CHICAGO--Echoplanar magnetic resonance imaging (MRI) was introduced
in the late 1970s to scan parts of the body that exhibit rapid
movement, such as the heart and brain. At the annual scientific
meeting of the Radiological Society of North America, Gary Leavitt,
MD, reported that an echoplanar imaging technique can complete
a full body MRI scan in less than a minute.
Whole-body scans performed on six volunteers using echoplanar
imaging were completed during a single patient breath hold, with
times ranging from 18 seconds to 40 seconds. A whole-body scan
using 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 scan
for metastases or tumor involvement in the blood vessels in patients
who are difficult to image in the standard way, because they cannot
remain relaxed and motionless for extended periods within the
MRI device. Claustrophobics and children, for example, usually
cannot undergo imaging without sedation. However, sedation can
cause serious adverse side effects, Dr. Leavitt said.
The ability of echoplanar imaging to provide a sweeping view of
the entire body also should allow screening of patients to search
for evidence of the spread of cancer, Dr. Leavitt added. Because
of the speed of echoplanar imaging, acquisition of radiologic
data over large anatomic regions is feasible, he said.
The echoplanar scanning technique uses an MRI device that has
been equipped with hardware and software designed to slash the
time needed to acquire imaging data by reducing the number of
radiofrequency pulses used.
Patients Move Through the Magnet
Magnetic resonance imaging sends as many as 128 or 256 pulses
of radiofrequency energy into the body and waits for a signal
or echo to return after each pulse. Echoplanar imaging, however,
obtains data for an entire imaging plane with one radiofrequency
pulse. Unlike conventional MRI, which bombards patients with radiofrequency
waves as they lie motionless within the machine, the echoplanar
scanning technique moves the patient through the magnet on a motorized