Heart Scanner - A Closer Look

Results: Harvey Greene holds plans for future locations of Toshiba Medical Systems’ new heart-scanning machine, which detected his blocked artery although he had no symptoms. JEBB HARRIS, THE REGISTER Graphic How the scanner works.   Ways to detect disease All methods for detecting heart disease have limitations. CT scans take pictures of the heart but expose the patient to radiation. Electrocardiograms measure the heart’s rhythm, but don’t provide a picture of the heart. Echocardiograms use ultrasound waves to take a picture of the heart but at a lower resolution. Magnetic resonance imaging (MRI) is promising but more expensive than CT scans. Angiograms are the best way to find blockages, but are invasive, lengthy and carry a small risk of stroke or infection.

When Harvey Greene volunteered recently to test out his employer's new heart scanner, he thought he was simply doing them a favor.

Greene, 62, had no symptoms or family history of heart disease. He's not overweight, walks two miles a day and usually takes the stairs when he makes hospital rounds as a medical-equipment installation coordinator for Tustin-based Toshiba Medical Systems.

But the scan performed on Toshiba's Aquilion 64 CFX showed plaque blockage in Greene's left anterior descending artery, which carries blood to the front of the heart. After a stress test a few weeks later, the Laguna Woods man received a stent device to open the artery, which had been 99 percent blocked.

"If I would have had a clot come through there, it would have been all over," Greene said. "I was probably a heartbeat away from having a massive heart attack."

The newest heart scanners offer a clearer, more detailed picture of the heart without invasive catheter procedures.

Toshiba and the UC Irvine School of Medicine are set to open a computed tomography (CT) education and research center on the school's campus this month that will use the Aquilion 64 CFX to detect heart disease.

Before the scanning, the patient receives a contrasting dye intravenously to help the radiologist interpret the images of the heart. The scanner rotates and quickly captures images of the heart while the patient lies down and holds his breath for about 10 seconds total.

Because the heart is constantly in motion, older scanners sometimes produced blurry pictures. The Aquilion's rapid-fire scanning essentially captures the heart at rest, allowing for clear, 3-D images. Doctors can rotate the images, projected onto a computer screen, to see the heart and arterial walls from every angle.

Detecting blocked arteries in the earliest stages of heart disease can reduce the need for surgical procedures, doctors said. Patients can be put on cholesterol-reducing drugs while blockages can still be reversed.

The gold standard for finding heart blockages is still the angiogram, an X-ray taken after a dye is released into the heart vessels through a catheter in the groin. Immediately following the angiogram, doctors can open a blockage by placing a stent or other device into the artery.

However, the angiogram carries some risk of stroke or infection, takes longer and is more expensive than the scanner. The scanner could be more appropriate for patients not believed to be at immediate risk for heart attack.

"The trend in angiography is imaging rather than intervention," said Dr. Kirk Ohanian, a radiologist and medical director at Newport Coast Advanced Imaging, which uses the Aquilion. "The benefit is for people who you don't want to subject to an angiogram and who you don't expect (will need) urgent intervention."

Biotechnology companies are continuing to improve the latest scanners' resolution quality in an effort to create a one-size-fits-all screening.

"The jump from where we were a year ago has been a four-fold difference in images we can take," Ohanian said. "With maybe 50 percent more improvement in the resolution we'll be pretty much there."

The high-tech scanners could prove helpful for screening patients in emergency rooms who complain of chest pain, making it easier to determine which patients are simply suffering from indigestion or a pulled muscle.

Some doctors are concerned that the new scanners will be overused, and patients could be unnecessarily exposed to radiation.

"Low-risk patients might insist that they have it. The doctors might use it randomly. There might be some financial incentives that the doctors might want to do it. I think the issues are not resolved yet and we have to be very careful," said Dr. Chowdhury Ahsan, a UCI assistant clinical professor. "Generally we will do this only on those who are intermediate- to high-risk patients."

Ahsan said he wouldn't recommend the scan for a 30-year-old woman with chest pain but no other issues, but he would order it for a 50-year-old man with diabetes whose father had had heart attacks.

If the scanner saves more people such as Harvey Greene from having heart attacks, it will have achieved its purpose, Ahsan said. "We are trying to build a program and our goal is as ambitious as zero heart attacks."