Postoperative magnetic resonance imaging artifact with cobalt-chromium versus titanium spinal instrumentation: presented at the 2013 Joint Spine Section Meeting. Clinical article

Cobalt-chromium alloy (CoCr) rods haves some preferred biomechanical properties over titanium rods for spinal fixation. The use of CoCr rods in spinal fusion is relatively new, and there is no study in the existing world literature assessing the artifact caused by these rods in patients undergoing postoperative MRI. The purpose of this study is to compare the amount of imaging artifact caused by these implants and to assess its impact on the visualization of neighboring neural structures. This study investigated MR images in patients who underwent implantation of thoracolumbar instrumentation using 5.5-mm-diameter CoCr rods between November 2009 and March 2011 and images obtained in a comparison group of patients who had 5.5-mm titanium rods implanted during the same time period. Axial measurements of the artifact created by the rods between the screw heads were compared between the groups. Two blinded board-certified radiologists performed the measurements independently. They scored the visualization of the spinal canal using a subjective scoring system of 1-3, with 1 representing very good visualization and 2 and 3 representing reduced (good or suboptimal, respectively) visualization as a result of rod-related artifact. All measurements and scores were independently provided for T1-weighted and T2-weighted fast spin echo sequences (1.5-T magnet, 5-mm slice thickness). A total of 40 levels from the CoCr group (6 patients) and 30 levels from the titanium group (9 patients) were included in the analysis. Visualization of the canal at all levels was rated a score of 1 (very good) by both evaluators for both the CoCr and titanium groups. The average artifact on T1-weighted images measured 11.8 ± 1.8 mm for the CoCr group and 8.5 ± 1.2 mm for the titanium group (p < 0.01). The corresponding measurements on T2-weighted images were 11.0 ± 2.3 mm and 8.3 ± 1.7 mm (p < 0.01), respectively. In a mixed regression model, the mean artifact measurement for the CoCr group was, on average, 3.5 mm larger than for the control group. There was no significant difference between the measurements of the 2 evaluators (p = 0.99). The artifact caused by CoCr rods is approximately 3.5 mm larger than that caused by titanium rods on axial T1- and T2-weighted MRI. However, artifact from either CoCr or titanium was not found to interfere with the evaluation of the spinal canal and surrounding neural elements

Ascending pharyngeal artery arising from a hypoplastic internal carotid artery

Normal vascular variants often have clinical/surgical significance and can be misinterpreted for pathology. We report a case ascending pharyngeal artery arising from a hypoplastic internal carotid artery. We provide clues to differentiate between dysgenesis and disease/thrombosis of the internal carotid artery

Presumed bilateral optic nerve sheath meningiomas presenting as optic neuritis

A 30-year-old man who developed acute blurred vision in the right eye and right periocular pain on eye movement proved to have a bilateral optic neuropathy and imaging evidence suggestive of bilateral optic nerve sheath meningiomas. This is an unusual presentation for optic nerve meningioma but a reminder that this entity may mimic optic neuritis

Osteoblastoma of the Frontal Sinuses Presenting with Headache and Blurred Vision: Case Report and Review of the Literature

Osteoblastoma is a rare benign bone tumor that usually arises in the vertebral column and long bones of young adults. Craniofacial involvement is extremely rare. To date, osteoblastoma of the frontal sinus has not been reported in the English literature. We report an osteoblastoma of both frontal sinuses in a 23-year-old male who presented with headache and blurry vision in the left eye. Computed tomography (CT) demonstrated an expansile lesion involving both frontal sinuses with sclerotic and fibrous components, eroding into the roof of the left orbit. On magnetic resonance imaging (MRI) the dense portion of the lesion showed signal void on all sequences, while the fibrous matrix was isointense to grey matter on T1-weighted and T2-weighted images and showed avid enhancement following intravenous contrast administration. Surgical resection was performed and histology was consistent with osteoblastoma

MR Imaging of the Spine: Urgent and Emergent Indications

Spinal emergencies and urgent conditions must be recognized early so that the diagnosis can be quickly confirmed and treatment can be instituted to possibly prevent permanent loss of function. The American College of Radiology provides guidelines for recognition of patients presenting with myelopathy or acute low back pain who require further evaluation for suspicion of more serious problems and contribute to appropriate imaging utilization. Spinal emergencies include spinal cord compression secondary to vertebral fracture or space occupying lesion, spinal infection or abscess, vascular or hematologic damage, severe disc herniation, and spinal stenosis