Computed tomography of monkey brain tumors

Thirty-five Japanese monkeys were inoculated intracerebrally with chick embryo fibroblasts that were producing Schmidt-Ruppin strain of Rous sarcoma virus. Tumors were induced in 54.3% (19/35). Computed tomography detected tumors in 10 symptomatic animals with an average latency of 32.6 (15-43) days. At autopsy, the brains were sectioned into 5 mm slices, coplanar to the CT image. Various CT features of high- and low-density area correlated well with the histopathological findings, such as tumor, hemorrhage, necrosis, and peritumoral edema. Contrast-enhanced CT detected 10 tumors greater than 4 mm in diameter, and there was +/- 2 mm potential error in determining tumor size. Follow-up CT revealed growth of tumors in four animals and stabilization of tumor in two animals. Large brain size, 90-110 g in adult monkeys, and availability of induced tumors offer an excellent brain tumor model for CT studies.