Disminución paradójica de la señal tras administrar contraste en las lesiones hepaticas hiperintensas en resonancia magnética: un criterio de hemorragia intratumoral

Paradoxical lesions that do not show relevant contrast uptake go from being hyperintense on precontrast images to hypointense in the arterial and portal phases after the administration of contrast. The increase in signal intensity in the liver parenchyma and the decrease in the signal of fat in gadolinium-enhanced out-of-phase T1- weighted gradient-echo images causes the dynamic range of the gray scale to narrow and lesions that were previously hyperintense with respect to the liver parenchyma become hypointense. The fact that liver lesions with hemorrhagic necrosis are clearly avascular intensifies this paradoxical phenomenon. The analyses of the uptake using the percentage of signal variation between the pre- and postcontrast images and between the arterial and portal phases have proven to be very useful for characterizing these lesions with hemorrhagic necrosis.