Digital Holography Speeds Surgery and Surgical Planning; Brain, Spine, Carotid and Pelvic Cases Reported.

MONTREAL--(BUSINESS WIRE)--Sept. 27, 1996--Doctors reporting at two medical conferences this week will describe how the Voxel Digital Holography System is helping them plan and perform surgeries.

The Voxel 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, literally extend out in space. Physicians can interact with the holograms as if they were interacting with the patient.

The studies will be presented at the annual meetings of the Congress of Neurological Surgeons (CNS) and Orthopedic Trauma Society nOTS) in Montreal and Boston respectively. The studies describe the clinical and economic utility of digital holography in planning and performing brain, spinal and pelvic surgeries, as well as in evaluating atherosclerotic disease.

Deep-Seated Brain Tumors: Holograms Make Surgery Simpler and Faster

Dr. William Bergman, Assistant Chief of Neurosurgery and Director of Neurosurgical Research at Santa Clara Valley Medical Center (San Jose, Calif.), investigated the use of holograms as a simple and inexpensive alternative to the complex image-guided removal of deep-seated brain lesions.

Stick-on markers (fiducials) were placed on the patient's skin, outlining the placement of burr holes for the proposed craniotomy. CT and MR scans were taken with the fiducials in place and holograms prepared. The two holograms were "fused" by superimposing them on top of each other. Prior to the surgery, instruments were placed inside the lifesize 3-D holographic projection to pre-determine location, fit and operative technique.

Burr holes were drilled on the patient at the location of the fiducials. "Measurements taken directly from the hologram were then used to effect a very precise tumor resection, with the smallest possible craniotomy," according to Dr. Bergman.

Dr. Bergman pointed out that "holograms allow a form of `image-guided' tumor resection and do so in a much simpler and less expensive manner than most of the commercially available devices."

Dr. Bergman's presentation will be part of the "Innovations in Technology and Techniques in Neurosurgery: a Look Towards the Future" program. Additionally, his abstract was prepublished on Neurosurgery://on-call. (Image-Guided Craniotomy Using a Holographic System, CNS Oral Presentation; Tuesday, October 1, 12:45 to 1 p.m.)

Skull Base: Holographically Assisted Neurosurgery (HANS) of Deep-Seated Tumors

In an equally complex application, Drs. John J. Collins, Chief of the Department of Neurosurgery, and Bradford S. Burton, Chief of MRI at Tripler Army Medical Center (Honolulu), utilized the holograms in preoperative planning and intraoperative confirmation of base-of-skull anatomy for the resection of a tumor.

3-D holograms were made of the patient's bony structures (from helical CT scans), vascular detail (from MR angiograms) and tumor margins (from MRI data). The clinicians evaluated how the holograms demonstrated the spatial relationships between the three interrelated structures -- bone, vessels and soft tissue pathology.

The "holograms presented these structures as vivid, stereoscopic, life-size images projected into space." The images possess the "unique characteristics" of transparency, interactivity and three-dimensionality that "facilitate preoperative planning." Specifically, the transparent holograms "allow visualization into and through bone to identify bony substructures." The interactive nature of the holograms allows doctors to place "instruments directly into the image to determine angles, distances and trajectories." The stereoscopic three-dimensional image "closely matches the intraoperative perception provided by the binocular operative microscope."

The holograms were used not only in preoperative planning, but in the OR to guide the surgeons during the delicate procedures. The surgeons concluded that the holograms "present in one image a vast amount of radiographic data," which provides surgeons with a "powerful tool for detailed preoperative planning as well as intraoperative guidance." (The Use of Holograms Generated from Very Thin-Slice Contrast Helical CT and MR Angiograms for Planning Cranial-Base Tumor Surgery: A Report of Three Cases; CNS Poster Presentation 294 - Tumor Section)

Holographic Display of Spinal Hardware More Accurate Than CT or Renderings

Dr. Wayne J. Olan, Chief of Neuroradiology at George Washington University Medical Center (Washington, D.C.), evaluated the use of holography to guide spinal procedures involving the use of stabilization hardware.

Holograms and 3-D computer renderings were prepared from helical 3-D CT scans of 15 patients with hardware. The computer renderings were "virtually non-diagnostic because of the artifacts," while the "holograms substantially reduced metallic artifacts." Specifically, "the artifact that previously rendered the study non-diagnostic was virtually no longer discernible on the holograms."

Dr. Olan concluded that the holograms, which "clearly display hardware, post-surgical changes and resultant anatomy, allow the clinician and the neuroradiologist to accurately assess the 3-D relationships in those patients with spinal hardware." (Holographic Display of Helical 3-D CT in Patients Status Post Spinal Hardware; CNS Poster Presentation 190 - Spine Section)

MRA Holography Plus CDI Effectively Assess Atherosclerotic Disease

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 MR Angiography (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 "MRA volumetric holograms and CDI provide an accurate depiction of lesions at the carotid bifurcation." 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 "appears to be an extremely effective tool in the preoperative evaluation of carotid atherosclerotic disease and may supplant angiography as a new gold standard." (Atherosclerotic Disease by Holographic MR Angiography and Color Doppler Ultrasound Imaging: Is There a New Gold Standard? CNS Poster Presentation 66; Vascular Section)

Pelvic Holograms Provide More Precise Information, Change Surgical Plans

Dr. Gregory A. Zych, Chief of Orthopaedic Trauma of the University of Miami, Ryder Trauma Center at Jackson Memorial Hospital, evaluated the use of holograms in determining the location and extent of pelvic and acetabular injuries.

This blinded study compared plain anterior/posterior pelvic radiographs plus two-dimensional CT scans with digital scout film plus holograms made from CT sections on 25 patients. Fifteen of these patients suffered from acetabular injuries and 10 had pelvic injuries. The studies were divided into two groups. One consisted of the plain AP radiographs and two-dimensional CT scans, the other of the digital scout film and holograms.

An experienced trauma radiologist classified the pelvic and acetabular injuries, as did two experienced orthopedic traumatologists who were blinded to the radiologist's interpretation. Additionally, for those patients who had subsequently undergone surgery, the findings at the time of surgery were correlated with the data from the imaging studies.

The clinicians found that "the combination of digital scout film and holograms resulted in a more precise diagnosis and provided more information as to the location and extent of fracture lines in injury than did the more traditional group of data." In particular, the holograms provide "the ability to reconstruct the data provided by a conventional CT scan into nearly a three-dimensional model."

During pre-operative planning, the doctors changed their intended surgical approach in four patients because of the additional information provided by the holograms and digital scout film. (Comparison of Plain Radiographs and Two-Dimensional CT with CT Digital Scout Film and Holograms in the Evaluation of Pelvic and Acetabular Injuries; OTS Poster Presentation 212)

Other Studies

In addition to the institutions cited above, numerous other prominent medical institutions throughout the country have studied the Voxel Digital Holography System, such as Beth Israel Hospital - Harvard Medical School; Mayo Clinic; University of California, San Diego; and Children's Hospital of Philadelphia - University of Pennsylvania.

The Voxel Digital Holography System was awarded FDA clearance in October 1995 and received a Notice of Allowability on 13 patent claims from the U.S. patent office in August 1996. Voxel, based in Laguna Hills, Calif., is a public company founded to develop, manufacture and market holographically based, volumetric display systems. -0-

Note to Editors: Voxel and Digital Holography are trademarks and Voxgram is a registered trademark of Voxel.

Video of some of these studies is available.

CONTACT: Voxel

Raymond Schulz, 714/348-3200

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