Rationale and Objectives
The purpose of this article is to review the spectrum of computed tomography (CT) and magnetic resonance imaging (MRI) findings of fat containing hepatocellular carcinoma (HCC), including serial contrast–enhanced imaging.
Materials and Methods
Imaging findings of 10 fat-containing HCCs on CT ( n = 2) or MRI ( n = 3) or on both CT and MRI ( n = 5) were retrospectively reviewed in 9 patients. Both techniques included serial contrast enhanced imaging in arterial, portal venous, and late venous phases.
Results
On non-contrast CT, fat containing HCC was either homogenously hypodense ( n = 6) or of mixed density (n = 1). The density values ranged between −11 and 9 HU. On MRI, homogenous ( n = 4) or heterogenous ( n = 4) signal loss was observed on T1-weighted out-of-phase images as compared to in-phase images. Enhancement patterns on serial contrast–enhanced CT and MRI included: arterial enhancement indistinguishable from the liver with venous wash out ( n = 2), arterial capillary blush with venous phase fading ( n = 2), and heterogenous arterial enhancement with unenhanced foci and venous phase wash out of enhancements. Larger lesions had late capsular enhancement.
Conclusions
Fat containing HCC has spectrum of imaging findings on CT and MRI. MRI with chemical shift technique depicts the fat content. Arterial contrast enhancement with venous washout or fading may help for the diagnosis of HCC in inconclusive cases.
Hepatocellular carcinoma (HCC) may rarely contain fat. Histopathologic features and imaging findings of fat containing HCC have been investigated . Fat content may be the initial finding of HCC during its early development from small hepatocellular regenerative and dysplastic nodules; therefore, its diagnosis and differentiation from other fat containing liver lesions is important . Imaging findings of fat containing HCC have been described on computed tomography (CT), ultrasound, and chemical shift magnetic resonance imaging (MRI) ( ). The latter technique was shown to depict the fat content of HCC not recognized on CT images. Presently, patients are screened for focal liver lesions with the serial contrast–enhanced techniques that comprise arterial, portal venous, and equilibrium phases in both in MRI and CT .
In this report, we retrospectively review spectrum of imaging findings of fat containing HCC on CT and MRI with the use of current imaging techniques that include multiphase contrast-enhanced imaging of the liver.
Materials and methods
Patients
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Imaging
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Image Analysis
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Results
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![Figure 1, A 54-year-old patient with fat containing hepatocellular cancer demonstrated on magnetic resonance imaging. On T1-weighted in-phase spoiled gradient echo (SGE) (repetition time [TR]/echo time [TE]/flip angle [FA]; 145/4.3/70) (a) , the lesion is isointense with the liver and cannot be demonstrated. A T1-weighted SGE (TR/TE/FA; 145/2.1/70) out-of-phase image (b) reveals homogenous signal loss of the lesion (arrow) ; on arterial phase image (SGE, TR/TE/FA; 145/2.1/70) (c) , the lesion enhances more than the background liver (arrow) and contrast washes out during portal venous phase (arrow) (d) .](https://storage.googleapis.com/dl.dentistrykey.com/clinical/FatContainingHCC/0_1s20S1076633209001408.jpg)
![Figure 2, Computed tomography (CT) and magnetic resonance imaging (MRI) of fat containing hepatocellular cancer in the posterior segment of the right liver lobe in a 65-year-old male. On arterial phase CT, the lesion reveals partial enhancement (long arrow) with skip areas of enhancement (short arrow) (a) ; on portal venous phase (b) , the enhancement washes out (long arrow) and skip areas of enhancement (short arrow) remain. On MRI, the lesion is mixed hyperintense (arrow) and isointense on T1-weighted in-phase spoiled gradient (SGE) (repetition time [TR]/echo time [TE]/flip angle [FA]; 145/4.3/70) (c) ; in-phase hyperintense signal areas, loose signal on T1-weighted out-of-phase image (TR/TE/FA; 145/2.1/70) (arrow) is consistent with the fat content (d) .](https://storage.googleapis.com/dl.dentistrykey.com/clinical/FatContainingHCC/1_1s20S1076633209001408.jpg)
![Figure 3, A 62-year-old female with small fat containing hepatocellular cancer in the anterior segment of the right liver lobe demonstrated on magnetic resonance imaging. On T1-weighted in-phase spoiled gradient echo (SGE) (repetition time [TR]/echo time [TE]/flip angle [FA]; 145/4.3/70) (a) , the lesion is slightly hyperintense (arrow) . A T1-weighted SGE (TR/TE/FA; 145/2.1/70) out-of-phase image (b) reveals homogenous signal loss of the lesion (arrow) ; on arterial phase image (fat-saturated SGE, TR/TE/FA; 145/4.3/70) (c) , the lesion becomes indistinguishable from the background liver (arrow) and contrast washes out during portal venous phase (arrow) (d) .](https://storage.googleapis.com/dl.dentistrykey.com/clinical/FatContainingHCC/2_1s20S1076633209001408.jpg)
Table 1
Spectrum of Imaging Findings of Fat Containing Hepatocellular Cancer
Lesions CT Findings MRI Findings Enhancement Size Lesion 1 Homogenously hypodense (3 HU) Uniformly iso/hyperintense I/P ∗ homogenous signal loss O/P ∗∗ on T1, isointense on T2 Arterial enhancement indistinguishable from liver parenchyma with venous phase washout 1,4 cm Lesion 2 Homogenously hypodense (4 HU) Uniformly iso/hyperintense I/P homogenous signal loss O/P on T1, mildly hyperintense on T2 Arterial capillary blush that fades during venous phase 1,6 cm Lesion 3 Homogenously hypodense (8 HU) Uniformly iso/hyperintense I/P+ homogenous signal loss O/P on T1, isointense on T2 Heterogeneous arterial enhancement with unnenhanced foci and venous phase contrast washout of arterial enhancements 1,5 cm Lesion 4 Mixed hypo-isodense (lowest-11 HU) Heterogeneously mixed signal I/P, hetrogenous signal loss O/P, mildly hyperintense on T2 Heterogeneous arterial enhancement with unnenhanced foci and venous phase contrast washout of arterial enhancements and late capsular enhancement 12 cm Lesion 5 Homogenously hypodense (9 HU) Uniformly iso/hyperintense I/P homogenous signal loss O/P on T1, isointense on T2 Arterial capillary blush that fades during venous phase 1,6 cm Lesion 6 Homogenously hypodense (6 HU) Arterial enhancement indistinguishable from liver parenchyma with venous phase washout 1,2 cm Lesion 7 Heterogeneously mixed signal I/P, heterogenous signal loss O/P, mildly hyperintense on T2 Heterogeneous arterial enhancement with unnenhanced foci and venous phase contrast washout of arterial enhancements and late capsular enhancement 2,4 cm Lesion 8 Heterogeneously mixed signal I/P, hetrogenous signal loss O/P, mildly hyperintense on T2 Heterogeneous arterial enhancement with unnenhanced foci and venous phase contrast washout of arterial enhancements 2,6 cm Lesion 9 Heterogeneously mixed signal I/P, hetrogenous signal loss O/P, mildly hyperintense on T2 Heterogeneous arterial enhancement with unnenhanced foci and venous phase contrast washout of arterial enhantments 2,1 cm Lesion 10 Homogenously hypodense (6 HU) Heterogeneous arterial enhancement with unnenhanced foci and venous phase contrast washout of arterial enhancements and late capsular enhancement 2,4 cm
I/P ∗ , in phase; O/P ∗∗ , out of phase.
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Discussion
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