الفهرس | Only 14 pages are availabe for public view |
Abstract Adequate knowledge of hepatic segmental anatomy is a golden rule, by which easy localization of hepatic tumors could be clearly elicited. Also, studying the pathophysiology of wide spectrum of hepatic tumors is a prerequisite for the radiologist to achieve comprehensive diagnostic efficacy. Previously, invasive contrast material enhanced conventional angiography was the main diagnostic tool in depiction of hepatic vascular anatomy. Recently, with the rapid scanning ability of multideteor CT, it is feasible to obtain a three-dimensional data set of the entire liver during a single breath hold. With reconstruction of these data; high quality three-dimensional images may be obtained in reconstructed sagittal, coronal, or curved planes. The most important parameters for high quality hepatic imaging are: the use of proper scan protocol, the optimization of contrast delivery, and the selection of appropriate phase of imaging acquisition. By MDCT, thin sections could be acquired as a routine basis, in a single breath hold. Three-dimensional CT angiography is obtained by imaging processing either by, maximum intensity projection, surface shaded display, or volume rendering. This will clearly elucidate the anatomic and pathologic characteristics than reading of axial images alone. Such unique imaging approaches may ultimately improve lesion detection, characterization, and surgical planning of different hepatic tumors. MDCT with advanced imaging processing allow for accurate evaluation of hepatic parenchyma with robust evaluation of neovascularity and tumor stains as well as arterio-portal shunts that may accompany some hepatic tumors and thus allow better assessment of tumor burden compared with routine axial images. MDCT angiography is not only used in depiction of hepatic arterial anatomy, specific hepatic arterial variants, and segmental localization of hepatic tumors, but also capable of detection of some features that are not well seen by axial plane. These include vascular displacement, encasement, invasion, neovascularity, tumor blush and arterio-portal shunt. The resectability of the lesions could be determined by volume display of the lesion, showing whether it has directly invaded the portal vein, inferior vena cava, or even the heart. Also, MDCT angiography provides valuable preoperative information about hepatic vascular architecture. MDCT with advanced imaging processing is useful in delineating uncommon hypervascular liver lesions that simulate tumors thus increasing the diagnostic efficacy of the CT and decreasing false positive diagnosis of hypervascular hepatic tumors. |