Summer 2009

Neurointerventional Radiologist Stretches the Boundaries

In March 2009, the American Stroke Association issued new guidelines for managing aneurysmal subarachnoid hemorrhage (SAH). They include guidance for the proper treatment of cerebral vasospasm after SAH, a condition that puts patients at risk for a major stroke. For neurointerventional radiologist Steven Hetts, M.D., this is an area of particular concern.

Hetts, who recently joined the UCSF faculty, is conducting clinical research on intracranial vasospasm after SAH. "Our hope is to prevent stroke through a collaboration among neurovascular, neurosurgery, the ICU and neuroradiology," says Hetts.

In his research, a team monitors patients carefully after SAH. If there is a clinical change for the worse, such as loss of consciousness or movement, the neuroradiologist does an angiogram to determine whether vessels are in spasm. If they are, the neuroradiologist can do a balloon angioplasty or infuse the patient intra-arterially with vasodilating medications. Under the new guidelines, both procedures may be relevant to prevent stroke.

"We believe if we're aggressive, we can achieve very good clinical outcomes," says Hetts.

Hetts' presence allows UCSF to extend this type of expertise — as well as expertise in treating metastatic cancers of the spine, embolization of arteriovenous malformations (AVMs) and coiling of intracranial aneurysms — to San Francisco General Hospital and San Francisco Veterans Affairs Medical Center.

To palliate pain and improve quality of life for patients with metastatic spine cancer, Hetts performs vertebroplasty and kyphoplasty procedures, as well as percutaneous tumor ablation. To treat AVMs, he is one of a select few neurointerventional radiologists experienced with ethylene vinyl alcohol copolymer (Onyx), a new glue that more effectively obliterates larger, more complex AVMs.

"Until now, people had been hesitant to adopt this liquid embolic agent, but the technology has advanced," says Hetts. "It's easier and safer to use, and enables us to do more complete embolizations."

Bringing Research Forward

Hetts is conducting other research as well. As part of a team that expects to begin translational research and clinical trials over the next two or three years, he is exploring a treatment for a variety of brain tumors in which chemotherapy is administered via microcatheter, achieving local drug delivery to the tumor while reducing systemic side effects.

He also is exploring the use of interventional MRI as a way to provide better and safer guidance for minimally invasive ischemic stroke treatment. The hypothesis is that in addition to avoiding radiation exposure, full visualization of brain tissue — rather than just blood vessels — will help avert the risk of hemorrhage caused by perfusion of dead tissue.

"As part of an NIH-funded joint venture between the University, Lawrence Livermore National Laboratory and private industry, we are developing catheters tipped with magnetic coils to use under MRI guidance that we can guide through blood vessels by remote control," says Hetts.

For more information, contact Steven Hetts, M.D. at (415) 353–1863.

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