Effectiveness of magnetic resonance angiography for mass screening of unruptured intracranial aneurysms

: Magnetic resonance angiography (MRA) is widely used in screening for unruptured intracranial aneurysm (UIA) in the prevention of onset of subarachnoid hemorrhage (SAH) in Japan. However, the clinical efficacy of mass screening of UIA using MRA has not been established. This study aims to establish the clinical efficacy of mass screening of UIA using MRA by decision-making. The decision tree is constructed simulating a flow of population (100,000 persons, aged 50-59) starting from the MRA screening until the final outcomes of quality adjusted life or death in ten years. In order to estimate the numerical values various parameters were used as follows, prevalence rate: 1%; sensitivity of MRA: 74%; specificity of MRA: 76%; death rate by intracranial angiography: 0.1%; rupture rate of UIA: 2%/year; death rate of SAH: 57%; and death rate for surgery for UIA: 0.0%. The following results were obtained: 1. The number of lives saved by the MRA screening was 760, while the number saved without MRA was 79. 2. The number of deaths in those receiving the MRA screening was 52, while the number of deaths without MRA was 104. 3. The level of quality adjusted life with the MRA screening was higher than that without MRA in all cases. In conclusion, mass screening of UIA using MRA appears to be effective.