- Dedicated MRI Systems for Head & Spine Imaging
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- Diagnostic Imaging in the Degenerative Diseases of the Cervical Spine | Neupsy Key
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Various shapes of plates in different sizes have been developed for anterior or posterior spine fusion. These devices can be used when posterior spinal elements are intact. They attach the lamina of 2 adjacent vertebrae. Interbody spacers could be solid ramp or hollow cages. Cages are filled with bone-graft material and inserted into the intervertebral space or replace a vertebra after its removal i.
Cages are usually made of titanium carbon fibers, polyetherether ketan PEEK or of cortical bone graft. Most cages contain 2 radiopaque markers to identify their position in radiographs and to enable their assessment. They are made in different shapes based on the method of approach to the intervertebral disc.
In anterior interbody fusion AIF , cages are more round in shape, while in posterior interbody fusion PIF they are more rectangular. Transforaminal interbody fusion TIF cages are more crescent-shaped. Expandable cylindrical or mesh cages are used in vertebral body replacement procedures. Cages are usually supported by additional posterior, anterior or lateral instrumentation i. For a standalone interbody fusion cage, the interbody spacer is fixed to the adjacent vertebral body with screws to eliminate the need for additional instrumentation support.
Retropulsion of the cage is a possible complication, but is more common in PIF. Expandable cages have broader surface area and duller edges at both ends, which minimize their subsidence and also allow immediate load bearing and stability after corpectomy. Dynamic stabilization devices are a new category of instruments that are in various stages of development. They can be used alone or in conjunction with other instrumentation.
They act by controlling the abnormal motion and uneven load in segments adjacent to the level of fusion in order to minimize progressive degeneration.
Dedicated MRI Systems for Head & Spine Imaging
Artificial ligaments e. Surgical techniques can be divided on the basis of perceived patient morbidity into minimally invasive or traditional-open procedures performed via either an anterior or posterior approach. In interbody fusion, the intervertebral disc or a complete vertebra is removed and replaced with bone graft.
Interbody fusion of the spine can be approached anteriorly or posteriorly. Anterior interbody fusion AIF has the advantage of a broader access to the disc space. However, it is limited by potential injury to major vessels and sympathetic nerve chain.
Extreme lateral interbody fusion approaches the anterior spine from the flank. In posterior interbody fusion PIF bilateral laminectomies are performed and bone-graft material is inserted into the disc space after the disc is removed. Posterior interbody fusion has the disadvantage of potential injury to nerve roots.
Retrograde migration of the graft or cage is also more common with the posterior approach. Transforminal interbody fusion TIF is a modified PIF that uses a more lateral approach and thus leaves the midline bone structures intact. Min et al. Overall, Lemcke et al. AIF is difficult in the presence of marked vascular calcification. Posterolateral fusion is an alternative for interbody fusion. In posterolateral fusion, adjacent vertebrae are fused together by placing the bone-graft material between the transverse processes. In comparison, interbody fusion provides a greater surface area of bone contact and produces a more favorable fusion compared to the posterolateral method.
Using cages in interbody fusions provides more immediate stability during bone graft incorporation. Postoperative imaging plays an important role in the assessment of fusion and bone formation. It is also helpful to detect instrument failure and other suspected complications.
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It is necessary to compare current images with previous studies to identify any subtle changes and disease progression. Evaluation of the postoperative spine usually begins with conventional radiographs in AP and lateral projections. It usually takes 6 to 9 months for a solid bone fusion to be established radiographically. Conventional radiographs are capable of detecting instrument failure, infection and other causes of failed fusion Figures 1 through 7.
Additional views in lateral flexion and extension are sometimes used to evaluate the presence of motion and the integrity of the fusion. Sometimes radiographs are nondiagnostic and, based on clinical suspicion and the type of the applied instrument, additional imaging with other modalities may be applied. Currently, computed tomography CT with multiplanar reconstruction MPR is considered the modality of choice for imaging bony detail and assessing osseous formation and hardware position despite artifact formation.
CT is also useful in demonstrating the spinal canal and its alignment and is capable of detecting infection and pseudarthrosis 12 Figure 8. Cook et al. In another study, Heithoff et al.
Diagnostic Imaging in the Degenerative Diseases of the Cervical Spine | Neupsy Key
Magnetic resonance imaging MRI has been used increasingly in recent years since introduction of titanium-based implants with reduced artifact compared to formerly used stainless-steel devices. These artifacts could be decreased even more by changing imaging parameters such as reducing echo time, increasing bandwidth and decreasing voxel size. Aligning the implant along the axis of the magnetic field also reduces artifact although it is often not completely achievable due to the multidirectional configuration of most hardware.
Spin echo sequences are less vulnerable to magnetic susceptibility artifact and give better quality images compared with gradient echo sequences. MRI is useful in detecting infection Figure 9 and assessing recurrent tumor. MRI is the modality of choice in assessing intraspinal contents. Myelography Figure 6 is an alternative when MRI is contraindicated or is nondiagnostic because of artifact. Radionuclide scans are mainly used to detect infection. Sonography is used to detect fluid collections and abscesses in the postoperative spinal fusion.
Potential complications of spinal surgery vary based on the site of surgery, surgical approach, underlying disease, applied instrumentation, surgeon skill and other clinical factors.
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Besides the common complications associated with spinal fusion procedures; there are some additional complications based on site, procedure and type of instrumentation. Hardware fracture Figures 1 through 4 occurs most commonly as a result of metal fatigue from the repeated stress in spinal movements.
The fractured appliance may not be displaced, making its detection difficult. A dislodged or fractured appliance does not necessarily indicate instability or clinical failure of the fusion but is most frequently associated with motion, instability and pseudarthrosis. This is an occasional indication for hardware removal.
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This will cause the bones to weaken and predisposes them to fracture and it leads to hardware failure. A loose appliance repeatedly moves and produces bone resorption or erosion. Fused bones are less mobile, which makes the bones vulnerable to fractures above or below the implants if subjected to trauma Figure Unsuccessful fusion may have other causes such as development of facet arthritis Figure 6C or disc disease above or below the fusion level.
This complication is reported in In the cervical spine, potential complications of the posterior approach are mainly neurological and include dural, nerve root or cord injury. The anterior approach is associated with risks of injuring the main vascular structures carotid and vertebral arteries, jugular vein , causing recurrent damage to the laryngeal nerve or soft tissue, such as the esophagus, trachea or lungs Figure Br J Gen Pract ; Diagnostic imaging for low back pain: Advice for high-value health care from the American College of Physicians.
Ann Intern Med ; Diagnosis and treatment of low back pain: A joint clinical practice guideline from the American College of Physicians and the American Pain Society. Above is the information needed to cite this article in your paper or presentation. Solid-organ transplantation in HIV-infected patients. N Engl J Med. The ICMJE is small group of editors of general medical journals who first met informally in Vancouver, British Columbia, in to establish guidelines for the format of manuscripts submitted to their journals.
The group became known as the Vancouver Group. Its requirements for manuscripts, including formats for bibliographic references developed by the U.
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An alternate version of ICMJE style is to additionally list the month an issue number, but since most journals use continuous pagination, the shorter form provides sufficient information to locate the reference. The NLM now lists all authors. Skip to main content. Issue: BCMJ, vol. Knowing as much as possible about your enemy precedes successful battle and learning about the disease process precedes successful management 4. Spondylodiskitis L Old Spondylodiskitis T1 T2 Diffusion Gibbus deformity short-segment structural thoracolumbar kyphosis resulting in sharp angulation Destructive processes involving T11 associated with kyphosis AP A and lateral B X-ray of the lumbar spine showing spondylitis of the second lumbar vertebral body L2 and lateral X-ray of the thoracic spine C of another patient showing a severe kyphosis as a consequence of T5-T6 spondylitis A T1 shows destruction of the intervertebral disc space and endplates of the adjacent vertebral bodies is marked , vertebral body alignment is normal , B T2 shows diskitis and destruction of the endplates of the adjacent vertebral bodies Edema of the bone marrow of L2 and L3 with intra-discal blue star and epidural abscess red arrows Epidural abscess with cord displacement and compression red arrows and paraspinal phlegmon within the left psoas muscle yellow arrows With paravertebral abscess T2 shows collapse of L1 vertebral body with irregularity of superior end plate of L2 along with bilateral psoas abscesses A T2 in TB shows T8 and T9 vertebral bodies are heterogeneously hyperintense arrows , B T2 in pyogenic infection shows L4 and L5 vertebral bodies are isointense arrows to adjacent normal vertebrae Normal spinal posterior elements T2 A , T1 fat-saturated image after intravenous gadolinium B showing spondylodiscitis arrow complicated by an SEA at the C level arrowheads Normal nerve roots , A T2 shows normal lumbar roots are individually visible and because they float freely in the spinal fluid they follow the rules of gravity by positioning more towards the back , B T1 , hardly shows the nerve roots situated posteriorly in the spinal canal Normal appearance of nerve roots in thecal sac on a T2 axial , note the slender caliber of the well-spaced nerve roots Patient with mild arachnoiditis , suggested by thickened nerve roots arrows on T2 axial , which do not appear as spatially separated in the sac as is typical T2 shows normal nerve roots T2 shows clumping of roots on the right side Normal "fanning" of nerve roots within the thecal sac arrows is apparent on this T2 sagittal view of the lumbar region In a patient with mild arachnoiditis, a T2 fails to demonstrate the usually fanning of nerve roots arrow on off-center sagittal views T2 axial image reveals moderately thickened nerve roots with abnormal distribution in the thecal sac arrows , compatible with clumping Post-operative , T2 axial image reveals moderately thickened nerve roots with abnormal distribution in the thecal sac arrows , compatible with clumping The empty sac sign is present due to peripheral adherence of nerve roots arrows to the arachnoid T2 shows the empty sac with clumping of the nerve roots to both sides T2 sagittal reveals central clumping of nerve roots and pseudotethering arrows T2 sagittal image reveals thickened nerve roots arrows , intradural cysts arrowheads and pseudotethering T2 shows extensive hyperintense nodular masses along the cervical ventral rami white arrows and brachial plexus bilaterally black arrows