<prompt> Best test to determine etiology of SAHEnhanced CTUnenhanced CTIntra aerial digital Substraction AngiographyMRI  <response>: C i.e. Intra aerial digital Substraction Once dx is done by CT Scan; digital substraction angiography DSA is done to determine etiology. DSA is most sensitive best inv. for determining etiologyQ. Now DSA is being replaced by noninvasive methods as MRA MRI - angiography CTA CT - Angiography. 