A covenant or agreement between two or more persons, with a lawful consideration or cause. Jacob. A deliberate engagement between competent parties, upon a legal consideration, to do or abstain from doing, some act. Wharton.
Enhancing means that the mass brightens up with contrast, meaning that there is a lot of blood vessels feeding the mass. These are imaging terms that radiologists use to describe a picture. <br /><br /> Inhomogeneous means that the whole mass does not look the same; the best I can describe is that it looks speckled. For example, a cyst that is filled with fluid will be homogeneous. Every part of what's inside the cyst will look identical, because it's just fluid in there.
Homogeneous catalysts are those that occupy the same phase as the reaction mixture (typically liquid or gas), while heterogeneous catalysts occupy a different phase. Generally, heterogeneous catalysts are solid compounds that are added to liquid or gas reaction mixtures.