Gadobutrol-enhanced MRI of the liver on a patient with hepatic hemangioma
Hemangiomas are common focal liver lesions, usually detected in the work up of asymptomatic patients.
MRI is the imaging method of choice to diagnose hemangiomas. On T1-w images, hemangiomas display low signal intensity and on T2-w, they are strikingly homogeneous, clearly demarcated from the adjacent parenchyma, with very high signal intensity, similar to cerebrospinal fluid (CSF), due to the long T2 relaxation time of its blood-filled vascular channels, a feature that has been coined as the bulb-light sign.
On diffusion MR images hemangiomas show increased signal intensity on high b value DWI because of the long T2 relaxation time rather than the restricted mobility of the water protons (T2 shine-through). On dynamic studies, hemangiomas exhibit early nodular peripheral enhancement (puddling), since its feeding vessels originate from the hepatic artery. Subsequent phases of liver enhancement reveal a progressive slow centripetal fill-in, with iso or even high signal intensity on delayed phases as compared to the normal liver parenchyma. This classical presentation is diagnostic with a high level of confidence.