E-ISSN 1305-3612
Abdominal Imaging - Original Article
Focal hypersteatosis: A Pseudolesion in patients with liver steatosis
1 Liver Imaging Team, Department of Radiology, Hacettepe University School of Medicine, Ankara, Turkey  
Diagn Interv Radiol ; : -

Abstract

Purpose: We aimed to describe US, CT and MRI findings of focal hypersteatosis(FHS).

 

Methods: We retrospectively reviewed our database for patients with hypersteatosis.  Over a 5-year period (February 2005 to September 2010)  an  overall 17321 patients underwent abdominal CT scan and final group consisted of 28 patients with focal hypersteatosis. All patients had US, CT and MRI studies. Size, area and density measurements were performed on CT images. Fat signal percentage (FSP) was measured on T1-weighted in and out-of phase gradient-echo images. FHS is defined based on MRI findings as area of more signal drop on out-of phase images compared to rest of the fatty liver.

 

Results: The period prevelance of focal hypersteatosis was measured 0.16 % over the 5-year period. Cancer was the most common diagnosis (22/28 patients,78.5%) and breast (32.1%,)and colorectal (25%) cancers were predominating.  FHS was seen in segment 4(n:26,92.8%), segment 8 (n:1,3.6%) and segment 3 (n:1,3.6%).  Shape was nodular in 21(75%) patients,  triangular or amorphous in the remaining 7(25%) patients.  FHS was hyperechoic and isoechoic in 5 (17.9%) and 23 (82.1%) patients, respectively. FHS was hypodense on CT of all patients relative to fatty liver. On MRI the FHS was hyperintense on T1-weighted in phase images in 17 (60.7%) patients. Median liver parenchymal FSP was 21.5% (range:10%-41.4%) and median FSP of hypersteatotic area was 32.5% (range:19%-45%).

 

Conclusion: Focal hypersteatosis is a pseudolesion that can be observed in patients with liver steatosis. It appears hypodense on CT and mostly isoechoic on US relative to fatty liver. It may mimic metastasis in cancer patients with steatosis, due to nodular shape and atypical location. MRI should be used for correct diagnosis,  in patients with equivocal findings on CT to avoid biopsy.

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