19 February 2010. The Alzheimer’s Disease Neuroimaging Initiative has provided AD researchers with reams of data. Could imaging do the same for those studying amyotrophic lateral sclerosis? Some researchers hope so (see ARF related news story). The latest news in the effort to image ALS comes out of the University of California in San Francisco, with a paper published online by the journal Neurology on February 10. Randall Rule and colleagues, in the laboratory of Norbert Schuff, attempted to match ALS severity with the level of blood flow in the brain.
The researchers recruited 16 subjects with ALS. They analyzed brain blood flow, or perfusion, with arterial spin labeling, a non-invasive form of magnetic resonance imaging. To correlate the perfusion results with symptoms, they used the ALS Functional Rating Scale to categorize severity of motor symptoms, and forced vital capacity to measure breath volume. A decrease on the rating scale or breath capacity was correlated with a drop in brain perfusion. To measure upper motor neuron involvement, they asked participants to rapidly tap their fingers and toes. Similarly, this was also related to perfusion.
“The current findings, while preliminary, are promising,” the authors write. “Brain perfusion may be a useful tool for monitoring disease progression and assessing treatments in ALS.” Currently, lower motor neuron deficits can be measured clinically, but there is no reliable means of determining deficits of upper motor neurons, though several functional and structural imaging techniques are under evaluation. One caveat in this study is that there was no control group, so it is impossible to compare the results to brain perfusion in healthy individuals.
Arterial spin labeling is a more practical technique than some other imaging modalities, wrote Martin Turner of Oxford University, UK, in an e-mail to ARF. Turner was not involved with the study. For example, there is no need to inject radioactive tracers, as PET imaging requires. Turner called the results “encouraging” but said a larger, controlled study, following participants for multiple timepoints, is required.
Clinicians desperately need biomarkers to both diagnose ALS and to track its course in clinical trials (see ARF related news story). “The technique has not that much potential for anything more than making correlations…yet,” wrote Jonathan Katz of the California Pacific Medical Center in San Francisco in an e-mail to ARF. He also was not part of the current work. But if researchers could reduce the amount of noise in the signal, making it easier to see changes, it “holds some promise,” Katz wrote.—Amber Dance.
Rule RR, Schuff N, Miller RG, Weiner MW. Gray matter perfusion correlates with disease severity in ALS. Neurology. 2010 Feb 10. Abstract