Management of carotid stenosis in women: Consensus document

Abstract

The Neuro Image by Scully et al.1 attempted to show that the new T2* susceptibility-weighted angiography (SWAN) MRI is more sensitive to show microbleeds not visualized on T2*-GRE. SWAN MRI may not be a familiar term to all neurologists. ESI techniques have recently gained popularity for being more sensitive in showing paramagnetic tissues compared with the standard T2*-GRE. This was initially commercialized as susceptibility-weighted imaging (SWI) by Siemens (Malvern, PA) MRI. SWI uses additional phase information to increase the sensitivity.2 We previously reported evidence for higher sensitivity of SWI over GRE.3 Since then, it is gradually replacing T2*-GRE in clinical imaging, especially in settings where Siemens MRI is used. Due to licensing and patent issues, different MRI vendors are often forced to slightly modify a sequence technique to avoid infringement. To provide an equivalent ESI technique, General Electric (Milwaukee, WI) modified the T2*-GRE by multiecho acquisition and postprocessing reconstruction as weighted average in its MRI and called it SWAN. Similarly, Philips (Andover, MA) MRI uses a different postprocessing technique called phase difference enhanced imaging (PADRE) to combine the phase information. The different ESI are probably superior to T2*-GRE. It would be interesting to compare ESI techniques from different vendors, comparing apples to apples.