Locoregional late effects of paravascular thorotrast deposits: results of the german thorotrast study.

PURPOSE

The aim of this study was to assess late effects of long-term exposure to alpha irradiation caused by paravascular Thorotrast deposits.

SUBJECTS AND METHODS

899 patients, who had received the radioactive contrast medium Thorotrast for angiography in the 1930s and 1940s, and 662 controls were followed-up since 1968 every two years by standardized clinical and laboratory examinations. Initially, X-ray plain films of the thorax, upper abdomen and the former injection site were performed. In selected patients the sites of paravascular Thorotrast deposits were evaluated by ultrasonography, CT and MRI.

RESULTS

Paravascular Thorotrast deposits were detected in 245 patients. Clinical symptoms related to deposits appeared 10 to 30 years after Thorotrast administration. The severity of symptoms depended on the location and extension of granulomas and were mainly caused by fibrosis, nerve paralysis and vascular changes. Four malignant tumors adjacent to granulomas were observed (one soft tissue sarcoma in the groin, two squamous cell carcinomas of the parotid gland and one lymphoepithelial carcinoma of the nasopharynx). MRI including MRA allowed an accurate determination of tissue damage, whereas the utility of US and CT was restricted due to strong sound attenuation and streak artefacts caused by the high X-ray absorption of Thorotrast.

DISCUSSION AND CONCLUSION

Locoregional late effects of paravascular Thorotrast deposits mainly comprise radiation induced, fibrotic tissue destruction. The incidence of malignant tumors, in particular sarcomas, adjacent to deposits, however, is much lower than initially expected.