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Achieva 1.5T applications at NeuroScience Imaging

Best Practice
Dr. Iaia, Alberto, M.D. Newark, Del., NeuroScience Imaging USA

Achieva 1.5T excels in neuro applications at NeuroScience Imaging

The Achieva 1.5T continues to build its credentials as a top-of-the-line imager at NeuroScience Imaging (NSI, Newark, Del., USA), which began operating the system in June 2004, predominantly for neurological cases.The Achieva system excels at MRA, routine brain and skull base imaging, which comprise NSI's staple daily applications, according to NSI medical director Dr.Alberto Iaia. While committed to an unmatched imaging standard today, Dr. Iaia is harnessing Achieva's advanced capabilities in MR spectroscopy (MRS), diffusion tensor imaging (DTI) and BOLD fMRI in efforts to evaluate and refine the sophisticated techniques that neurosurgeons will rely on in the near future.
Dr. Alberto Iaia NeuroScience Imaging
Dr. Alberto Iaia
NeuroScience Imaging

NSI taps into multi-channel system's power in brain imaging

In addition to his duties at NSI, neuroradiologist Alberto Iaia, M.D., also is medical director at ChristianaCare Imaging Center (Neward, Del., US), where he gained experience on the Philips high field platform (Intera 1.5T). While impressed with that system, in evaluating NSI's high field purchase, Dr. Iaia felt compelled to compare the major vendors' 1.5T systems head-to-head - if not actually imaging on them, then by traveling to RSNA in 2003 and spending time evaluating relative system strengths on the exhibit floor.


"We wanted to do cutting edge imaging, including diffusion tensor imaging, BOLD fMRI, perfusion studies and MR spectroscopy," he says. "But image quality here and now was definitely the number one factor. From the image quality I saw on the various systems, I was very much impressed with that of Achieva, the new release in 2003. And, in particular, when I looked at the MRA image quality, I thought Achieva definitely had an edge over the competitors. The MRA quality, even using the SENSE coil, to make it a shorter acquisition study, was outstanding for the circle of Willis and certainly for the extracranial vasculature as well."

Absent artifacts

In clinical practice at NSI, both routine and contrast-enhanced MRA studies on Achieva have justified Dr. Iaia's system choice. "In the circle of Willis, for instance, with the 3D time-of-flight, I don't see the typical susceptibility artifact from pneumatized air cells in the petrous apex," he observes. "It's wonderful to obtain extremely high quality, smooth-looking vessels - including in all the areas we usually don't bother looking because we assume than any narrowing is really artifactual. So, that's really afforded me the ability to call, for instance, stenoses in the cavernous and petrous portions."


As with every other neuro study, NSI uses SENSE in the MRA exams as well. Nearly universally, SENSE is employed at the center to reduce overall scan times to maintain a very tight schedule. "We didn't realize the impact of SENSE imaging until one week in which the SENSE Head coil was down for a presumed malfunction and the technologists were not happy," Dr. Iaia recalls. "The image quality, however, is still outstanding. If you put SENSE and 'non-SENSE' images side by side it would be hard to find any difference."


Dr. Iaia also is very impressed with the MRA reconstructions the Achieva provides. "With the Achieva reconstruction, when you do tumble and left-to-right rotation, you retain the same degree of smooth delineation of the vessel contour - whether you're looking at it en face or actually rotating the dataset in space," he says.


  MIPs of the inner ear structures, imaged with the T2 DRIVE

  sequence for IACs.

Effective fat suppression in skull base, neck imaging

Another prominent advantage of Achieva 1.5T, in Dr. Iaia's view, is fat suppression. "In skull base studies, the degree of fat suppression is extremely homogenous and reliably so. And we achieve that excellent fat suppression even in areas where there usually is susceptibility," he notes. "For instance, if you're looking at the pterygopaltine fossa adjacent to the maxillary sinus, we can look at that area with fat suppression and not 'burn it out' with susceptibility from air."


Also notable is the suppression of CSF on FLAIR sequences. "A few vendors have been finding CSF pulsation artifacts and been having difficulties getting rid of them," Dr. Iaia observes. "The CSF suppression I've seen on Achieva is nothing less than outstanding."

DTI, MRS, BOLD fMRI shine spotlight on brain for neurosurgeons

As clinicians and scientists drive relentlessly toward more non-invasive and less invasive interventions in the brain (e.g. RF ablation, Gamma Knife« surgery), imaging advances are actually expanding the opportunities for more aggressive resections using traditional approaches. A growing cadre of neurosurgeons is even reluctant to proceed without the kind of information that sophisticated imaging techniques such as DTI, MR spectroscopy, BOLD fMRI and perfusion provide, Dr. Iaia says.


"For instance, a neurosurgeon from Sloan Kettering Cancer Center who spoke at the American Society of Neuroradiology last year said he would not go to the OR anymore without having that kind of functional and anatomic information," he recalls. "These MRI techniques really arm the neurosurgeon with the information that helps him or her identify what is vasogenic edema, what is tumor, and whether the tumor has infiltrated the white matter fiber tracts or merely displaced them. This has helped surgeons who, for instance, will ordinarily avoid attacking a lesion that affects Broca's area or the arcuate fasciculus - because disrupting the arcuate fasciculus could cause a conductive aphasia. If you can show the surgeon that the fasciculus is only displaced and not actually invaded by the tumor, then there's a solid chance to resect the lesion safely.


"This is also complemented by BOLD fMRI imaging," he adds "to determine whether the patient's speech center is active on the usual side - the left - or if this patient has bilateral language mapping." With the next Achieva software release, NSI will begin performing BOLD studies in earnest.

DTI evaluated in several applications

In terms of DTI, Dr. Iaia's knowledge comes not just from the literature and medical conferences, but from actual experience using NSI's Achieva system and a workstation.


"A recent case of a recurrent glioblastoma showed us that you can clearly appreciate the difference where the fibers are continuous and where they're interrupted by tumor infiltration," he recalls. "And there are measurements of fractional anisotropy that are different between the two sides; the degree of reduction of fractional anisotropy is not as pronounced in the scenario with mere displacement and vasogenic edema. Normally, when you look at the white matter edema on the FLAIR images, it's always difficult to determine what is edematous tissue and what is tissue infiltrated by tumor."


More recently, Dr. Iaia has been examining white matter fractional anisotropy in people with multiple sclerosis (MS). His focus is not only those areas that appear abnormal on FLAIR and T2-weighted images, but also "periplaque" and normalappearing white matter.


"Several studies have shown that some patients with MS have areas of normal appearing white matter that still show statistically significant reduction of fractional anisotropy compared to normal white matter in a control population," he explains. "In one recent case here, a patient - who seemingly had a very minimal amount of visible white matter plaque - had much larger areas of abnormal fractional anisotropy, which might reasonably be predictive of either future plaques or a lower grade of demyelination."

Brain protocol to include DTI and more

In preparation for larger roles at NSI for techniques such as DTI, MR spectroscopy and perfusion, Dr. Iaia intends to obtain DTI for newly diagnosed neoplasm or recurring neoplasm and MR spectroscopy in selected cases in an effort to create an imaging battery that will appeal to the desires of Newark-area neurosurgeons for better characterization of pathology and anatomy.


"I want to establish a tumor protocol whereby every patient that is heading for the OR will get a perfusion study, a BOLD study, and a DTI study," Dr. Iaia says. "I think that combination really arms the neuroimager, as well as the neurosurgeon and neurooncologist, with a tremendous amount of functional, anatomical and pathological data that is ideal to program the patient's optimal care."


Given more time in NSI's busy practice, a logical addition to such a protocol would be MR spectroscopy, Dr. Iaia adds. "We use MR spectroscopy now in certain occasions to work up lesions that are not necessarily diagnostic by conventional imaging sequences, for example, a patient with an abnormality that potentially has features of neoplasia, demyelination or inflammation," he says. "A combination of perfusion and single voxel MRS often allows me to understand that, if it's a hyperperfused lesion - and if the lesion does have a certain choline to creatine ratio - it is more likely to be in the neoplastic category than are hypoperfused lesions with a different spectrum."


NSI clinicians also employ multi-voxel MRS and perfusion in instances where patients who have a known tumor return after radiation therapy and have an enhancing abnormality and vasogenic edema. "We try to determine which areas are recurrent tumor and which regions are only radiation-induced changes."


With less than a year of Achieva 1.5T research and clinical work behind it, NSI has nonetheless plumbed a great many of Achieva's advertised capabilities. "We've done a lot in the last nine months, but the way I see it we've just barely tapped into Achieva's full potential."

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Aug 12, 2005

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Best Practice
Achieva 1.5T
Release 1
Nova, Nova Dual, Pulsar
Brain, Brain stem, IAC, Neck, Neuro, Spectroscopy, Vascular

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