Scientists say they have invented a helmet that can quickly diagnose whether a patient has had a stroke.

The new invention could speed up diagnosis and treatment of stroke and aid the recovery process, they believe. 

The helmet uses microwave signals to test whether there has been a bleed or a clot inside the patient's brain.

Unless treatment is initiated quickly after a stroke, there can be brain damage and disability. The new device, it is hoped, will aid earlier diagnosis and treatment.

Tests with an earlier version of the equipment found that it could in many cases differentiate between strokes caused by bleeds and clots

The researchers say the device needs more testing, but could be a useful part of stroke care in the future.

The helmet was developed by researchers in Sweden, and their findings are reported in the journal Transactions on Biomedical Engineering.