الفهرس 
Anatomy of the LiverOnly 14 pages are availabe for public view
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Abstract
HCC is the most common primary liver malignancy and usually occurs in the setting of cirrhosis.
Early detection of the small HCC is an important aspect of the liver imaging that has implications for patient treatment and prognosis. The choice of imaging technique depends on the clinical question and the patient’s clinical condition; in general, US and CT remain the first imaging tests for screening and characterizing most patients with suspected liver tumors.
However, US-based screening for HCC has a sub-optimal sensitivity and specificity, especially when liver cirrhosis is present. Hence patients with an abnormal liver US showing cirrhosis or focal mass often undergo CEUS, CT or MRI examination.
CEUS is highly effective for characterizing small (10–20mm) nodules in liver cirrhosis. On CEUS, AP vascular intensity and pattern are highly accurate for the diagnosis of small HCC in liver cirrhosis. On CEUS, arterial hypervascularity may be sufficient to suggest the diagnosis of small HCC. Infrequent iso/hypovascular HCC may erroneously suggest RN/DN necessitating biopsy or short interval follow-up.
Tri-phasic helical CT using a large-dose bolus injection of contrast material is one of the primary methods of diagnosing hepatocellular carcinoma. Arterial phase images are better than the portal venous and delayed phase images in the detection of Small hepatocellular carcinoma.
Magnetic resonance imaging (MRI) is extremely useful in the early detection and characterization of small HCC and several studies have demonstrated the superiority of MRI in detection of HCC when compared to CT.
Dual modality PET/CT scanning provides accurately
fused morphologic (CT) and functional (PET) data sets. A very small tumor is well detected by PET but can be missed by CT. On the other hand, a large tumor with minimal functional deviations may be seen on a CT image, put may not be detected by PET. In both situations, PET CT would localize the tumor accurately.
A suspicious lesion on the sonogram generally requires additional imaging studies to confirm the stage of the tumour and sensitivity for detection of small nodules may be low. The addition of arterial phase imaging to conventional CT scanning increases the number of tumour nodules detected, but in nodular cirrhotic livers the sensitivity to detect HCC is low. The overall sensitivity of MRI is similar to that of triphasic CT scan, but in patients with nodular cirrhotic livers MRI has better sensitivity and specificity.
Dynamic MRI should thus be used to examine HCC in liver cirrhosis as it may be more appropriate than helical CT for the detection of small HCCs.
Because of lower cost and higher specificity of US examination, we propose as a diagnostic and therapeutic strategy the combination of US and MRI.