Saigal G, Pattany P, Quencer R, Pasquale-Styles M, Norenberg M, Marcillo A, Post MJD
University of Miami, Florida

Purpose and Background:
Spinal cord injuries can be both devastating and debilitating. About 11,000 spinal cord injuries occur in the US alone, each year. The ultimate objective of research in spinal cord injury is being able to find more effective treatments, the eventual goal being able to find a cure for paralysis following spinal cord injury. Various therapies are being developed to combat this injury and help in restoration of neurological function. One of these includes administration of steroids in the spinal cord immediately following injury. Other promising strategies being explored at the present time include treatment with growth factors and transplantation with nerve cells, Schwann cells and stem cells. Complete understanding of spinal cord injury is key to guiding development of new treatment strategies. Remarkably much is still unknown about pathology to the spinal cord following injury.

Wallerian degeneration is a post injury phenomenon which begins almost immediately following spinal cord injury. It can be divided into antegrade and retrograde (Wallerian) degeneration, with anterograde degeneration proceeding distally towards the axon terminals and retrograde degeneration proceeding proximally towards the cell body. Antegrade Wallerian degeneration has been extensively studied by pathology as well as imaging. It is thought to occur almost immediately following injury and evidence of early antegrade Wallerian degeneration has been demonstrated as early as 12 days after injury. The complete process is however slow and complete breakdown and removal of debris may take up to 2 years. Retrograde Wallerian degeneration also known as ‘dieback’ phenomenon is a less well understood entity. Although retrograde changes in the corticospinal tracts have been demonstrated on histopathology studies, this concept has not gained widespread acceptance. Some researchers have postulated the presence of ascending fibers in the corticospinal tract thus hypothesizing that changes seen in the corticospinal tracts above the level of injury actually represent antegrade Wallerian degeneration of these tracts. MR imaging has been useful in demonstrating changes seen in the spinal cord due to antegrade Wallerian degeneration. These changes were initially studied with conventional imaging MR techniques. More recently, though diffusion imaging has been found to be more sensitive in evaluating these changes. To our knowledge, retrograde Wallerian degeneration or ‘dieback’ phenomenon has not been studied using MR. We believe that demonstration of retrograde Wallerian degeneration would be important in determining the extent of axonal loss following injury to the spinal cord and would provide vital information in evaluating treatment strategies.

Materials & Methods:
Post mortem specimens of 6 patients were evaluated by histopathology and MR. The cross sectional images of the cord were acquired using a T1-weighted spin-echo sequence with the following imaging parameters: 800/20/4 (TR/TE/NEX) with a 3 mm slice thickness, 4 cm field of view (FOV), and 256 X 256 matrix, and 12 to 17 contiguous slices. Similarly, the T2-weighted images were acquired using spin-echo sequence with the following imaging parameters: 2000/80/6 (TR/TE/NEX).

Cross sectional DWI of the cord were acquired with diffusion encoding being applied along the slice-select, frequency-encoding, and phase-encoding axes. Five different b values of 0, 250, 500, 750, 1000 s/mm2 were used along each of the three orthogonal axes to obtain calculated ADC images. The diffusion-weighted image parameters were 3000/100/1 (TR/TE/Nex) with 256×256 image matrix; 12 to 17 contiguous slices, each 3 mm thick and FOV of 40 mm. Injury to death intervals varied from 12 to 40 years. Following this, the spinal cords were examined histopathologically following fixation. They were then sectioned and grossly examined. Sections were processed by routine histologic methods and embedded in paraffin. They were then stained using hematoxylin and eosin and special stains specifically luxol fast blue for myelin and silver stain for axons. The histopathology and the imaging findings were then correlated.

Results:
Histopathological examinations demonstrated definite evidence of axonal loss in all specimens above the level of injury consistent with retrograde wallerian degeneration. MR imaging was useful in corroborating these findings. We found that diffusion imaging was more useful than conventional imaging in the detection of these changes.

Conclusion:
Retrograde wallerian degeneration does occur. Our study demonstrated that diffusion imaging may be more sensitive than other conventional MR imaging in detecting these changes. Based on our findings in post mortem spinal cords, we believe that MR imaging may serve as a promising tool in the evaluation of Wallerian degeneration non-invasively in vivo. This information could prove critical in the use of future treatment strategies such as cord transplantation.

Rosioreanu A, Ortiz O, Natarajan V, Gregorius D, Koehler V, De Moura A, Luchs JS
Winthrop-University Hospital
Mineola, N.Y.

Purpose:
To determine and compare the differences in radiation exposure to the interventional spine radiologist during vertebroplasty as compared to kyphoplasty.

Methods:
A prospective collection of data was obtained during 10 vertebroplasty and 10 kyphoplasty procedures performed in the thoracic and lumbar spine by an experienced neuroradiologist. Bi-plane fluoroscopy was used to perform all of the procedures. A bilateral transpedicular approach was utilized in all cases. The same types of radiation shielding devices were used in all of the cases and the device position was kept constant for all cases. Pulsed fluoroscopy was utilized in all procedures, with pulse 1 (7.5 pulses/sec) fluoroscopy used during needle positioning and pulse 2 (15 pulses/sec) used for the cement delivery portion of the procedure. Radiation exposure to the operator was measured using an electronic pocket dosimeter (Aloka Co., Ltd.) and radiation exposure rate (mR/hr) was monitored using a handheld ionization chamber (Victoreen, model 470A). The pocket dosimeter was placed in the operators left vest pocket, in all cases the side closest to the fluoroscopy unit. An injection device (EZ Flow CDS, ArthroCare Corporation) was used for vertebroplasty procedures and the Kyphon kit (Kyphon Co.) was used for all of the kyphoplasty procedures. A bilateral, transpedicular approach was used for all procedures. Each procedure was divided into needle positioning time and exposure for a specific vertebral level, as well as cement delivery time and exposure for that same level. The exposure times during each procedure and doses received by the interventionalist were recorded.

Results:
The average time for fluoroscopy during vertebroplasty was 11.2 minutes, which included an average of 5.2 minutes of needle positioning time and 6.0 minutes of cement delivery time. The average radiation exposure reading was 48.9 micro-Sieverts for the entire vertebroplasty procedure. This included an average of 21.2 micro-Sieverts of exposure during needle positioning and 27.7 micro-Sieverts of exposure during cement delivery. The average fluoroscopy time for kyphoplasty was 13.2 minutes, which included an average of 8.5 minutes for needle positioning and 4.7 minutes for cement delivery. The average radiation exposure reading during the kyphoplasty procedure was 226.5 micro-Sieverts for the entire kyphoplasty procedure. This included an average of 105.7 micro-Sieverts of exposure during needle positioning and 120.8 micro-Sieverts during cement delivery. The difference in total radiation exposure level between vertebroplasty and kyphoplasty was statistically significant (p<0.01; Student’s t-test).

Conclusion:
With respect to radiation, operator exposure rates for kyphoplasty are significantly higher than those observed with vertebroplasty. The two major factors which contribute to this phenomena are increased procedure and fluoroscopy time associated with kyphoplasty as well as the closer proximity to the fluoroscopy unit that is required when using the handheld drill and bone filler devices in kyphoplasty.

References:

1. Mathis JM, Barr JD, Belkoff SM, et al. Percutaneous vertebroplasty: A developing standard of care for vertebral compression fractures. AJNR Am J Neuroradiol 2001; 22:373-381
2. Wong WH, Olan WJ, Belkoff SM. Balloon kyphoplasty, in Mathis JM, Deramond H, Belkoff SM (eds): Percutaneous Vertebroplasty. New York, Springer-Verlag, pp 109-124, 2002

Mehfoud, David P., Vossough, Arastoo, and Melhem, Elias R.
Department of Radiology, Hospital of the University of Pennsylvania
Philadelphia, PA

Purpose:
Three-dimensional fast spin echo with driven equilibrium (3D-FSE-DE) pulse sequence has been recently introduced as a possible means for evaluating the cervical spine. High spatial resolution, hyperintense CSF (myelographic effect), and spin echo based contrast at relatively short acquisiton time are all desirable features of 3D-FSE-DE, possibly enabling it to provide a comprehensive evaluation of the cervical spine and to replace more conventional sequences (T2-weighted 2D FSE and 3D T2*-weighted GRE). We tested the ability of 3D-FSE-DE to demonstrate T2-hyperintense cord lesions by comparing it to the current imaging "gold standard", T2-weighted (long TR) 2D FSE.

Materials & Methods:
Seventy consecutive patients referred for cervical spine MR imaging at our institution were evaluated. Axial 2D-FSE (TR/TE=6870/129) and 3D-FSE-DE (TR/TE=500/124) imaging of the entire cervical spine was performed. The two sequences were matched for coverage, field of view (200mm), and slice thickness (3mm). The images were independently evaluated for the presence of T2-hyperintense lesions in the cervical cord by two readers. A confidence level of high or low was assigned to each lesion found. The 2D-FSE sequence was hypothesized to be the gold standard and tests characteristics were accordingly calculated.

Results: A total of 63 intramedullary lesions of the cervical spine were detected in 27 patients. The agreement rate of the two readers on the 3D-FSE-DE sequence was 100% and 87% for high and low confidence lesions, respectively. On the 2D-FSE sequence, reader agreement was 98.5% and 71% for high and low confidence lesions, respectively. When compared to 2D-FSE, the 3D-FSE-DE pulse sequence demonstrated an overall sensitivity of 35% and a specificity of 95% in the detection of intramedullary cervical cord lesions. Calculated sensitivity and specificity were almost identical for the two readers.

Conclusion: The 3D-FSE-DE pulse sequence has a low sensitivity for detection of T2-hyperintense intramedullary lesions of the cervical spine and thus should not be used in lieu of the 2D-FSE sequence for the evaluation of these lesions.

Agris JM, Zoarski GH, Stallmeyer MJB. and Ortiz AO*
University of Maryland Medical Center
Baltimore, Maryland
*Winthrop-University Hospital
Mineola, New York

Purpose:
Vertebroplasty has revolutionized the treatment of compression fractures. Claims of enhance safety attributable to “low pressure delivery” with larger bore systems are thus far unsubstantiated. We set out to determine whether intravertebral injection pressure measurements differ substantially between various delivery systems and devices. A simple mathematical model representing the different systems by variable resistance predicts that intravertebral pressure should be the same for a constant rate injection no matter which system is used.

Materials & Methods:
A cadaveric model was designed to measure intravertebral pressure during injection of a standardized poly-methylmethacrylate formulation (Secours, ArthroCare Corporation) through three different delivery systems: an 11-gauge (2.3 mm) disposable bone biopsy needle (Cook, Inc., Bloomington, IN), a 6-gauge (4.1 mm) CDO cannula (American Osteomedix, Irvine, CA), and the (4.0 mm) KyphX Inflatable Bone Tamp system (Kyphon, Inc., Sunnyvale, CA). After vertebral access, the tip of a contralateral 11-gauge needle was placed in close proximity to the tip of the device being tested; a pressure transducer was attached to the second needle. Saline flush confirmed continuity across the system. Intravertebral pressures were monitored during administration of 6cc of poly-methylmethacrylate (Secours, ArthroCare Corporation) at a fixed rate of 4cc/min by power injector (Medrad, Inc. Indianola, PA). Finally, measurements were obtained during manual cement delivery using two different delivery cannulas and blunt stylets (AOM and Kyphon), and a hand crank device (EZflow CDS, ArthroCare Corporation).

Results:
Pressure measurements were acquired over a range of 0-500mm Hg (0-9.8atm). The 11-gauge needle system reached a maximum intravertebral pressure (Pmax) of 170mm Hg (3.3psi). The AOM system reached a Pmax of 290mm Hg (5.7psi). Inflation of the KyphX balloon to a maximum of 225psi generated a Pmax of 100mm Hg (2psi); Pmax during subsequent filling of the cavity with poly-methylmethacrylate was 160mm Hg (3.1psi). Manual cement delivery with the Kyphon BFD generated average peak intravertebral pressures of 261mm Hg (5.1psi). Manual delivery with the EZflow CDS system generated a Pmax of 220mm Hg (4.3psi).
Conclusion: Our results demonstrate little difference in Pmax between the 11-gauge needle and the Kyphon balloon system with constant rate cement delivery. In comparison, the larger bore AOM CDO generated a 75% higher peak intravertebral pressure. Manual cement delivery with the EZflow CDS generated a peak intravertebral pressure which was 29% higher than constant rate delivery using the same 11-gauge needle. If a stylet was used for cement delivery with any system, regardless of size, the Pmax exceeded 500mm Hg (9.8psi). The broad conclusion that larger bore systems provide lower intravertebral pressures during cement delivery is incorrect, and operator training remains essential to the safe performance of percutaneous vertebroplasty. As might be expected, all factors influencing cement delivery in a cadaver cannot be predicted by a simple mathematical model. Additional studies using an acrylic vertebral body model will be performed to minimize variability inherent in cadaveric specimens.

Scientific Paper to be presented by Jacob M. Agris
MS PowerPoint for Windows on CD-ROM
Contact Information:
Jacob M. Agris, M.D., Ph.D.
Division of Neuroradiology
University of Maryland Medical Center
22 S. Greene Street
Baltimore, Maryland 21201
(410) 328-5112 voice
(410) 389-7496 pager

Smith, SE.
Mirvis, SE.
University of Maryland Medical Center and R. Adam Cowley Shock Trauma Center
Baltimore, MD

A pictorial essay of thoracolumbar spine injuries is provided with the following learning objectives:

1. To better understand the various forces of injury that act on the thoracolumbar spine and the resultant characteristic abnormalities on radiographs, as well as advanced imaging (Computed Tomography and Magnetic Resonance Imaging).
2. To review the anatomy of the thoracolumbar spine and adjacent musculature
3. To be able to identify secondary soft tissue or neural complications of thoracolumbar spine injuries.

Principle Author: Smith, SE. (ASSR Member)
Poster previously presented at the RSNA 2002.

Stacy E. Smith, MD
Department of Radiology, University of Maryland Medical Center
22 S Greene Street, Baltimore, MD, 21201
Phone: (410) 328-8133
Email: ssmith@umm.edu

Michael Rothman, MD
Kevin N. Waninger, MD, MS

Abstract:
Helmet and shoulder pads remain in place during the initial radiographic evaluation of the helmeted athlete with a suspected cervical spine injury. Standard football equipment may preclude x-ray clearance. This prospective study evaluates whether CT scans of the cervical spine can be used in the initial evaluation of the helmeted football player with a potential cervical spine injury.

Five male football players were fitted with equipment. Multiple 3.0 mm helically acquired, axially displayed, computed tomographic images of the cervical spine were obtained from the skull base inferiorly through T1, with images filmed at soft tissue and bone windows. Sagittal and coronal reformatted images were performed. All series were reviewed by a board-certified fellowship-trained neuroradiologist. Studies were evaluated for image clarity and diagnostic capability in this clinical setting.

Lateral scout films all demonstrated mild segmental degradation, depending on the location of the metallic snaps overlying the spine. AP scouts were fully diagnostic. All bone windows were of full diagnostic quality. The soft tissue windows showed minimal localized artifact occurring at the same levels as seen in the lateral scout views. This minimal streak artifact did not affect the diagnostic quality of the soft tissue windows. Reconstructed images were uniformly of full diagnostic quality.

When CT scans were reviewed as a unit, sufficient information was available to allow reliable clinical decision making. All study films were of full diagnostic quality. Based on the data obtained in this study, all helmeted players with suspicion of cervical spine injury may undergo CT scanning as the diagnostic procedure of choice, without any significant diagnostic limitations due to the presence of the helmet or shoulder pads. If CT scanning is not immediately available, then the equipment may need to be removed or mechanically altered upon arrival to the emergency room to allow radiographic clearance.

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Michael Rothman, MD
Kevin N. Waninger, MD, MS
Michael Heller, MD
Saint Luke’s Hospital
Bethlehem, PA
Department of Emergency Medicine
St. Luke’s Hospital
801 Ostrum Street
Bethlehem, PA, 18015
Phone: 610-865-7727
Fax: 610-954-2153
knwaninger@aol.com

Background:
It is currently recommended that helmet and shoulder pads remain in place during the initial clinical and radiographic evaluation of the helmeted athlete with a potential cervical spine injury. The objective of this prospectively designed, single subject study is to study whether MRI may play a role in the initial evaluation and management of the helmeted football player with a cervical spine injury.

Methods:
One male was fitted using equipment (football helmet @ Riddell, shoulder pads @ Douglas) worn during the collegiate season at Lehigh University. Standard MRI using a routine clinical 0.7T High Field Open MRI scanner (GE Signa System, Milwaukee, WI) was employed for the evaluation using standard clinical parameters (sagittal-T1, FSE-T2, STIR and axial FSE-T2 series). All series were reviewed by a single board-certified fellowship-trained neuroradiologist. Studies were evaluated for image clarity and diagnostic capability in this clinical setting.

Results:
Standard MRI series were all of extremely limited quality, even using sequences and slice selection designed to minimize artifact rendering MRI evaluation in this setting not clinically useful. This study demonstrates that current MRI techniques play no role in the clearance of the cervical spine (with currently available brands of helmet and shoulder pads in place) without prior equipment removal or associated with metals (fast spin echo T2-weighted series). When all MRI series were reviewed as a whole, sufficient evidence was not available to allow clinical decision making.

Discussion:
The amount and type of metal within the standard football helmet and shoulder pads results in sufficient field inhomogeneity and SKEW artifact to preclude adequate evaluation of the cervical structures, manipulation.

Luchs J.S., Rosioreanu A., Gregorius D., Natarajan V., Koehler V., Ortiz O.
Department of Radiology
Winthrop University Hospital
Mineola, N.Y.

Abstract:
Many factors affect radiation exposure during spine interventional procedures. These include tube selection and position (AP, lateral, or biplane), procedure time, technique, and the requirement for close proximity to patient during the procedure. This educational exhibit discusses several helpful techniques and devices that are available to reduce radiation exposure for the interventionalist and other personnel. Our measurements have shown that additional shielding placed on the patient and/or between the patient and personnel can significantly reduce scatter radiation by up to 98%. The additional shielding includes a 0.5mm lead equivalent apron placed on the patient’s lower torso and legs, 0.5 mm lead equivalent mobile barrier, and a 1.0 mm lead equivalent mobile barrier. We have also demonstrated that using a personal radiation monitor will raise the operator’s awareness to radiation exposure. The audio signal from this device alerts the operator to increases in radiation exposure. Finally, our data demonstrated that by extending the injection tubing length for manual hand injection, the radiation exposure to the operator is significantly reduced.

References:

1. Radiation protection system for interventional procedures of the upper extremity: evaluation in a phantom model. Haku, T. etal. JIVR 2002;13:815-822.
2. Using a sterile disposable protective surgical drape for reduction of radiation exposure to interventionalists. King, J. etal. AJR 2002;178:153-157.
3. Occupational radiation exposure to interventional radiologist: a prospective study. Marx, MV etal. JVIR 1992; 597-606.

Kapoor V, Rothfus W.E., Grahovac S.Z., Latchaw R.E.
University of Pittsburgh Medical Center
Pittsburgh, PA

Objectives:
Discography is an inherently painful preoperative procedure aimed at identifying pathological disc(s) prior to surgery. We describe a simplified and safe approach to cervical, thoracic and lumbar discography using biplane fluoroscopy with examples of normal and abnormal patterns.

Learning points:
After reviewing this exhibit registrants should:

* Understand the technical aspects of safely performing discography using biplane fluoroscopy,
* Know how to avoid iatrogenic pain and complications related to needle placement at discography, and
* Recognize normal and abnormal appearance of intervertebral discs at discography.

Rosioreanu A, Flieder A, Ortiz O, Chernoff M, Solomon N
Winthrop-University Hospital
Mineola, NY

A 48-year-old male presented with acute severe back pain and was unable to bear weight on his left leg. Past medical history was significant for infantile poliomyelitis with disuse atrophy of his right lower extremity. Clinical evaluation revealed swelling of his left foot and elbow. A PPD skin test was negative. Laboratory tests revealed a urine uric acid of 1231 mg/24h and an erythrocyte sedimentation rate of 37 mm/hr. The patient’s foot and elbow swelling resolved following treatment with Colchicine. However, his left-sided lower back pain persisted and a bone scan showed increased radiotracer uptake in the left sacroiliac joint that was suspicious for infection.

Contrast-enhanced MRI of the lumbar spine showed low signal on T1 and T2-weighted sequences and abnormal enhancement within the left sacroiliac joint. A biopsy of this joint was requested to assess for possible joint infection. Subtle juxtaarticular erosions were noted on the CT scan that was performed during the biopsy. The biopsy specimen showed foci of acute inflammation with no evidence of infection or neoplasm. Microbiologic analysis showed no evidence of infection. Unilateral sacroiliac joint involvement by acute gout is an uncommon presentation of this disease that can mimic an infectious process within the sacroiliac joint.

References:

1. Resnick CS, Resnick D: Radiology of Disorders of the Sacroiliac Joints, JAMA 1985; 253:2863-2866
2. Bastani B, Vemuri R, Gennis M: Acute Gouty Sacroiliitis: A Case Report and Review of the Literature, Mt Sinai J Med 1997; 64:383-385