Specificity of computed tomography in the diagnosis of supratentorial neoplasms. Consideration of metastases and meningiomas.

A previously unsuspected linear relationship between the initial density and the amount of uptake of various tumors is described. As a rule, initially radiodense neoplasms enhance less than radiolucent neoplasms. For a given amount of enhancement, meningiomas are initially more radiodense than metastases; also, breast metastases are more radiodense than lung metastases. The density versus uptake curve tends to show certain specificity for a given type of neoplasm. Absolute differentiation of histologic types is still not possible on the basis of these curves. The correlation, however, is interesting and seems to be related to the amount of damage to the blood-brain barrier and the degree of calcification, vascularity, and cellularity of the various tumors. With improved precision of scanners the specificity of the CT image may be improved.