Focal iron sparing mimicking liver lesion in post-transfusion iron overload: A case report

Abstract

Iron sparing, a rare imaging phenomenon in the context of hepatic iron overload, can mimic true liver lesions and pose significant diagnostic challenges-especially in oncologic patients with a history of frequent blood transfusions. We present the case of a 68-year-old woman with metastatic breast cancer and transfusion-dependent anemia who developed hepatic iron overload following multiple red blood cell transfusions. MRI showed a hyperintense lesion in segment 4b on a fat-suppressed Dixon sequence, raising initial concern for pathology. T2* mapping and chemical shift imaging revealed hepatic iron overload with relative sparing in segment 4, characterized by a marked signal drop on in-phase imaging and reduced T2* relaxation time in the surrounding liver parenchyma; the spared region itself showed a comparatively longer T2* time, consistent with focal iron sparing rather than a true lesion. Additionally, an aberrant right gastric vein supplying this region suggested altered perfusion as a possible underlying mechanism. This case underscores the importance of identifying focal iron sparing to prevent misdiagnosis and avoid unwarranted interventions.

Keywords: Case report; Focal iron sparing; Iron overload; Liver MRI; MRI pitfalls; Pseudolesion.

Fig. 1

Iodine contrast-enhanced computed tomography (CT) performed on Philips IQon spectral CT with (A) virtual noncontrast, (B) portal venous contrast phase, (C) Z-effective map visualizing effective atomic number, and (D) virtual mono-energetic CT at 40 keV accentuating iodine-enhanced structures.

Fig. 2

Focal iron sparing in segment 4 (*). (A) In phase and (B) opposed phase image showing signal drop on of the liver parenchyma in phase, while the lesion itself is showing relatively less signal drop. (C) T1 hyperintense lesion in fat-suppressed mDixon sequence. (D) mDixon Quant T2*-map demonstrating higher T2* relaxation time of the lesion compared to the residual liver parenchyma, indicating focal iron sparing.

Fig. 3

Dixon sequence in (A) arterial and (B) portal venous phase showing accessory perfusion of posterior segment 4 by an aberrant right gastric vein (arrows). (C) + (D) Different multiplanar reformations (MPRs) of the aberrant right gastric vein in a contrast-enhanced CT in portal venous phase (arrows). The vein originates from the lesser curvature of the stomach and directly supplies segment 4 of the liver. Note the different contrast enhancement between the aberrant venous vessel and the arterial vessels (ie, the celiac trunk and the common hepatic artery).