الفهرس 
AcknowledgmentOnly 14 pages are availabe for public view
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Abstract
Spinal fusion implant have become valuable hardware tools in arthopaedic surgery and are used for variety of spinal condition,including traumatic and osteoporotic unstable vertebral fracture , symptomatic spondylolithisthesis , spinal stenosis and for correction of spine deformity After spine surgery patient may have minimal or no relief of symptom and may develop new or recurrent symptoms either shortely or long after initial surgery. proper placement of pedicle screw is important not only for the prevention of neurological injury but also for maintainance of long term spinal stability .screw placement is considered optimal when it traverse the centralaspect of the pedicle and is aligned parallel to superior end plate(neutral position) Imaging of patient with spine fusion implant can be difficult with MRI,especially ferromagnetic implant causes significant artifact .the routine CT technique also has an important impact on severity of the artifact with high miliamere second,high peak kilovoltage setting leading to reduction of artifact Advances in CT imaging technology have made CT accepted to be gold standard technique for postoperative screw evaluation CT is now widely accepted as a standard for non invasive assessment of spinal fusion,fine cuts imaging,multiplanar reconstruction and metal artifact reduction have increased the ability to assess fusion on CT.