Object Despite the frequent multiplicity and development of new spinal cord hemangioblastomas that require multiple resections in patients with von Hippel-Lindau (VHL) disease, the long-term effects of spinal surgery on spinal column stability in this neoplasia disorder are not known. To determine the effect of multilevel cervical laminectomy for spinal cord tumor resection in VHL, the authors analyzed long-term clinical and radiographic outcomes. Methods The authors included consecutive patients enrolled in a prospective VHL disease natural history study who underwent cervical laminectomy(s) for spinal cord hemangioblastoma resection. Serial clinical examinations, neck disability indices, and radiographs (static and dynamic), as well as operative records, were analyzed. Results Twenty-five adult patients (16 female, 9 male) with VHL disease underwent 34 operations (mean 1.4 ± 0.7 [± SD]/patient) for the resection of cervical spinal cord hemangioblastomas (mean number of lamina removed/surgery 3.0 ± 1.3)....

Long-term stability after multilevel cervical laminectomy for spinal cord tumor resection in von Hippel-Lindau disease.

PURPOSE: To assess the relationship between heart valve history and susceptibility artifacts at magnetic resonance (MR) imaging of the brain in patients with Bjork-Shiley convexoconcave (BSCC) valves. MATERIALS AND METHODS: MR images of the brain were obtained in 58 patients with prosthetic heart valves: 20 patients had BSCC valve replacements, and 38 had other types of heart valves. Two experienced neuroradiologists determined the presence or absence of susceptibility artifacts in a consensus reading. Artifacts were defined as characteristic black spots that were visible on T2*-weighted gradient-echo MR images. The statuses of the 20 explanted BSCC valves—specifically, whether they were intact or had an outlet strut fracture (OSF) or a single-leg fracture (SLF)—had been determined earlier. Number of artifacts seen at brain MR imaging was correlated with explanted valve status, and differences were analyzed with nonparametric statistical tests. RESULTS: Significantly more patients with BSCC valves (17 [85...

Björk-Shiley convexoconcave valves: susceptibility artifacts at brain MR imaging and mechanical valve fractures.

Metallic artifacts in magnetic resonance (MR) imaging occur mostly in patients who have received an implant at surgery. Similar artifacts are now increasingly recognized in patients in whom high-speed drills have been used. A 15-year-old male with neurofibromatosis 2 had undergone excision of acoustic neurofibroma on the left 1.5 years prior to the present admission. MR imaging to evaluate the acoustic neurofibroma on the right showed a metallic artifact at the site of the previous surgery. Computed tomography did not show any evidence of metal debris. The artifact was probably caused by metallic dust or debris from a high-speed drill during the first surgery. We suggest that care should be taken to prevent deposition of such debris in the operative field to prevent this complication.

Magnetic Resonance Imaging Artifact Following Acoustic Neurofibroma Surgery : Case Report

¶ Background. The anterior approach for cervical discectomy with methacrylate-implant involves manipulations on vertebral bodies and ligaments. Foreign materials like methacrylate and fibrin sponge are inserted. On postoperative MRI it may be difficult to differentiate pathological from “normal” findings caused by routine manipulations.  Method. In this study 14 patients free of symptoms after anterior discectomy with methacrylate-implant were examined clinically and a MRI was performed on the 7th day after surgery and again after a 6 month follow-up. All patients had an uneventful recovery and no signs of inflammation after surgery.  Findings. Independent of the underlying pathology (e.g. soft or hard disc) 73% of the patients had a signal reduction within the vertebral bodies adjacent to the operated disc on T1-weighted spin-echo images on the 7th postoperative day. Signal intensities were normal after 6 months in all patients. Remarkable metal artifacts were present in one patient only. The methacrylate-implant could be identified as a hypo-intense structure on all sequences at any time without artifacts. In 80% of the cases a hyperintensity was found on T2-weighted images between the methacrylate-implant and the dura on the 7th postoperative day. A protrusion of the posterior ligament was present at the level of the operated disc on day 7 after surgery, which had resolved completely 6 months later. This may mimic residual disc tissue or osteophytes early after surgery.  Interpretation. It is very important to know this “normal” postoperative appearance of the cervical spine in order to avoid misinterpretations.

MRI-Findings After Uncomplicated Anterior Cervical Discectomy

We herein report on a case in which magnetic resonance angiography (MRA) following carotid endarterectomy revealed the appearance of angiostenosis due to an artifact of metallic powder, which was thought to have come from an old surgical instrument. The patient was a 77-year-old male. Carotid endarterectomy (CEA) was performed for stenosis in the internal carotid artery of his left neck (82%). Upon observing a decline in renal function following CEA surgery, a postoperative cervical MRA revealed the appearance of high-grade stenosis at the common carotid artery on which surgery was performed. No stenosis was revealed upon carotid ultrasonography and angiography. In the original MRA image, an orbicular low intensity area was observed in concordance with the narrow segment. 3D computed tomography (3D-CT) revealed a metallic finding, suggesting it was an artifact caused by metal powder. Close inspection of the metal surgical instruments used during surgery revealed slight damage to a suture snare which had been used for 30 years. Going forward, it is necessary to pay attention to old surgical instruments, introduce a system by which the number of years and the frequency of use of each surgical instrument can be learned, and replace them with new equipment as necessary.

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One Case of Suspected Angiostenosis Revealed by MRA Following Carotid Endarterectomy Due to a Rare Cause

Artifacts are occasionally encountered on magnetic resonance imaging after operation. These may be due to minute metallic particles from neurosurgical instruments. Particles not detectable on plain x-ray films or computerized tomography scans may cause local change of magnetic resonance activity, resulting in a deceptive magnetic resonance appearance. Three illustrative case reports are presented.

Jürgen Bunke

Papers

Postoperative magnetic resonance imaging artifacts: Report of three cases