Evaluation of pedicle screw position on computerized tomography scans

2003 ◽  
Vol 98 (1) ◽  
pp. 104-109
Author(s):  
Jin Sup Yeom ◽  
Moon Sang Chung ◽  
Choon-Ki Lee ◽  
Yeongho Kim ◽  
Namkug Kim ◽  
...  
Keyword(s):  
Pedicle Screw ◽  
Computerized Tomography ◽  
Pedicle Screws ◽  
Ct Scans ◽  
Metal Artifact ◽  
Content Type ◽  
Screw Insertion ◽  
Bone Window ◽  
Screw Position ◽  
Fine Print

✓ The quality of a computerized tomography (CT) scan is significantly reduced by metal artifact caused by a pedicle screw system. The purpose of this study was to develop a method of facilitating the evaluation of pedicle screw position on CT scans obtained after screw insertion. The authors developed an algorithm to process spiral CT scans in a personal computer. This uses a digital image enhancement technique, the curve change-based intensity transformation algorithm. This method can generate a clear image of the screw outlines while reducing metal artifact. The resulting images are displayed in arbitrary planes as well as in axial, coronal, and sagittal planes, to support better the evaluation of pedicle screw position. The algorithm was tested using CT scans obtained in 37 patients in whom 186 pedicle screws had been placed. There were five types of screw systems, all of which were made of titanium alloys. In all cases algorithm-based determination of screw position became more convenient and more accurate than when using the conventional bone window setting. In addition, it provided better soft-tissue visualization than the bone window. The software, by displaying clear outlines of screws and decreasing metal artifact, as well as by reconstructing the images in arbitrary planes, was more helpful in identifying the position of pedicle screws than the conventional bone window setting.

Clinicopathological investigation of gyral high density on computerized tomography following severe head injury in children

1995 ◽  
Vol 82 (6) ◽  
pp. 995-1001 ◽  
Author(s):  
Takehide Onuma ◽  
Yasuko Shimosegawa ◽  
Motonobu Kameyama ◽  
Hiroaki Arai ◽  
Kiyoshi Ishii
Keyword(s):  
Computerized Tomography ◽  
Head Trauma ◽  
Brain Atrophy ◽  
High Density ◽  
Ct Scans ◽  
Severe Head Trauma ◽  
Content Type ◽  
Subacute Stage ◽  
Fine Print ◽  
Diffuse Brain

✓ The authors have treated five cases of severe head trauma in children in which abnormally high density along gyri, “gyral high density,” was seen on plain computerized tomography (CT) scans in the subacute stage of the injury. The prognosis in all cases was poor, with either severe disability or a vegetative state as the outcome due to significant brain atrophy following gyral high density. This pathology was classified into three clinical stages: 1) acute stage, cerebral ischemia in which there is diffuse low density of the cerebrum on CT scans (most marked on the 3rd and 4th days); 2) subacute stage, hemorrhagic infarction showing gyral high density on plain CT scans (between 1 and 4 weeks); and 3) chronic stage, brain atrophy (beginning 4 weeks after the trauma). In their consecutive series of head-injured patients (516 children, 1459 adults), the authors did not find gyral high density on CT scan in adults. This is probably due to the fact that adults who suffer the severe head trauma associated with diffuse brain swelling or diffuse brain edema cannot survive, thus making this gyral high density unique to children.

Three-dimensional fluoroscopy-guided percutaneous thoracolumbar pedicle screw placement

2003 ◽  
Vol 99 (3) ◽  
pp. 324-329 ◽  
Author(s):  
Langston T. Holly ◽  
Kevin T. Foley
Keyword(s):  
Pedicle Screw ◽  
Three Dimensional ◽  
Pedicle Screws ◽  
Screw Placement ◽  
Content Type ◽  
Image Guided ◽  
Spinal Navigation ◽  
Mean Diameter ◽  
The Mean ◽  
Fine Print

✓ The authors sought to evaluate the feasibility and accuracy of three-dimensional (3D) fluoroscopic guidance for percutaneous placement of thoracic and lumbar pedicle screws in three cadaveric specimens. After attaching a percutaneous dynamic reference array to the surgical anatomy, an isocentric C-arm fluoroscope was used to obtain images of the region of interest. Light-emitting diodes attached to the C-arm unit were tracked using an electrooptical camera. The image data set was transferred to the image-guided workstation, which performed an automated registration. Using the workstation display, pedicle screw trajectories were planned. An image-guided drill guide was passed through a stab incision, and this was followed by sequential image-guided pedicle drilling, tapping, and screw placement. Pedicle screws of various diameters (range 4–6.5 mm) were placed in all pedicles greater than 4 mm in diameter. Postoperatively, thin-cut computerized tomography scans were obtained to determine the accuracy of screw placement. Eighty-nine (94.7%) of 94 percutaneous screws were placed completely within the cortical pedicle margins, including all 30 lumbar screws (100%) and 59 (92%) of 64 thoracic screws. The mean diameter of all thoracic pedicles was 6 mm (range 2.9–11 mm); the mean diameter of the five pedicles in which wall violations occurred was 4.6 mm (range 4.1–6.3 mm). Two of the violations were less than 2 mm beyond the cortex; the others were between 2 and 3 mm. Coupled with an image guidance system, 3D fluoroscopy allows highly accurate spinal navigation. Results of this study suggest that this technology will facilitate the application of minimally invasive techniques to the field of spine surgery.

Intracerebral myiasis from Hypoderma bovis larva in a child

1989 ◽  
Vol 71 (6) ◽  
pp. 929-931 ◽  
Author(s):  
Müfit Kalelioğlu ◽  
Gönül Aktürk ◽  
Fadiil Aktürk ◽  
Sezer Ş. Komsuoğlu ◽  
Kayhan Kuzeyü ◽  
...  
Keyword(s):  
Computerized Tomography ◽  
Ct Scans ◽  
Intracerebral Hematoma ◽  
Review Of The Literature ◽  
Content Type ◽  
First Case ◽  
Hypoderma Bovis ◽  
History Of ◽  
Exact Identification ◽  
Fine Print

✓ Cerebral myiasis with a 10-day history of convulsions due to an intracerebral hematoma caused by a Hypoderma bovis larva is reported in an 8-year-old child. Computerized tomography (CT) showed the hematoma in a right parieto-occipital location. The H. bovis larva and the extensive intracerebral hematoma were discovered during surgery. Among human parasitoses, cerebral myiasis is rare: a review of the literature revealed only two reports, one published in 1969 and one in 1980. This is the first case that has been diagnosed as cerebral myiasis with exact identification of the Hypoderma bovis larva both from the CT scans and at surgery in a patient during life.

Thoracic pedicle screws: postoperative computerized tomography scanning assessment

2004 ◽  
Vol 100 (4) ◽  
pp. 325-331 ◽  
Author(s):  
Robert F. Heary ◽  
Christopher M. Bono ◽  
Margaret Black
Keyword(s):  
Computerized Tomography ◽  
Pedicle Screws ◽  
Ct Scanning ◽  
Screw Placement ◽  
Grading System ◽  
Content Type ◽  
Thoracic Pedicle Screws ◽  
Grade Ii ◽  
Grade Iii ◽  
Fine Print

Object. The authors evaluated the accuracy of placement of thoracic pedicle screws by performing postoperative computerized tomography (CT) scanning. A grading system is presented by which screw placement is classified in relation to neurological, bone, and intrathoracic landmarks. Methods. One hundred eighty-five thoracic pedicle screws were implanted in 27 patients with the assistance of computer image guidance or fluoroscopy. Postoperative CT scanning was conducted to determine a grade for each screw: Grade I, entirely contained within pedicle; Grade II, violates lateral pedicle but screw tip entirely contained within the vertebral body (VB); Grade III, tip penetrates anterior or lateral VB; Grade IV, breaches medial or inferior pedicle; and Grade V, violates pedicle or VB and endangers spinal cord, nerve root, or great vessels and requires immediate revision. Based on anatomical morphometry, the spine was subdivided into upper (T1–2), middle (T3–6), and lower (T7–12) regions. Statistical analyses were performed to compare regions. The mean follow-up period was 37.6 months. The following postoperative CT scanning—documented grades were determined: Grade I, 160 screws (86.5%); Grade II, 15 (8.1%); Grade III, six (3.2%); Grade IV, three (1.6%); and Grade V, one (0.5%). Among cases involving screw misplacements, Grade II placement was most common, and this occurred most frequently in the middle thoracic region. Conclusions. The authors' grading system has advantages over those previously described; however, further study to determine its reliability, reproducibility, and predictive value of clinical sequelae is warranted. Postoperative CT scanning should be considered the gold standard for evaluating thoracic pedicle screw placement.

Pedicle screw insertion in the thoracolumbar spine: comparison of 4 guidance techniques in the intact cadaveric spine

2011 ◽  
Vol 14 (5) ◽  
pp. 664-669 ◽  
Author(s):  
Husam Alhabib ◽  
Andrew Nataraj ◽  
Mohammed Khashab ◽  
James Mahood ◽  
Frank Kortbeek ◽  
...  
Keyword(s):  
Pedicle Screw ◽  
Thoracolumbar Spine ◽  
Pedicle Screws ◽  
Pedicle Screw Fixation ◽  
Anatomical Landmarks ◽  
Imaging Data ◽  
Anatomical Dissection ◽  
Screw Insertion ◽  
Fluoroscopic Navigation ◽  
Screw Position

Object Pedicle screw fixation is a mainstay of thoracolumbar stabilization. Screw insertion using anatomical landmarks and fluoroscopy is common but can be technically challenging and generally involves substantial exposure to ionizing radiation. Computerized navigation has been reported to improve accuracy but is expensive and complex. The authors undertook this study to evaluate these 3 methods in comparison with a fourth technique using standard cervical distractor screws to mark the entry point and trajectory. Methods Four cadaveric human spines were used for this study. After an initial CT scan, 34 pedicle screws were inserted in each intact spine from T-1 to L-5 using the following 4 screw insertion guidance techniques (1 technique per specimen): use of anatomical landmarks, use of cervical distractor screws and spot fluoroscopy, fluoroscopy-based navigation, and fluoroscopy- and CT-based navigation (using merged imaging data). Postprocedural CT and anatomical dissection were then performed to evaluate screw position for site and degree of breach. Results The cervical distractor screw method had a breach rate of 5.9% versus 29.4%, 32.4%, and 20.6% for use of anatomical landmarks, fluoroscopic navigation, and fluoroscopic-CT navigation, respectively (p < 0.05). There is also a significant association between degree of medial and distal breach and the method of screw insertion (p < 0.05). Conclusions Cervical distractor screws as pedicle markers offer favorable insertion accuracy and reduction of radiation exposure compared with the other 3 methods used in clinical practice.

Vascular malformation simulating a glioma on computerized tomography

1981 ◽  
Vol 54 (1) ◽  
pp. 125-127 ◽  
Author(s):  
Patrick M. Foy ◽  
Leandro Lozada ◽  
Malcolm D. Shaw
Keyword(s):  
Arteriovenous Malformation ◽  
Computerized Tomography ◽  
Vascular Malformation ◽  
Ct Scans ◽  
Venous Aneurysm ◽  
Content Type ◽  
Fine Print

✓ A patient with an arteriovenous malformation and giant venous aneurysm was erroneously diagnosed as having an oligodendroglioma on computerized tomography (CT). This case highlights some of the problems of interpretation of CT scans and the dangers of misinterpretation, particularly in the surgical context.

Localization of brain tumors with a simple scalp-mounted fiducial device

1989 ◽  
Vol 70 (2) ◽  
pp. 280-281 ◽  
Author(s):  
Henry Hirschberg
Keyword(s):  
Brain Tumors ◽  
Ct Scan ◽  
Computerized Tomography ◽  
Ct Images ◽  
Ct Scans ◽  
Content Type ◽  
Varying Length ◽  
Fine Print

✓ A method is described for marking the site of a tumor on the scalp based on information from computerized tomography (CT) scans. The technique employs a syrinx-shaped array of radiopaque catheters of varying length taped to the patient's scalp for visualization on the CT scan. Fiducial markings on the CT images allow the transfer of the tumor's location directly onto the scalp. The device can be placed anywhere on the scalp, including in a parasagittal position.

Percutaneous pedicle screw fixation of the lumbar spine: preliminary clinical results

2002 ◽  
Vol 97 (1) ◽  
pp. 7-12 ◽  
Author(s):  
Kevin T. Foley ◽  
Sanjay K. Gupta
Keyword(s):  
Lumbar Spine ◽  
Pedicle Screw ◽  
Screw Fixation ◽  
Pedicle Screws ◽  
Pedicle Screw Fixation ◽  
Posterior Fixation ◽  
Content Type ◽  
Insertion Device ◽  
Lumbar Pedicle ◽  
Fine Print

Object. Standard techniques for pedicle screw fixation of the lumbar spine involve open exposures and extensive muscle dissection. The purpose of this study was to report the initial clinical experience with a novel device for percutaneous posterior fixation of the lumbar spine. Methods. An existing multiaxial lumbar pedicle screw system was modified to allow screws to be placed percutaneously by using an extension sleeve that permits remote manipulation of the polyaxial screw heads and remote engagement of the screw-locking mechanism. A unique rod-insertion device was developed that linked to the screw extension sleeves, allowing for a precut and -contoured rod to be placed through a small stab wound. Because the insertion device relies on the geometrical constraint of the rod pathway through the screw heads, minimal manipulation is required to place the rods in a standard submuscular position, there is essentially no muscle dissection, and the need for direct visual feedback is avoided. Twelve patients (six men and six women) who ranged in age from 23 to 68 years underwent pedicle screw fixation in which the rod-insertion device was used. Spondylolisthesis was present in 10 patients and osseous nonunion of a prior interbody fusion was present in two. All patients underwent successful percutaneous fixation. Ten patients underwent single-level fusions (six at L5—S1, three at L4–5, and one at L2–3), and two underwent two-level fusions (one from L3–5 and the other from L4—S1). The follow-up period ranged from 10 to 19 months (mean 13.8 months). Conclusions. Although percutaneous lumbar pedicle screw placement has been described previously, longitudinal connector (rod or plate) insertion has been more problematic. The device used in this study allows for straightforward placement of lumbar pedicle screws and rods through percutaneous stab wounds. Paraspinous tissue trauma is minimized without compromising the quality of spinal fixation. Preliminary experience involving the use of this device has been promising.

scholarly journals Improved accuracy of computer-assisted cervical pedicle screw insertion

2003 ◽  
Vol 99 (3) ◽  
pp. 257-263 ◽  
Author(s):  
Yoshihisa Kotani ◽  
Kuniyoshi Abumi ◽  
Manabu Ito ◽  
Akio Minami
Keyword(s):  
Real Time ◽  
Pedicle Screw ◽  
Computer Assisted ◽  
Insertion Technique ◽  
Content Type ◽  
Cervical Pedicle Screw ◽  
Screw Insertion ◽  
Pedicle Screw Insertion ◽  
Cervical Pedicle ◽  
Fine Print

Object. The authors introduce a unique computer-assisted cervical pedicle screw (CPS) insertion technique used in conjunction with specially modified original pedicle screw insertion instruments. The accuracy of screw placement as well as surgery-related outcome and complication rates were compared between two groups of patients: those in whom a computer-assisted and those in whom a conventional manual insertion technique was used. Methods. The screw insertion guiding system consisted of a modified awl, probe, tap and a screwdriver specially designed for a computer-assisted CPS insertion. Using this system, real-time instrument/screw tip information was three dimensionally identified in each step of screw insertion. Seventeen patients underwent CPS fixation in which a computer-assisted surgical navigation system was used. The cervical disorders consisted of spondylotic myelopathy with segmental instability or kyphosis, metastatic spinal tumor, rheumatoid spine, and postlaminectomy kyphosis. The rate of pedicle wall perforation was significantly lower in the computer-assisted group than that in the other group (1.2 and 6.7%, respectively; p < 0.05). The screw trajectory in the horizontal plane was significantly closer to the anatomical pedicle axis in the computer-assisted group compared with the manual insertion group (p < 0.05). This factor significantly reduced the incidence of screw perforation laterally. Complications such as neural damage or vascular injury were not demonstrated in the computer-assisted group (compared with 2% in the manual insertion treatment group). The overall surgery-related outcome was satisfactory. Conclusions. In contrast to the previously reported computer-assisted technique, our CPS insertion technique provides real-time three-dimensional instrument/screw tip information. This serves as a powerful tool for safe and accurate pedicle screw placement in the cervical spine.

CT-assisted stereotaxic aspiration of colloid cysts of the third ventricle

1985 ◽  
Vol 62 (2) ◽  
pp. 238-242 ◽  
Author(s):  
Juan J. Rivas ◽  
Ramiro D. Lobato
Keyword(s):  
Computerized Tomography ◽  
Third Ventricle ◽  
Ct Scanning ◽  
Ct Scans ◽  
Content Type ◽  
The Third ◽  
Colloid Cysts ◽  
Reproducible Method ◽  
Inner Diameter ◽  
Fine Print

✓ A technique is reported for the stereotaxic evacuation of colloid cysts of the third ventricle using a stereotaxic system adapted for computerized tomography (CT) scanning. This is an accurate, simple, and reproducible method that avoids the risks of direct approaches. Successful intracystic aspiration resulting in the cure of the patient may be difficult when the viscosity of the cyst contents is high. Thus, the authors use a large cannula (1.8 mm in inner diameter) to evacuate cysts that appear hyperdense on CT scans; these seem to contain a thicker colloid material than hypodense or isodense cysts.

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