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[Postoperative computed tomography: study of 10 cases on reactive ring-enhancement in brain].

This paper presents 10 cases with CT appearances of postoperative reactive ring-enhancement in the brain, which were not reported in our country. The mechanisms and differential diagnosis of postoperative ring-enhancement are discussed with reports in the literature. The ring-enhancement at surgical margin is the reactive change of the brain traumatized by operation and related to postoperative pathological processes such as breakdown of blood-brain barrier, vascular granulation and luxury perfusion. This paper demonstrates that reactive ring-enhancement appears as early as 2-4 wk and may last as long as 7 wk after operation. It disappears gradually in 7 wk and cannot exist over 3 mon after operation. In the first 3 mon after operation, peripheral enhancement around the surgical site may be operative reaction, or residual tumor and cerebral abscess. The presence of ring-enhancement beyond 3 mon should be viewed as evidence of pathological process other than postoperative change. This paper emphasizes that ring-enhancement at margin of the surgical site with fine clinical manifestations in the early postoperative period is probably normal postoperative reaction. Close follow-up enhanced CT scan proves to be an effective measure to avoid misdiagnosis and unnecessary reexploration.