VECTOR PRINCIPLE IN THE DIFFERENTIAL DIAGNOSIS OF ABDOMINAL MASSES

II. RIGHT UPPER QUADRANT

An appreciation of the anatomic relationships of the organs of the right upper quadrant as accomplished by sectional anatomy is the key to an understanding of the normal roentgenologic examination of that area. Alteration by tumefaction may be defined by the manner in which the normal relationships are modified, pointing to a site of origin. If the origin of the vector displacement is then determined, the organ of primary involvement is likewise discovered.

Precise localization of the point of origin of a mass is possible when the mass is just large enough to be detected on a roentgenogram. The larger the mass becomes, the more displacements occur and the greater the chance for overlap of primary site results. Pseudocysts of the pancreas may be the greatest violator, since they may seek a path and present at a distance from the original pancreatic bed.

The descending duodenum divides the upper abdomen into approximately equal quadrants and serves as a useful landmark in separating abdominal masses. This is summarized in Figure 23 and Table 1. Further delineation of a mass to easily opacified adjacent structures, such as colon, stomach, and kidney, and determination of the vascular supply make localization more specific, roentgenologic diagnosis more precise, and surgical approach more effective.

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