Ultrafast Full-Body MRI Eases Procedure in Claustrophobics, Kids

CHICAGO--Echoplanar magnetic resonance imaging (MRI) was introducedin the late 1970s to scan parts of the body that exhibit rapidmovement, such as the heart and brain. At the annual scientificmeeting of the Radiological Society of North America, Gary Leavitt,MD, reported that an echoplanar imaging technique can completea full body MRI scan in less than a minute.

Whole-body scans performed on six volunteers using echoplanarimaging were completed during a single patient breath hold, withtimes ranging from 18 seconds to 40 seconds. A whole-body scanusing standard MRI would take 45 minutes or more, said Dr. Leavitt,of Yale University School of Medicine.

The speed of echoplanar imaging should make it easier to scanfor metastases or tumor involvement in the blood vessels in patientswho are difficult to image in the standard way, because they cannotremain relaxed and motionless for extended periods within theMRI device. Claustrophobics and children, for example, usuallycannot undergo imaging without sedation. However, sedation cancause serious adverse side effects, Dr. Leavitt said.

The ability of echoplanar imaging to provide a sweeping view ofthe entire body also should allow screening of patients to searchfor evidence of the spread of cancer, Dr. Leavitt added. Becauseof the speed of echoplanar imaging, acquisition of radiologicdata over large anatomic regions is feasible, he said.

The echoplanar scanning technique uses an MRI device that hasbeen equipped with hardware and software designed to slash thetime needed to acquire imaging data by reducing the number ofradiofrequency pulses used.

Patients Move Through the Magnet

Magnetic resonance imaging sends as many as 128 or 256 pulsesof radiofrequency energy into the body and waits for a signalor echo to return after each pulse. Echoplanar imaging, however,obtains data for an entire imaging plane with one radiofrequencypulse. Unlike conventional MRI, which bombards patients with radiofrequencywaves as they lie motionless within the machine, the echoplanarscanning technique moves the patient through the magnet on a motorizedtable.

The whole-body echoplanar scanning technique was well toleratedby all six volunteers, including a patient with a history of claustrophobia.

Dr. Leavitt said that the images were equal or superior in qualityto a series of control scans obtained while patients were confinedwithin the magnet. "Moving patients through the magnet actuallygives us the potential to create a better quality picture becauseevery image is being taken in the middle, or isocenter, of themagnet," he said.