Enhancement pattern and appearance of hepatocellular carcinoma through triple-phase MDCT

Abstract

Introduction : Hepatocellular carcinoma (HCC) is the most common cancer in Southeast Asia. It was the first cause of death in cancer patient in Thailand. Over the decade Multidetector computed tomography (MDCT) had been used in clinical practices.This technique allows three to seven times faster scan of the liver than single detector helical CT scanner, so uniform hepatic enhancement can be achieved during hepatic arterial and portal venous phases. There are few authors who study HCC characteristics while others focus on the improvement of lesion conspicuity using multiple phase scans.

Objective : To describe enhancement patterns, appearance of HCC using triple¬ phase MDCT and association between HCC appearance and tumor size.

Setting : Bangkok Metropolitan Administration General Hospital.

Research design : A retrospective descriptive study.

Patients : Thirty-five patients with HCC whose triple phase MDCT study was available between June 2007 and February 2009 at BMA General Hospital.

Methods : The triple-phase MDCT imaging (nonenhanced or NECT, hepatic arterial or HAP and portal venous phases or PVP) and clinical data of 35 patients with 58 HCC were reviewed in the aspects of HCC enhancement pattern and appearance. The diagnosis of HCC was confirmed by pathological results in 20 cases, by high level of serum alpha-fetoprotein and characteristic angiographic findings in 15 cases.

Results : Most frequent enhancement pattern of HCC was heterogeneous hyperattenuation on HAP and became heterogeneous hypoattenuation on PVP (47%). Almost all tumors revealed contrast washout on PVP (93%). Seventy-two percent of HCC had hypervascular component. Ninety-five percent of HCC were isoattenuation or hypoattenuation on NECT. Abnormal internal vessels were found in 31%>. Venous invasion, tumor capsule and calcification were evidenced in 26%>, 24%> and 2%, respectively. Abnormal internal vessels and heterogeneous appearance of HCC were more common in large tumor size ( p = 0.007, p = 0.001, respectively). No association between contrast washout on PVP and tumor size.

Conclusion : The most frequent enhancement pattern of HCC using triple-phase MDCT is heterogeneous hyperattenuation on HAP and heterogeneous hypoattenuation on PVP, the same findings as found on single detector helical CT scanner apart from increased incidence of hypervascular HCC, contrast washout on PVP and abnormal internal vessels. There are statistical associations between abnormal internal vessels, heterogeneous appearance of HCC and the tumor size.