PMC4899674_01
FNH in a 27-year old female with a history of oral contraceptive pill use. (A) Precontrast T1WI shows an isointense mass with a hypointense central scar (arrowhead) in segment 5 of the liver. (B) Following intravenous administration of gadobenate dimeglumine, a late arterial phase T1WI shows an avidly enhancing lobular mass (arrow) with a nonenhancing central scar (arrowhead). Note the hypovascular fibrous septa radiating from the scar. (C) Five-minute-delayed T1WI shows that the mass is isointense, with the liver parenchyma and the central scar enhancing. (D) A T2WI view with fat saturation shows the isointense mass and hyperintense central scar (arrowhead).
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T1-weighted imaging, iso-intense to mildly hyperintense on T2-weighted imaging, and iso-intense on delayed postcontrast sequences. The central scar was hyperintense on T2-weighted imaging and demonstrated delayed enhancement (Fig. 1).
Near-complete regression of FNH in a 31-year-old female with a history of oral contraceptive use; images taken 48 months after Fig. 1. (A) Precontrast T1WI shows that the segment 5 mass has significantly decreased in size (arrow). (B) Following intravenous administration of gadobenate dimeglumine, a late-arterial-phase T1WI shows no significant enhancement in the expected location of the mass. (C) Three-minute-delayed postcontrast T1WI shows a small focus of enhancement (arrow), residuum of the previously seen FNH.
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OCP use was no longer documented in the patient's chart, she underwent MRI of the abdomen with and without contrast. On this followup study, the FNH lesion in the inferior right lobe of the liver had significantly regressed, measuring 0.6 x 0.8 cm in its largest dimensions (Fig. 2).
PMC4899674_02
FNH in a 46-year-old female with Cowden syndrome and a history of hormone replacement therapy. (A) Precontrast T1WI shows a 6.5-x-4.4cm mass that is isointense to the liver parenchyma in segment 2 of the liver (arrow). (B) Following intravenous administration of gadodiamide, the mass avidly enhances in the late arterial phase T1WI. The fibrous central scar is nonenhancing (arrowhead). (C) On a five-minute-delayed T1WI, the central scar enhances. Note that the left hepatic vein is displaced by the mass, mimicking rim enhancement. (D) On T2WI, the central scar within this FNH lesion lacks typical hyperintensity.
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Hemangiomas and cysts were also observed in the liver (Fig. 3).
A 53-year-old female with Cowden's syndrome whose FNH lesion (arrow) has regressed. An enhanced CT image taken 90 months after Figure 3 shows marked involution of the mass in segment 2 of the liver. The mass measures 2.1 x 1.9 cm.
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The previously observed FNH within the left lobe of the liver had regressed to 2.1 x 1.9 cm (Fig. 4).