Comparing a new MRI approach to SPECT, Japanese researchers have settled on nuclear medicine as the best way to predict cerebral perfusion for the time being.
The results of a preliminary study, done by imaging specialists at various Japanese institutions including Yamanashi Medical University in Nakakoma, were presented at the 1999 RSNA meeting. The group imaged nine patients in three different ways: Flow-sensitive alternating inversion recovery (FAIR), a technology that uses two-dimensional spin-echo planar sequences without contrast administration; a dynamic, contrast-enhanced 2-D gradient-echo EPI sequence; and I-123-IMP SPECT. The group hoped to establish a correlation between the MR signal intensity and the regional cerebral blood flow.
The results showed that image quality produced by the FAIR technique was very poor, while the quality of images generated by the nuclear medicine technology were the best. The results are an example of how FAIR continues to find its foothold in imaging, said Dr. Jia-Hong Gao, chief of the MR division at the Research Imaging Center, University of Texas Health Science Center in San Antonio.
"The principals for using FAIR to measure cerebral blood flow are there, but the technology isn't finished yet," said Gao. "I don't think the conclusion (of this study) is that FAIR isn't any good. We just haven't arrived at a point where it is a standard way to measure blood flow."
Gao said he is currently comparing PET and MR in cerebral blood flow measurement, which he expects to complete in the next few months. So far, results generated by the two modalities have been similar in terms of image quality, he said. In December 1999, Gao and his colleagues published the results of a studying comparing FAIR to blood oxygenation level-dependent-based (BOLD), event-related fMRI and found the former to be a more direct reflection of hemodynamic response (Magn Reson Med 1999 Dec;42(6):1011-1013).
From the nuclear imaging perspective, the positive result in favor of SPECT was not a surprise.
"The I-123 is nearly ideal for measuring cerebral perfusion," said Dr. Sue Abreu, medical director of quality assurance and a nuclear medicine specialist at Fort Bragg Hospital in North Carolina.
"This is an interesting study," Abreu said. "FAIR is not something I would rush to use to replace doing SPECT studies, but it's always interesting to note when one technique doesn't work as well as another. Not every study should show success. It's important to publish the less successful ones as well."
By Shalmali Pal
AuntMinnie.com staff writer
December 28, 1999
Copyright © 1999 AuntMinnie.com
