Histopathological study correlated with Gd-DTPA-enhanced MR imaging in glioma

In order to clarify the histopathological correlation with Gd-DTPA-enhanced MR imaging in glioma, brain specimens from seven cases of glioblastoma multiforme, two cases of benign astrocytoma, and two cases of radiation injury were investigated. T1-weighted MR imagings were obtained before and after the injection of Gd-DTPA (dose: 0.1 m mol/kg). The authors classified the patterns of enhancement into four types : (1) Delineated enhanced type (a delineated and homogeneously enhanced solid or a ring-like region): This type correlated with two histopathological types. One was stable or had a slowly proliferating tumoral tissue. Their specimens show a moderately increased vascularity and not so anaplastic tumor cells. The other was radiation-injury tissue. Here coagulation necrosis and fibrinoid necrosis were found, but no tumor cells. (2) Undelineated enhanced type (an undelineated and heterogeneously enhanced solid region): This type correlated with viable and highly proliferating glioma tissue. A high vascularity of the endotherial proliferating vessels, highly anaplastic tumor cells, and mitosis were observed. (3) Slightly enhanced type: In this area, edema with increasing capillary vessels was observed. Some tumor cells were also seen. (4) Non-enhanced type: Normal brain tissue; benign astrocytoma were not enhanced by Gd-DTPA. X-ray CT scanning is said to be unable to distinguish viable tumoral tissue from radiation-injury tissue. Histopathological correlations with Gd-DTPA-enhanced MR imagings have shown that the undelineated and heterogeneously enhanced areas corresponded to proliferating viable glioma tissue, while the delineated and homogeneously enhanced areas corresponded to radiation-injury tissue or to relatively stable glioma tissue. Gd-DTPA enhancement corresponded well to the increased vascularity of abnormal vessels, but not necessarily to tumoral cells. (author)