engleski

Incidence of atypical hepatic hemangioma on MRI

The aim of our work was to evaluate the incidence of atypical presentation of hepatic hemangioma based on T2-weighted signal features and vascular features. Hemangiomas are the most common benign tumors of the liver with an autopsy incidence between 0, 4 and 20%. The female-to-male ratio varies from 2:1 to 5:1. In typical cases (high signal intensity on T2-weigthed spin-echo sequences, which is identical to that of cerebrospinal fluid (CFS)), and typical vascular enhancement on dynamic gadolinium-enhanced T1-weighted gradient-echo sequences (peripheral nodular enhancement in arterial phase slowly progressing centripetally to complete or nearly complete fill-in of the entire lesion by 10 min) the sensitivity and specificity of MRI is 98% and the accuracy is 99%. Hemangiomas may show T2 signal intensity that is not as bright as CFS and may not present previously described characteristic vascular pattern. Haemorrhage, thrombosis, extensive hyalinization, liquefaction, fibrosis and relative composition of vascular spaces and connective tissue in the lesion cause the change of signal intensity on T2-weighted images. Vascular characteristics and follow – up may help in diagnosis but sometimes biopsy or even surgery can not be avoided. The presence of the “ bright-dot-sign” - tiny enhancing dots in the lesion is helpful in diagnosis of this type of heamagioma. Differentiation of hypervascular hemangioma from other hypervascular tumors is difficult. Persistence of enhancement on delayed-phase images suggests diagnosis of hemangioma but in most cases especially when T2 signal intensity is not typical close follow-up is recommended. 287 patients underwent abdominal MRI between December 2007 and January 2009. 1.5 T MR scanner was used (Magnetom Avanto, Siemens, Erlangen, Germany) using standard protocol for abdominal imaging. In 37 patients (16 men and 21 women ; age 25-75 years ; mean age 50.6 years) hepatic hemangiomas were diagnosed. Only 5 patients with diagnosis of hepatic hemangioma had primary malignant disease. Other patients had either benign disease or the lesions were accidental finding during ultrasound or computed tomography examination. T2-weighted signal features of hemangiomas were analyzed on turbo spin echo sequence (HASTE) with and without fat suppression. Vascular features were analyzed on multiphasic gadolinium-enhanced T1-weighted gradient echo 3-dimensional (3D), fat-suppressed breath-hold sequence (VIBE). 37 patients had 74 hemangiomas. 18 patients (48%) had two or more lesions. One patient had 10 lesions. 59 hemangiomas (79.7%) showed typical T2 weighted signal features (identical to cerebrospinal fluid), while 15 (20.3%) had atypical T2 presentation. 50 (67.5 %) hemangiomas showed most common and typical vascular features, peripheral nodular enhancement with slow centripetal progression with complete or nearly complete fill-in. Six hemangiomas (8.1%) demonstrated the „ bright-dot sign“ . All of them had typical T2 weighted signal features. 18 (24.3%) showed rapid filling of the entire lesion – hypervascular hemangiomas. All hypervascular hemangiomas were small tumors from 5x5 mm, to 20x21 mm in diameter. 11 (14.8%) hypervascular hemangiomas showed atypical T2-weighted signal features. Only 3 hemangiomas with atypical T2 – weighted signal features showed typical vascular features. Those atypical cases we followed-up from 9 months to one or more years. Some of them were followed-up before MRI with ultrasound or CT. All patients with primary malignant disease had typical presentation of hepatic hemangioma. T2-weighted signal intensity and vascular features usually enable accurate diagnosis of hepatic hemangioma. Differential diagnosis is rather complicated in atypical cases that are not so rare (14.8 % in our study). Follow-up confirmed benign nature of the lesions. Small size and persistence of enhancement during the late phases permit us diagnosis of hemangioma in the cases of hypervascular lesions.

hepatic hemangioma; atypical hemangioma; incidence; MRI

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