Las Vegas imaging center serves as proving ground

July 1, 2008

The patient who reported for a CT scan at the Spring Valley imaging center in Las Vegas complained of headaches, but the images returned by the newly installed AquilionOne CT scanner indicated something much worse was probably on the way. Neuroradiologist Dr. William Orrison defined a major region of hypoperfusion in the brain, a warning sign that the patient was at risk of stroke.

The patient who reported for a CT scan at the Spring Valley imaging center in Las Vegas complained of headaches, but the images returned by the newly installed AquilionOne CT scanner indicated something much worse was probably on the way. Neuroradiologist Dr. William Orrison defined a major region of hypoperfusion in the brain, a warning sign that the patient was at risk of stroke.

There were, however, no obvious signs of vascular pathology. The scanner showed no major stenoses in the arteries leading to the hypoperfusion; vessels were intact. Orrison, medical director of the Spring Valley center, ascribed the defect to microvascular disease, a clinical problem with no established therapy.

"We may have to come up with new treatment regimens for these individuals," he said. "But at least AquilionOne gives us an opportunity to identify the disease."

This was the first such patient seen at the center, one of several Nevada Imaging Centers in Las Vegas, but likely not the last. AquilionOne had been operating only about five weeks when Diagnostic Imaging came to visit. In that time, close to 300 patients had been scanned on the system, as the imaging center channeled its patient load to this, the third AquilionOne installation in the U.S. The site was chosen because of its high number of patients.

At the time, two other AquilionOne sites were operating, one at Johns Hopkins University, the other at Brigham and Women's Hospital. Both had been concentrating on neuro and cardiac protocols since their scanners, featuring the industry's only wide area detector with 320 detector rows, began running last October. AquilionOne can capture the whole heart in a single spin of the imaging chain. It can perform an arteriogram, venogram, digital subtraction angiogram, and perfusion scan in a single examination with data acquired during a series of rotations.

The CT detector, its 16-cm width four times that of 64-slice scanners, makes this possible. The 320 detector elements, each 0.5 mm wide, rotate once every 350 msec, acquiring data that are both volumetric and dynamic.Like the Hopkins and Brigham sites, the Spring Valley center performs cardiac and neuro exams. But the staff does much more. Their mission is to find ways to streamline patient and data handling in a high-throughput environment where virtually every kind of CT exam is done.

After little more than a month in service, the AquilionOne at Spring Valley had been used to scan the body from chest to pelvis and from the neck to the tiny bones in the ear. It had even scanned moving joints.

"The dynamic images of major joints have been particularly exciting for me because they're something I have never seen before," Orrison said.

The brain scans may be especially appealing to the neuroradiologist, who describes the future of healthcare as finding the signs of disease before the disease takes effect, so patients can be treated preventively.

"With AquilionOne, we are finding ischemic areas of the brain that I don't think I would have been able to diagnose with any other modality," he said.

Orrison is collaborating with cardiologist Tony DeFrance to develop a cardiac program at the center. DeFrance, medical director of CVCTA Education, a diagnostic and educational imaging center in San Francisco, lauds the AquilionOne as providing a wealth of new information, such as finding tiny deposits of plaque in coronary vessels. Image quality is substantially better than that of 64-slice scanners, he said.

"Because the data are acquired in one heartbeat, the contrast is completely uniform," he said. "Otherwise, a scan would take five or six heartbeats; the contrast would be moving and you would see misregistration from the multiple segments."

DeFrance uses the power of Vital Images' Vitrea fX, a workstation specially designed to handle data coming from AquilionOne, to look inside the chambers of a volumetric reconstruction of a heart scanned at the center. A self-described "vessel walker," the cardiologist uses the workstation to walk the multiplanar reformat of the left anterior descending coronary artery to the tip of the heart.

"You can see here a little plaque," he said, pointing to the left anterior descending artery. "You wouldn't see that on an angiogram. The AquilionOne has beautiful image quality, and it's done with 3 mSv of dose."

Taken together, the wide-ranging work done at the Spring Valley center in the brain, chest, and body will help Toshiba prepare for the commercial launch later this summer of its new scanner. The company will position AquilionOne as a radiological workhorse, capable of handling the most demanding challenges of brain and heart scanning, yet easily capable of doing any routine scan. The Spring Valley center, with its high patient throughput, will lay the groundwork for applying this system to a wide spectrum of work at the installations that follow.

"We want to be sure we can do large numbers of patients on a continuous basis," said Doug Ryan, senior director of Toshiba's CT business unit.

At the end of May, about 10 AquilionOne units were operating at various sites around the world; another 50 were on order. Among the sites scheduled to take delivery soon were the National Institutes of Health Clinical Center, Beth Israel Deaconess Medical Center, University of Florida Shands, and Arkansas Children's Hospital.

Toshiba's growing list of luminaries will look into protocols not only for brain, heart, and high throughput, but also lung and pediatric applications. With these, customers taking delivery in late summer and beyond will be able to get the most out of their systems right from the start, Ryan said.

Minimizing dose is a key component of all the protocols in development. Early use of the system has documented a 75% drop in dose for heart studies and 20% reduction elsewhere in the body. The gains come from leveraging the wide area detector to eliminate the need for overlapping helical scans, Ryan said.

"We can give you a much lower dose with much bigger clinical utility," he said.