Research on focal nodular hyperplasia with MSCT and postprocessing

ACG clinical guideline: the diagnosis and management of focal liver lesions

Focal liver lesions (FLL) have been a common reason for consultation faced by gastroenterologists and hepatologists. The increasing and widespread use of imaging studies has led to an increase in detection of incidental FLL. It is important to consider not only malignant liver lesions, but also benign solid and cystic liver lesions such as hemangioma, focal nodular hyperplasia, hepatocellular adenoma, and hepatic cysts, in the differential diagnosis. In this ACG practice guideline, the authors provide an evidence-based approach to the diagnosis and management of FLL.

Hepatic focal nodular hyperplasia in children: Imaging features on multi-slice computed tomography

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 contrast-enhanced 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.

Biologic and clinical features of benign solid and cystic lesions of the liver

The widespread use of imaging analyses, either routinely or to evaluate symptomatic patients, has increased the detection of liver lesions (tumors and cysts) in otherwise healthy individuals. Although some of these incidentally discovered masses are malignant, most are benign and must be included in the differential diagnosis. The management of benign hepatic tumors ranges from conservative to aggressive, depending on the nature of the lesions. New imaging modalities, increased experience of radiologists, improved definition of radiologic characteristics, and a better understanding of the clinical features of these lesions have increased the accuracy of diagnoses and reduced the need for invasive diagnostic tests. These advances have led to constant adjustments in management approaches to benign hepatic lesions. We review the biologic and clinical features of some common hepatic lesions, to guide diagnosis and management strategies.

Dual-phase computed tomographic angiography of focal nodular hyperplasia: defining predictable postcontrast attenuation levels relative to aorta and inferior vena cava

PURPOSE

To test the clinical observation that the postcontrast attenuation level of focal nodular hyperplasia (FNH) at dual-phase computed tomography (CT) rarely exceeds 50% of aortic enhancement or absolute inferior vena cava (IVC) enhancement.

MATERIALS AND METHODS

Nineteen pathologically proven FNHs in 17 female patients imaged with intravenous contrast-enhanced multidetector CT, of which 15 had arterial and venous phase acquisitions, were evaluated. Two radiologists retrospectively reviewed each CT study in consensus, using axial sections, multiplanar reconstructions, and 3-dimensional rendering techniques (volume rendering and maximum intensity projection). Recorded were precontrast and postcontrast attenuation of mass, the liver, the aorta, and the IVC; lesion size; segmental location; subjective appearance; contour; and presence of central scar, pseudocapsule, septations, feeding artery, or draining vein.

RESULTS

The mean FNH attenuation level was lower than 50% of the mean aortic attenuation during the arterial phase (115 vs 144 Hounsfield units) and also lower than the mean IVC attenuation in the portal venous phase (142 vs 153 Hounsfield units). Across cases, the FNH arterial phase attenuation was lower than 50% of the aortic attenuation in 74% (14/19). The portal venous attenuation level of FNH was lower than or equal to that of the IVC in 80% (12/15). One of the 2 enhancement patterns was present in 100% (15/15) of cases. Other common findings included feeding artery and draining vein (18/19), absence of pseudocapsule (18/19), and smooth contour (13/19). A central scar was identified in only 8 of 19 cases, and no lesion contained septations.

CONCLUSIONS

In this series of patients imaged with contrast-enhanced multidetector CT, most FNHs demonstrated arterial attenuation levels lower than 50% of the aorta and/or portal venous attenuation levels lower than or equal to those of the IVC.