AASLD CRITERIA FOR HCC

Q.All are true regading AASLD criteria for diagnosis of HCC in cirrhosis except

a.use of multiphasic CT/MRI

b.arterial hyperattenuation of lesion

c.portal venous phase hypoattenation of thelesion

d.delayed phase hyperatenuation of the lesion

e.portal veous phase /delayed phase washout

ANS.---d

The radiologic diagnosis of hepatocellular carcinoma can be made at either CT or MR imaging, provided that a multiphasic contrast material–enhanced study is used.

Characteristically, hepatocellular carcinoma enhances during the arterial phase because of its blood supply from abnormal hepatic arteries. Contrast medium in the surrounding liver parenchyma is diluted during this phase because the parenchymal blood supply arises mostly from the portal veins, which are not yet opacified.

 In the portal venous phase, the surrounding liver parenchyma becomes relatively hyperattenuated and the lesion is perceived to be hypoattenuated because of its lack of portal venous supply. This appearance is the so-called washout effect. Occasionally, washout is evident only during a delayed phase sequence. 

Thus, a four-phase imaging study is required: non–contrast-enhanced phase, arterial phase, portal venous phase, and delayed phase

  Images should be acquired in four phases: non–contrast-enhanced phase (before the injection of contrast material), late arterial phase (about 20 seconds after the injection), portal venous phase (50 seconds after the injection), and delayed phase (>120 seconds after the injection). The optimal timing for image acquisition in the delayed phase is debated, varying between 2 and 15 minutes after contrast material injection. Contrast-enhanced US studies have shown that approximately 90% of hepatocellular carcinomas demonstrate washout by 5 minutes after injection of the microbubble contrast agent . Use of a 5-minute delay may be the practical choice for the timing of the delayed phase.

Precontrast and dynamic postcontrast T1-weighted three-dimensional fat-suppressed gradient-echo sequences are required, in addition to T2 (with and without fat saturation) and T1 in-phase and opposed-phase imaging. Timing of the dynamic contrast-enhanced sequences is the same as that used for the CT examination. Emphasis on precise breath-holding is extremely important.

Systematic review has shown that MR imaging is more sensitive than CT in the diagnosis of hepatocellular carcinoma (81% vs 68%)