. Dynamic Permeability and Quantitative Susceptibility
Peter Hannon, MD
Guo X, et al
Known by many neurologists by the board-ready “popcorn” appearance on MRI, cerebral cavernous malformations (CCMs) are characterized by low-pressure capillary dillitations with a propensity to seep or leak blood due to vascular permeability, and thus accumulate iron depositions over time. Sequelae include epilepsy, focal deficits and stroke, and depending of size and symptoms, CCMs may require surgical intervention. In their current article, authors Mikati et al describe novel MRI imaging techniques to help characterize and follow CCMs over time, specifically Dynamic Contrast Enhanced Quantitative Perfusion (DCEQP) to measure vascular permeability, and Quantitative Susceptibility Mapping (QMI) to assess iron deposition.
In a previous article, the authors described the decrease of iron deposition and lesion burden in murine CCM models by Rho Kinase (ROCK) inhibition by Fasudil, and were looking for a method to monitor this potential therapy in a clinical setting. Twenty-one patients with CCM were imaged, all but 5 with a familial form of CCMs. A positive correlation was found between the mean QSM susceptibility and mean permeability of the lesions via DCEQP, which would make sense, as leaky lesions would seem more likely to accumulate iron deposition. The authors note that these findings were independent of lesion volume, differing contrast agents used or whether patients were on a statin.
The study is somewhat limited by small sample size and a disproportionate number of familial vs. sporadic cases of CCM, but illustrates novel MRI imaging techniques that could help monitor potential treatments over time. If these results continue to hold out over larger and more diverse sample sizes, then DCEQP could be a measure of “active” or ongoing permeability, and QMI could help measure the overall burden of this activity. In a non-invasive manner, both could not only help monitor a response to new treatments for CCMs, but also help determine whether treatment is even indicated.