الفهرس 
Anatomy of the liverOnly 14 pages are availabe for public view
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Abstract
The liver is a common site for malignant neoplasms. Hepatocellular carcinoma is a leading cause of death from cancer throughout the world. In addition the liver is considered one of the most common sites of malignant deposits.
During the past decade a number of ultrasonographic contrast agents have been rapidly developed and used to study smaller and deeper structures in the body, where the spatial resolution of gray scale imaging and Doppler sensitivity become impaired. Ultrasound contrast agents promise to improve the sensitivity of current ultrasound diagnosis and have the potential of expanding the broad range of ultrasound applications.
A variety of intravenous ultrasound contrast agents can improve the detection of flow in small and deep vessels throughout the body. Thus enhancing the visualization of microvasculature associated with cancer by revealing additional signals, either within the lesion itself or within the marginal regions. So, metastatic liver lesions show previously undetected enhancement of Doppler signals in the marginal regions of the lesions whereas malignant liver tumors as hepatocellular carcinoma and cholangiocellular carcinoma produced additional Doppler signals within the tumor.
Thus, intramural flow signals favor a malignant tumor. The absence of flow signals is a frequent finding in benign lesions, but does not rule out malignancy.
Ultrasound contrast enhanced Doppler improved the diagnostic confidence and visualization of the portal venous system compared to base line scans with insufficient Doppler signals and proved reliable compared to dynamic CT and MRI. It allows a faster Doppler examination and could confirm the absence of any pathology. Therefore ultrasound contrast agents may reduce the need for more invasive and expensive investigations.
However, the technical difficulty represented by the need of highly qualified scales for evaluation of the amount of Doppler signals within the lesion is still not available, and a considerable overlapping of vascularity patterns among hepatocellular carcinoma, cholangiocellular carcinoma and hypervascular metastasis as all these malignant lesions show enhanced (perilesional and intralesional) signals. Also Doppler artifacts associated with ultrasound contrast agents as blooming and short half life of contrast agent is not suitable for long standard investigation of the liver.
Despite these limitations we believe that ongoing development of sensitive, new and artifact reducing techniques as well as improvement of scaling facilities will enhance visualization of intralesional vessels architecture and make contrast enhanced ultrasound a more powerful diagnostic tool in detection of lesion vascularity, diagnosis and differentiation of liver tumors.