas in the arterial phase and isodense in the portal and equilibrium phases. Pseudocapsule was very rare (1/12, 8.3%) in pediatric FNH.With the exception of central scars and fibrous septa within the lesions, all 12 cases of pediatric FNH were homogenously enhanced on the contrast-enhanced CT images, significantly hyperdense in the arterial phase (12/12, 100.0%), and isodense in the portal venous phase (7 / 12,58.3%) and equilibrium phase (11/12, 91.7%). Central feeding arteries inside the tumors were observed on CTA images for all 12 cases of FNH, an no neova scularization of malignant tumors was noted. In nine cases (75.0%), there was a spoke-wheel shaped centrifugal blood supply inside the tumors. The draining hepatic vein was detected in 8 cases of pediatric FNH. However, the draining vessels in the other 4 cases could not be detected. No associated hepatic adenoma or hemangioma was observed in the livers of the 12 pediatric cases. CONCLUSION: The characteristic imaging appearances of MSCT and CTA may reflect the pathological and hemodynamic features of pediatric FNH. Dynamic multi-phase MSCT and CTA imaging is an effective method for diagnosing FNH in children.