JAS Neuroimaging Program:
The neuroanatomical program of the Neuroimaging Facility utilizes advanced imaging technology in the areas of magnetic resonance imaging (MRI), magnetic resonance angiography (MRA), computerized tomography (CT), and computerized tomographic angiography (CTA) to provide exquisite
definition of the normal and abnormal brain.
Housed in approximately 10,000 square feet, this
modern imaging facility provides state-of-the-art diagnostic imaging clinical evaluations. The
acquisition of the recent design "open" MRI scanner allows for the evaluation of patients who can not be accommodated in conventional "tube" MRI systems.
Magnetic Resonance Imaging (MRI)
Two networked MRI systems are available within the Facility whose capabilities complement
each other. An additional MRI (network linked) is located in our sister facility at the UNM Hospital.
A new Picker Edge 1.5T system currently anchors the MRI capabilities, providing a full range of
imaging options including MR spectroscopy and fast imaging sequences. This system represents
a full performance high-field scanner providing the highest resolution and image quality. This
system is also a platform appropriate for research and application of new MRI techniques.
The Picker Outlook 0.23T system represents the new open magnet design that allows much
improved patient access and monitoring during scanning. This allows patients too large or
claustrophobic for normal (cylinder) magnet designs to be comfortably scanned. The relatively
low field strength allows monitoring equipment to be brought closer to the magnet. The ready
patient access of the C-arm design allows interventional MRI procedures to replace some
procedures currently done using x-ray fluoroscopy. This system incorporates a number of new
MRI developments to allow rapid production of high quality images.
Complete data interchange capabilities, as well as imaging pulse sequence design and
implementation, are available for these systems and provide support for new clinical procedures
and are employed for specialized research requirements.
Current research activities are directed to improving imaging efficiency (e.g., segmented
sequences using new K-space data sampling patterns), spatial resolution (e.g., limited field of
view imaging using combinations of localizing pulses), and temporal resolution. Improvements
in the temporal resolution (e.g., by optimizing acquisition within cardiac cycles, reduced-data
reconstructions, and by projection or column imaging) provide the high-speed used in dynamic
imaging of contrast agent uptake for identification of pathology and for monitoring initial
characteristics of contrast passage measurement of accessible blood volume changes (i.e.,
contrast-based MR functional imaging). The images produced that contain different types of
anatomical information are incorporated into the image analysis and display activities described
Additional research topics include the use of simulated altitude exposures for both the study of Acute Mountain Sickness and as a model for water shifts to the head that occur with disease or during space flight and weightlessness. Experimental research
is also under way to develop imaging sequences that are more sensitive to intracranial bleeding
and changes in brain water content, understand MRI characteristics at low and high magnetic
field strengths, and evaluate the significance of object size changes observed in MR images.
MR Apparant Diffusion Coefficient Imaging (ADC)
This powerful technique is being evaluated in the early detection and evaluation of stroke patients. It is also employed in assessing Multiple Sclerosis and brain edema.
MR Perfusion Imaging
The is a dynamic technique that takes advantage of the rapid echo-planar-imaging (EPI) capabilities of the Picker Edge scanner. By examination of the image characteristics taken during injection of gadolinium contrast agents, tissue perfusion and blood volume mapping can be assessed.
Magnetic Resonance Angiography (MRA)
MRA is increasingly being established as an important clinical procedure for assessing the
effectiveness of blood delivery to regions of the brain. Both MRI systems offer effective
angiography capabilities that support both clinical and research activities of the Facility.
The proximity of vessel structures with respect to pathology is often an important consideration
in surgical planning. Research is ongoing in improving MRA capabilities so that vessels can be
more effectively identified, avoided, and/or used as landmarks to guide surgeons to pathology.
Improved visualization of the tortuous vascular structure is provided by holographic display.
Localization of vessel structures on the brain surface allows intraoperative systems to
accommodate brain swelling and movement during surgery.
Additional blood flow research at the Facility includes the development of quantitative blood
flow measurement sequences to more accurately assess blood delivery and the computer
simulation and modeling of blood flow effects on the signals that are made into images.
Computed Tomography Angiography (CTA)
Clinical neuroradiology relies extensively on the complementary information available from
MRI and CT, with the application of either or both being dictated by the specifics of clinical
A new Siemens Somatom Plus CT system is available within the Facility and is fully capable of
the latest imaging procedures including continuous spiral scanning and CT angiography.
Additional interventional procedures can also be performed in conjunction with this system. CT
image information is being incorporated into the development of new types of display
X-ray Computed Tomography (CT)
Computed tomography angiography (CTA) is a relatively noninvasive method that allows for the
evaluation of vascular structures without the risk of routine angiography. By using the advanced
technique of spiral CT, a large volume of patient information can be obtained in seconds. Spiral
CT, unlike conventional CT, uses a continuous rotating gantry while the patient advances
through the scanning plane. When the scan is performed during an appropriately timed
intravenous contrast injection, reconstructed images can demonstrate detailed arterial anatomy.
The data can also be applied to a variety of three-dimensional techniques, including holography.
Bone and soft tissue structures may be left in the image or may be removed to allow improved
visualization of vascular anatomy from any angle. CTA may be performed quickly, and on an
outpatient basis. CTA is advantageous in imaging uncooperative or claustrophobic patients.
The spiral CT images can be obtained routinely in only 36 seconds and scans can be obtained
without the constraints of body size or indwelling medical appliances that may prohibit
Last Modified: July 14, 1999
Copyright 1999 John A Sanders, VAMC