John Hopkins testing 256-slice CT
Johns Hopkins Medicine has installed for three months of initial safety and clinical testing an advanced 256-slice CT scanner. The new 2-metric-ton device, the first of its kind in North America and only the second outside of Japan, has four times the detector coverage of its immediate predecessor, the 64-CT. It can measure subtle changes in blood flow or minute blockages forming in blood vessels no bigger than the average width of a toothpick (1.5 millimeters) in the heart and brain. 
Made by Toshiba, the Aquilion beta 256 is expected to win approval for general clinical use within a year, Toshiba said. Hopkins is negotiating the purchase of the equipment, which has a sticker price of more than $1 million. 
Johns Hopkins cardiologist João Lima, M.D., who will lead all cardiovascular testing, said the scanner’s strength means it can find the earliest signs of restricted blood flow, long before symptoms appear or an organ becomes permanently damaged. 
Lima, an associate professor at The Johns Hopkins University School of Medicine and its Heart Institute, said blockages in arteries, veins or capillaries in any organ can simmer for years, with signs of chest pain, severe fatigue and headache emerging only after the disease has become seriously life-threatening. 
The key technological advance of the 256-CT, which looks like a patient table surrounded by a massive, doughnut-shaped metal ring, called a central gantry, is its greater number of detectors, which cover in a single scan four times the area of the 64-CT. 
Interventional neuroradiologist Kieran Murphy, MD, an associate professor of radiology at Hopkins, said he believes that whole-head perfusion imaging scans will be able to find slowed blood flow areas in the brain that are vulnerable to stroke, and with just one scan. 
Murphy, who is in charge of neurological testing with the scanner, says the expanded coverage is a “tremendous advantage” over older machines, where images had to be matched and stacked, “like reconstructing layers of a marble statue on top of each other over time,” a technologically complex procedure.

Cooling systems, he also notes, will no longer be required to deal with the friction and heat caused by multiple rotations of the gantry, although a cooling system will still be required for the computer hardware.