Researchers found “no significant increase in risk” of meningioma among patients exposed to CT examinations of the head, according to a new study published in Radiology.

Lead author Arvid C. Nordenskjöld, MD, of Karolinska Institutet in Stockholm, Sweden, and colleagues retroactively studied data from more than 26,000 patients who received CT examinations of the head from 1973 to 1992. The data were then compared to a control group of more than 96,000 patients who were not exposed to CT.

“Studies examining the link between radiation and intracranial tumors have shown meningioma to be more likely to develop than other brain tumors,” the authors wrote. “Because meningioma is the most common brain tumor and because CT of the head is one of the most common CT examinations, investigation of meningiomas may be useful to assess tumor risk from CT examinations.”

Overall, 112 cases of meningioma were found after five years. More than 42 percent of the cases were from patients who had been exposed to CT of the head, and more than 57 percent were from the unexposed control group. The authors pointed out that, of the meningioma cases from patients exposed to CT, one-third “had clinical information on the radiology report that necessitated study exclusion” such as prevalent meningioma or a brain tumor at the time of the CT examination.

“Overall, we did not find any significantly increased risk of meningioma once referral notes and radiologic data had been taken into account,” the authors wrote. Those referral notes and radiology reports are important to remember, they added, because not taking them into account would have resulted in the risk of meningioma being “overstated” for patients exposed to CT examinations of the head.

Nordenskjöld et al. did note that their study had limitations. The team lacked information on CT examinations performed at different hospitals, for instance. Also, some meningioma cases may have not been reported to national registries if surgery was never performed.