CT estimations of mean attenuation values and volume in testicular tumors: a comparison with surgical and histologic findings.

Lymphadenectomy was carried out in 40 patients with retroperitoneal nodal metastases from testicular tumors who had undergone chemotherapy with or without radiation therapy. Two other patients, who died of their disease during chemotherapy, were included in the study. The postoperative or postmortem histologic results were compared with the mean tumor attenuation values and tumor volumes calculated from computed tomographic (CT) examinations. There was good separation between changes in CT numbers for those masses with persistent active malignancy (37.7 +/- 4.8 HU) and those masses with no evidence of malignancy (18.7 +/- 7.8 HU). Serum markers were elevated at the time of surgery in only two of the seven patients with active malignancy. There was no correlation between volume and malignancy or nonmalignancy for tumors greater than 20 ml; tumors less than 20 ml showed no evidence of malignancy. It is proposed that the mean CT number may be the most important parameter for measuring the therapeutic response of abdominal metastases from testicular tumors larger than 20 ml.