Exact use of FSYNC pin in 9150

Hi

I am working on gyro based image stabilization and using the MPU 9150. I am looking for a way to synchronize the camera and the MPU so that I can have the gyro values at the precise instant when I have a camera frame.

While going through the datasheet and register map I could only gather that FSYNC can be either used to generate an interrupt via the MPU to the host processor from an external trigger or can be latched and its value can be read based on EXT_SYNC_SET value.

How then can the FSYNC be used for synchronization as claimed when describing the FSYNC pin?

Thanks