“…Each of these techniques is simple to perform, but has significant potential limitations. A confounding factor of both T 2 -and T 2 ⁎ -based imagings is that measurements are also affected by changes in the water contentassociated for example with destructive brain processes (Bartzokis et al, 2004a) -and can mask the changes in iron content (Gelman et al, 1999;Haacke et al, 2005;Haller et al, 2010;Schenck and Zimmerman, 2004;Vymazal et al, 2007). Ex vivo histological staining of putamen samples from HD patients demonstrated elevated putamen iron levels (Chen et al, 1993) but there was little correlation to T 2 -weighted imaging of these samples.…”