UHealth’s Specialized Neurosonology Lab Focuses on Cerebrovascular Health
Neurosonology — the ultrasonic imaging of neural structures — allows physicians at UHealth – the University of Miami Health System to get a unique and very detailed look at the health of the arteries inside and outside the brain. This can mean a more precise diagnosis, prognosis and management of people after a stroke, transient ischemic attack and even asymptomatic cerebrovascular disease.
The technology is not new, and many health care settings offer this non-invasive imaging. What sets UHealth’s Patrick Cesarano Neurovascular Laboratory — which performs and interprets almost 2,400 of these procedures annually — apart is a high level of specialized expertise in using cerebrovascular ultrasound to interpret plaque composition, predict stroke risk, measure the ability of the arteries to withstand stress (endothelial function), and more.
“We really pay more attention to what the plaque looks like, the surface area of the plaque, and we routinely report this to the ordering physician. We provide a more detailed description,” said Sebastian Koch, M.D., professor of clinical neurology at the University of Miami Miller School of Medicine, who is director of the laboratory. “I don’t think that this is typically done with a routine carotid ultrasound.”
Ultrasound is easy to perform, relatively inexpensive and avoids radiation exposure, which is especially relevant for monitoring patients with established disease over time.
“Ultrasound lends itself very, very nicely to longitudinal monitoring of a large patient population,” Koch said. “Because of UHealth’s specialized expertise, treatment of both inpatients and outpatients, and ultrasound-driven examinations beyond the routine, we are more of a boutique neurosonology laboratory.”
Koch recalls the case of a young man who was referred to UHealth after his third stroke within eight months on the right side of the brain.
“He had undergone every conceivable test, including a catheter cerebral angiogram, with no clear diagnosis,” said Koch. “We repeated a carotid ultrasound and saw an ulcerated [cracked] plaque in the carotid artery which only caused about 40 percent narrowing. For that reason, it had remained undetected by other diagnostic tests. We sent him for a carotid endarterectomy, i.e. surgical removal of the plaque, and he has been stroke free for several years.”
Performing a reliable and useful cerebrovascular ultrasound is “very tricky,” Koch added. “We always say ultrasound is very technician-dependent and equipment-dependent, but it’s really as much art as it is science.”
The lab has a highly specialized ultrasound technician, Nelly Campo, who only performs neurovascular ultrasound.
A broad range of services
The neurosonology laboratory’s services include looking at the carotid, vertebral and other arteries outside the brain, as well as the arteries in the brain using transcranial ultrasound.
“In addition to these standardized examinations, we have very specialized ways of doing ultrasound that are not as commonly performed in the community,” Koch said. Emboli detection studies, for example, help physicians evaluate plaque over time.
Emboli detection can inform prognosis and therapy, as well. For example, when ultrasound reveals unstable carotid artery plaque, physicians may consider changing a patient’s medication or referring them for a surgical procedure.
Another technique not typically performed with ultrasound elsewhere evaluates how the lining of the arteries responds to stress from reduced blood flow. As an example, a patient with 70 to 80 percent plaque build-up in a carotid artery generally has less blood flow to their brain.
“We have ways of measuring how that side of the brain compensates by asking the patient to inhale a mixture of carbon dioxide. That leads to a dilatation of the artery. Then we ask the patient to hyperventilate, which leads to constriction of the artery,” Koch said, describing a vasomotor reactivity test, which can help predict a patient’s stroke risk.
“The more a patient is able to dilate and constrict, the more responsive the linings of the artery are, and the more likely the patient is able to compensate for stress, like lower levels of blood flow. It is the equivalent of a stress test of the brain.”
Risk evaluation for children
The neurosonology laboratory also evaluates children with sickle cell disease using transcranial Doppler technology.
“Some are really young children, in their first 10 years of life, who are at risk for having a stroke,” said Jose Romano, M.D., chief of the Stroke Division in the Miller School’s Department of Neurology. “We work closely with Dr. Ofelia Alvarez, the medical director of the Pediatric Sickle Cell Program in the Department of Pediatrics, to screen children with sickle cell disease in order to identify those who need transfusion treatment. We are also collaborating with Dr. Alvarez on cutting-edge research involving pediatric neurosonology to improve outcomes in these children.”
Koch and colleagues typically monitor these children every six to 12 months for blood flow velocity. When it exceeds a certain threshold, the children typically receive exchange transfusions to lower the proportion of their blood that carries sickle cells.
“Ultrasound really is the way to manage these children,” Koch said.
Another novel use of ultrasound in children, is the detection of a patent foramen ovale (PFO), or a hole in the heart that didn’t close the way it should after birth.
“We have a good way of looking for a PFO,” Koch said. “The neurosonology team performs a bubble study that can indicate, indirectly, presence of a PFO in the heart. When bubbles are injected into the arm of a patient without a PFO, they circulate to the lung and get filtered out. In a patient with a PFO, however, the bubbles can cross the heart and go up through the arteries into the brain. It’s a good screening test.”
One of the missions of the laboratory is involvement in cutting-edge research. The laboratory has been an ultrasound site for important national trials in stroke prevention in sickle cell disease (STOP Trial) and is currently a certified lab in the NIH funded CREST trial. In addition, it is the core lab for the multicenter, NIH-funded MyRIAD study evaluating mechanisms and predictors of stroke in intracranial atherosclerosis. Moreover, investigator initiated research on vertebral origin disease, plaque ulcers and fibromuscular dysplasia has led to presentation at international conferences and peer-reviewed publications.