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Holography Aids in Difficult Vascular, Spinal and Cranial Procedures, Neurosurgeons Report at AANS
For Immediate Release
April 14, 1997 ñ Denver ñ Physicians reporting at the American Association of Neurological Surgeons (AANS) annual meeting describe how the Voxel Digital Holography System is helping them plan and perform complex neurosurgeries.
The Digital Holography System uses data routinely collected by Computed Tomography (CT) and Magnetic Resonance (MR) scanners to produce true three-dimensional images. The life-size, transparent holograms, Voxgrams"š, literally extend out in space. Voxgrams enable a physician to interact in, around and through an image as if it were a real specimen of anatomy.
The presentations focus on how Digital Holography is helping physicians treat difficult neurovascular pathology, complex spinal diseases and cranial abnormalities.
Holographically Guided Surgery: Applications and the Merging of Technologies ñ Dr. Frederick W. Rupp, Assistant Professor of Neuroradiology at the University of New Mexico School of Medicine (Albuquerque), describes how neurosurgeons are currently using holograms to help them treat conditions such as spinal fractures, degenerative diseases and tumors.
The 3-D, life-size images ìportray a large amount of CT and MRI data in a unified fashionî and allow the physicians to precisely measure and ìpracticeî the angle of
hardware insertion preoperatively. Intraoperatively, the ìholograms can be placed at the surgeonÃs side for referenceî and ìphysicians can see multiple views simply by looking around the Voxgrams.î Additionally, surgeons can ìfuseî the Voxgrams, combining data sets from complementary modalities (such as CT and MR myelograms) for a more complete and accurate view of the patientÃs condition. In Dr. RuppÃs experience, the holograms ìhave made a significant difference in approachî in difficult surgical cases.
Future potential applications discussed by Dr. Rupp include combining Digital Holography with frameless stereotactic technology, and superimposing holograms onto the patient, giving physicians an accurate, 3-D ìguideî to the patientÃs anatomy. (Invited presentation, Holography and the Merging of Technologies, Image-guided Spine Surgery session, Wednesday, April 16, 2:45 to 4:00)
Holographic Guidance in Lumbar Foramen Surgery ñ Dr. William C. Bergman, Assistant Chief of Neurosurgery and Director of Neurosurgical Research at Santa Clara Valley Medical Center (San Jose, California), evaluated the use of Digital Holography in preoperative and intraoperative planning of lumbar foramenotomies.
Holograms from CT data were compared to standard CT images with regard to usefulness for preoperative planning. The ìmid-air bony image allowed the surgeon to actually place an instrument on a facsimile of the patient's spine and enabled measurements to be made in terms in ëKerrison bitesà rather than millimeters.î This information helped the surgeons to more realistically evaluate the amount of bone that was appropriate for removal.
Dr. Bergman concluded that, ìalthough the holograms contain only information present on the parent CT, the life-like representation gave the surgeon a more realistic appreciation of the pathology.î Holographic imaging of the lumbar spine is ìhighly usefulî in preoperative and intraoperative planning, and ìthe information obtained significantly complements and even surpasses the parent study.î (The Microanatomy of the Lumbar Foramen Studied With Holographic Imaging, Spine Poster 1352) For Cranioplasties, Holographic Images Yield Savings ñ Dr. Bergman also evaluated the use of holography as an inexpensive method of creating cosmetically appealing cranioplastic molds. This study focused on particularly difficult cranioplasties that have, until now, been best served by expensive, computer-generated molds.
Holograms from CT images were reversed on the lightbox, forming a ìpartially free-standing, transparent mirrorî image of the intact region. A model of the proposed cranioplasty was hand molded until it accurately fit into the light image. This model was used to create a negative mold that was, in turn, used to develop a methyl methacrylate cranioplasty.
Dr. Bergman concluded that holographic images can ìprovide a satisfactory and economic alternative to computer-generated cranioplasties.î (The Use of Holographic Images as an Aid in Difficult Cranioplasties, General Interest Poster 1215)
Holography Aids Repair of Traumatic Craniospinal Dislocation ñ Dr. Sandy A. Shatsky, Chief of Neurosurgery at Santa Clara Valley Medical Center and Associate Clinical Professor at Stanford University School of Medicine, evaluated the efficacy of holograms in helping treat traumatic dislocations of the craniospinal junction.
Twelve patients, some of whom were comatose and/or paralyzed, underwent standard plain film and CT imaging. The latter was augmented with sagittal and coronal reconstructions of spiral or planar axial images. Holograms were made of the CT data from two patients and MR data from one patient to aid in understanding the injury and its surgical reconstruction.
Dr. Shatsky found that ìthe 3-D holograms of the dislocations made it easier to understand the anatomic distortions of extremely complex injuries.î Dr. Shatsky is currently using Digital Holography for a large series of traumatic spine injuries. (Imaging and Operative Repair of Traumatic Dislocations of the Craniospinal Junction, Trauma and Critical Care Poster 1394)
Holograms Speed Diagnosis, Increase Accuracy of CTA Data ñ Dr. Wayne J. Olan, Chief of Neuroradiology at George Washington University Medical Center (Washington, D.C.), examined whether Digital Holography could improve the display of CT Angiography (CTA) of cerebral vasculature, especially as compared to renderings.
Helical CTA exams of the cerebral vasculature of 25 patients were acquired and life-size holograms generated. The doctors used the holograms to duplicate the exact perspective of the anatomy and pathology seen at surgery.
The ìtransparent 3-D light sculptures of anatomyî permit ìgreater appreciation of depth.î The holograms ìallow the reader to quickly choose the optimal perspective for viewing pathology with nearly infinite adjustability within a 45∞ viewing cone. This allows rapid identification of normal anatomy, obvious pathology and the important anatomical relationships between the two.î
Dr. Olan concluded that ìCTA-based neurovascular pathology is easily visualizedî with Voxgrams. ìThe transparency and easily adjustable viewing perspective of the hologram allow a much greater appreciation of pathology and related anatomy as compared with surface renderings.î (Holographic Display vs. ì3-Dî Surface Renderings of Neurovascular Pathology from CTA Data, Cerebrovascular Poster 1086)
Holograms Improve Accuracy of MR Angiograms for Neurovascular Disease ñ Dr. Olan also compared Digital Holography with standard MR Angioigraphy (MRA) display. Life-size holograms were produced from MRA of 20 patients. Unlike standard Maximum Intensity Projections (MIPs) of MRA data, ìthe hologram presents 100 percent of the data from a wide viewing angle. Because the hologram is truly 3-D, greater appreciation of depth is afforded through normal physiological depth cues.î
Dr. Olan concluded that the adjustable viewing perspective, transparency and ìgreater availability of data of the holograms allow a much greater appreciation of pathology and related anatomy as compared with MRA MIPs.î (Holographic Display vs. Reformatted MRA of Neurovascular Pathology, Cerebrovascular Poster 1056)
Carotid MRA Holograms + Ultrasound May Be a New Standard in Imaging ñ Dr. Steven M. Wetzner, Chairman of the Department of Radiology of New England Baptist Hospital (Boston), evaluated the combination of MRA-based holograms plus ultrasound as a potential alternative to angiography in the assessment of atherosclerotic disease.
Thirty patients underwent standard color Doppler ultrasound (CDI) and MRA. Volumetric holograms were created from the MRA data. Two independent viewers evaluated the MRA and CDI images for diagnostic concurrence and for the potential for therapeutic intervention.
The doctors found that both the ìMRA volumetric holograms and CDI provide an accurate depiction of lesions at the carotid bifurcation.î In 28 of the 30 patients, the sonographic images agreed with the holographic appearance of the luminal stenosis. In the remaining two patients, the sonographic images suggested that there was vessel occlusion, whereas the MRA hologram accurately demonstrated that the arteries were partially open. Dr. Wetzner concluded that the combination of CDI and holographic MRA ìappears to be an extremely effective tool in the preoperative evaluation of carotid atherosclerotic disease and may supplant angiography as a new gold standard.î (Holographic MR Angiography [HMRA] and Color Doppler Ultrasound Imaging [CDI] of Atheriosclerotic Disease: Is There a New ìGold Standard?î Cerebrovascular Poster 1030)
Other Studies ñ In addition to the institutions cited above, several other prominent medical institutions throughout the country have studied Digital Holography, including Beth Israel Hospital-Harvard Medical School, Massachusetts General Hospital, Mallinckrodt Institute of Radiology, Walter Reed Army Medical Center and UCLA.
The Digital Holography System was awarded FDA clearance in October 1995. Voxel, based in Laguna Hills, California, is a public company founded to develop, manufacture and market holographically based, volumetric display systems. More information is available on the companyÃs web site (http://www.voxel.com).
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Note to Editor: Video of some of the studies is available.
Voxel and Digital Holography are trademarks, and Voxgram is a registered trademark of Voxel.
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