MRI detection of cerebral microbleeds: size matters.
PURPOSE
Cerebral microbleeds (CMB) play an important role as an imaging biomarker notably in vascular and neurodegenerative diseases. Current clinical brain MRI underestimates the number of CMB with respect to histopathology. It is expected that small CMBs are more likely to be false-negatives, yet this has not been demonstrated and the average size of false-negative and true-positive CMBs have not been established.


METHODS
The radiologic-histopathologic correlation study was approved by the local review board and included 42 consecutive cases (mean age at death, 80.7 ± 10.0 years; 23 females and 19 men) between 12 January 2012 and 10 December 2012 having undergone brain autopsy. Postmortem SWI (susceptibility-weighted imaging) images were acquired on a clinical 3T system using parameters similar to clinical routine. The detection of CMB on postmortem MRI was compared with corresponding histopathological slices.


RESULTS
Postmortem MRI detected 23 true-positive CMB. Histopathology additionally detected 68 CMBs (false-negative MRI CMBs). The average size true-positive MRI CMBs had on histopathology was 3.6 ± 7.1 mm3. The average size false-negative MRI CMBs was significantly smaller (p < 0.05), measuring 0.3 ± 1.2 mm3 on histopathology.


CONCLUSION
Size matters. As expected, the average size of true-positive MRI CMB was around 10 times larger as compared with false-negative MRI CMB. Evidently, in addition to size, other factors will influence the detectability of CMB, including iron content, ratio of Fe2+/Fe3+, spatial configuration, and location, yet this remains to be elucidated in future studies.
['Haller|Sven|S|http://orcid.org/0000-0001-7433-0203', 'Scheffler|Max|M|', 'Salomir|Rares|R|', 'Herrmann|François R|FR|', 'Gold|Gabriel|G|', 'Montandon|Marie-Louise|ML|', 'Kövari|Enikö|E|']
D000368:Aged D000369:Aged, 80 and over D015415:Biomarkers D002543:Cerebral Hemorrhage D005188:False Negative Reactions D005260:Female D006801:Humans D021621:Imaging, Three-Dimensional D008279:Magnetic Resonance Imaging D008297:Male
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