ISSN 1305-3825 | E-ISSN 1305-3612
Abdominal Imaging - Original Article
Focal sparing of iron and fat in liver tissue in patients with hemosiderosis: diagnosis with combination of R2* relaxometry and proton density fat fraction calculation by MRI
1 Department of Radiology, Hacettepe University School of Medicine, Ankara, Turkey  
2 GE Healthcare MRI, Istanbul, Turkey  
Diagn Interv Radiol 2011; 17: 323-327
DOI: 10.4261/1305-3825.DIR.4134-10.1
Key Words: liver • magnetic resonance imaging • iron overload• hemosiderosis
Abstract

PURPOSE
To demonstrate magnetic resonance imaging (MRI) findings of the focal sparing of iron and fat in liver tissue in patients with hepatic iron overload.

 

MATERIALS AND METHODS
We retrospectively reviewed 48 liver MRIs performed in patients with hemosiderosis from 2007–2009. We selected five (10%) of these patients based on the observation of focal signal abnormalities in the posterior aspect of segment 4, anterior to the portal vein, on in- and out-of-phase T1-weighted gradient-echo images. To further characterize this signal abnormality in segment 4, we calculated the simultaneous proton density fat fraction and R2* relaxometry using the investigational version of a quantitative chemical shift-based water-fat separation method known as IDEAL-IQ with a multiecho gradient echo sequence. Visual assessment and objective measurements were performed for the focal sparing of iron and fat.

 

RESULTS
The diagnoses of the five patients included thalassemia (n=3), aplastic anemia (n=1), and myelodosysplastic syndrome (n=1). The focal sparing of iron was hypointense on R2* relaxometry compared to the rest of the liver. Fat fraction images failed to demonstrate a heterogeneous fat distribution. The focal sparing of fat in the liver with iron overload appeared as a reduced fat-containing area (fat fraction, 4%) in segment 4 compared to the remainder of the left lobe (fat fraction, 12%). The R2* map revealed no difference between the focal fat-sparing area and the rest of the liver. Areas in which focal fat and iron sparing occurred were not visible on post-contrast and diffusion-weighted images.

 

CONCLUSION
Focal fat and iron sparing in patients with liver siderosis can mimic a lesion. Quantitative MRI techniques can help to characterize abnormal signal changes in segment 4 of the liver in patients with hepatic iron overload and can eliminate the need for biopsy of pseudolesions.

Key Words
Authors
All
Author's Corner
Reviewer's Corner
Survey
Copyright © Turkish Society of Radiology | Latest Update: 01.11.2017