[Clinicoradiological studies and frequency of incidental meningiomas on brain check-up]

The purpose of this study is to evaluate clinico-radiological findings and to estimate frequency of incidental meningiomas detected by brain check-up (BC). A total of 12,258 healthy adults (8,515 men and 3,743 women) had BC, using physical check-up, brain magnetic resonance imaging (MRI) and MR angiography. Mean age (SD) was 52.6 (11.4) years, 52.7 (11.2) in men and 52.5 (11.8) in women. Duration of this study was between April 2004 and March 2007. BC subjects were divided into the first BC and the repeated BC group. The number of the first BC subjects was 5,056 (3,284 men and 1,772 women). In the repeated group defined that they had the first BC before April 2004 in our center, there were 7,202 subjects (5,231 men and 1,971 women). Fifteen subjects (7 men and 8 women) were diagnosed as meningiomas. Fourteen cases were detected by the first BC and one case by the repeated BC. The percentage of incidental meningiomas in the first BC group was calculated as 0.28, 0.18 in men and 0.45 in women. The sex ratio of women/men was 2.5. The mean age of those cases was 55.2 (10.1), 54.6 (12.9) in men and 55.8 (7.7) in women. Incidental rate of meningioma in the repeated BC group was calculated as 0.01% and 0.02% in men. No subjects had meningioma at age < or = 30 years. Asymptomatic meningiomas were seen in 14 cases (93.3 %) and they expected BC to ascertain healthy and normal brain by themselves. The size of tumors was ranged 10 to 46 mm and mean (SD) was 21.3 (10.2) mm. The locations of meningiomas were variable. Three cases had surgical removal. Twelve cases were under investigation on MRI. In middle-aged working subjects, incidental rates of asymptomatic meningiomas detected by BC are not uncommon in Japan. We should pay more attention to incidental meningioma when brain MRI is performed in 40-60 years women.