MRI Guidance, Remote-Controlled Catheter Technology May Improve Visualization of the Brain During Stroke Treatment

The new findings should advance the field of neurointervention, a discipline that facilitates stroke treatment by navigating a catheter (the tubing through which clot-dissolving drugs or clot retrieval devices are applied) through the blood vessels, from a point of entry in the groin up to the problematic spot in the brain. Neurointerventionists typically undertake this approach by manually directing the catheter and visualizing its progress under conventional X-ray guidance.

With MARC, the researchers tried to determine if a remote-controlled catheter under magnetic resonance imaging (MRI) guidance could more effectively accomplish maneuvering through complex vessel anatomy, which would ultimately allow for the enhanced visualization of the brain tissue affected during a stroke. “Given that MRI is the gold standard by which we determine brain tissue viability, it is exciting that we potentially now have new MRI-compatible technology that enables us, while treating a stroke, to make real-time assessments about whether brain tissue is dead or alive,” said Steven Hetts, MD, lead study author and associate professor of radiology at the University of California, San Francisco (UCSF; USA). “The implications are numerous, including improved medical decision-making, which would naturally result in optimizing patient safety and clinical outcomes.”

To evaluate the performance of MARC, Dr. Hetts and his colleagues tried to determine mean procedure times and success data for a custom, clinical-grade MARC prototype under MRI guidance as compared to a manually-navigated catheter, under both MRI and standard X-ray guidance—each procedure utilizing a cryogel vascular model designed to simulate the main and branch blood vessels in a living human. The MRI-guided procedures were performed at 1.5 Tesla using a balanced steady-state free precession sequence in the type of clinical MRI scanner available in most hospitals.

The study findings showed that MARC was clearly visible under MRI guidance and was used to effectively complete 192 (80%) of 240 total turns around blood vessels as compared to the manually directed catheter under both MRI and X-ray guidance, at 144 (60%) of 240 total turns and 119 (74%) of 160 total turns, respectively. MARC also was faster than the manually directed catheter under MRI, with a mean procedure time of 37 seconds per turn as compared to 55 seconds, but comparable to the manually directed catheter under X-ray guidance which required a mean of 44 seconds for each turn. When assessing the time required steering the various angles of branch vessels at turns of 45°, 60°, and 75°, MARC was shown to be faster than the manually directed catheter under MRI guidance.

“Given that the success of neurointerventional stroke treatment is directly tied to how fast and accurately physicians can eliminate the impact of a clot and restore blood flow to viable portions of the brain, technology that facilitates this objective stands to be transformative,” said Dr. Hetts. “By proving that MRI-guided neurointervention could be more effective than current standard approaches to stroke treatment, we are taking a significant step forward in the advancement of our field.”

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University of California, San Francisco