Report from Stanford MDCT: Prototype 256-slice CT proves its might in stroke imaging

Rapid whole-brain CT perfusion imaging on a prototype 256-slice unit provides good results in stroke patients and may become competitive with other imaging modalities, according to research from Japan presented Friday at the Stanford Multidetector-Row CT Symposium in San Francisco.The prototype system, developed by Toshiba, has a wide detector that allows imaging of an entire organ in a single rotation at a low radiation dose. Clinical trials are now complete, and a commercial system is due to hit the global market by summer 2008, according to the company.CT perfusion has limitations on today's units due to lack of coverage of the whole brain, said Dr. Kazuhiro Katada, a professor of radiology at Fujita Health University in Toyoake. Multiple scans may be required, increasing radiation exposure to the patient, and parts of the brain such as the parietal lobe are not well visualized. Katada showcased performance of 256-slice CT in 11 patients with ischemic cerebrovascular disease, at low system settings of 80 kV and 80 mA. Scanning took about 50 seconds, and effective dose ranged from just 3.5 mSv to 4.6 mSv. Results were compared with conventional CT perfusion imaging and, in some cases, SPECT.Compared with conventional CT perfusion, the 256-slice images offered better visualization of lesions that were in the superior parietal lobe and remote effects, including crossed cerebellar diaschisis. Results were well matched to SPECT findings.Since it is possible to fuse the images with CT angiography studies to enable functional and morphologic assessment, whole-brain CT perfusion could some day provide a one-stop shop for ischemic brain disease assessment, Katada said.There are currently only two prototype 256-slice systems, one of which has been used in clinical trials at various sites. The most recent trial was conducted at Johns Hopkins University, which had a prototype unit for three months up to May 25. The university tested the scanner in 80 patients in a range of areas, including heart, brain, and orthopedic applications.Using the clinical trial data from Johns Hopkins and other centers, system developers have now finalized reconstruction algorithms, said Douglas Ryan, senior director of the CT business unit at Toshiba. Data analysis is still proving to be a challenge, Currently, 10 64-slice consoles are required for data processing, Ryan said in an interview at the conference with Toshiba expects major neuroimaging institutions to be among the early adopters, because of the potential benefits of whole-brain imaging in stroke. Few facilities have access to MR on a 24/7 basis to service stroke patients, Ryan said. Centers could accommodate these patients with 256-slice CT instead. "If a patient comes in at 3 a.m., within 15 minutes, you can get a complete perfusion analysis with arterial and venous overlays. It's just like a road map, making it crystal clear what is going on in the brain. Treatment and management of stroke are going to change dramatically," Ryan said.

Toshiba expects early adopters will also include the nine international sites taking part in the company's CorE 64 (Coronary Evaluation on 64) trial, including the following institutions:

• Johns Hopkins University
• Beth Israel Deaconess Medical Center
• Toronto University Health Network, Canada
• Leiden University, the Netherlands