GE combines MRI and cardiac cath to improve efficiencies

Replacing the image intensifier with a digital flat-panel detector last year made it possible for GE’s Innova product to run MRI along side cardiac cath. Flat-panel sensors are not vulnerable to magnetic waves, as are conventional image intensifiers. Now GE has taken on the next challenge: convincing cardiologists that combining the two makes clinical sense.

At the American College of Cardiology meeting in Orlando in mid-March, the company debuted the X-MRI suite, a fusion of its all-digital cath lab with the version 8.4 Signa CV/i, a 1.5-tesla MRI scanner optimized for cardiovascular imaging. The idea is to take advantage of MRI’s growing ability to assess cardiac function, perfusion, and viability to determine which patients need coronary interventions and in which arteries. After angioplasty or stenting, the patient would be taken back for another MRI scan to confirm whether the procedure improved the supply of blood and oxygen to the heart.

Incorporated into the X-MRI are several innovations aimed at improving efficiency and productivity. The angio suite and MRI scanner, which would be located in adjoining rooms, share a common detachable table. This permits staff to use a separate room to prepare patients for the initial MRI scan, placing leads and coils and giving instructions, such as how and when to do breath-holds. The interconnection also allows the patient to be wheeled between the scanner and cath lab without need for additional setup.

The latest version of Signa CV/i itself incorporates several improvements that were on display at the ACC show. New software includes sequences for the imaging of gross cardiac anatomy, ventricular function, rest and stress perfusion imaging, viability testing, and angiography of the proximal coronary arteries.

A long-standing deficiency of cardiac MRI, its need for extended scanning, has been overcome. Cardiac iDrive enables real-time interactive localization of all imaging planes in about two minutes. The entire exam takes no more than 30 minutes, according to GE. To minimize idle time, the CV/i can scan the next patient while completing the image processing, reconstruction, and networking for the previous exam.

It’s still too early to know how practical the system will turn out to be, but on-site MRI has potential advantages over both nuclear imaging and echocardiography, said David Weber, manager of MRI global growth for GE.

“We know the image quality is exquisite for perfusion, wall motion, and viability, but this is an emerging application, and we need to do rigorous clinical studies to establish sensitivity and specificity,” Weber said.

The first X-MRI installation is in the works in a stroke lab at Massachusetts General Hospital. GE hopes to have three or four cardiovascular X-MRI operations up and running by the end of September.

Also expected to make its commercial debut in the fall is GE’s TwinSpeed MRI scanner. This dual-gradient scanner was shown as a work-in-progress at the annual meeting of the RSNA last year (SCAN, 01/17/01). TwinSpeed will eventually replace CV/i in the X-MRI suite. Weber said, offering a 48-cm field-of-view, rather than the Signa CV/i’s 40-cm FOV. It will also be much quieter than the CV/i, an important improvement for medical staff who may need to be in the room to monitor an unstable patient during the scan.