Gillian Gordon Perue, MBBS, DM
Cheng AL, Batool S, McCreary CR, Lauzon ML, Frayne R, Goyal M, et al. Susceptibility-Weighted Imaging is More Reliable Than T2*-Weighted Gradient-Recalled Echo MRI for Detecting Microbleeds. Stroke. 2013
Cerebral Microbleeds (CMBs) have become increasingly important because clinically they may represent an early imaging biomarker for asymptomatic patients at high risk of intracranial hemorrhage and/or dementia. Therefore, early detection of CMBs may provide an opportunity to intervene and slow the progression of commonly associated cerebrovascular diseases such as hypertensive vasculopathy and cerebral amyloid angiopathy.
In an elegantly designed study recently published in Stroke, Cheng and colleagues evaluate the detection and quantification of cerebral microbleeds on GRE vs. SWI among three blinded independent rates of varying levels of expertise (research expert, practicing radiologist and a 4thyear radiology resident). The authors made an effort to ensure standardization and minimize bias by training each rater on reading GRE sequences prior to the start of the study and having each rater review the studies more than 2 weeks apart in random order without clinical information.
The study included 31 participants in a 3T MRI based study on biomarkers for cerebral amyloid angiopathy (CAA). Among these patients, 9 had CAA and 22 were healthy non- stroke controls. For each rater, the use of SWI improved the detection of CMBs when compared to detection by GRE: Rater 1 (13%, p 0.25), Rater 2 (30%, p=0.04), and Rater 3 (184%, p0.008), Kappa 0.57-0.74.
Interestingly, among the control group 9 total CMBs were found on GRE vs. 19 on SWI. This raises the question; how much is too much when it comes to microbleeds?
That is to say, “Can the presence of a few microbleeds be considered normal?” “And if so, what is the normal range?” As our imaging techniques advance and become more accessible for clinical use, the more relevant these questions become. I invite you to read the article and join the discussion on cerebral microbleeds.