May 06, 2002
Laurie Barclay, MD
Two studies presented April 29 and April 30 at the American Roentgen Ray Society's annual meeting in Atlanta, Georgia, highlight new frontiers in imaging brain disorders: computed tomography (CT) angiography for vascular disease and tensor diffusion magnetic resonance imaging (MRI) for multiple sclerosis (MS).
"We are now using CT angiography with three-dimensional and maximum intensity projection in all cases of suspected vascular lesion of the brain," lead author Ashok Nath, MD, from Khoula Hospital in Oman, says in a news release. "The neurosurgeons have so much faith in the technique, they are using the images to plan surgery of patients with intracranial aneurysms and arteriovenous malformations (AVMs)."
In 50 patients with intracranial hemorrhage on plain CT, CT angiography scan with 3-dimensional and maximum intensity projection accurately diagnosed 30 intracranial aneurysms and 9 AVMs, including some aneurysms as small as 2 mm. The entire procedure takes only a few minutes and uses less radiation than digital subtraction angiography (DSA).
Although the technique missed 3 vascular lesions later seen on DSA, Nath attributes this to the radiologist's inexperience using the new technique. Subsequently, this technique detected 2 aneurysms that had been missed on DSA.
In the second study from Duke University Medical Center, tensor diffusion MRI showed abnormalities around MS plaques seen on conventional MRI, suggesting more accurate assessment of disease burden.
"Tensor diffusion imaging is a form of MR imaging that [measures] the rate and direction of water particles in the white matter structures of the brain," says lead author James Provenzale, MD. "Tensor imaging is allowing us to more accurately detect abnormalities in MS patients, which may allow us to diagnose the disease before the patient has any symptoms; early detection can mean earlier treatment."
Standard MR images do not necessarily correlate well with the patient's actual condition, Provenzale says, because the images may be normal until the patient has advanced disease. Tensor diffusion MRI shows abnormalities that are more extensive and in different regions.
Provenzale predicts that tensor diffusion MRI will eventually help detect degenerative conditions, such as Alzheimer's disease, in the earliest stages when treatment is most effective. Currently, his group uses it in Krabbe's disease with good results.
"If we scan patients at risk for the disease within the first month of life, and begin treatment immediately, their brains remain more similar to those of normal children than those infants treated later," he says.
AARS Annual Meeting. April 29-30, 2002.
Reviewed by Gary D. Vogin, MD
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