Imaging studies of primary hepatic cancer

Niloofar Mirzaei,1,* Mohammad hossein jamshidi,2

1. Department of Radiologic Technology, Faculty of Paramedicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.
2. Department of Radiologic Technology, Faculty of Paramedicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.

Abstract

Introduction

Primary hepatic cancer is the fifth most common cancer worldwide and the third leading cause of cancer mortality in the united states, after lung and stomach cancer. an estimated 24,120 new cases from liver and intrahepatic bile duct cancer in the united states are expected to occur during 2010, resulting in approximately 18,910 deaths. hepatocellular carcinoma (hcc) is a highly vascular tumor, receiving the majority of its blood supply from branches of the hepatic artery, as opposed to the liver parenchyma that receives 70% of its supply from the portal vein. this “arterialization” of the vascular supply to the tumor accounts for its classic imaging hallmark: enhancement in the arterial phase and washout of contrast media in the portal venous phase. imaging modalities used in diagnosis include ultrasound, computed tomography (ct), magnetic resonance imaging (mri), and angiography.

Methods

Publications were retrieved by a systematic search of multiple bibliographic databases, including medline, embase, scopus, cochrane library, web of science, biomed central, science direct, and google scholar. the language of search was restricted to english

Results

Contrast-enhanced studies allow for the diagnosis of hcc without necessitating biopsy; four-phase helical ct and multiphase dynamic contrast-enhanced mri are the most reliable imaging tests for hcc. ultrasound is the preferred test in screening for hcc. however, imaging quality is dependent both on the operator and patient body habitus. neoplastic lesions less than 3 cm in size are typically hypoechoic, well circumscribed, and homogenous. as tumor size exceeds 3 cm, the appearance on ultrasound is more heterogenous, isoechoic, or hyperechoic, and central hypoechoic regions representing fibrous septae may be observed. ultrasound can also reveal vascular patency or intrahepatic thrombosis, and color doppler ultrasound can provide an estimate of mean velocity blood flow of the hepatic vessels. contrastenhanced ultrasonography is not widely utilized in the united states, but has been shown in several studies to have superior accuracy to standard ultrasound. four-phase helical ct consists of unenhanced, hepatic arterial, portal venous, and delayed phases, and it is often carried out after detection of an abnormality on ultrasound. the typical ct findings of hcc during the arterial phase 25 seconds after contrast injection are increased enhancement of the tumor as compared with nontumoros liver parenchyma. seventy seconds after contrast injection, during the portal venous phase, the lesion is either isodense or hypodense; 300 seconds later, during the delayed phase, hcc is typically hypodense due to the early “washout” of contrast. mri has been shown to be more accurate than ct in the detection of neoplastic lesions. gadolinium-enhanced mri demonstrates a hyperintense image of the tumor in the arterial phase, isointensity in the portal phase, and hypointensity in the delayed phase. t2-weighted images typically demonstrate hyperintensity; t1-weighted images reveal variable intensity.

Conclusion

Sensitivity of mri and ct in detecting hcc has been noted to be 81% and 68%, respectively, and specificity of mri and ct is 85% and 93%, respectively. mri can more reliably differentiate hcc from regenerating or dysplastic nodules as compared with ct.

Keywords

Hepatic cancer, carcinoma, imaging.